Removal of Pb and Cu Metals by PVDF/Clay Membranes Obtained Through Solution Blow Spinning Technique

Removal of Pb and Cu Metals by PVDF/Clay Membranes Obtained Through Solution Blow Spinning Technique | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Removal of Pb and Cu Metals by PVDF/Clay Membranes Obtained Through Solution Blow Spinning Technique Gabriel Cruz Dias, Lincon Zaradosny, Alex Otávio Sanches, Mirian Cristina Santos, and 1 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-8273482/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 12 You are reading this latest preprint version Abstract Metal contamination in effluents is a serious environmental problem. When heavy metals such as lead, mercury and cadmium are released into industrial or urban wastewater, they can persist in the environment for long periods. These metals are toxic to aquatic life and can accumulate in the food chain, harming human health. In this work, nanocomposites with micro and nanoscale fiber matrix of poly (vinylidene fluoride)–PVDF with addition of montmorillonite clay, in concentrations were produced by the technical solution of blow spinning. Adsorption tests showed that the ideal conditions for the highest removal rate (87%) were using nanocomposites at a concentration of 30% for 24 h in water/ethanol (95/5 V/V). The pseudo-second order and Langmuir models were the most suitable for describing the kinetic and adsorption isothermal data, respectively. Membrane tests indicated that nanocomposites with 10% clay were the most suitable, achieving a removal rate of more than 90% of metals Solution Blow Spinning PVDF membrane Clay Metal Removal Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 Figure 10 Introduction Contamination by metals in effluents represents a serious environmental issue. The release of heavy metals such as lead, mercury, and cadmium in industrial or urban wastewater results in long-lasting damage to the environment. These toxic metals harm aquatic life, affect human health, and have adverse impacts on aquatic ecosystems. Prolonged exposure to these pollutants can lead to metal poisoning, neurological diseases, and cancer. Therefore, it is essential to properly manage and treat effectiveness to minimize this contamination and safeguard water quality, ecosystems, and human health. From this perspective, polymeric nanofibers emerge with significant potential for environmental remediation. Polymeric micro and nanofibers are materials in which the length is at least a hundred times greater than their diameter [1]. When this parameter is reduced to the micro or nano scale, these materials exhibit highly interesting properties, including high surface area, porosity, and excellent mechanical performance [2,3]. These characteristics make them ideal candidates for applications in filters [4–7], reinforcement components in membranes [8,9], sensors [10–12], matrices for catalyst immobilization [2,13] controlled drug and medication release, wound dressings for skin regeneration and more [4–18]. To address a certain lack of previous techniques, a new method for fiber production called solution blow spinning (SBS) [19,25]. This method employs the concepts of electrospinning, with the key difference being that in SBS, electrical forces are replaced by a moving fluid, using only pressurized gas. Its advantages include the absence of the need for an electric field, low cost, and high productivity rates—approximately at least 100 times faster than electrospinning. Among the polymers used in the production of fibrous mats, poly (vinylidene fluoride)—PVDF stands out for its pyro and piezoelectric activities and has received significant attention as a membrane material due to its good chemical and mechanical resistance properties, thermal stability, and high hydrophobicity [26]. Polymeric materials can also be employed in composite manufacturing. Composites can be defined as any material with at least two phases that exhibit properties of both constituent phases and even display new properties not found in either of the individual phases. When at least one of the phases is on the nanoscale, the composites are referred to as membranes [27]. Nanostructured polymeric membranes obtained through solution blow spinning are advanced materials with a highly porous structure and uniform nanoporous distribution. These membranes are manufactured through a blow spinning process, in which a polymer dissolved in a solvent is extruded through a needle-shaped nozzle and subjected to a stream of hot air. The application of these membranes is extensively studied in metal removal. Due to their nanostructured nature, polymeric membranes offer a large surface area and high selectivity for capturing heavy metals present in aqueous solutions. The nanometer-sized pores act as traps, selectively retaining metal ions and allowing purified liquid to pass through the membrane. These membranes hold promise for various applications, including industrial wastewater treatment, drinking water purification, and pollutant removal in recycling processes. Additionally, nanostructured polymeric membranes can be easily produced on a large scale and exhibit good mechanical and chemical stability. However, it is important to note that research and development in this area are ongoing to further enhance the properties and efficiency of these membranes, making them more viable for practical metal removal applications. Among the additives used in membrane manufacturing, we will focus on clays, which, among other characteristics, possess porosity and high ion exchange capacity, making them excellent candidates for producing adsorptive membranes [28,29]. In this study, membranes were produced with a polymeric matrix of poly(vinylidene fluoride) (PVDF) in the form of micro and nanofibers, with montmorillonite clay as the filler, using the solution blow spinning (SBS) technique. The objective is to study the morphological, thermal, mechanical, and wettability properties of the membranes. The study also aims to produce two types of membranes, both with a fibrous polymeric matrix (PVDF), the first incorporating montmorillonite clay to evaluate the efficiency of metal removal (Cu 2+ and Pb 2+ ) as well as adsorption mechanisms through kinetic models and adsorption isotherms. The study will also explore their application in metal removal through the membrane process. Materials and Methods The polymer used was poly (vinylidene fluoride)—PVDF, acquired from Atofina do Brasil–SOLEF 1008 in powder form. The solvent used was N, N-Dimethylformamide—DMF, manufactured by Synth produtos para laboratório Ltd.a. The montmorillonite clay K10 was purchased from Sigma Aldrich. It was stored in a desiccator with silica to minimize moisture absorption. In a beaker containing DMF, the desired amount of clay was added. The concentrations were calculated relative to the mass of PVDF (3%, 5%, 10%, 20%, and 30%, as shown in Table 1 ). These solutions were kept under constant stirring for 12 h to ensure the dispersion of the clay in DMF. The concentration of the PVDF solution was kept constant. After the solutions were ready, the PVDF solution was slowly added to the clay-containing solution, and the final solution was stirred for 5 min under magnetic stirring and then for an additional 5 min under mechanical stirring, both at room temperature. Micro and nanofibers of PVDF were obtained using the SBS method. The PVDF/DMF solution was prepared by dissolving PVDF in DMF at a temperature of 70ºC with constant stirring for 1 h and then allowed to cool to room temperature. The experimental parameters used were obtained from a previous study, and they are as follows: polymer concentration (c) 30% (w/v); flow rate 76 µL/min; pressure 140 kPa; working distance (D) 21 cm; collector speed ω = 80 rpm. For the membrane production, the quantity of solution was kept constant at 5 mL (Table 1 ) Table 1 Quantities of materials used for solution preparation. Concentration (m/m) Clay/DMF PVDF/DMF Clay(g) DMF (mL) PVDF (g) DMF (mL) 3% 0.045 1.0 1.5 4.5 5% 0.075 10% 0.150 20% 0.300 1.3 30% 0.450 1.5 The thickness of the membranes was determined by using a thickness gauge by comparing with the Tesa model TT10 mark. For all membranes, 10 measurements were taken at different points along the membranes. Microscopy measurements were conducted using a Zeiss instrument, model EVO LS15, operating at voltages ranging from 5.00 kV to 10.00 kV. The average fiber diameters were obtained using ImageJ software. Adsorption studies were conducted in water and water/ethanol solutions containing heavy metals. The determination of the Point of Zero Charge (PZC) was carried out through an 11-point experiment, where aqueous solutions with initial pH values of 1–12 were prepared (sodium hydroxide for basic pH and nitric acid for acidic pH). Then, membrane samples cut into approximately 1.5 cm square pieces were deposited in each solution at a mass concentration of 30% relative to PVDF and left for 24 h. After this process, the final pH values of the solutions were measured using a Gehaka pH meter, model PG 1800, and a graph of final pH versus initial pH was constructed. The PZC is the point where the experimental curve of final pH vs. initial pH intersects the line corresponding to final pH = initial pH. The results of the adsorption tests were analyzed by high-resolution flame atomic absorption spectrometry using a SpectrAA model 300 (AnalytikJena, Germany). In this experiment, the number of heavy metals (adsorbate) and the concentration of the membranes (adsorbent) were kept constant at 5 mg/L and 30% (w/w), respectively, while varying the contact time. All experiments were conducted at room temperature, under neutral pH, on a stirring table with a rotation speed of approximately 60 rpm. The solution volume used was 20 mL, and the membranes were cut into 1.5 cm square pieces with a weight of approximately 50 mg. To conduct a study with different amounts of adsorbent, the amount of heavy metals (5 mg/L), adsorption time (24 h), temperature (room temperature), and neutral pH were kept constant, while varying the clay content in the membranes (3, 5, 10, 20, and 30% relative to the PVDF mass). All membranes were cut into 1.5 cm square pieces, with a weight of around 50 mg, and 20 mL of solution was used, which was placed on a stirring table with a rotation speed of 60 rpm. The adsorption isotherm reflects the interaction between solutes and adsorbents. To obtain these isotherms, the adsorbent amount was kept constant while varying the adsorbate concentration Temperature, contact time, and pH were also unchanged. All tests were conducted on a stirring table with a rotation speed of 60 rpm, and the samples were cut into square pieces with a weight of approximately 50 mg. The metal concentrations in the solution were obtained from a standard solution with 1000 ppm of the studied metal, in the case of lead (Pb) and copper (Cu) and diluted to the desired concentrations. Table 2 summarizes the configurations of the adsorption tests. Table 2 Adsorption Test Variables. Test Variables Contact Time Concentration of solution (mg/L) Adsorbent concentration (%) in relation to mass Adsorption Balance 1, 2, 5, 9, 15, 24 and 48 5 30 Concentration studies 24 5 0, 3, 5, 10, 20 and 30 Adsorption Isotherms 24 1, 2, 2.5, 3.0, 3.5, 4.0, 4.5 and 5.0 30 The membrane tests were conducted by forcing the solution containing the heavy metal to pass through the membranes under the action of a pressure of approximately ± 1 bar, generated by a vacuum pump, using the experimental apparatus mentioned. The filtration area was 12.5 cm 2 , and the experiments were carried out at room temperature (25°C), with a solute concentration (lead or copper) in the solutions (water and water/ethanol (95/05)) of 5 mg/L. Results and Discussion For illustrative purposes, Fig. 2 presents a micrograph as an example, due to its similarity, of the 3% PVDF membrane, along with histograms showing the diameter distribution of micro- and nanofibers for all incorporations. Also noteworthy is the X-ray diffractometry of the membranes, emphasizing their incorporation into the obtained material. In general, the micrograph analysis shows uniform, smooth, cylindrical membranes with few agglomerations, indicating the success of its production and the suitability of the experimental parameters adopted. However, details of the material's morphology and its dependence or independence on the incorporation of the material are presented in another work by the respective authors. The presence of these two crystalline phases in PVDF is due to the membrane production process, characteristic of the technique, and the ease of formation of the β phase. It is known that rapid evaporation of the solvent at high rates leads to the α crystalline phase, and the β phase can be obtained through its stretching. In addition, other crystalline peaks at 2θ = 6.10°, 9.06° and 19.94° of the clay are observed, which were determined using the ICSD standards (46-1045) and (46-1212) as corresponding to quartz (SiO2) and aluminum oxide (Al 2 O 3 ), respectively. With the incorporation of the fillers, some imperfections are noticeable along the fibers, with a higher occurrence for the 30% concentration (highlighted in red in Fig. 2 f), which likely represents clay clusters due to their high quantity in the membranes. With the aim of quantifying the difficulty that the increased filler content caused to the process, the same amount of solution (5 mL) was used for all productions, and the thickness of the membranes was measured. The histograms were generated based on the measurement of the diameter of 200 fibers. This change in the experimental setup resulted in improvements, but it was not sufficient to completely resolve the issue. Most likely, this is because the added fillers to the solution were not dissolved. As a result, when they are introduced and ejected through the nozzle, they adhere to the fibers, acting as a kind of “weight” on the polymeric threads. We can seek confirmation for this phenomenon using everyday examples. For instance, take a piece of string and let it fall; it tends to fall slowly (remember that we are in the air, not in an idealized vacuum). Now, tie a small stone to the string and release it. In this configuration, the weight creates a slingshot effect, causing it to fall more rapidly. Similarly, we can assume that the fillers function like these small stones, and during the spinning process, they are thrown more rapidly toward the collector, leaving the fibers behind, which end up getting lost along the way. It is observed that up to 10%, there is a slight decrease in the thickness of the membranes compared to pure PVDF film. This change is subtle and does not represent a significant variation. However, when the addition of fillers is doubled (20%) and tripled (30%), the diameter of the membranes decreases considerably. The 30% concentration represents a limit, as further increases would lead to a significant reduction in membrane thickness, making them less suitable for desired applications. Despite the challenges encountered, the SBS technique is highly promising, being much faster and more efficient when compared to the primary technique currently used for the production of polymeric fibers, electrospinning. For comparison purposes in the present study, the membranes were produced from a 30% (w/v) solution, using 5 mL of solution (1.5 g of polymer), resulting in films around 500 µm (approximately 333 µm per gram of polymer). For the study of the adsorption of metals Pb 2+ and Cu 2+ by PVDF membranes with clay, the appropriate pH condition of the solution was initially determined through the determination of the Point of Zero Charge (PZC). Once this condition was determined, other factors were investigated, including the adsorbent concentration, contact time of the membranes with the solution, and the study of kinetic and isothermal adsorption models. All tests were conducted in separate solutions, one being aqueous and the other a mixture of water and ethanol at a concentration of 95/5. The results of these studies are presented in the following sections. The determination of the point of zero charge was carried out to investigate the surface charge of the membranes. The results obtained for PVDF membranes with 30% clay, both in water and in the water/ethanol mixture (95/5), are shown in Fig. 3. As observed, the point of intersection between the curves is at 6.9 and 6.4 for water and water/ethanol, respectively. These values indicate the point at which the material’s pH is neutral (the number of positive charges is equal to the number of negative charges). When the solid comes into contact with a solution with a pH below this point, it becomes positively charged, favoring the adsorption of anions. Conversely, when the solution’s pH is above the PZC, the solid becomes negatively charged, favoring the adsorption of cations. Although the PZC is a characteristic of the solid, there was a slight difference in the PZC between the media (water and water/ethanol). This may suggest that ethanol is penetrating more easily into the nanocomposite (keeping in mind that the matrix is hydrophobic), having greater contact with the dispersed clay inside, resulting in a lower PZC [26–28]. The adsorption tests presented in the following sections were conducted at pH levels close to the point of zero charge (PZC), thus minimizing, as much as possible, any influence of the liquid medium on the adsorption process. The concentration of adsorbents incorporated into the membranes has a significant influence on the adsorption process. Therefore, the removal behavior of metals was studied concerning different concentrations of adsorbents. The maximum limit of adsorbent used was 30% because quantities above this resulted in thin and fragile films, as reported in the characterizations. Thus, adsorption tests were conducted for membranes containing 3%, 5%, 10%, 20%, and 30% clay in a 20 mL aqueous solution of lead ions–Pb 2+ (II) and copper ions–Cu 2+ (II), with the adsorbent quantity (5 mg/L) and time (24 h) held constant. The data obtained for clay membranes are presented in Table 3 in terms of the final metal concentration (C f ) and the amount of adsorbed ions (N f ). The mass (mg) in Table refers to the mass the composite, which was used in the N f calculations [49–55]. The assessment of the influence of immersion time on the adsorption process of metals on clay-based membranes was conducted for samples containing 30%, (Fig. 4 ). Table 3 Results obtained for adsorption as a function of Pb and Cu concentration for clay incorporated membranes in an aqueous medium. Membranes Pb Cu Mass (mg) C f (mg/L) N f µmol/g) Mass (mg) C f (mg/L) N f (µmol/g) PVDF Pure 57.2 4.64 1.10 54.3 4.92 0.79 PVDF/Clay 3% 35.5 4.90 1.21 41.9 4.85 1.60 PVDF/Clay 5% 43.4 4.69 1.25 36.7 4.88 1.57 PVDF/Clay 10% 45.5 4.72 1.32 29.7 4.78 2.93 PVDF/Clay 20% 35.9 4.79 1.48 37.7 4.66 3.37 PVDF/Clay 30% 35.3 4.64 1.92 31.3 4.05 10.16 The choice of this composition for this study was based on the results regarding adsorption as a function of concentration, where this parameter proved to be more efficient (Table 4 ) [29–31]. It is interesting to observe that the adsorption of lead and copper exhibits similar behaviors in both media, with a rapid adsorption in the initial hours followed by a gradual deceleration (Tables 4 and 5 ). This is a typical pattern in adsorption processes, where initially there is a high availability of adsorption sites, resulting in the rapid adsorption of metal ions. As time progresses, these sites become occupied, making the adsorption slower until saturation is reached (Fig. 5 ). Table 4 Results obtained from adsorption tests as a function of time for clay-incorporated membranes in an aqueous medium. Contact Time Water Pb Cu Mass (mg) C f (mg/L) N f (µmol/g) Mass (mg) C f (mg/L) N f (µmol/g) 1h 33.1 4.94 0.34 25.5 4.44 6.86 2h 29.3 4.89 0.56 26.0 4.17 10.09 5h 32.4 4.72 1.01 21.7 4.28 10.48 9h 29.1 4.67 1.30 28.1 3.89 12.45 15h 34.0 4.50 1.59 22.4 3.94 14.83 24h 33.5 4.50 1.61 23.2 3.89 15.07 48h 32.6 4.56 1.49 23.3 3.94 14.26 Table 5 Results obtained from adsorption tests as a function of time for clay-incorporated membranes in an ethanolic medium. Contact Time Water/Ethanol Pb Cu Mass (mg) C f (mg/L) N f (µmol/g) Mass (mg) C f (mg/L) N f (µmol/g) 1h 27.9 4.11 3.08 23.9 4.39 8.10 2h 27.2 4.11 3.15 21.0 4.39 9.21 5h 31.2 3.78 3.78 20.3 4.10 13.96 9h 35.8 3.56 3.89 22.2 3.96 14.79 15h 26.5 3.67 4.86 27.4 3.72 14.72 24h 30.7 3.44 4.89 23.1 3.62 18.76 48h 31.5 3.39 4.94 25.5 3.53 18.17 This behavior suggests that the adsorption kinetics for both metals follow a similar pattern, regardless of the medium used [31–35]. It is also noticeable that the adsorption of metal ions is higher in the water/ethanol mixture, and this is likely related to the hydrophobicity of the membranes. As described in the contact angle analyses, ethanol acts as a surfactant in water, reducing its surface tension, increasing solid wettability, and consequently allowing the solution to penetrate the membranes, reaching a greater number of active sites and increasing ion adsorption. Furthermore, as described in some studies, adsorption in an ethanol medium is superior to an aqueous medium because water has a high electric dipole moment, causing metal ions to be attracted to the negative ends of water molecules, making their interaction with the adsorbent solid more difficult [36–43]. Comparing the results obtained with respect to the test media, the ethanol medium yielded better results for both lead and copper. Regarding the type of adsorbent, the membranes showed higher adsorption values, indicating greater efficiency in the removal of Pb and Cu ions, a fact that may be related to their greater wettability over time. For clarity, a comparison of the adsorbed values for the 24h time point is presented in Table 6 . Table 6 Comparison of metal removal between different media. Initial concentration (C 0 ) Metal Clay Water Water/Ethanol 5 mg/L Pb 4.50mg/L (10%) 3.44mg/L (31%) Cu 3.89mg/L (22%) 3.62mg/L (28%) For the adjustments of the kinetic models, experimental data on the determination of equilibrium time for PVDF/clay membranes (Fig. 6 and Fig. 7) in aqueous and water/ethanol (95/05) mixture media for the adsorption of metals Pb and Cu were used [40–43]. These data were applied to the pseudo-first-order and pseudo-second-order models, which will be presented in the following sections. The correlation coefficients (R 2 ) for both Pb and Cu in the aqueous medium are relatively low, 0.933 and 0.875, respectively. In the ethanolic medium, the obtained values are even lower, 0.772 for Pb and 0.674 for Cu. These results indicate that the adsorption of Pb and Cu on the clay-containing membranes does not occur via a first-order reaction. This is because a correlation factor closer to 1 is more suitable for describing the kinetics of the reaction between a particular material and a metal. As seen in Table 7 , the pseudo-second-order model provides values of N fmax for both Pb and Cu that are closer to the experimental N f in both aqueous and ethanolic media. Regarding the correlation coefficient, it is also closer to 1 in this model, indicating that the pseudo-second-order model best describes the adsorption kinetics. This suggests that adsorption primarily occurs in a monolayer. Table 7 Parameters obtained from the fitting of the pseudo-first-order and pseudo-second-order kinetic models in aqueous and ethanolic mdia for clay-incorporated membranes. Solution Parameters Pb Cu Models Water N f (µmol/g) Experimental 1.61 15.07 Water/Ethanol (95/05) N f (µmol/g) Experimental 4.89 18.76 Pseudo-first-order Water N f max (µmol/g) K 1 (h − 1 ) R 2 2.08 -0.119 0.933 11.39 -0.100 0.875 Water/Ethanol (95/05) N f max (µmol/g) K 1 (h − 1 ) R 2 3.57 -0.115 0.772 9.55 -0.030 0.641 Pseudo-second- order Water N f max (µmol/g) K 2 (g/µmol.h) h (µmol/g.h) R 2 2.12 81.27x10 − 3 0.38 0.998 15.90 36.37 x10 − 3 9.19 0.978 Water/Ethanol (95/05) N f max (µmol/g) K 2 (g/µmol.h) h (µmol/g.h) R 2 5.01 153.55 x10 − 3 3.85 0.971 15.96 61.20 x10 − 3 15.58 0.989 The initial adsorption rate (h) has relatively high values, indicating that surface adsorption on the solid is rapid. However, due to the hydrophobic nature of the matrix, there is greater difficulty for metallic ions to reach the active sites inside the nanocomposite, leading to a longer time for adsorption stabilization. It is also noticeable that h values are higher when only 5% ethanol is added to water, confirming that its presence facilitates the adsorption process, as observed in previous characterizations. The results for the clay-containing membranes obtained in the study of the variation in the initial concentration of metals Pb and Cu are presented graphs in Fig. 8 , facilitating the analysis of the data from Tables 8 and 9 , the were plotted between N f and N 0 . Table 8 Influence of the initial adsorbate concentration: clay-incorporated membranes in an aqueous medium. Initial Concentration C 0 (mg/L) Pb Cu Mass (mg) C f (mg/L) N f (µmol/g) Mass (mg) C f (mg/L) N f (µmol/g) 1.0 38.5 0.78 0.56 19.2 0,56 7.29 2.0 29.9 1.67 1.08 18.4 1.50 8.55 2.5 29.2 2.17 1.10 19.1 1.94 9.16 3.0 35.5 2.56 1.21 16.3 2.44 10.73 3.50 37.5 3.00 1.29 19.2 2.67 13.66 4.00 36.5 3.50 1.32 17.8 3.22 13.75 4.50 39.3 3.83 1.63 20.5 3.56 14.50 5.00 33.5 4.50 1.61 23.2 3.89 15.07 Table 9 Influence of the initial adsorbate concentration: membranes with clay in ethanol medium. Initial concentration C 0 (mg/L) Pb Cu Mass (mg) C f (mg/L) N f (µmol/g) Mass (mg) C f (mg/L) N f (µmol/g) 1.0 26.7 0.39 2.21 23.3 0.58 5.73 2.0 24.7 1.00 3.91 24.9 1.43 7.17 2.5 26.4 1.44 3.86 23.9 1.72 10.29 3.0 25.6 1.83 4.40 26.5 2.05 11.26 3.50 23.0 2.50 4.20 21.4 2.72 11.49 4.00 23.1 2.72 4.91 24.6 3.00 12.74 4.50 29.8 2.89 5.20 24.7 3.39 14.21 5.00 30.7 3.44 4.90 23.1 3.62 18.75 Note that for the standardization of the conventions adopted in this study, the unit of initial concentration was converted from mg/L to µmol/L. From the graphs, it is observed that as the initial concentration increases, the amount of adsorbed ions also increases, regardless of the medium (water or a water/ethanol mixture 95/05) or the metal (Pb or Cu). This indicates that higher concentrations of the metal could be adopted, as there was no saturation of active sites in the medium. However, when analyzing the final metal concentrations in Tables, it can be seen that for all configurations, more than 50% of the adsorbate remains present. This is likely because the interaction of the metal with the solution is greater than with the solid, so increasing the copper concentration might result in a higher amount of ions adsorbed, but the final concentration would still be high [44–46]. The application of the Langmuir and Freundlich models provides a better characterization of the adsorbent. The curves for each model are presented in Figs. 9 and 10 . For the Langmuir model, the heterogeneity factor (n) and the amount of ions adsorbed in the multilayer (K f ) of the Freundlich model were determined. All the data are presented in Table 10 . It is evident that the Langmuir model is the one that best fits the experimental data, regardless of the metal and medium used, as the R 2 values were closer to 1 compared to the Freundlich model. Therefore, it can be assumed that adsorption occurs in a monolayer, corroborating the pseudo-second-order kinetic model. This characteristic arises because intermolecular forces decrease with distance, making it difficult to form multilayers [47–54]. Table 10 Summary of adsorption isotherm parameters for clay membranes. Models Solution Parameters Pb Cu Langmuir Water N fmáx (µmol/g) b L/µmol) R L R 2 2.54 0.075 0.36 0.953 18.92 0.044 0.23 0.914 Water/Ethanol (95/05) N fmáx (µmol/g) b (L/µmol) R L R 2 6.02 0.298 0.12 0.934 19.40 0.047 0.13 0.951 Freundlich Water n (mol/L) K f (µmol/g) R 2 1.706 15.84 0.942 2.490 43.67 0.816 Water/Ethanol (95/05) n (mol/L) K f (µmol/g) R 2 2.723 24.06 0.863 1.94 61.30 0.894 The N fmax calculated by Langmuir was close to theoretical value, confirming the better fit of this model to the experimental results. Through the Langmuir adsorption equilibrium constant, it was possible to calculate the dimensionless separation factor (RL), which indicates whether the adsorption of metals in different media is favorable or not. Since the results of all tests were less than 1, it can be concluded that the adsorption is of the favorable type [58–60]. The Langmuir equilibrium constant is also related to the adsorption energy. Therefore, the higher its value, the more chemically the adsorption occurs [50–54]. Thus, the low values presented in the results (ranging from 0.044 to 0.298) may suggest that the adsorption process is of a physical nature. The separation percentage (PS), where C 0 and C f are the concentrations of the initial and final metals. The membranes produced in the present work, being composed of a matrix with micro and nanopolymeric fibers, exhibit high porosity, allowing the passage of fluids (liquid or gas), which enables their application as membranes (Fig. 11 ). Thus, membrane tests were carried out with the assistance of a vacuum pump under the same conditions as the adsorption tests, using water and a water/ethanol mixture (95/5), both containing 5 mg/L of lead and copper, at room temperature (25°C). The membranes used were pure PVDF, as well as membranes with clay, at concentrations of 10 and 30%. The results in terms of final metal concentrations for the fibrous membranes with clay are presented in Table 11 , promising results for the application of membranes [54–66] with clay as membrane material, achieving a 92% removal of copper in an aqueous medium for the film with 10% clay. Table 11 Membrane Testing: Clay Membranes. Membrane Water Ethanol Pb (mg/L) Cu(mg/L) Pb(mg/L) Cu(mg/L) PVDF Pure 0.60 1.05 0.74 1.09 10% Clay 0.51 0.41 0.67 0.98 30% Clay 1.00 1.22 1.13 1.05 It is noteworthy that even pure PVDF exhibited low concentrations of metals, demonstrating the effectiveness of the fibrous structure in impurity removal. The addition of 10% by mass of clay created active sites throughout the membrane, aiding in the elimination of metals. However, increasing the concentration of the load to 30% resulted in a deterioration of the process, which may have been caused by two factors [54–58]. The first factor is the presence of aggregates, as demonstrated by EDX measurements, which can act as facilitation points for water passage. The second factor is related to mechanical properties, which are significantly worsened with the high concentration of the loads. Thus, when pressure is applied to allow water to pass through the hydrophobic membrane, the pores widen, and the solution passes without major difficulties, carrying the metals along with it [56–60]. Regarding the medium, it is evident that there was no improvement as observed in the adsorption process. The incorporation of 5% ethanol was used to facilitate water penetration into the membranes, but in membrane testing where pressure is applied for solution passage, ethanol does not contribute to this process [60–66]. Additionally, there is an inverse relationship between selectivity and permeability, meaning high selectivity is related to low permeability. As observed in the contact angle measurements, ethanol facilitates solution penetration into the surface, reducing the selectivity of the membranes. This also explains the good results presented by pure PVDF, which, being thicker and showing less variation in contact angle over time (lower permeability), exhibits high selectivity, achieving an 88% removal of lead. Conclusions In the present work, membranes formed by a fibrous polymeric matrix were successfully produced through the solution blow spinning technique with the incorporation of clay. Scanning Electron Microscopy (SEM) confirmed that the membranes consist of fibers with average diameters smaller than 200 nm, which have a strong correlation with the solution viscosity. Metal adsorption tests of the membranes indicated that membranes with 30% loading presented the best results and showed that the adsorbent amount increased, suggesting that higher values could be adopted, emphasizing the stabilization of adsorption after 24 h, which was adopted as the ideal time for subsequent tests. The incorporation of 5% ethanol into the aqueous medium improved lead and copper removal. The pseudo-second-order kinetic model best fit the experimental data, and the Langmuir isotherm model best represented adsorption for both metals, indicating a favorable adsorption isotherm. Membrane tests demonstrated that membranes with a 10% loading showed the best results, with removal rates exceeding 90%. Membranes with 30% loading exhibited low performance due to their poor mechanical properties. Comparing the two metal removal techniques studied, the membranes showed significant and promising results in both. For adsorption (batch) processes, membranes with a higher loading are more suitable, while for membrane processes, good mechanical performance is required, with membranes containing 10% loading being the most appropriate. Declarations Conflict of interest The author declares no conflict of interest, financial or otherwise Author Contribution G.C.D.: Responsible for data curation, writing the original draft, and reviewing and editing; L.Z.: Collated image data and reviewed and edited the manuscripts; A.O.S.: Collated image data and reviewed and edited the manuscripts; M.C.S.: Handled Data Curation and methodology; L.F.M: Involved in conceptualization, data curation, funding acquisition, methodology, and review and editing. 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1","display":"","copyAsset":false,"role":"figure","size":644273,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eFigure 2\u003c/strong\u003e. Scanning Electron Microscopy images of PVDF membrane with clay\u003c/p\u003e","description":"","filename":"Picture1.jpg","url":"https://assets-eu.researchsquare.com/files/rs-8273482/v1/4283aa77503ef73b3a0317ac.jpg"},{"id":98640455,"identity":"f596a039-c0c5-4e37-973d-c41de5c37277","added_by":"auto","created_at":"2025-12-19 18:23:07","extension":"jpg","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":144742,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eFigure 3.\u003c/strong\u003e Determination of the Point of Zero Charge (PZC) for the clay nanocomposite: (a) water; (b) water/ethanol.\u003c/p\u003e","description":"","filename":"Picture2.jpg","url":"https://assets-eu.researchsquare.com/files/rs-8273482/v1/a366864cb8b67ee2c4e692ea.jpg"},{"id":98775957,"identity":"ee42e146-8b5d-4f65-be4f-fe3cca247f2a","added_by":"auto","created_at":"2025-12-22 12:21:41","extension":"jpg","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":81851,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eFigure 4\u003c/strong\u003e. Amount of adsorbed ions (N\u003csub\u003ef\u003c/sub\u003e) as a function of adsorbent concentration for all clay-incorporated membranes, for Lead (a) and Copper (b).\u003c/p\u003e","description":"","filename":"Picture3.jpg","url":"https://assets-eu.researchsquare.com/files/rs-8273482/v1/0ca6dae963cc6b48fe7ae2c5.jpg"},{"id":98640458,"identity":"ab281e28-8b59-465d-af17-734e5d534238","added_by":"auto","created_at":"2025-12-19 18:23:07","extension":"jpg","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":94347,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eFigure 5.\u003c/strong\u003e The number of adsorbed ions as a function of immersion time for clay-incorporated membranes.\u003c/p\u003e","description":"","filename":"Picture4.jpg","url":"https://assets-eu.researchsquare.com/files/rs-8273482/v1/efe84de6763a8d34bbca62b7.jpg"},{"id":98775257,"identity":"a961885a-c1ee-4b47-a3d5-b3ffaf391832","added_by":"auto","created_at":"2025-12-22 12:19:01","extension":"jpg","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":29574,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eFigure 6\u003c/strong\u003e. Fitting to the pseudo-first-order kinetic model clay-incorporated membranes.\u003c/p\u003e","description":"","filename":"Picture5.jpg","url":"https://assets-eu.researchsquare.com/files/rs-8273482/v1/7795046841339da8973fcc15.jpg"},{"id":98640472,"identity":"967d175b-6177-4c9e-b2a5-533e2ca655c4","added_by":"auto","created_at":"2025-12-19 18:23:07","extension":"jpg","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":182647,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eFigure 7.\u003c/strong\u003e Fitting to the pseudo-second-order kinetic model for clay-incorporated membranes.\u003c/p\u003e","description":"","filename":"Picture6.jpg","url":"https://assets-eu.researchsquare.com/files/rs-8273482/v1/5a0a5e2ccf93ed1332c47577.jpg"},{"id":98640462,"identity":"bde749b4-3003-49db-bbce-1896a1eb0233","added_by":"auto","created_at":"2025-12-19 18:23:07","extension":"jpg","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":95171,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eFigure 8.\u003c/strong\u003e Influence of the initial adsorbate concentration: clay-incorporated membranes.\u003c/p\u003e","description":"","filename":"Picture7.jpg","url":"https://assets-eu.researchsquare.com/files/rs-8273482/v1/6dca2b5ba8b4523c5e494660.jpg"},{"id":98640470,"identity":"da1271ca-1b76-4cf7-8018-5f6fa6ff02aa","added_by":"auto","created_at":"2025-12-19 18:23:07","extension":"jpg","order_by":8,"title":"Figure 8","display":"","copyAsset":false,"role":"figure","size":162518,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eFigure 9.\u003c/strong\u003eFit to the Langmuir isotherm model: membranes with clay\u003c/p\u003e","description":"","filename":"Picture8.jpg","url":"https://assets-eu.researchsquare.com/files/rs-8273482/v1/64dc381b0df2e1dc3300be7d.jpg"},{"id":98775042,"identity":"c794e53a-748b-4410-986f-ff5be1a95830","added_by":"auto","created_at":"2025-12-22 12:18:03","extension":"jpg","order_by":9,"title":"Figure 9","display":"","copyAsset":false,"role":"figure","size":164176,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eFigure 10.\u003c/strong\u003e \u0026nbsp;Fit to the Freundlich isotherm model: PVDF/Clay\u003cem\u003e.\u003c/em\u003e\u003c/p\u003e","description":"","filename":"Picture9.jpg","url":"https://assets-eu.researchsquare.com/files/rs-8273482/v1/b85d55c282d4573c61fbd7dc.jpg"},{"id":98775584,"identity":"177a2a25-dda2-4534-9c23-3e1a98bf70e5","added_by":"auto","created_at":"2025-12-22 12:20:24","extension":"jpg","order_by":10,"title":"Figure 10","display":"","copyAsset":false,"role":"figure","size":59299,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eFigure 11.\u003c/strong\u003e Digital Photograph of the Experimental Apparatus for Membrane Testing.\u003c/p\u003e","description":"","filename":"Picture10.jpg","url":"https://assets-eu.researchsquare.com/files/rs-8273482/v1/e6cdf2e7c7da9af84ad3d17b.jpg"},{"id":98797902,"identity":"18f5d150-27de-4ca6-b685-b15170b7337b","added_by":"auto","created_at":"2025-12-22 14:01:39","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":2769030,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-8273482/v1/5207e326-b4ef-4cad-b8b0-bea4a6fa9d89.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Removal of Pb and Cu Metals by PVDF/Clay Membranes Obtained Through Solution Blow Spinning Technique","fulltext":[{"header":"Introduction","content":"\u003cp\u003e \u003cdiv class=\"BlockQuote\"\u003e \u003cp\u003eContamination by metals in effluents represents a serious environmental issue. The release of heavy metals such as lead, mercury, and cadmium in industrial or urban wastewater results in long-lasting damage to the environment. These toxic metals harm aquatic life, affect human health, and have adverse impacts on aquatic ecosystems. Prolonged exposure to these pollutants can lead to metal poisoning, neurological diseases, and cancer. Therefore, it is essential to properly manage and treat effectiveness to minimize this contamination and safeguard water quality, ecosystems, and human health. From this perspective, polymeric nanofibers emerge with significant potential for environmental remediation.\u003c/p\u003e \u003cp\u003ePolymeric micro and nanofibers are materials in which the length is at least a hundred times greater than their diameter [1]. When this parameter is reduced to the micro or nano scale, these materials exhibit highly interesting properties, including high surface area, porosity, and excellent mechanical performance [2,3]. These characteristics make them ideal candidates for applications in filters [4\u0026ndash;7], reinforcement components in membranes [8,9], sensors [10\u0026ndash;12], matrices for catalyst immobilization [2,13] controlled drug and medication release, wound dressings for skin regeneration and more [4\u0026ndash;18].\u003c/p\u003e \u003cp\u003eTo address a certain lack of previous techniques, a new method for fiber production called solution blow spinning (SBS) [19,25]. This method employs the concepts of electrospinning, with the key difference being that in SBS, electrical forces are replaced by a moving fluid, using only pressurized gas. Its advantages include the absence of the need for an electric field, low cost, and high productivity rates\u0026mdash;approximately at least 100 times faster than electrospinning.\u003c/p\u003e \u003cp\u003eAmong the polymers used in the production of fibrous mats, poly (vinylidene fluoride)\u0026mdash;PVDF stands out for its pyro and piezoelectric activities and has received significant attention as a membrane material due to its good chemical and mechanical resistance properties, thermal stability, and high hydrophobicity [26].\u003c/p\u003e \u003cp\u003ePolymeric materials can also be employed in composite manufacturing. Composites can be defined as any material with at least two phases that exhibit properties of both constituent phases and even display new properties not found in either of the individual phases. When at least one of the phases is on the nanoscale, the composites are referred to as membranes [27].\u003c/p\u003e \u003cp\u003eNanostructured polymeric membranes obtained through solution blow spinning are advanced materials with a highly porous structure and uniform nanoporous distribution. These membranes are manufactured through a blow spinning process, in which a polymer dissolved in a solvent is extruded through a needle-shaped nozzle and subjected to a stream of hot air.\u003c/p\u003e \u003cp\u003eThe application of these membranes is extensively studied in metal removal. Due to their nanostructured nature, polymeric membranes offer a large surface area and high selectivity for capturing heavy metals present in aqueous solutions. The nanometer-sized pores act as traps, selectively retaining metal ions and allowing purified liquid to pass through the membrane.\u003c/p\u003e \u003cp\u003eThese membranes hold promise for various applications, including industrial wastewater treatment, drinking water purification, and pollutant removal in recycling processes. Additionally, nanostructured polymeric membranes can be easily produced on a large scale and exhibit good mechanical and chemical stability.\u003c/p\u003e \u003cp\u003eHowever, it is important to note that research and development in this area are ongoing to further enhance the properties and efficiency of these membranes, making them more viable for practical metal removal applications. Among the additives used in membrane manufacturing, we will focus on clays, which, among other characteristics, possess porosity and high ion exchange capacity, making them excellent candidates for producing adsorptive membranes [28,29].\u003c/p\u003e \u003cp\u003eIn this study, membranes were produced with a polymeric matrix of poly(vinylidene fluoride) (PVDF) in the form of micro and nanofibers, with montmorillonite clay as the filler, using the solution blow spinning (SBS) technique. The objective is to study the morphological, thermal, mechanical, and wettability properties of the membranes.\u003c/p\u003e \u003cp\u003eThe study also aims to produce two types of membranes, both with a fibrous polymeric matrix (PVDF), the first incorporating montmorillonite clay to evaluate the efficiency of metal removal (Cu\u003csup\u003e2+\u003c/sup\u003e and Pb\u003csup\u003e2+\u003c/sup\u003e) as well as adsorption mechanisms through kinetic models and adsorption isotherms. The study will also explore their application in metal removal through the membrane process.\u003c/p\u003e \u003c/div\u003e \u003c/p\u003e"},{"header":"Materials and Methods","content":"\u003cp\u003e \u003cdiv class=\"BlockQuote\"\u003e \u003cp\u003eThe polymer used was poly (vinylidene fluoride)\u0026mdash;PVDF, acquired from Atofina do Brasil\u0026ndash;SOLEF 1008 in powder form. The solvent used was N, N-Dimethylformamide\u0026mdash;DMF, manufactured by Synth produtos para laborat\u0026oacute;rio Ltd.a. The montmorillonite clay K10 was purchased from Sigma Aldrich. It was stored in a desiccator with silica to minimize moisture absorption.\u003c/p\u003e \u003cp\u003eIn a beaker containing DMF, the desired amount of clay was added. The concentrations were calculated relative to the mass of PVDF (3%, 5%, 10%, 20%, and 30%, as shown in Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). These solutions were kept under constant stirring for 12 h to ensure the dispersion of the clay in DMF. The concentration of the PVDF solution was kept constant. After the solutions were ready, the PVDF solution was slowly added to the clay-containing solution, and the final solution was stirred for 5 min under magnetic stirring and then for an additional 5 min under mechanical stirring, both at room temperature.\u003c/p\u003e \u003cp\u003eMicro and nanofibers of PVDF were obtained using the SBS method. The PVDF/DMF solution was prepared by dissolving PVDF in DMF at a temperature of 70\u0026ordm;C with constant stirring for 1 h and then allowed to cool to room temperature. The experimental parameters used were obtained from a previous study, and they are as follows: polymer concentration (c) 30% (w/v); flow rate 76 \u0026micro;L/min; pressure 140 kPa; working distance (D) 21 cm; collector speed ω\u0026thinsp;=\u0026thinsp;80 rpm. For the membrane production, the quantity of solution was kept constant at 5 mL (Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e)\u003c/p\u003e \u003c/div\u003e \u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eQuantities of materials used for solution preparation.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"5\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eConcentration (m/m)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c3\" namest=\"c2\"\u003e \u003cp\u003eClay/DMF\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c5\" namest=\"c4\"\u003e \u003cp\u003ePVDF/DMF\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cb\u003eClay(g)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u003cb\u003eDMF\u003c/b\u003e\u003c/p\u003e \u003cp\u003e\u003cb\u003e(mL)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003cb\u003ePVDF\u003c/b\u003e\u003c/p\u003e \u003cp\u003e\u003cb\u003e(g)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u003cb\u003eDMF\u003c/b\u003e\u003c/p\u003e \u003cp\u003e\u003cb\u003e(mL)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e3%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.045\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\" morerows=\"2\" rowspan=\"3\"\u003e \u003cp\u003e1.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\" morerows=\"4\" rowspan=\"5\"\u003e \u003cp\u003e1.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\" morerows=\"4\" rowspan=\"5\"\u003e \u003cp\u003e4.5\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e5%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.075\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e10%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.150\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e20%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.300\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1.3\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e30%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.450\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1.5\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003e \u003cdiv class=\"BlockQuote\"\u003e \u003cp\u003eThe thickness of the membranes was determined by using a thickness gauge by comparing with the Tesa model TT10 mark. For all membranes, 10 measurements were taken at different points along the membranes. Microscopy measurements were conducted using a Zeiss instrument, model EVO LS15, operating at voltages ranging from 5.00 kV to 10.00 kV. The average fiber diameters were obtained using ImageJ software.\u003c/p\u003e \u003cp\u003eAdsorption studies were conducted in water and water/ethanol solutions containing heavy metals. The determination of the Point of Zero Charge (PZC) was carried out through an 11-point experiment, where aqueous solutions with initial pH values of 1\u0026ndash;12 were prepared (sodium hydroxide for basic pH and nitric acid for acidic pH). Then, membrane samples cut into approximately 1.5 cm square pieces were deposited in each solution at a mass concentration of 30% relative to PVDF and left for 24 h. After this process, the final pH values of the solutions were measured using a Gehaka pH meter, model PG 1800, and a graph of final pH versus initial pH was constructed. The PZC is the point where the experimental curve of final pH vs. initial pH intersects the line corresponding to final pH\u0026thinsp;=\u0026thinsp;initial pH.\u003c/p\u003e \u003cp\u003eThe results of the adsorption tests were analyzed by high-resolution flame atomic absorption spectrometry using a SpectrAA model 300 (AnalytikJena, Germany). In this experiment, the number of heavy metals (adsorbate) and the concentration of the membranes (adsorbent) were kept constant at 5 mg/L and 30% (w/w), respectively, while varying the contact time. All experiments were conducted at room temperature, under neutral pH, on a stirring table with a rotation speed of approximately 60 rpm. The solution volume used was 20 mL, and the membranes were cut into 1.5 cm square pieces with a weight of approximately 50 mg.\u003c/p\u003e \u003cp\u003eTo conduct a study with different amounts of adsorbent, the amount of heavy metals (5 mg/L), adsorption time (24 h), temperature (room temperature), and neutral pH were kept constant, while varying the clay content in the membranes (3, 5, 10, 20, and 30% relative to the PVDF mass). All membranes were cut into 1.5 cm square pieces, with a weight of around 50 mg, and 20 mL of solution was used, which was placed on a stirring table with a rotation speed of 60 rpm.\u003c/p\u003e \u003cp\u003eThe adsorption isotherm reflects the interaction between solutes and adsorbents. To obtain these isotherms, the adsorbent amount was kept constant while varying the adsorbate concentration Temperature, contact time, and pH were also unchanged. All tests were conducted on a stirring table with a rotation speed of 60 rpm, and the samples were cut into square pieces with a weight of approximately 50 mg.\u003c/p\u003e \u003cp\u003eThe metal concentrations in the solution were obtained from a standard solution with 1000 ppm of the studied metal, in the case of lead (Pb) and copper (Cu) and diluted to the desired concentrations. Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e summarizes the configurations of the adsorption tests.\u003c/p\u003e \u003c/div\u003e \u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eAdsorption Test Variables.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"4\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTest Variables\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eContact Time\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eConcentration of solution (mg/L)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eAdsorbent concentration (%) in relation to mass\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAdsorption Balance\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1, 2, 5, 9, 15, 24 and 48\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e30\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eConcentration studies\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e24\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0, 3, 5, 10, 20 and 30\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAdsorption Isotherms\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e24\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1, 2, 2.5, 3.0, 3.5, 4.0, 4.5 and 5.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e30\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003e \u003cdiv class=\"BlockQuote\"\u003e \u003cp\u003eThe membrane tests were conducted by forcing the solution containing the heavy metal to pass through the membranes under the action of a pressure of approximately\u0026thinsp;\u0026plusmn;\u0026thinsp;1 bar, generated by a vacuum pump, using the experimental apparatus mentioned. The filtration area was 12.5 cm\u003csup\u003e2\u003c/sup\u003e, and the experiments were carried out at room temperature (25\u0026deg;C), with a solute concentration (lead or copper) in the solutions (water and water/ethanol (95/05)) of 5 mg/L.\u003c/p\u003e \u003c/div\u003e \u003c/p\u003e"},{"header":"Results and Discussion","content":"\u003cp\u003eFor illustrative purposes, Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e2\u003c/span\u003e presents a micrograph as an example, due to its similarity, of the 3% PVDF membrane, along with histograms showing the diameter distribution of micro- and nanofibers for all incorporations. Also noteworthy is the X-ray diffractometry of the membranes, emphasizing their incorporation into the obtained material.\u003c/p\u003e \u003cp\u003eIn general, the micrograph analysis shows uniform, smooth, cylindrical membranes with few agglomerations, indicating the success of its production and the suitability of the experimental parameters adopted. However, details of the material's morphology and its dependence or independence on the incorporation of the material are presented in another work by the respective authors.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003cdiv class=\"BlockQuote\"\u003e \u003cp\u003eThe presence of these two crystalline phases in PVDF is due to the membrane production process, characteristic of the technique, and the ease of formation of the β phase. It is known that rapid evaporation of the solvent at high rates leads to the α crystalline phase, and the β phase can be obtained through its stretching.\u003c/p\u003e \u003cp\u003eIn addition, other crystalline peaks at 2θ\u0026thinsp;=\u0026thinsp;6.10\u0026deg;, 9.06\u0026deg; and 19.94\u0026deg; of the clay are observed, which were determined using the ICSD standards (46-1045) and (46-1212) as corresponding to quartz (SiO2) and aluminum oxide (Al\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e), respectively.\u003c/p\u003e \u003cp\u003eWith the incorporation of the fillers, some imperfections are noticeable along the fibers, with a higher occurrence for the 30% concentration (highlighted in red in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e2\u003c/span\u003ef), which likely represents clay clusters due to their high quantity in the membranes. With the aim of quantifying the difficulty that the increased filler content caused to the process, the same amount of solution (5 mL) was used for all productions, and the thickness of the membranes was measured. The histograms were generated based on the measurement of the diameter of 200 fibers.\u003c/p\u003e \u003cp\u003eThis change in the experimental setup resulted in improvements, but it was not sufficient to completely resolve the issue. Most likely, this is because the added fillers to the solution were not dissolved. As a result, when they are introduced and ejected through the nozzle, they adhere to the fibers, acting as a kind of \u0026ldquo;weight\u0026rdquo; on the polymeric threads. We can seek confirmation for this phenomenon using everyday examples.\u003c/p\u003e \u003cp\u003eFor instance, take a piece of string and let it fall; it tends to fall slowly (remember that we are in the air, not in an idealized vacuum). Now, tie a small stone to the string and release it. In this configuration, the weight creates a slingshot effect, causing it to fall more rapidly. Similarly, we can assume that the fillers function like these small stones, and during the spinning process, they are thrown more rapidly toward the collector, leaving the fibers behind, which end up getting lost along the way.\u003c/p\u003e \u003cp\u003eIt is observed that up to 10%, there is a slight decrease in the thickness of the membranes compared to pure PVDF film. This change is subtle and does not represent a significant variation. However, when the addition of fillers is doubled (20%) and tripled (30%), the diameter of the membranes decreases considerably. The 30% concentration represents a limit, as further increases would lead to a significant reduction in membrane thickness, making them less suitable for desired applications.\u003c/p\u003e \u003cp\u003eDespite the challenges encountered, the SBS technique is highly promising, being much faster and more efficient when compared to the primary technique currently used for the production of polymeric fibers, electrospinning. For comparison purposes in the present study, the membranes were produced from a 30% (w/v) solution, using 5 mL of solution (1.5 g of polymer), resulting in films around 500 \u0026micro;m (approximately 333 \u0026micro;m per gram of polymer).\u003c/p\u003e \u003cp\u003eFor the study of the adsorption of metals Pb\u003csup\u003e2+\u003c/sup\u003e and Cu\u003csup\u003e2+\u003c/sup\u003e by PVDF membranes with clay, the appropriate pH condition of the solution was initially determined through the determination of the Point of Zero Charge (PZC). Once this condition was determined, other factors were investigated, including the adsorbent concentration, contact time of the membranes with the solution, and the study of kinetic and isothermal adsorption models.\u003c/p\u003e \u003cp\u003eAll tests were conducted in separate solutions, one being aqueous and the other a mixture of water and ethanol at a concentration of 95/5. The results of these studies are presented in the following sections. The determination of the point of zero charge was carried out to investigate the surface charge of the membranes. The results obtained for PVDF membranes with 30% clay, both in water and in the water/ethanol mixture (95/5), are shown in Fig.\u0026nbsp;3.\u003c/p\u003e \u003c/div\u003e \u003c/p\u003e \u003cp\u003e \u003cdiv class=\"BlockQuote\"\u003e \u003cp\u003eAs observed, the point of intersection between the curves is at 6.9 and 6.4 for water and water/ethanol, respectively. These values indicate the point at which the material\u0026rsquo;s pH is neutral (the number of positive charges is equal to the number of negative charges). When the solid comes into contact with a solution with a pH below this point, it becomes positively charged, favoring the adsorption of anions. Conversely, when the solution\u0026rsquo;s pH is above the PZC, the solid becomes negatively charged, favoring the adsorption of cations.\u003c/p\u003e \u003cp\u003eAlthough the PZC is a characteristic of the solid, there was a slight difference in the PZC between the media (water and water/ethanol). This may suggest that ethanol is penetrating more easily into the nanocomposite (keeping in mind that the matrix is hydrophobic), having greater contact with the dispersed clay inside, resulting in a lower PZC [26\u0026ndash;28]. The adsorption tests presented in the following sections were conducted at pH levels close to the point of zero charge (PZC), thus minimizing, as much as possible, any influence of the liquid medium on the adsorption process.\u003c/p\u003e \u003cp\u003eThe concentration of adsorbents incorporated into the membranes has a significant influence on the adsorption process. Therefore, the removal behavior of metals was studied concerning different concentrations of adsorbents. The maximum limit of adsorbent used was 30% because quantities above this resulted in thin and fragile films, as reported in the characterizations.\u003c/p\u003e \u003cp\u003eThus, adsorption tests were conducted for membranes containing 3%, 5%, 10%, 20%, and 30% clay in a 20 mL aqueous solution of lead ions\u0026ndash;Pb\u003csup\u003e2+\u003c/sup\u003e (II) and copper ions\u0026ndash;Cu\u003csup\u003e2+\u003c/sup\u003e (II), with the adsorbent quantity (5 mg/L) and time (24 h) held constant. The data obtained for clay membranes are presented in Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e in terms of the final metal concentration (C\u003csub\u003ef\u003c/sub\u003e) and the amount of adsorbed ions (N\u003csub\u003ef\u003c/sub\u003e). The mass (mg) in Table refers to the mass the composite, which was used in the N\u003csub\u003ef\u003c/sub\u003e calculations [49\u0026ndash;55]. The assessment of the influence of immersion time on the adsorption process of metals on clay-based membranes was conducted for samples containing 30%, (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e4\u003c/span\u003e).\u003c/p\u003e \u003c/div\u003e \u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab3\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 3\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eResults obtained for adsorption as a function of Pb and Cu concentration for clay incorporated membranes in an aqueous medium.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"7\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eMembranes\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colspan=\"3\" nameend=\"c4\" namest=\"c2\"\u003e \u003cp\u003ePb\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colspan=\"3\" nameend=\"c7\" namest=\"c5\"\u003e \u003cp\u003eCu\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cb\u003eMass\u003c/b\u003e\u003c/p\u003e \u003cp\u003e\u003cb\u003e(mg)\u003c/b\u003e\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u003cb\u003eC\u003c/b\u003e\u003csub\u003e\u003cb\u003ef\u003c/b\u003e\u003c/sub\u003e\u003c/p\u003e \u003cp\u003e\u003cb\u003e(mg/L)\u003c/b\u003e\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003cb\u003eN\u003c/b\u003e\u003csub\u003e\u003cb\u003ef\u003c/b\u003e\u003c/sub\u003e\u003c/p\u003e \u003cp\u003e\u003cb\u003e\u0026micro;mol/g)\u003c/b\u003e\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u003cb\u003eMass\u003c/b\u003e\u003c/p\u003e \u003cp\u003e\u003cb\u003e(mg)\u003c/b\u003e\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003e\u003cb\u003eC\u003c/b\u003e\u003csub\u003e\u003cb\u003ef\u003c/b\u003e\u003c/sub\u003e\u003c/p\u003e \u003cp\u003e\u003cb\u003e(mg/L)\u003c/b\u003e\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c7\"\u003e \u003cp\u003e\u003cb\u003eN\u003c/b\u003e\u003csub\u003e\u003cb\u003ef\u003c/b\u003e\u003c/sub\u003e\u003c/p\u003e \u003cp\u003e\u003cb\u003e(\u0026micro;mol/g)\u003c/b\u003e\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePVDF Pure\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e57.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e4.64\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e1.10\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e54.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e4.92\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e0.79\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePVDF/Clay 3%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e35.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e4.90\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e1.21\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e41.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e4.85\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e1.60\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePVDF/Clay 5%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e43.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e4.69\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e1.25\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e36.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e4.88\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e1.57\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePVDF/Clay 10%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e45.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e4.72\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e1.32\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e29.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e4.78\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e2.93\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePVDF/Clay 20%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e35.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e4.79\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e1.48\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e37.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e4.66\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e3.37\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePVDF/Clay 30%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e35.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e4.64\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e1.92\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e31.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e4.05\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e10.16\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003cdiv class=\"BlockQuote\"\u003e \u003cp\u003eThe choice of this composition for this study was based on the results regarding adsorption as a function of concentration, where this parameter proved to be more efficient (Table\u0026nbsp;\u003cspan refid=\"Tab4\" class=\"InternalRef\"\u003e4\u003c/span\u003e) [29\u0026ndash;31]. It is interesting to observe that the adsorption of lead and copper exhibits similar behaviors in both media, with a rapid adsorption in the initial hours followed by a gradual deceleration (Tables\u0026nbsp;\u003cspan refid=\"Tab4\" class=\"InternalRef\"\u003e4\u003c/span\u003e and \u003cspan refid=\"Tab5\" class=\"InternalRef\"\u003e5\u003c/span\u003e). This is a typical pattern in adsorption processes, where initially there is a high availability of adsorption sites, resulting in the rapid adsorption of metal ions. As time progresses, these sites become occupied, making the adsorption slower until saturation is reached (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e5\u003c/span\u003e).\u003c/p\u003e \u003c/div\u003e \u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab4\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 4\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eResults obtained from adsorption tests as a function of time for clay-incorporated membranes in an aqueous medium.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"7\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eContact Time\u003c/p\u003e \u003cp\u003eWater\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colspan=\"3\" nameend=\"c4\" namest=\"c2\"\u003e \u003cp\u003ePb\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colspan=\"3\" nameend=\"c7\" namest=\"c5\"\u003e \u003cp\u003eCu\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cb\u003eMass (mg)\u003c/b\u003e\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u003cb\u003eC\u003c/b\u003e\u003csub\u003e\u003cb\u003ef\u003c/b\u003e\u003c/sub\u003e \u003cb\u003e(mg/L)\u003c/b\u003e\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003cb\u003eN\u003c/b\u003e\u003csub\u003e\u003cb\u003ef\u003c/b\u003e\u003c/sub\u003e \u003cb\u003e(\u0026micro;mol/g)\u003c/b\u003e\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u003cb\u003eMass (mg)\u003c/b\u003e\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003e\u003cb\u003eC\u003c/b\u003e\u003csub\u003e\u003cb\u003ef\u003c/b\u003e\u003c/sub\u003e\u003c/p\u003e \u003cp\u003e\u003cb\u003e(mg/L)\u003c/b\u003e\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c7\"\u003e \u003cp\u003e\u003cb\u003eN\u003c/b\u003e\u003csub\u003e\u003cb\u003ef\u003c/b\u003e\u003c/sub\u003e\u003c/p\u003e \u003cp\u003e\u003cb\u003e(\u0026micro;mol/g)\u003c/b\u003e\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e1h\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e33.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e4.94\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.34\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e25.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e4.44\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e6.86\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e2h\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e29.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e4.89\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.56\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e26.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e4.17\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e10.09\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e5h\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e32.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e4.72\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e1.01\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e21.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e4.28\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e10.48\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e9h\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e29.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e4.67\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e1.30\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e28.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e3.89\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e12.45\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e15h\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e34.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e4.50\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e1.59\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e22.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e3.94\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e14.83\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e24h\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e33.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e4.50\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e1.61\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e23.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e3.89\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e15.07\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e48h\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e32.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e4.56\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e1.49\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e23.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e3.94\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e14.26\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab5\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 5\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eResults obtained from adsorption tests as a function of time for clay-incorporated membranes in an ethanolic medium.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"7\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eContact Time\u003c/p\u003e \u003cp\u003eWater/Ethanol\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colspan=\"3\" nameend=\"c4\" namest=\"c2\"\u003e \u003cp\u003ePb\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colspan=\"3\" nameend=\"c7\" namest=\"c5\"\u003e \u003cp\u003eCu\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cb\u003eMass (mg)\u003c/b\u003e\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u003cb\u003eC\u003c/b\u003e\u003csub\u003e\u003cb\u003ef\u003c/b\u003e\u003c/sub\u003e\u003c/p\u003e \u003cp\u003e\u003cb\u003e(mg/L)\u003c/b\u003e\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003cb\u003eN\u003c/b\u003e\u003csub\u003e\u003cb\u003ef\u003c/b\u003e\u003c/sub\u003e\u003c/p\u003e \u003cp\u003e\u003cb\u003e(\u0026micro;mol/g)\u003c/b\u003e\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u003cb\u003eMass\u003c/b\u003e\u003c/p\u003e \u003cp\u003e\u003cb\u003e(mg)\u003c/b\u003e\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003e\u003cb\u003eC\u003c/b\u003e\u003csub\u003e\u003cb\u003ef\u003c/b\u003e\u003c/sub\u003e\u003c/p\u003e \u003cp\u003e\u003cb\u003e(mg/L)\u003c/b\u003e\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c7\"\u003e \u003cp\u003e\u003cb\u003eN\u003c/b\u003e\u003csub\u003e\u003cb\u003ef\u003c/b\u003e\u003c/sub\u003e\u003c/p\u003e \u003cp\u003e\u003cb\u003e(\u0026micro;mol/g)\u003c/b\u003e\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e1h\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e27.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e4.11\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e3.08\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e23.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e4.39\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e8.10\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e2h\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e27.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e4.11\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e3.15\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e21.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e4.39\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e9.21\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e5h\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e31.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e3.78\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e3.78\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e20.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e4.10\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e13.96\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e9h\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e35.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e3.56\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e3.89\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e22.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e3.96\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e14.79\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e15h\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e26.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e3.67\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e4.86\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e27.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e3.72\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e14.72\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e24h\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e30.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e3.44\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e4.89\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e23.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e3.62\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e18.76\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e48h\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e31.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e3.39\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e4.94\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e25.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e3.53\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e18.17\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003cdiv class=\"BlockQuote\"\u003e \u003cp\u003eThis behavior suggests that the adsorption kinetics for both metals follow a similar pattern, regardless of the medium used [31\u0026ndash;35]. It is also noticeable that the adsorption of metal ions is higher in the water/ethanol mixture, and this is likely related to the hydrophobicity of the membranes. As described in the contact angle analyses, ethanol acts as a surfactant in water, reducing its surface tension, increasing solid wettability, and consequently allowing the solution to penetrate the membranes, reaching a greater number of active sites and increasing ion adsorption.\u003c/p\u003e \u003cp\u003eFurthermore, as described in some studies, adsorption in an ethanol medium is superior to an aqueous medium because water has a high electric dipole moment, causing metal ions to be attracted to the negative ends of water molecules, making their interaction with the adsorbent solid more difficult [36\u0026ndash;43]. Comparing the results obtained with respect to the test media, the ethanol medium yielded better results for both lead and copper. Regarding the type of adsorbent, the membranes showed higher adsorption values, indicating greater efficiency in the removal of Pb and Cu ions, a fact that may be related to their greater wettability over time. For clarity, a comparison of the adsorbed values for the 24h time point is presented in Table\u0026nbsp;\u003cspan refid=\"Tab6\" class=\"InternalRef\"\u003e6\u003c/span\u003e.\u003c/p\u003e \u003c/div\u003e \u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab6\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 6\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eComparison of metal removal between different media.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"4\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eInitial concentration (C\u003csub\u003e0\u003c/sub\u003e)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eMetal\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c4\" namest=\"c3\"\u003e \u003cp\u003eClay\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u003cb\u003eWater\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003cb\u003eWater/Ethanol\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003e5 mg/L\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cb\u003ePb\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e4.50mg/L (10%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e3.44mg/L (31%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cb\u003eCu\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e3.89mg/L (22%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e3.62mg/L (28%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003e \u003cdiv class=\"BlockQuote\"\u003e \u003cp\u003eFor the adjustments of the kinetic models, experimental data on the determination of equilibrium time for PVDF/clay membranes (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e6\u003c/span\u003e and Fig.\u0026nbsp;7) in aqueous and water/ethanol (95/05) mixture media for the adsorption of metals Pb and Cu were used [40\u0026ndash;43]. These data were applied to the pseudo-first-order and pseudo-second-order models, which will be presented in the following sections.\u003c/p\u003e \u003c/div\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003cdiv class=\"BlockQuote\"\u003e \u003cp\u003eThe correlation coefficients (R\u003csup\u003e2\u003c/sup\u003e) for both Pb and Cu in the aqueous medium are relatively low, 0.933 and 0.875, respectively. In the ethanolic medium, the obtained values are even lower, 0.772 for Pb and 0.674 for Cu. These results indicate that the adsorption of Pb and Cu on the clay-containing membranes does not occur via a first-order reaction. This is because a correlation factor closer to 1 is more suitable for describing the kinetics of the reaction between a particular material and a metal.\u003c/p\u003e \u003cp\u003eAs seen in Table\u0026nbsp;\u003cspan refid=\"Tab7\" class=\"InternalRef\"\u003e7\u003c/span\u003e, the pseudo-second-order model provides values of N\u003csub\u003efmax\u003c/sub\u003e for both Pb and Cu that are closer to the experimental N\u003csub\u003ef\u003c/sub\u003e in both aqueous and ethanolic media. Regarding the correlation coefficient, it is also closer to 1 in this model, indicating that the pseudo-second-order model best describes the adsorption kinetics. This suggests that adsorption primarily occurs in a monolayer.\u003c/p\u003e \u003c/div\u003e \u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab7\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 7\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eParameters obtained from the fitting of the pseudo-first-order and pseudo-second-order kinetic models in aqueous and ethanolic mdia for clay-incorporated membranes.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"5\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eSolution\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eParameters\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003ePb\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eCu\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eModels\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eWater\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eN\u003csub\u003ef\u003c/sub\u003e (\u0026micro;mol/g)\u003c/p\u003e \u003cp\u003eExperimental\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e1.61\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e15.07\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eWater/Ethanol (95/05)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eN\u003csub\u003ef\u003c/sub\u003e (\u0026micro;mol/g)\u003c/p\u003e \u003cp\u003eExperimental\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e4.89\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e18.76\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003ePseudo-first-order\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eWater\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eN\u003csub\u003ef\u003c/sub\u003e\u003csup\u003emax\u003c/sup\u003e (\u0026micro;mol/g)\u003c/p\u003e \u003cp\u003eK\u003csub\u003e1\u003c/sub\u003e (h\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e)\u003c/p\u003e \u003cp\u003eR\u003csup\u003e2\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e2.08\u003c/p\u003e \u003cp\u003e-0.119\u003c/p\u003e \u003cp\u003e0.933\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e11.39\u003c/p\u003e \u003cp\u003e-0.100\u003c/p\u003e \u003cp\u003e0.875\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eWater/Ethanol (95/05)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eN\u003csub\u003ef\u003c/sub\u003e\u003csup\u003emax\u003c/sup\u003e (\u0026micro;mol/g)\u003c/p\u003e \u003cp\u003eK\u003csub\u003e1\u003c/sub\u003e (h\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e)\u003c/p\u003e \u003cp\u003eR\u003csup\u003e2\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e3.57\u003c/p\u003e \u003cp\u003e-0.115\u003c/p\u003e \u003cp\u003e0.772\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e9.55\u003c/p\u003e \u003cp\u003e-0.030\u003c/p\u003e \u003cp\u003e0.641\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003ePseudo-second- order\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eWater\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eN\u003csub\u003ef\u003c/sub\u003e\u003csup\u003emax\u003c/sup\u003e (\u0026micro;mol/g)\u003c/p\u003e \u003cp\u003eK\u003csub\u003e2\u003c/sub\u003e (g/\u0026micro;mol.h)\u003c/p\u003e \u003cp\u003eh (\u0026micro;mol/g.h)\u003c/p\u003e \u003cp\u003eR\u003csup\u003e2\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e2.12\u003c/p\u003e \u003cp\u003e81.27x10\u003csup\u003e\u0026minus;\u0026thinsp;3\u003c/sup\u003e\u003c/p\u003e \u003cp\u003e0.38\u003c/p\u003e \u003cp\u003e0.998\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e15.90\u003c/p\u003e \u003cp\u003e36.37 x10\u003csup\u003e\u0026minus;\u0026thinsp;3\u003c/sup\u003e\u003c/p\u003e \u003cp\u003e9.19\u003c/p\u003e \u003cp\u003e0.978\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eWater/Ethanol (95/05)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eN\u003csub\u003ef\u003c/sub\u003e\u003csup\u003emax\u003c/sup\u003e (\u0026micro;mol/g)\u003c/p\u003e \u003cp\u003eK\u003csub\u003e2\u003c/sub\u003e (g/\u0026micro;mol.h)\u003c/p\u003e \u003cp\u003eh (\u0026micro;mol/g.h)\u003c/p\u003e \u003cp\u003eR\u003csup\u003e2\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e5.01\u003c/p\u003e \u003cp\u003e153.55 x10\u003csup\u003e\u0026minus;\u0026thinsp;3\u003c/sup\u003e\u003c/p\u003e \u003cp\u003e3.85\u003c/p\u003e \u003cp\u003e0.971\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e15.96\u003c/p\u003e \u003cp\u003e61.20 x10\u003csup\u003e\u0026minus;\u0026thinsp;3\u003c/sup\u003e\u003c/p\u003e \u003cp\u003e15.58\u003c/p\u003e \u003cp\u003e0.989\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003e \u003cdiv class=\"BlockQuote\"\u003e \u003cp\u003eThe initial adsorption rate (h) has relatively high values, indicating that surface adsorption on the solid is rapid. However, due to the hydrophobic nature of the matrix, there is greater difficulty for metallic ions to reach the active sites inside the nanocomposite, leading to a longer time for adsorption stabilization.\u003c/p\u003e \u003cp\u003eIt is also noticeable that h values are higher when only 5% ethanol is added to water, confirming that its presence facilitates the adsorption process, as observed in previous characterizations.\u003c/p\u003e \u003cp\u003eThe results for the clay-containing membranes obtained in the study of the variation in the initial concentration of metals Pb and Cu are presented graphs in Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e8\u003c/span\u003e, facilitating the analysis of the data from Tables\u0026nbsp;\u003cspan refid=\"Tab8\" class=\"InternalRef\"\u003e8\u003c/span\u003e and \u003cspan refid=\"Tab9\" class=\"InternalRef\"\u003e9\u003c/span\u003e, the were plotted between N\u003csub\u003ef\u003c/sub\u003e and N\u003csub\u003e0\u003c/sub\u003e.\u003c/p\u003e \u003c/div\u003e \u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab8\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 8\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eInfluence of the initial adsorbate concentration: clay-incorporated membranes in an aqueous medium.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"7\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eInitial Concentration\u003c/p\u003e \u003cp\u003eC\u003csub\u003e0\u003c/sub\u003e (mg/L)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colspan=\"3\" nameend=\"c4\" namest=\"c2\"\u003e \u003cp\u003ePb\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colspan=\"3\" nameend=\"c7\" namest=\"c5\"\u003e \u003cp\u003eCu\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cb\u003eMass\u003c/b\u003e\u003c/p\u003e \u003cp\u003e\u003cb\u003e(mg)\u003c/b\u003e\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u003cb\u003eC\u003c/b\u003e\u003csub\u003e\u003cb\u003ef\u003c/b\u003e\u003c/sub\u003e\u003c/p\u003e \u003cp\u003e\u003cb\u003e(mg/L)\u003c/b\u003e\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003cb\u003eN\u003c/b\u003e\u003csub\u003e\u003cb\u003ef\u003c/b\u003e\u003c/sub\u003e\u003c/p\u003e \u003cp\u003e\u003cb\u003e(\u0026micro;mol/g)\u003c/b\u003e\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u003cb\u003eMass (mg)\u003c/b\u003e\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003e\u003cb\u003eC\u003c/b\u003e\u003csub\u003e\u003cb\u003ef\u003c/b\u003e\u003c/sub\u003e\u003c/p\u003e \u003cp\u003e\u003cb\u003e(mg/L)\u003c/b\u003e\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c7\"\u003e \u003cp\u003e\u003cb\u003eN\u003c/b\u003e\u003csub\u003e\u003cb\u003ef\u003c/b\u003e\u003c/sub\u003e\u003c/p\u003e \u003cp\u003e\u003cb\u003e(\u0026micro;mol/g)\u003c/b\u003e\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e1.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e38.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.78\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.56\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e19.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0,56\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e7.29\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e2.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e29.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e1.67\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e1.08\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e18.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e1.50\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e8.55\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e2.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e29.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e2.17\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e1.10\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e19.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e1.94\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e9.16\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e3.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e35.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e2.56\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e1.21\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e16.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e2.44\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e10.73\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e3.50\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e37.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e3.00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e1.29\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e19.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e2.67\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e13.66\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e4.00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e36.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e3.50\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e1.32\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e17.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e3.22\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e13.75\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e4.50\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e39.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e3.83\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e1.63\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e20.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e3.56\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e14.50\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e5.00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e33.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e4.50\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e1.61\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e23.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e3.89\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e15.07\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab9\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 9\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eInfluence of the initial adsorbate concentration: membranes with clay in ethanol medium.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"7\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eInitial concentration\u003c/p\u003e \u003cp\u003eC\u003csub\u003e0\u003c/sub\u003e (mg/L)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colspan=\"3\" nameend=\"c4\" namest=\"c2\"\u003e \u003cp\u003ePb\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colspan=\"3\" nameend=\"c7\" namest=\"c5\"\u003e \u003cp\u003eCu\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cb\u003eMass\u003c/b\u003e\u003c/p\u003e \u003cp\u003e\u003cb\u003e(mg)\u003c/b\u003e\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u003cb\u003eC\u003c/b\u003e\u003csub\u003e\u003cb\u003ef\u003c/b\u003e\u003c/sub\u003e\u003c/p\u003e \u003cp\u003e\u003cb\u003e(mg/L)\u003c/b\u003e\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003cb\u003eN\u003c/b\u003e\u003csub\u003e\u003cb\u003ef\u003c/b\u003e\u003c/sub\u003e\u003c/p\u003e \u003cp\u003e\u003cb\u003e(\u0026micro;mol/g)\u003c/b\u003e\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u003cb\u003eMass (mg)\u003c/b\u003e\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003e\u003cb\u003eC\u003c/b\u003e\u003csub\u003e\u003cb\u003ef\u003c/b\u003e\u003c/sub\u003e\u003c/p\u003e \u003cp\u003e\u003cb\u003e(mg/L)\u003c/b\u003e\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c7\"\u003e \u003cp\u003e\u003cb\u003eN\u003c/b\u003e\u003csub\u003e\u003cb\u003ef\u003c/b\u003e\u003c/sub\u003e\u003c/p\u003e \u003cp\u003e\u003cb\u003e(\u0026micro;mol/g)\u003c/b\u003e\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e1.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e26.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.39\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e2.21\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e23.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.58\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e5.73\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e2.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e24.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e1.00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e3.91\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e24.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e1.43\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e7.17\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e2.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e26.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e1.44\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e3.86\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e23.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e1.72\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e10.29\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e3.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e25.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e1.83\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e4.40\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e26.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e2.05\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e11.26\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e3.50\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e23.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e2.50\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e4.20\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e21.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e2.72\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e11.49\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e4.00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e23.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e2.72\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e4.91\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e24.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e3.00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e12.74\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e4.50\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e29.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e2.89\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e5.20\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e24.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e3.39\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e14.21\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e5.00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e30.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e3.44\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e4.90\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e23.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e3.62\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e18.75\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003cdiv class=\"BlockQuote\"\u003e \u003cp\u003eNote that for the standardization of the conventions adopted in this study, the unit of initial concentration was converted from mg/L to \u0026micro;mol/L. From the graphs, it is observed that as the initial concentration increases, the amount of adsorbed ions also increases, regardless of the medium (water or a water/ethanol mixture 95/05) or the metal (Pb or Cu). This indicates that higher concentrations of the metal could be adopted, as there was no saturation of active sites in the medium. However, when analyzing the final metal concentrations in Tables, it can be seen that for all configurations, more than 50% of the adsorbate remains present.\u003c/p\u003e \u003cp\u003eThis is likely because the interaction of the metal with the solution is greater than with the solid, so increasing the copper concentration might result in a higher amount of ions adsorbed, but the final concentration would still be high [44\u0026ndash;46]. The application of the Langmuir and Freundlich models provides a better characterization of the adsorbent. The curves for each model are presented in Figs.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e9\u003c/span\u003e and \u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e10\u003c/span\u003e.\u003c/p\u003e \u003c/div\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003cdiv class=\"BlockQuote\"\u003e \u003cp\u003eFor the Langmuir model, the heterogeneity factor (n) and the amount of ions adsorbed in the multilayer (K\u003csub\u003ef\u003c/sub\u003e) of the Freundlich model were determined. All the data are presented in Table\u0026nbsp;\u003cspan refid=\"Tab10\" class=\"InternalRef\"\u003e10\u003c/span\u003e. It is evident that the Langmuir model is the one that best fits the experimental data, regardless of the metal and medium used, as the R\u003csup\u003e2\u003c/sup\u003e values were closer to 1 compared to the Freundlich model.\u003c/p\u003e \u003cp\u003eTherefore, it can be assumed that adsorption occurs in a monolayer, corroborating the pseudo-second-order kinetic model. This characteristic arises because intermolecular forces decrease with distance, making it difficult to form multilayers [47\u0026ndash;54].\u003c/p\u003e \u003c/div\u003e \u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab10\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 10\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eSummary of adsorption isotherm parameters for clay membranes.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"5\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eModels\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eSolution\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eParameters\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003ePb\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eCu\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eLangmuir\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eWater\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eN\u003csub\u003efm\u0026aacute;x\u003c/sub\u003e (\u0026micro;mol/g)\u003c/p\u003e \u003cp\u003eb L/\u0026micro;mol)\u003c/p\u003e \u003cp\u003eR\u003csub\u003eL\u003c/sub\u003e\u003c/p\u003e \u003cp\u003eR\u003csup\u003e2\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e2.54\u003c/p\u003e \u003cp\u003e0.075\u003c/p\u003e \u003cp\u003e0.36\u003c/p\u003e \u003cp\u003e0.953\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e18.92\u003c/p\u003e \u003cp\u003e0.044\u003c/p\u003e \u003cp\u003e0.23\u003c/p\u003e \u003cp\u003e0.914\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eWater/Ethanol\u003c/p\u003e \u003cp\u003e(95/05)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eN\u003csub\u003efm\u0026aacute;x\u003c/sub\u003e (\u0026micro;mol/g)\u003c/p\u003e \u003cp\u003eb (L/\u0026micro;mol)\u003c/p\u003e \u003cp\u003eR\u003csub\u003eL\u003c/sub\u003e\u003c/p\u003e \u003cp\u003eR\u003csup\u003e2\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e6.02\u003c/p\u003e \u003cp\u003e0.298\u003c/p\u003e \u003cp\u003e0.12\u003c/p\u003e \u003cp\u003e0.934\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e19.40\u003c/p\u003e \u003cp\u003e0.047\u003c/p\u003e \u003cp\u003e0.13\u003c/p\u003e \u003cp\u003e0.951\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eFreundlich\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eWater\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003en (mol/L)\u003c/p\u003e \u003cp\u003eK\u003csub\u003ef\u003c/sub\u003e (\u0026micro;mol/g)\u003c/p\u003e \u003cp\u003eR\u003csup\u003e2\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e1.706\u003c/p\u003e \u003cp\u003e15.84\u003c/p\u003e \u003cp\u003e0.942\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e2.490\u003c/p\u003e \u003cp\u003e43.67\u003c/p\u003e \u003cp\u003e0.816\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eWater/Ethanol\u003c/p\u003e \u003cp\u003e(95/05)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003en (mol/L)\u003c/p\u003e \u003cp\u003eK\u003csub\u003ef\u003c/sub\u003e (\u0026micro;mol/g)\u003c/p\u003e \u003cp\u003eR\u003csup\u003e2\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e2.723\u003c/p\u003e \u003cp\u003e24.06\u003c/p\u003e \u003cp\u003e0.863\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e1.94\u003c/p\u003e \u003cp\u003e61.30\u003c/p\u003e \u003cp\u003e0.894\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003e \u003cdiv class=\"BlockQuote\"\u003e \u003cp\u003eThe N\u003csub\u003efmax\u003c/sub\u003e calculated by Langmuir was close to theoretical value, confirming the better fit of this model to the experimental results. Through the Langmuir adsorption equilibrium constant, it was possible to calculate the dimensionless separation factor (RL), which indicates whether the adsorption of metals in different media is favorable or not. Since the results of all tests were less than 1, it can be concluded that the adsorption is of the favorable type [58\u0026ndash;60].\u003c/p\u003e \u003cp\u003eThe Langmuir equilibrium constant is also related to the adsorption energy. Therefore, the higher its value, the more chemically the adsorption occurs [50\u0026ndash;54]. Thus, the low values presented in the results (ranging from 0.044 to 0.298) may suggest that the adsorption process is of a physical nature.\u003c/p\u003e \u003cp\u003eThe separation percentage (PS), where C\u003csub\u003e0\u003c/sub\u003e and C\u003csub\u003ef\u003c/sub\u003e are the concentrations of the initial and final metals. The membranes produced in the present work, being composed of a matrix with micro and nanopolymeric fibers, exhibit high porosity, allowing the passage of fluids (liquid or gas), which enables their application as membranes (Fig.\u0026nbsp;\u003cspan refid=\"Fig8\" class=\"InternalRef\"\u003e11\u003c/span\u003e).\u003c/p\u003e \u003c/div\u003e \u003c/p\u003e \u003cp\u003e \u003cdiv class=\"BlockQuote\"\u003e \u003cp\u003eThus, membrane tests were carried out with the assistance of a vacuum pump under the same conditions as the adsorption tests, using water and a water/ethanol mixture (95/5), both containing 5 mg/L of lead and copper, at room temperature (25\u0026deg;C). The membranes used were pure PVDF, as well as membranes with clay, at concentrations of 10 and 30%.\u003c/p\u003e \u003cp\u003eThe results in terms of final metal concentrations for the fibrous membranes with clay are presented in Table\u0026nbsp;\u003cspan refid=\"Tab11\" class=\"InternalRef\"\u003e11\u003c/span\u003e, promising results for the application of membranes [54\u0026ndash;66] with clay as membrane material, achieving a 92% removal of copper in an aqueous medium for the film with 10% clay.\u003c/p\u003e \u003c/div\u003e \u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab11\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 11\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eMembrane Testing: Clay Membranes.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"5\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eMembrane\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colspan=\"2\" nameend=\"c3\" namest=\"c2\"\u003e \u003cp\u003eWater\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colspan=\"2\" nameend=\"c5\" namest=\"c4\"\u003e \u003cp\u003eEthanol\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cb\u003ePb (mg/L)\u003c/b\u003e\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u003cb\u003eCu(mg/L)\u003c/b\u003e\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003cb\u003ePb(mg/L)\u003c/b\u003e\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u003cb\u003eCu(mg/L)\u003c/b\u003e\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePVDF Pure\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e0.60\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e1.05\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.74\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e1.09\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e10% Clay\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e0.51\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.41\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.67\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.98\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e30% Clay\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e1.00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e1.22\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e1.13\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e1.05\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003e \u003cdiv class=\"BlockQuote\"\u003e \u003cp\u003eIt is noteworthy that even pure PVDF exhibited low concentrations of metals, demonstrating the effectiveness of the fibrous structure in impurity removal. The addition of 10% by mass of clay created active sites throughout the membrane, aiding in the elimination of metals. However, increasing the concentration of the load to 30% resulted in a deterioration of the process, which may have been caused by two factors [54\u0026ndash;58].\u003c/p\u003e \u003cp\u003eThe first factor is the presence of aggregates, as demonstrated by EDX measurements, which can act as facilitation points for water passage. The second factor is related to mechanical properties, which are significantly worsened with the high concentration of the loads. Thus, when pressure is applied to allow water to pass through the hydrophobic membrane, the pores widen, and the solution passes without major difficulties, carrying the metals along with it [56\u0026ndash;60].\u003c/p\u003e \u003cp\u003eRegarding the medium, it is evident that there was no improvement as observed in the adsorption process. The incorporation of 5% ethanol was used to facilitate water penetration into the membranes, but in membrane testing where pressure is applied for solution passage, ethanol does not contribute to this process [60\u0026ndash;66].\u003c/p\u003e \u003cp\u003eAdditionally, there is an inverse relationship between selectivity and permeability, meaning high selectivity is related to low permeability. As observed in the contact angle measurements, ethanol facilitates solution penetration into the surface, reducing the selectivity of the membranes. This also explains the good results presented by pure PVDF, which, being thicker and showing less variation in contact angle over time (lower permeability), exhibits high selectivity, achieving an 88% removal of lead.\u003c/p\u003e \u003c/div\u003e \u003c/p\u003e"},{"header":"Conclusions","content":"\u003cp\u003e \u003cdiv class=\"BlockQuote\"\u003e \u003cp\u003eIn the present work, membranes formed by a fibrous polymeric matrix were successfully produced through the solution blow spinning technique with the incorporation of clay. Scanning Electron Microscopy (SEM) confirmed that the membranes consist of fibers with average diameters smaller than 200 nm, which have a strong correlation with the solution viscosity.\u003c/p\u003e \u003cp\u003eMetal adsorption tests of the membranes indicated that membranes with 30% loading presented the best results and showed that the adsorbent amount increased, suggesting that higher values could be adopted, emphasizing the stabilization of adsorption after 24 h, which was adopted as the ideal time for subsequent tests.\u003c/p\u003e \u003cp\u003eThe incorporation of 5% ethanol into the aqueous medium improved lead and copper removal. The pseudo-second-order kinetic model best fit the experimental data, and the Langmuir isotherm model best represented adsorption for both metals, indicating a favorable adsorption isotherm.\u003c/p\u003e \u003cp\u003eMembrane tests demonstrated that membranes with a 10% loading showed the best results, with removal rates exceeding 90%. Membranes with 30% loading exhibited low performance due to their poor mechanical properties. Comparing the two metal removal techniques studied, the membranes showed significant and promising results in both. For adsorption (batch) processes, membranes with a higher loading are more suitable, while for membrane processes, good mechanical performance is required, with membranes containing 10% loading being the most appropriate.\u003c/p\u003e \u003c/div\u003e \u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e \u003ch2\u003eConflict of interest\u003c/h2\u003e \u003cp\u003eThe author declares no conflict of interest, financial or otherwise\u003c/p\u003e \u003c/p\u003e\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\u003cp\u003eG.C.D.: Responsible for data curation, writing the original draft, and reviewing and editing; L.Z.: Collated image data and reviewed and edited the manuscripts; A.O.S.: Collated image data and reviewed and edited the manuscripts; M.C.S.: Handled Data Curation and methodology; L.F.M: Involved in conceptualization, data curation, funding acquisition, methodology, and review and editing.\u003c/p\u003e\u003ch2\u003eAcknowledgement\u003c/h2\u003e\u003cp\u003eThe authors thank the Brazilian Federal Agencies: CAPES: CAPES process: 88887136426/2017/00, CNPq process CNPq: 465571/2014-0 and FAPESP agency FAPESP process: 2014/50945-4, both for financial support to the research. 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Preparation and characterization of highly hydrophobic poly(vinylidene fluoride)\u0026ndash;Clay nanocomposite nanofiber membranes (PVDF\u0026ndash;clay NNMs) for desalination using direct contact membrane distillation. Journal of Membrane Science, Amsterdam, v. 397\u0026ndash;398, p.80\u0026ndash;86, abr. 2012\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eTiwari, V.; Srivastava, G. Structural, dielectric and piezoelectric properties of 0\u0026ndash;3 PZT/PVDF composites. Ceramics International, Kidlington, v. 41, n. 6, p.8008\u0026ndash;8013, jul. 2015.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eAraujo, A. L. P. de et al. Adsor\u0026ccedil;\u0026atilde;o de Ni\u0026sup2; e Zn\u0026sup2; em Clay calcinada: Estudo de equil\u0026iacute;brio em coluna de leito fixo. Cer\u0026acirc;mica, S\u0026atilde;o Carlos, v. 59, p.382\u0026ndash;388, 2013.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLeszczynska, A.; Pielichowski, K. Application of thermal analysis methods for characterization of polymer/montmorillonite nanocomposites. Journal of Thermal Analysis and Calorimetry, Budapest, v. 93, n. 3, p.677\u0026ndash;687, set. 2008.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eGu, A.; Liang, G. Thermal degradation behaviour and kinetic analysis of epoxy/montmorillonite nanocomposites. Polymer Degradation and Stability, London, v. 80, n. 2, p.383\u0026ndash;391, jan. 2003.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003ePrasanth, R. et al. Effect of nano-clay on ionic conductivity and electrochemical properties of poly(vinylidene fluoride) based nanocomposite porous polymer membranes and their application as polymer electrolyte in lithium ion batteries. European Polymer Journal, Kidlington, v. 49, n. 2, p.307\u0026ndash;318, fev. 2013.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSilvano, J. R. et al. Effect of reprocessing and clay concentration on the degradation of polypropylene/montmorillonite nanocomposites during twin screw extrusion. Polymer Degradation and Stability, London, v. 98, n. 3, p.801\u0026ndash;808, mar. 2013\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eChiu, F. Comparisons of phase morphology and physical properties of PVDF nanocomposites filled with organoclay and/or multi-walled carbon nanotubes. Materials Chemistry and Physics, Lausanne, v. 143, n. 2, p.681\u0026ndash;692, jan. 2014.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eShang, J.et al. Contact angles of aluminosilicate clays as affected by relative humidity and exchangeable cations. Colloids and Surfaces A: Physicochemical and Engineering Aspects, Amsterdam, v. 353, n. 1, p.1\u0026ndash;9, jan. 2010.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eAndrade, C. T.. membranas TERN\u0026Aacute;RIOS DE AMIDO TERMOPL\u0026Aacute;STICO E POLI(BUTADIENO MALEATADO). Qu\u0026iacute;mica Nova, S\u0026atilde;o Carlos, v. 35, p.1146\u0026ndash;1150, 2012.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBonyadi, S.; Chung, T. S. Flux enhancement in membrane distillation by fabrication of dual layer hydrophilic\u0026ndash;hydrophobic hollow fiber membranes. Journal of Membrane Science, Amsterdam, v. 306, n. 1\u0026ndash;2, p.134\u0026ndash;146, dez. 2007.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003ePrince, J.a. et al. Preparation and characterization of highly hydrophobic poly(vinylidene fluoride)\u0026ndash;Clay nanocomposite nanofiber membranes (PVDF\u0026ndash;clay NNMs) for desalination using direct contact membrane distillation. Journal of Membrane Science, Amsterdam, v. 397\u0026ndash;398, p.80\u0026ndash;86, abr. 2012.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eWenzel, R. N. 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Synthesis and characterization of 3-[(thiourea)-propyl]-functionalized silica gel and its application in adsorption and catalysis. New Journal of Chemistry, Cambridge, v. 37, n. 7, p.1933\u0026ndash;1944, 2013.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSantos, E. A. et al. The influence of the counter ion competition and nature of solvent on the adsorption of mercury halides on SH-modified silica gel. Colloids and Surfaces A: Physicochemical and Engineering Aspects, Amsterdam, v. 201, p.275\u0026ndash;282, 2002.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003e\u0026Ouml;zcan, A.; \u0026Ouml;zcan, A. Adsorption of acid dyes from aqueous solutions onto acid-activated bentonite. Journal of Colloid and Interface Science, Maryland Heights, v. 276, n. 1, p.39\u0026ndash;46, ago. 2004.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKoushkbaghi, S. et al. Fabrication of PET/PAN/GO/Fe 3 O 4 nanofibrous membrane for the removal of Pb(II) and Cr(VI) ions. Chemical Engineering Journal, Amsterdam, v. 301, p.42\u0026ndash;50, out. 2016.\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"journal-of-materials-science-polymers","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"","sideBox":"Learn more about [ Journal of Materials Science: Polymers](https://link.springer.com/journal/44493)","snPcode":"44493","submissionUrl":"https://submission.springernature.com/new-submission/44493/3?","title":"Journal of Materials Science: Polymers","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Springer Open","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"Solution Blow Spinning, PVDF, membrane, Clay, Metal Removal","lastPublishedDoi":"10.21203/rs.3.rs-8273482/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-8273482/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eMetal contamination in effluents is a serious environmental problem. When heavy metals such as lead, mercury and cadmium are released into industrial or urban wastewater, they can persist in the environment for long periods. These metals are toxic to aquatic life and can accumulate in the food chain, harming human health. In this work, nanocomposites with micro and nanoscale fiber matrix of poly (vinylidene fluoride)\u0026ndash;PVDF with addition of montmorillonite clay, in concentrations were produced by the technical solution of blow spinning. Adsorption tests showed that the ideal conditions for the highest removal rate (87%) were using nanocomposites at a concentration of 30% for 24 h in water/ethanol (95/5 V/V). The pseudo-second order and Langmuir models were the most suitable for describing the kinetic and adsorption isothermal data, respectively. Membrane tests indicated that nanocomposites with 10% clay were the most suitable, achieving a removal rate of more than 90% of metals\u003c/p\u003e","manuscriptTitle":"Removal of Pb and Cu Metals by PVDF/Clay Membranes Obtained Through Solution Blow Spinning Technique","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-12-19 18:23:02","doi":"10.21203/rs.3.rs-8273482/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2026-02-05T11:52:34+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-01-20T09:41:44+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-01-13T08:35:06+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-01-08T07:25:27+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"72843410080943067767762403907436778133","date":"2025-12-23T04:37:44+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"307585968367852040245428236407799280323","date":"2025-12-20T02:51:48+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"153906627344986030722246518747161891598","date":"2025-12-18T15:00:05+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"117575968062176511618223232925844052111","date":"2025-12-17T17:10:54+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2025-12-17T14:53:53+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2025-12-15T01:00:19+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2025-12-15T00:59:14+00:00","index":"","fulltext":""},{"type":"submitted","content":"Journal of Materials Science: Polymers","date":"2025-12-03T19:56:02+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"journal-of-materials-science-polymers","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"","sideBox":"Learn more about [ Journal of Materials Science: Polymers](https://link.springer.com/journal/44493)","snPcode":"44493","submissionUrl":"https://submission.springernature.com/new-submission/44493/3?","title":"Journal of Materials Science: Polymers","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Springer Open","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"14b90d21-467a-4835-8c0c-b00cabdda3da","owner":[],"postedDate":"December 19th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[],"tags":[],"updatedAt":"2026-04-25T20:38:42+00:00","versionOfRecord":[],"versionCreatedAt":"2025-12-19 18:23:02","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-8273482","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-8273482","identity":"rs-8273482","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}