Management of a ciprofloxacin as a contaminant of emerging concern in water using microalgae bioremediation: mechanism, modeling, and kinetic studies

Management of a ciprofloxacin as a contaminant of emerging concern in water using microalgae bioremediation: mechanism, modeling, and kinetic studies | 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 Management of a ciprofloxacin as a contaminant of emerging concern in water using microalgae bioremediation: mechanism, modeling, and kinetic studies Heba Salah, Nabila Shehata, Noha Khedr, Khaled N. M. Elsayed This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-4596545/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 17 Dec, 2024 Read the published version in Microbial Cell Factories → Version 1 posted 9 You are reading this latest preprint version Abstract Pharmaceutical residues which are labeled as a new class of environmental contaminants have potentially negative environmental and human health effects. Recently, biosorption is one of the most appealing choices to manage these pharmaceutical wastes in water. However, the environmental limitations of the adsorbent material are an obstacle to the development of this process. Hence, the current study suggested two biosorbents; Chlorella vulgaris and Synechocystis sp. microalgae to manage Ciprofloxacin (CIP) in water. The experimental results showed that the optimal adsorption conditions are an initial CIP concentration of 4.0 mg L − 1 and pH 5 and 3 for Synechocystis sp. and C. vulgaris , respectively. The adsorption process fitted well with the pseudo-second-order kinetic model. The main mechanism of biosorption is the complexation of CIP with carboxyl, hydroxyl, carbonyl, and amido groups which was confirmed by Fourier-transform infrared spectroscopy (FTIR), Scanning electron microscopy (SEM), and energy-dispersive X-ray spectrometry (EDX) analyses which represent the presence of CIP on the cyanobacterial cell surface and intracellularly. These results revealed that the adsorption mechanism of CIP by Synechocystis sp. PCC6803 and C. vulgaris provide theoretical guidance for insight into the biosorption mechanisms of pharmaceutical residues by other strains. Contaminants of emerging concern (CEC) Adsorption Ciprofloxacin Synechocystis sp. PCC6803 C. vulgaris Antibiotics Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 Introduction Conventional water treatment systems have been shown to provide inadequate treatment of pollutants of emergent concern (CEC) [ 1 ]. The increasing worldwide contamination of freshwater with a manifold of pharmaceutical residues threatens aquatic organisms and human health. The environmental effects of pharmaceuticals, antibiotics, and disinfectants are of increasing concern [ 2 ]. The CEC has posed raising concerns recently. They are increasingly discharged in water and wastewater at worryingly high levels and being treated ineffectively in water and wastewater treatment systems. The CEC can be classified as pharmaceuticals, personal care products, pesticides and industrial chemicals [ 3 ]. Due to the inevitable environmental release, antibiotics have been detected in global water which brings challenges to not only targeted bacteria but also to the health of non-target species such as fishes, plants, and algae [ 4 ]. Wastewater from animal husbandry, aquaculture, and the pharmaceutical industry is the major source of antibiotics in the environment [ 5 ]. Pharmaceutical residues are responsible for a number of harmful pollutants, such as antibiotics [ 6 ]. Antibiotics are often found in various environments and can be extremely dangerous for both human health and ecosystems [ 7 ]. Pollutants not subject to regulation are increasingly found in wastewater discharges, due to modern consumption patterns. These compounds are generally referred to be contaminants of emergent concern (CEC) due to the potential effects of their existence in the world's water systems. Pharmaceuticals, personal care products, industrial additives, insecticides, and a variety of chemical compounds have all been detected in wastewater [ 3 , 8 ]. Antibiotics, including ciprofloxacin (CIP), are used to mitigate or cure microbial infections and illnesses in veterinary, human, and aquatic systems by targeting specific bacteria. These antibiotics continually enter the aquatic environment by multiple pathways, such as hospital wastewater and pharmaceutical wastewater, veterinary, human excretions, and sewers, reaching treatment facilities in amounts ranging from ng/L to µg/L [ 9 ]. The occurrence of CIP in the surface water could achieved 5.02 mg/ L [ 10 ]. The emergence of antibiotic-resistant genes (ARGs) and bacteria (ARBs), which cause 700,000 annual fatalities, is the main issue connected to antibiotic-polluted water [ 11 ]. Due to their resistance to the specific antibiotics suggested for their therapy, ARBs are extremely difficult to treat [ 12 ]. Ciprofloxacin (CIP) is a significant pharmaceutical drug belonging to the fluoroquinolone (FQ) class that targets both Gram-positive and Gram-negative bacteria to treat serious illnesses. Its global emissions are primarily found in surface water, which accounts for 25% of the total emission, and municipal wastewater, which accounts for 58% of the total emission [ 13 ]. This family of antibiotics is extremely mobile in the aquatic environment due to its hydrophilic characteristics. fluoroquinolone antibiotic ciprofloxacin is found in a variety of sources, including drinking water and WWTP effluents, due to its significant usage in both human and veterinary medicine [ 14 ]. Like other antibiotics, CIP can stack up in the cells of an organism and pose a major risk to human health. The successful removal of CIP is therefore feasible given adequate consideration to their high levels in a variety of wastewaters, stability, resistance to decomposition, and possible ecotoxicity [ 15 ]. Antibiotic removal has been accomplished by a variety of methods, including coagulation, membrane separation, advanced oxidation, adsorption, photocatalysis, electrolysis, and biological degradation. These methods have several drawbacks, including high energy and material costs and secondary contamination from the addition of other chemicals. Adsorption, on the other hand, is the most adaptable and extensively utilized of these because of its great removal capacity, high efficiency, straightforward design, and simplicity of usage. In this regard, biosorption which relies on the ability of various types of live and inactive dead biomasses (heat, dried, chemically treated) to bind and concentrate contaminants from water-based solutions has emerged as an environmentally friendly, practical, and financially viable method for the removal of antibiotics [ 16 ]. An ecologically benign method with great promise for antibiotic elimination is microalgae-based wastewater treatment. The precise antibiotics and microalgae species used, however, determine how well CIP is removed by microalgae [ 7 , 17 ]. Microalgae are photosynthetic eukaryotic or prokaryotic organisms that can grow single, in chains or colonies, or filamentous forms. They can be found in a variety of ecosystems, including airborne, aquatic, and terrestrial habitats [ 18 ]. Microalgae serve a significant role in the oxygen production in aquatic ecosystems, as well as an important element of the food chain. Microalgae have attracted interest in the bioremediation research community for their capacity for acclimation and eliminating the antibiotics themselves from contaminated water, yielding important biomass [ 11 ]. The antibiotic removal effectiveness of the adsorption technique is strongly reliant on the adsorbent, which is often costly. Accelerated oxidation and photocatalysis may be usually successful, but they require expensive chemical agents or catalysts, as well as the potential generation of secondary pollutants. In contrast, microalgae wastewater treatment is a biological process that requires minimal chemical agents and may be tailored to successfully remove new pollutants such as antibiotics [ 19 ]. The biosorption efficiency depends on the sorbent properties (Microalgae) and pollutant structures [ 20 ]. In microalgae, the cell walls include polymer assemblages and functional groups that can facilitate biosorption [ 16 ]. Factors affecting antibiotic removal performance by microalgae are (1) algal species, (2) antibiotic classes and concentration, (3) algal growth conditions [ 19 ]. Some literature comparing different algal species on ciprofloxacin removal is presented in Table 1 . This study aimed to determine the biosorption capability of Synechocystis sp. and C. vulgaris for antibiotic ciprofloxacin at different concentrations and investigated in comparison with the control medium. The selected microalgae species are Synechocystis sp. and Chlorella vulgaris without modification in powder form at a constant concentration in the removal of CIP as CEC. A thorough investigation is conducted on process optimization by the adjustment of process parameters, such as time, pH, dosage, and starting concentration, in addition to the isotherm of adsorption and kinetic investigations. Table 1 Illustrate removal of ciprofloxacin by different Microalgae species and removal mechanisms. Microalgae Initial antibiotic concentration and removal rate, hydraulic retention time removal mechanisms. WW Category Ref. Chlamydomonas mexicana 2 mg/L and 13%, 11d Biodegradation, accumulation, and adsorption Bold’s Basal medium [ 21 ] Nannochloris sp. 57 ng/L and 100%, 7d Direct photolysis Water from Las Vegas wash [ 22 ] Chlamydomonas pitschmannii 2 mg/L and 1.6%, 11d Biodegradation, accumulation, and adsorption Bold’s Basal medium [ 21 ] Ourococcus multisporus 2 mg/L and 2%, 11d Biodegradation, accumulation, and adsorption Bold’s Basal medium [ 21 ] Chlorella Vulgaris 2 mg/L and 0%, 11d Biodegradation, accumulation, and adsorption Bold’s Basal medium [ 21 ] Chlamydomonas Mexicana 2 mg/L and 56%, 11d Biodegradation, accumulation, and adsorption Bold’s Basal medium + sodium acetate (4g/L) [ 21 ] The mixture of algae-bacteria consortia in pilot high-rate algae pond (HRAP) 1.31 mg/L and 20.1%, 24h (8 h sunlight/16h dark) Photodegradation during daytime, and adsorption during nighttime Real domestic wastewater [ 23 ] Reagents and Materials Ciprofloxacin, C 17 H 18 FN 3 O 3 , is supplied from Organo for pharmaceutical and chemical industries (ORGANO PHARMA), Egypt. CIP concentrations were 10 mg/L, and 20 mg/L in the examination. Figures (1) represents the chemical structure of CIP. The molecular weight of CIP is 331.34 g/mol. The molecular structure of CIP is given in Fig. 1 [ 16 ]. pKa values of CIP and ionic forms of CIP is shown in Fig. 2 [ 24 ]. 2.2 Algae and Incubation Conditions: In BG11 cultivation medium, C. vulgaris was grown with the addition of NaCl, while Synechocystis sp ., which is sensitive to NaCl, was also grown in BG11 cultivation medium, but without the addition of NaCl. Fluorescent light was used for a 12 h light/12h dark cycle at 20 º C. 2.3 CIP concentrations in removal technique: CIP is used in different concentrations with constant algal concentration. To measure the removal efficiency of CIP by microalgae, we prepare 0.1 g from selected microalgae species in 200 ml distant water (control sample). The CIP concentrations were 2 mg, and 4mg in prepared media, 0.1 microalgae in 200 ml distant water (test samples). 2.4 Bio-adsorption studies: The monitoring was carried out by taking 5mL aliquots of medium for the determination of CIP concentration. All samples were centrifuged in the Universal Centrifuge Model: PLC-036 GEMMYCO made in Taiwan (model of centrifuge) before analysis. The maximum absorbance for C. vulgaris and Synechocystis sp. algae name was inspected by scanning between 200 and 400 nm using a UV-Vis spectrophotometer 1800 UV-2600 (Shimadzu, Japan), and the maximum absorbance was found at 400 nm. All experiments were carried out in repeat and the average results were reported. All graph plotting was carried out with the origin. Results and Discussion 3.1 Impact of pH To investigate the effect of pH on the adsorption of CIP, 20 mg/L CIP solution was mixed with 0.5 g/L microalgae by using a shaker for 12 hours at different pH values ranging from 3.0 to 11.0. the optimum pH values for the biosorption CIP onto C. vulgaris and Synechocystis sp. is 3.5 and 5.5, respectively which corresponds to removal efficiency of 90%. The optimal pH is vital because it affects ionization degree, adsorbent surface charge, and speciation of the adsorbate [ 25 , 26 ]. two pKa values of CIP: for the basic-N moiety is 8.89 ± 0.11 and for the carboxylic acid group is 5.90 ± 0.15 [ 24 ]. The acid dissociation constant (pKa) of CIP is less than 6.0 when it is in its cation form because the amine group has been protonated, and it is more than 8.7 when it is in its anion form because the carboxylic group has lost a proton. The majority of CIP molecules are zwitterionic species, and their pH range is 6.0–8.7. [ 27 , 28 ]. C. vulgaris and Synechocystis have a pH ZPC of 3.0. Hence, when the pH increased from pH 1 to pH 3, the removal of CIP increased because of improved electrostatic attraction which results from the opposite charge between the CIP and the microalgae. In contrast, at high pH, CIP removal was significantly reduced. This may be due to the zwitterionic nature of CIP. At higher pH (pH > 5.9), both CIP and the algal biomass possess negative charges and the repulsion forces will be the dominant. Figure 3 illustrates that pH ranges from 3 to 7 resulting in higher CIP adsorption because of hydrophobic interactions between functional groups on the waste surface of C. vulgaris and CIP are responsible for the mechanism of biosorption. Comparing the removal of CIP efficiency at different pH, the adsorption of CIP decreases due to increased pH. pKa value of CIP was 8.7 for the amine group and the value of pKa of CIP was 6.1 for the carboxylic acid group on piperazine moiety [ 29 ]. Due to the carboxyl group's proton being removed, CIP is present in an anion form [ 30 , 31 ]. CIP is a cation that is present in solutions with a pH lower than 6.1, but likewise, CIP is present in solution as a zwitterionic form when the pH of the solution ranges from 6.1 to 8.7. The removal of CIP increased when the pH was less than 6, for the reason that electrostatic charge on the algae surface and CIP [ 32 ]. However, CIP removal was significantly reduced at high pH. It may occur due to algae surface charging and the nature of the zwitterion of CIP. High removal efficiencies are the result of ionic interactions between the surface of the adsorbent and CIP in acidic solutions [ 27 , 32 , 33 ]. The opposite charge between the electrostatic charging on the microalgae surface and the CIP causes electrostatic attraction, which leads to high removal efficiency. 3.2 Adsorption isotherm modeling The adsorption isotherm can be used to determine the biosorbent's capability as well as the adsorption behavior required to remove the pollutant [ 34 ]. The Langmuir, Freundlich, Dubinin-Radushkevich, Baudu, and Fritz-Schlunder biosorption isotherms were used in the current study to investigate the characteristics of each of C. vulgaris 's and synechocystis 's characteristics in the removal of CIP. Adsorption models in a nonlinear form are statistically more dependable compared to models in a linear form [ 35 ]. To determine the equilibrium adsorption capacity, use the following equation [ 36 ]: $${q}_{e}=\frac{v\left({C}_{i}-{C}_{e}\right)}{m}$$ Where q e equilibrium adsorption capacity q e (mg/g), V refers to the sample's volume (L), C i represents the beginning concentration of the solute (mg/L), C e is the equilibrium concentration of the solute (mg/L) and m is the quantity of adsorbent used (g). Use the following equation to determine the percentage of contaminant water removal [ 37 ] $$\text{R}\text{e}\text{m}\text{o}\text{v}\text{a}\text{l} \text{e}\text{f}\text{f}\text{i}\text{c}\text{i}\text{e}\text{n}\text{c}\text{y}=\frac{{C}_{i}-{C}_{e}}{{C}_{i}}\times 100\%$$ Ten models have been investigated for the biosorption of CIP onto C. vulgaris and Synechocystis sp.1 (Fig. 4 . And Table 2 .). The results showed that the Freundlich model is the best to describe the CIP@ C. vulgaris where the calculated adsorption capacity is close to the calculated one in addition to a high correlation coefficient (R 2 = 0.944), followed by Dubinin-Radushkevich and Langmuir with q max 10.32 and 14.37 mg/g and R 2 = 0.903 and 0.943, respectively [ 38 ]. The other models are not suitable for describing the CIP@ C. vulgaris system such as Baudu, Redlich-Peterson, and Khan even with their high correlation coefficients (R 2 = 0.953, 0.948, and 0.948, respectively) where the predicted q max according to these models are less than the experimental one. Also, the Sips and Toth models didn’t fit the data well where the calculated values of q max according to these models are higher than the experimental one even with their high R 2 values (0.944, and 0.944). Fritz-schlunder, and Langmuir-Freundlich can’t be used for the modeling of CIP@ C. vulgaris system where R 2 is low (0.82 and 0.832, respectively) and the calculated values of q max are far away than the experimental one. For the CIP@ Synechocystis sp. system, Freundlich is the best model to describe the system with calculated q max close to the experimental one and acceptable R 2 (0.80). Followed by Redlich-Peterson (R 2 = 0.805). Baudu, Sips, Langmuir-Freundlich, Toth, Fritz-schlunder, and Kahn failed to describe the CIP system where the predicted q max values according to these models are far away from the experimental one. Although Langmuir and Dubinin-Radushkevich yield calculated q max close to the experimental, however, R 2 is low 0.748 and 0.726, respectively. Table 2 The parameters of the adsorption isotherm model for CIP@ C. Vulgaris and CIP@ Synechocystis sp. systems Adsorption models Parameter C. Vulgaris Syn . Sp. Adsorption models Parameter C. Vulgaris Syn . Sp. 2- parameters isotherm Langmuir q max 14.373 8.135 3-parameters isotherm Redlich-Peterson K R 1.567 12.0 K L 0.063 0.303 a R 0.452 4.3 R 2 0.943 0.748 Β 0.630 0.686 Freundlich K f 1.283 2.286 R 2 0.948 0.805 1/n F 0.598 0.370 Sips Q m 11939.624 16276 R 2 0.944 0.800 Ks 0.000 0.000 Dubinin-Radushkevich q max 10.322 7.452 1/n 0.598 0.370 K ad 0.001 0.000 R 2 0.944 0.800 R 2 0.903 0.726 Langmuir-Freundlich 𝑞 MLF 938.18 938.180 4-parameters isotherm Baudu q m 1.379 2.43 𝐾LF 9.563 9.6E-08 b 0 76.783 998.2 𝑀LF 0.372 0.372 x 0.574 0.370 R 2 0.832 0.800 y 47.678 22.71 Toth K e 23362 46048 R 2 0.953 0.86 K L 45336 32002 5-parameters isotherm Fritz-schlunder q mFSS 67.409 84.8 n 0.401 0.629 K 1 0.202 0.254 R 2 0.944 0.800 K 2 9.924 8.305 Kahn Q m 2.705 1.169 m 1 6.385 6.25 b K 0.486 6.695 m 2 5.808 5.93 a K 0.512 0.62 R 2 0.953 0.82 R 2 0.948 0.86 Kinetics The kinetic of the adsorption process yields significant insights to design a batch adsorption system and it also provides optimum operating conditions for full-scale operation. Therefore, the experimental results of CIP adsorption onto both microalgae were studied using pseudo 1st order (PFO), Pseudo 2nd order (PSO), Avrami, mixed 1st and 2nd (MFSO) and intraparticle diffusion models, whose results are represented in in Fig. 5 and Tables 3 . Four models; PFO, PSO, Avrami, and MFSO can describe the CIP@ C. Vulgaris system, especially at the higher concentration of CIP following the order: MFSO (R 2 = 0.982) > PFO (R 2 = 0.981) and Avrami (R 2 = 0.981) > PSO (R 2 = 0.979) while in the lower concentration of CIP, MFSO (R 2 = 0.937) and PSO (R 2 = 0.937) are better than PFO (R2 = 0.890) and Avrami (R 2 = 0.890). On the other hand, the intraparticle diffusion model is not suitable for this system where the predicted data do not agree with the experimental one as well as R 2 values are low (0.484 − 0.065). For the CIP@Cy Sp., PFO (R 2 = 0.937), PSO (R 2 = 0.937), Avrami (R 2 = 0.937), and MFSO (R 2 = 0.937) can fit the data well with excellent matching between the experimental and the predicted data in addition to high values of R 2 while at lower concentrations, the correlation coefficients decreased to 0.708, 0.631, 0.708 and 0.708 for PFO, PSO, MFSO and Avrami models, respectively. On the other hand, the intraparticle diffusion model is not suitable for CIP@ Synechocystis sp. at both initial concentrations of CIP. Table 3 The parameters of kinetic models describing the adsorption of CIP onto C. vulgaris and Synechocystis sp. Model Parameters C. vulgaris Synechocystis sp. Conc. 10 mg/L Conc. 20 mg/L Conc. 10 mg/L Conc. 20 mg/L Pseudo-first-order q e [mg/g] 1.600 7.083 0.887 15.715 k 1 [L/mg] 0.094 0.478 0.100 0.253 R 2 0.890 0.981 0.708 0.923 Pseudo-second-order q e [mg/g] 1.712 7.145 0.892 16.138 k 2 0.077 0.349 0.278 0.032 R 2 0.937 0.979 0.631 0.962 The Mixed 1, 2-order Model q e [mg/g] 1.710 7.098 0.887 16.124 K 0.000 0.175 0.100 0.001 f 2 0.998 0.859 0 0.998 R 2 0.937 0.982 0.708 0.962 Avrami q e [mg/g] 1.600 7.083 0.887 15.715 k av 0.380 0.854 0.390 0.621 n av 0.249 0.559 0.256 0.407 R 2 0.890 0.981 0.708 0.923 Intraparticle diffusion k ip 0.033 0.050 0.003 0.137 c ip 0.826 6.200 0.678 11.793 R 2 0.484 0.065 0.020 0.292 Discussion of the characterization results FTIR Fourier transform infrared spectroscopy (FT-IR ) is a common instrumental tool used for the identification of several functional groups of any organic material (liquids, solids, and gases) by the measurement and determination of its emission spectra or infrared absorption [ 39 ]. The impact of CIP adsorption onto C. vulgaris and Synechocystis sp. on the change in its chemical structures was detected via FTIR analyses. The results showed that stretching vibration of water molecules owning to the intermolecular bonding of OH- appear at 3293.452 cm − 1 and 3414.190 cm − 1 for C. vulgaris and Synechocystis sp., respectively [ 40 ]. The asymmetrical (-C-H) and stretching (-C-H) vibration have been detected at 2933.767 cm − 1 and 1400.41 cm − 1 for C. vulgaris and 2929.20 cm − 1 Synechocystis Sp. [ 41 ]. 2933.767 cm − 1 belonging to CH and CH 2 groups the aliphatic of carbohydrates lipids and proteins. 1646.01 cm − 1 C = O group amide I band of protein. the band of carbohydrate CO group at1041.408 cm − 1 . 1535.336 cm − 1 amide II band. 1539.176 cm − 1 amide II band [ 42 ]. The presence of band 1539.176 cm − 1 indicates the stretching vibration of N–H of amide II and the bending vibration of C–N. For C. vulgaris , the characteristic bands appear at 3293.452 cm − 1 (stretching, N-H of protein) [ 43 , 44 ], 1648.624 cm − 1 (stretching, C = O of protein and C = C)[ 45 ], 1539.176 cm − 1 (bending, amide (N-H and C-H) and Vibration (C-N) stretching of protein [ 46 ] and stretching, C = C) [ 43 ], 1400.407 cm − 1 (stretching, C = C) [ 43 ], 1108.482 cm − 1 (Carbohydrate V (-O-C) of polysaccharides, Nucleic acid, stretching of phosphodiesters Carbohydrate [ 44 ] and Alkyl stretching) [ 43 ], 1041.408 cm − 1 (Carbohydrate V(C-O-C) of polysaccharides and alkyl stretching) and 613.338 cm − 1 (Alkyl stretching). For Synechocystis Sp., the characteristic bands were detected at 1646.01 cm-1 (C = O highly conjugated [ 47 ] and the stretching vibration of amide I in proteins [ 45 ], 1535.336 cm − 1 (Carboxyl group in salt from –COO − [ 47 ], the stretching vibration of amide II in proteins,.[ 45 ] 1400.593 cm − 1 (CH 3 [ 47 ], asymmetrical C-H bending mode of -CO-CH 2 - or CO-CH 3 groups [ 41 ], stretching vibration of C = O in the carboxyl group [ 48 , 49 ], 1114.017 cm − 1 (C-O stretch and O–H bend in phenoxy structures, ethers [ 47 ]. After the CIP adsorption, there is no significant change in the two spectra of the microalgae except the variation in the intensity of the bands. This may refer to that the adsorption process occurred due to the presence of amide, hydroxyl, carboxyl, and carbonyl groups. The intensity of the bands after CIP adsorption decreased in the case of C. vulgaris (Fig. 6 a) and increased in the case of Synechocystis Sp. (Fig. 6 a). This may be attributed to the involvement of various functional groups on C. vulgaris in the attachment of CIP. and the formation of new bands with higher density in the case of Synechocystis Sp . which agreed with the SEM results and adsorption isotherm modeling. SEM The surface morphology of the two biomasses before and after CIP adsorption was observed using SEM (Fig. 7 ). The two biomasses exhibit heterogeneous surfaces and possess small cavities/crakes on their surfaces. Figures (7a) confirms that C. vulgaris is irregularly shaped, with a close, compact, and smoother structure, and after the biosorption of CIP (Fig. 7 b), it exfoliated which may be attributed to the attachment of CIP to specific functional groups onto the biomass in monolayer form which is agreed with the results of the adsorption isotherm modeling. Synechocystis sp., (Fig. 7 c), has an irregular shape. After adsorption, the surfaces of the cells were compact with some roughness. It can be seen also (Fig. 7 d) the aggregation of some attachments onto the surface owing to the precipitation or accumulation of CIP on the cavity on the cell surface which agreed with the modeling results suggesting that Freundlich isotherm is the predominant in CIP@ Synechocystis Sp. Mapping and EDX The surface morphology of the two biomasses before and after CIP adsorption was observed using SEM (Fig. 8 , and Fig. 9 ). The two biomasses exhibit heterogeneous surfaces and possess small cavities/crakes on their surfaces. Figures (8a) confirms that C. vulgaris is irregularly shaped, with a close, compact, and smoother structure, and after the biosorption of CIP (Fig. 8 b), it exfoliated which may be attributed to the attachment of CIP to specific functional groups onto the biomass in monolayer form which is agreed with the results of the adsorption isotherm modeling. Synechocystis sp., (Fig. 9 a), has an irregular shape. After adsorption, the surfaces of the cells were compact with some roughness. It can be seen also (Fig. 9 b) the aggregation of some attachments onto the surface owing to the precipitation or accumulation of CIP on the cavity on the cell surface which agreed with the modeling results suggesting that Freundlich isotherm is predominant in CIP and Synechocystis Sp. The EDX analytical data indicated that oxygen, carbon, nitrogen, and iron were present in the microalgae). This result confirmed the successful incorporation of CIP molecules into the C. vulgaris and Synechocystis sp. algae[ 50 ]. The study showed that applying microalgae successfully removes CIP compounds from contaminated water. Conclusion In the current study, the removal of CIP was investigated from contaminated water by using microalgae as an adsorbent. The two types of algae used in the current research are chlorella vulgaris and Synechocystis sp. The effects of several factors on removing CIP by microalgae were tested (e.g., pH, CIP dosage, adsorbent concentrations, contact time, and temperature ). The adsorption of CIP increases with an increase in adsorbent dose and contact time, up to a definite limit. Based on isotherm data, the adsorption of CIP by microalgae follows the Langmiur isotherm model. The kinetic data show that CIP adsorption fits second-order kinetic models depending on R 2 values and the comparison of calculated and experimental q e values. The microalgae are from the best biosorbent and the most cost-effective strategies for achieving this goal, in the removal of CIP and wastewater treatment. Abbreviations CIP Ciprofloxacin C. vulgaris Chlorella Vulgaris Synechocystis sp.1 Synechocystis sp . PCC6803 FQ fluoroquinolones ARB Antibiotic-resistant bacteria ARG Antibiotic-resistant gene CEC Contaminants of emerging concern FLU Flutamide SEM Scanning Electron Microscope FTIR Fourier-transform infrared spectrum Ppm parts per million PZC Point of zero charge XPS X-ray photoelectron spectroscopic q max Maximum adsorption capacity (mg g −1 ) PFO Pseudo-First-Order PSO Pseudo-Second-Order MFSO Mixed first anf second q e Refers to the amount of adsorbate in the adsorbent at equilibrium (mg g −1 ) C 0 The initial equilibrium dye concentration (mg L −1 ) C e The equilibrium dye concentration (mg L −1 ) V The volume of solution, L W the mass of adsorbent used, g K L Langmuir isotherm constant (L/mg) K f Freundlich adsorption capacity (mg g −1 ) K LF Langmuir–Freundlich equilibrium constant for heterogeneous solids 1/ n F Freundlich adsorption intensity n the empirical constant k1 the pseudo-first-order rate constant, min-1 k2 The rate constant of pseudo-second-order adsorption, g/(mg min) Declarations Author contributions The contributions of all authors must be described in the following manner: The authors confirm their contribution to the paper as follows: Khaled N. M. Elsayed (Manuscript writing, Data acquisition, Software analysis, Supervision, Conceptualization, Editing and revision, Methodology, and manuscript preparation); Nabila Shehata (Manuscript writing, Data acquisition, Software analysis, Supervision, Conceptualization, Editing and revision, Methodology, and manuscript preparation); Noha Khedr (Manuscript writing, Data acquisition, Software analysis, Supervision, Conceptualization, Editing and revision, Methodology, and manuscript preparation); Heba Salah (Manuscript writing, Data acquisition, Software analysis, Conceptualization, Methodology, and manuscript preparation). The author confirms sole responsibility for the following: study Manuscript writing, Data acquisition, Software analysis, Supervision, Conceptualization, Editing and revision, Methodology, and manuscript preparation. Data availability All data generated or analyzed during this study are included in this manuscript. Further data including source data are available from the corresponding author on reasonable request. Ethics approval and consent to participate. Not applicable. Consent for publication. Not applicable. Competing interests The authors declare no competing interests. Funding declarations The coauthors declare that there is no funding for this manuscript. References Prosenc F, Piechocka J, Škufca D, Heath E, Griessler Bulc T, Istenič D, et al. Microalgae-based removal of contaminants of emerging concern: Mechanisms in Chlorella vulgaris and mixed algal-bacterial cultures. J Hazard Mater. 2021;418:126284. Mishra RK, Mentha SS, Misra Y, Dwivedi N. Emerging pollutants of severe environmental concern in water and wastewater: A comprehensive review on current developments and future research. Water-Energy Nexus. 2023;6:74–95. Luo Y, Guo W, Ngo HH, Nghiem LD, Hai FI, Zhang J, et al. 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Int J Biol Macromol. 2023;253. Leng L, Wei L, Xiong Q, Xu S, Li W, Lv S, et al. Use of microalgae based technology for the removal of antibiotics from wastewater: A review. Chemosphere [Internet]. 2020;238:124680. Available from: https://doi.org/10.1016/j.chemosphere.2019.124680 Rodiguez S, Cano P, Adroguer M. Removal and Degradation of Pharmaceutically Active Compounds in Wastewater Treatment. Handb. Environ. Chem. 2021. Xiong JQ, Kurade MB, Kim JR, Roh HS, Jeon BH. Ciprofloxacin toxicity and its co-metabolic removal by a freshwater microalga Chlamydomonas mexicana. J Hazard Mater. 2017;323:212–9. Bai X, Acharya K. Algae-mediated removal of selected pharmaceutical and personal care products (PPCPs) from Lake Mead water. Sci Total Environ. 2017;581–582:734–40. Hom-Diaz A, Norvill ZN, Blánquez P, Vicent T, Guieysse B. Ciprofloxacin removal during secondary domestic wastewater treatment in high rate algal ponds. Chemosphere. 2017;180:33–41. Al-Mashhadani ESM, Al-Mashhadani MKH. Utilization of Chlorella vulgaris after the Extraction Process in Wastewater Treatment as a Biosorption Material for Ciprofloxacin Removal. J Ecol Eng. 2023;24:1–15. Babel S, Kurniawan TA. Cr(VI) removal from synthetic wastewater using coconut shell charcoal and commercial activated carbon modified with oxidizing agents and/or chitosan. Chemosphere. 2004;54:951–67. Gao R, Wang J. Effects of pH and temperature on isotherm parameters of chlorophenols biosorption to anaerobic granular sludge. J Hazard Mater. 2007;145:398–403. Zhu X, Tsang DCW, Chen F, Li S, Yang X. Ciprofloxacin adsorption on graphene and granular activated carbon: Kinetics, isotherms, and effects of solution chemistry. Environ Technol (United Kingdom). 2015;36:3094–102. Çetinkaya Dönmez G, Aksu Z, Öztürk A, Kutsal T. A comparative study on heavy metal biosorption characteristics of some algae. Process Biochem. 1999;34:885–92. Danalıoğlu ST, Bayazit ŞS, Kerkez Kuyumcu Ö, Salam MA. Efficient removal of antibiotics by a novel magnetic adsorbent: Magnetic activated carbon/chitosan (MACC) nanocomposite. J Mol Liq. 2017;240:589–96. El-Shafey ESI, Al-Lawati H, Al-Sumri AS. Ciprofloxacin adsorption from aqueous solution onto chemically prepared carbon from date palm leaflets. J Environ Sci. 2012;24:1579–86. de Oliveira Carvalho C, Costa Rodrigues DL, Lima ÉC, Santanna Umpierres C, Caicedo Chaguezac DF, Machado Machado F. Kinetic, equilibrium, and thermodynamic studies on the adsorption of ciprofloxacin by activated carbon produced from Jerivá (Syagrus romanzoffiana). Environ Sci Pollut Res. 2019;26:4690–702. Li N, Wang P, Wang S, Wang C, Zhou H, Kapur S, et al. Electrostatic charges on microalgae surface: Mechanism and applications. J Environ Chem Eng. 2022;10:107516. Yin D, Xu Z, Shi J, Shen L, He Z. Adsorption characteristics of ciprofloxacin on the schorl: Kinetics, thermodynamics, effect of metal ion and mechanisms. J Water Reuse Desalin. 2018;8:350–9. Habibzadeh M, Chaibakhsh N, Naeemi AS. Optimized treatment of wastewater containing cytotoxic drugs by living and dead biomass of the freshwater microalga, Chlorella vulgaris. Ecol Eng. 2018;111:85–93. Tran HN, You SJ, Hosseini-Bandegharaei A, Chao HP. Mistakes and inconsistencies regarding adsorption of contaminants from aqueous solutions: A critical review. Water Res. 2017;120:88–116. Qalyoubi L, Al-Othman A, Al-Asheh S. Removal of ciprofloxacin antibiotic pollutants from wastewater using nano-composite adsorptive membranes. Environ Res. 2022;215:114182. M-Ridha MJ, Zeki SL, Mohammed SJ, Abed KM, Hasan HA. Heavy Metals Removal from Simulated Wastewater using Horizontal Subsurface Constructed Wetland. J Ecol Eng. 2021;22:243–50. Balarak D, Mahvi AH, Shim MJ, Lee SM. Adsorption of ciprofloxacin from aqueous solution onto synthesized NiO: Isotherm, kinetic and thermodynamic studies. Desalin Water Treat. 2021;212:390–400. Kumar J. Photoelectron spectroscopy: Fundamental principles and applications. Handb. Mater. Charact. 2018. Chen Y, Zou C, Mastalerz M, Hu S, Gasaway C, Tao X. Applications of micro-fourier transform infrared spectroscopy (FTIR) in the geological sciences—A Review. Int J Mol Sci. 2015;16:30223–50. Wang SH, Griffiths PR. Resolution enhancement of diffuse reflectance i.r. spectra of coals by Fourier self-deconvolution: 1. C-H stretching and bending modes. Fuel. 1985;64:229–36. Mecozzi M, Pietroletti M, Scarpiniti M, Acquistucci R, Conti ME. Monitoring of marine mucilage formation in Italian seas investigated by infrared spectroscopy and independent component analysis. Environ Monit Assess. 2012;184:6025–36. Dharani V. Fourier transform infrared (FTIR) spectroscopy for the analysis of lipid from chlorella vulgaris. / Elixir Appl Biol [Internet]. 2013;61:16753. Available from: https://www.researchgate.net/publication/278158162 Indhumathi P, Soundararajan M, Syed Shabudeen PS, Shoba US, Suresh E. Utilization, isolation and characterization of Chlorȩlla vulgaris for carbon sequestration and waste water treatment by performing FTIR spectral studies. Asian J Microbiol Biotechnol Environ Sci. 2013;15:661–6. Zhang Z, Yan K, Zhang L, Wang Q, Guo R, Yan Z, et al. A novel cadmium-containing wastewater treatment method: Bio-immobilization by microalgae cell and their mechanism. J. Hazard. Mater. 2019. p. 420–7. Brandenburg K, Seydel U. Infrared spectroscopy of glycolipids. Chem Phys Lipids. 1998;96:23–40. Painter P, Starsinic M, Coleman M. DETERMINATION OF FUNCTIONAL GROUPS IN COAL BY FOURIER TRANSFORM INTERFEROMETRY. Fourier Transform Infrared Spectra. 1985;169–241. Xie Q, Liu N, Lin D, Qu R, Zhou Q, Ge F. The complexation with proteins in extracellular polymeric substances alleviates the toxicity of Cd (II) to Chlorella vulgaris. Environ Pollut. 2020;263:114102. Zhang J, Li Q, Zeng Y, Zhang J, Lu G, Dang Z, et al. Bioaccumulation and distribution of cadmium by Burkholderia cepacia GYP1 under oligotrophic condition and mechanism analysis at proteome level. Ecotoxicol Environ Saf. 2019;176:162–9. Singh S, Verma E, Niveshika, Tiwari B, Mishra AK. Exopolysaccharide production in Anabaena sp. PCC 7120 under different CaCl2 regimes. Physiol Mol Biol Plants. 2016;22:557–66. Additional Declarations No competing interests reported. Cite Share Download PDF Status: Published Journal Publication published 17 Dec, 2024 Read the published version in Microbial Cell Factories → Version 1 posted Editorial decision: Revision requested 08 Aug, 2024 Reviews received at journal 19 Jul, 2024 Reviews received at journal 18 Jul, 2024 Reviewers agreed at journal 10 Jul, 2024 Reviewers agreed at journal 09 Jul, 2024 Reviewers invited by journal 08 Jul, 2024 Editor assigned by journal 22 Jun, 2024 Submission checks completed at journal 22 Jun, 2024 First submitted to journal 17 Jun, 2024 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-4596545","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":326634237,"identity":"33fcf54c-02bb-4e69-9cf1-69ab9587fa6e","order_by":0,"name":"Heba Salah","email":"","orcid":"","institution":"Beni-Suef University","correspondingAuthor":false,"prefix":"","firstName":"Heba","middleName":"","lastName":"Salah","suffix":""},{"id":326634238,"identity":"8fd7467e-19b5-49bf-9b29-3007ad174c68","order_by":1,"name":"Nabila Shehata","email":"","orcid":"","institution":"Beni-Suef University","correspondingAuthor":false,"prefix":"","firstName":"Nabila","middleName":"","lastName":"Shehata","suffix":""},{"id":326634239,"identity":"005c9ed8-34f2-4922-8d35-44ab67aafce9","order_by":2,"name":"Noha Khedr","email":"","orcid":"","institution":"Beni-Suef University","correspondingAuthor":false,"prefix":"","firstName":"Noha","middleName":"","lastName":"Khedr","suffix":""},{"id":326634240,"identity":"69e6d743-88d4-4c4f-ba20-d27ee482a44f","order_by":3,"name":"Khaled N. M. Elsayed","email":"data:image/png;base64,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","orcid":"","institution":"Beni-Suef University","correspondingAuthor":true,"prefix":"","firstName":"Khaled","middleName":"N. M.","lastName":"Elsayed","suffix":""}],"badges":[],"createdAt":"2024-06-18 01:37:34","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-4596545/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-4596545/v1","draftVersion":[],"editorialEvents":[{"content":"https://doi.org/10.1186/s12934-024-02591-y","type":"published","date":"2024-12-17T15:58:37+00:00"}],"editorialNote":"","failedWorkflow":false,"files":[{"id":60623524,"identity":"6ae99c3e-64d2-4caa-9801-b7b4dc9a2bf4","added_by":"auto","created_at":"2024-07-18 21:50:17","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":6229,"visible":true,"origin":"","legend":"\u003cp\u003eThe structure of CIP (purity \u0026gt;98%, molecular weight, 331.3 g/moL)\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-4596545/v1/066ce63b574e2d13213017a6.png"},{"id":60623527,"identity":"b9bdbf4b-de13-438f-943b-914f1b5ad291","added_by":"auto","created_at":"2024-07-18 21:50:17","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":166804,"visible":true,"origin":"","legend":"\u003cp\u003epKa values of CIP and ionic forms of CIP.\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-4596545/v1/5a3a238fb75ef5eadd1dd118.png"},{"id":60623904,"identity":"d0016304-9fa5-410f-8189-3791b5320f24","added_by":"auto","created_at":"2024-07-18 21:58:17","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":121075,"visible":true,"origin":"","legend":"\u003cp\u003eEffect of pH of solution on the biosorption of CIP onto \u003cem\u003eC. vulgaris\u003c/em\u003eand\u003cem\u003e Synechocystis\u003c/em\u003e sp. at an initial concentration of 20 mg/L and room temperature of 20 °C.\u003c/p\u003e","description":"","filename":"floatimage3.png","url":"https://assets-eu.researchsquare.com/files/rs-4596545/v1/3a19b7e804774e4284e1803f.png"},{"id":60623905,"identity":"27b2a323-0cfd-41b8-867c-3cedd8d468f6","added_by":"auto","created_at":"2024-07-18 21:58:17","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":487300,"visible":true,"origin":"","legend":"\u003cp\u003eAdsorption isotherm modeling of Microalgae and CIP: (a) \u003cem\u003eChlorella vulgaris\u003c/em\u003e and (b) \u003cem\u003eSynechocystis\u003c/em\u003e sp.\u003c/p\u003e","description":"","filename":"floatimage4.png","url":"https://assets-eu.researchsquare.com/files/rs-4596545/v1/54d141e0392c83ca9a2995f6.png"},{"id":60623526,"identity":"4262e042-9eba-457a-a88b-55ee77f03e67","added_by":"auto","created_at":"2024-07-18 21:50:17","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":738816,"visible":true,"origin":"","legend":"\u003cp\u003ethe kinetic modeling of the biosorption of CIP onto 50 mg/L of \u003cem\u003eC. vulgaris\u003c/em\u003e, \u003cem\u003eSynechocystis\u003c/em\u003esp. (a) \u003cem\u003eC. vulgaris conc. \u003c/em\u003e10 mg/L of CIP\u003cem\u003e, \u003c/em\u003e(b)\u003cem\u003e C. vulgaris conc. \u003c/em\u003e\u003cstrong\u003e20 mg/L \u003c/strong\u003eCIP\u003cem\u003e,\u003c/em\u003e (c)\u003cem\u003eSynechocystis\u003c/em\u003e sp. at conc. 10 mg/L\u003cem\u003e \u003c/em\u003eCIP\u003cem\u003e \u003c/em\u003e(d)\u003cem\u003e Synechocystis\u003c/em\u003esp. at conc. \u003cstrong\u003e20 mg/L \u003c/strong\u003eCIP.\u003c/p\u003e","description":"","filename":"floatimage5.png","url":"https://assets-eu.researchsquare.com/files/rs-4596545/v1/33391bd049c3a3709372c0de.png"},{"id":60623529,"identity":"6af8dff6-8095-4aeb-aa1f-e8d4b4494505","added_by":"auto","created_at":"2024-07-18 21:50:17","extension":"png","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":558816,"visible":true,"origin":"","legend":"\u003cp\u003eThe FT-IR of \u003cem\u003eC. vulgaris\u003c/em\u003e (a) and \u003cem\u003eSynechocystis\u003c/em\u003eSp. (b) before and after CIP adsorption\u003c/p\u003e","description":"","filename":"floatimage6.png","url":"https://assets-eu.researchsquare.com/files/rs-4596545/v1/f888dd91a1c1a49b7fbe7750.png"},{"id":60623531,"identity":"d9eed844-4ffd-4a87-b307-2638de2d94a4","added_by":"auto","created_at":"2024-07-18 21:50:17","extension":"png","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":2132080,"visible":true,"origin":"","legend":"\u003cp\u003eScanning Electron Microscope images of \u003cem\u003eC. vulgaris\u003c/em\u003e before (a) and after (b) biosorption of CIP and \u003cem\u003eSynechocystis\u003c/em\u003e sp. before (c) and after (d) biosorption of CIP\u003c/p\u003e","description":"","filename":"floatimage7.png","url":"https://assets-eu.researchsquare.com/files/rs-4596545/v1/daa89e272e2e617694414325.png"},{"id":60623906,"identity":"9f334b09-a9d4-4fbf-9356-bd8a6e794537","added_by":"auto","created_at":"2024-07-18 21:58:17","extension":"png","order_by":8,"title":"Figure 8","display":"","copyAsset":false,"role":"figure","size":5386367,"visible":true,"origin":"","legend":"\u003cp\u003eMapping and EDX of\u003cem\u003e C. vulgaris \u003c/em\u003ebiomass\u003c/p\u003e","description":"","filename":"8.png","url":"https://assets-eu.researchsquare.com/files/rs-4596545/v1/b6c12a4024711a830c1ebda7.png"},{"id":60623532,"identity":"174782c8-92a1-4817-a15f-b10a17f6aa1f","added_by":"auto","created_at":"2024-07-18 21:50:17","extension":"png","order_by":9,"title":"Figure 9","display":"","copyAsset":false,"role":"figure","size":4910264,"visible":true,"origin":"","legend":"\u003cp\u003eMapping and EDX of\u003cem\u003e Synechocystis\u003c/em\u003e sp.\u003c/p\u003e","description":"","filename":"9.png","url":"https://assets-eu.researchsquare.com/files/rs-4596545/v1/e4c2bea74a14be3056ab4580.png"},{"id":72202031,"identity":"d5677ba2-3324-48be-ac10-1af76fd8577d","added_by":"auto","created_at":"2024-12-23 16:13:45","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":19661355,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-4596545/v1/ef4b6ba6-d8d9-40d1-91d3-a037dd0f60c9.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Management of a ciprofloxacin as a contaminant of emerging concern in water using microalgae bioremediation: mechanism, modeling, and kinetic studies","fulltext":[{"header":"Introduction","content":"\u003cp\u003eConventional water treatment systems have been shown to provide inadequate treatment of pollutants of emergent concern (CEC) [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]. The increasing worldwide contamination of freshwater with a manifold of pharmaceutical residues threatens aquatic organisms and human health. The environmental effects of pharmaceuticals, antibiotics, and disinfectants are of increasing concern [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]. The CEC has posed raising concerns recently. They are increasingly discharged in water and wastewater at worryingly high levels and being treated ineffectively in water and wastewater treatment systems. The CEC can be classified as pharmaceuticals, personal care products, pesticides and industrial chemicals [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]. Due to the inevitable environmental release, antibiotics have been detected in global water which brings challenges to not only targeted bacteria but also to the health of non-target species such as fishes, plants, and algae [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]. Wastewater from animal husbandry, aquaculture, and the pharmaceutical industry is the major source of antibiotics in the environment [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]. Pharmaceutical residues are responsible for a number of harmful pollutants, such as antibiotics [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eAntibiotics are often found in various environments and can be extremely dangerous for both human health and ecosystems [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]. Pollutants not subject to regulation are increasingly found in wastewater discharges, due to modern consumption patterns. These compounds are generally referred to be contaminants of emergent concern (CEC) due to the potential effects of their existence in the world's water systems. Pharmaceuticals, personal care products, industrial additives, insecticides, and a variety of chemical compounds have all been detected in wastewater [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e, \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]. Antibiotics, including ciprofloxacin (CIP), are used to mitigate or cure microbial infections and illnesses in veterinary, human, and aquatic systems by targeting specific bacteria. These antibiotics continually enter the aquatic environment by multiple pathways, such as hospital wastewater and pharmaceutical wastewater, veterinary, human excretions, and sewers, reaching treatment facilities in amounts ranging from ng/L to µg/L [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e]. The occurrence of CIP in the surface water could achieved 5.02 mg/ L [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]. The emergence of antibiotic-resistant genes (ARGs) and bacteria (ARBs), which cause 700,000 annual fatalities, is the main issue connected to antibiotic-polluted water [\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]. Due to their resistance to the specific antibiotics suggested for their therapy, ARBs are extremely difficult to treat [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eCiprofloxacin (CIP) is a significant pharmaceutical drug belonging to the fluoroquinolone (FQ) class that targets both Gram-positive and Gram-negative bacteria to treat serious illnesses. Its global emissions are primarily found in surface water, which accounts for 25% of the total emission, and municipal wastewater, which accounts for 58% of the total emission [\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e]. This family of antibiotics is extremely mobile in the aquatic environment due to its hydrophilic characteristics. fluoroquinolone antibiotic ciprofloxacin is found in a variety of sources, including drinking water and WWTP effluents, due to its significant usage in both human and veterinary medicine [\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e]. Like other antibiotics, CIP can stack up in the cells of an organism and pose a major risk to human health. The successful removal of CIP is therefore feasible given adequate consideration to their high levels in a variety of wastewaters, stability, resistance to decomposition, and possible ecotoxicity [\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e]. Antibiotic removal has been accomplished by a variety of methods, including coagulation, membrane separation, advanced oxidation, adsorption, photocatalysis, electrolysis, and biological degradation. These methods have several drawbacks, including high energy and material costs and secondary contamination from the addition of other chemicals. Adsorption, on the other hand, is the most adaptable and extensively utilized of these because of its great removal capacity, high efficiency, straightforward design, and simplicity of usage. In this regard, biosorption which relies on the ability of various types of live and inactive dead biomasses (heat, dried, chemically treated) to bind and concentrate contaminants from water-based solutions has emerged as an environmentally friendly, practical, and financially viable method for the removal of antibiotics [\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e]. An ecologically benign method with great promise for antibiotic elimination is microalgae-based wastewater treatment. The precise antibiotics and microalgae species used, however, determine how well CIP is removed by microalgae [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e, \u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eMicroalgae are photosynthetic eukaryotic or prokaryotic organisms that can grow single, in chains or colonies, or filamentous forms. They can be found in a variety of ecosystems, including airborne, aquatic, and terrestrial habitats [\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e]. Microalgae serve a significant role in the oxygen production in aquatic ecosystems, as well as an important element of the food chain. Microalgae have attracted interest in the bioremediation research community for their capacity for acclimation and eliminating the antibiotics themselves from contaminated water, yielding important biomass [\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]. The antibiotic removal effectiveness of the adsorption technique is strongly reliant on the adsorbent, which is often costly. Accelerated oxidation and photocatalysis may be usually successful, but they require expensive chemical agents or catalysts, as well as the potential generation of secondary pollutants. In contrast, microalgae wastewater treatment is a biological process that requires minimal chemical agents and may be tailored to successfully remove new pollutants such as antibiotics [\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e]. The biosorption efficiency depends on the sorbent properties (Microalgae) and pollutant structures [\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e]. In microalgae, the cell walls include polymer assemblages and functional groups that can facilitate biosorption [\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eFactors affecting antibiotic removal performance by microalgae are (1) algal species, (2) antibiotic classes and concentration, (3) algal growth conditions [\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e]. Some literature comparing different algal species on ciprofloxacin removal is presented in Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e. This study aimed to determine the biosorption capability of Synechocystis sp. and C. vulgaris for antibiotic ciprofloxacin at different concentrations and investigated in comparison with the control medium. The selected microalgae species are \u003cem\u003eSynechocystis\u003c/em\u003e sp. and \u003cem\u003eChlorella vulgaris\u003c/em\u003e without modification in powder form at a constant concentration in the removal of CIP as CEC. A thorough investigation is conducted on process optimization by the adjustment of process parameters, such as time, pH, dosage, and starting concentration, in addition to the isotherm of adsorption and kinetic investigations.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e\u003cdiv class=\"gridtable\"\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\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\u003eIllustrate removal of ciprofloxacin by different Microalgae species and removal mechanisms.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e\u003ccolgroup cols=\"5\"\u003e\u003c/colgroup\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMicroalgae\u003c/p\u003e \u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eInitial antibiotic concentration and removal rate, hydraulic retention time\u003c/p\u003e \u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eremoval mechanisms.\u003c/p\u003e \u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eWW Category\u003c/p\u003e \u003c/th\u003e\u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eRef.\u003c/p\u003e \u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eChlamydomonas mexicana\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e2 mg/L and 13%, 11d\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eBiodegradation, accumulation, and adsorption\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eBold’s Basal medium\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e[\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e]\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eNannochloris sp.\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e57 ng/L and 100%, 7d\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eDirect photolysis\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eWater from Las Vegas wash\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e[\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e]\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eChlamydomonas pitschmannii\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e2 mg/L and 1.6%, 11d\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eBiodegradation, accumulation, and adsorption\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eBold’s Basal medium\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e[\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e]\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eOurococcus multisporus\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e2 mg/L and 2%, 11d\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eBiodegradation, accumulation, and adsorption\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eBold’s Basal medium\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e[\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e]\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eChlorella Vulgaris\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e2 mg/L and 0%, 11d\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eBiodegradation, accumulation, and adsorption\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eBold’s Basal medium\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e[\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e]\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eChlamydomonas Mexicana\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e2 mg/L and 56%, 11d\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eBiodegradation, accumulation, and adsorption\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eBold’s Basal medium + sodium acetate (4g/L)\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e[\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e]\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eThe mixture of algae-bacteria consortia in pilot high-rate algae pond (HRAP)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1.31 mg/L and 20.1%, 24h (8 h sunlight/16h dark)\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003ePhotodegradation during daytime, and adsorption during nighttime\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eReal domestic wastewater\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e[\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e]\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/table\u003e\u003c/div\u003e \u003cp\u003e\u003c/p\u003e\n\n \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e "},{"header":"Reagents and Materials","content":"\u003cp\u003eCiprofloxacin, C\u003csub\u003e17\u003c/sub\u003eH\u003csub\u003e18\u003c/sub\u003eFN\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e, is supplied from Organo for pharmaceutical and chemical industries (ORGANO PHARMA), Egypt. CIP concentrations were 10 mg/L, and 20 mg/L in the examination. Figures\u0026nbsp;(1) represents the chemical structure of CIP. The molecular weight of CIP is 331.34 g/mol. The molecular structure of CIP is given in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e [\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e]. pKa values of CIP and ionic forms of CIP is shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e [\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e].\u003c/p\u003e\u003ch2\u003e2.2 Algae and Incubation Conditions:\u003c/h2\u003e\u003cp\u003eIn BG11 cultivation medium, \u003cem\u003eC. vulgaris\u003c/em\u003e was grown with the addition of NaCl, while \u003cem\u003eSynechocystis sp\u003c/em\u003e., which is sensitive to NaCl, was also grown in BG11 cultivation medium, but without the addition of NaCl. Fluorescent light was used for a 12 h light/12h dark cycle at 20 º C.\u003c/p\u003e\u003ch2\u003e2.3 CIP concentrations in removal technique:\u003c/h2\u003e\u003cp\u003eCIP is used in different concentrations with constant algal concentration. To measure the removal efficiency of CIP by microalgae, we prepare 0.1 g from selected microalgae species in 200 ml distant water (control sample). The CIP concentrations were 2 mg, and 4mg in prepared media, 0.1 microalgae in 200 ml distant water (test samples).\u003c/p\u003e\u003ch2\u003e2.4 Bio-adsorption studies:\u003c/h2\u003e\u003cp\u003eThe monitoring was carried out by taking 5mL aliquots of medium for the determination of CIP concentration. All samples were centrifuged in the Universal Centrifuge Model: PLC-036 GEMMYCO made in Taiwan (model of centrifuge) before analysis. The maximum absorbance for \u003cem\u003eC. vulgaris\u003c/em\u003e and \u003cem\u003eSynechocystis sp.\u003c/em\u003e algae name was inspected by scanning between 200 and 400 nm using a UV-Vis spectrophotometer 1800 UV-2600 (Shimadzu, Japan), and the maximum absorbance was found at 400 nm. All experiments were carried out in repeat and the average results were reported. All graph plotting was carried out with the origin.\u003c/p\u003e"},{"header":"Results and Discussion","content":"\u003cdiv id=\"Sec7\" class=\"Section2\"\u003e \u003ch2\u003e3.1 Impact of pH\u003c/h2\u003e \u003cp\u003eTo investigate the effect of pH on the adsorption of CIP, 20 mg/L CIP solution was mixed with 0.5 g/L microalgae by using a shaker for 12 hours at different pH values ranging from 3.0 to 11.0. the optimum pH values for the biosorption CIP onto \u003cem\u003eC. vulgaris\u003c/em\u003e and \u003cem\u003eSynechocystis\u003c/em\u003e sp. is 3.5 and 5.5, respectively which corresponds to removal efficiency of 90%. The optimal pH is vital because it affects ionization degree, adsorbent surface charge, and speciation of the adsorbate [\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e, \u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e]. two pKa values of CIP: for the basic-N moiety is 8.89 ± 0.11 and for the carboxylic acid group is 5.90 ± 0.15 [\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e]. The acid dissociation constant (pKa) of CIP is less than 6.0 when it is in its cation form because the amine group has been protonated, and it is more than 8.7 when it is in its anion form because the carboxylic group has lost a proton. The majority of CIP molecules are zwitterionic species, and their pH range is 6.0–8.7. [\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e, \u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e]. \u003cem\u003eC. vulgaris\u003c/em\u003e and \u003cem\u003eSynechocystis\u003c/em\u003e have a pH\u003csub\u003eZPC\u003c/sub\u003e of 3.0. Hence, when the pH increased from pH 1 to pH 3, the removal of CIP increased because of improved electrostatic attraction which results from the opposite charge between the CIP and the microalgae. In contrast, at high pH, CIP removal was significantly reduced. This may be due to the zwitterionic nature of CIP. At higher pH (pH \u0026gt; 5.9), both CIP and the algal biomass possess negative charges and the repulsion forces will be the dominant.\u003c/p\u003e \u003cp\u003eFigure \u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e illustrates that pH ranges from 3 to 7 resulting in higher CIP adsorption because of hydrophobic interactions between functional groups on the waste surface of \u003cem\u003eC. vulgaris\u003c/em\u003e and CIP are responsible for the mechanism of biosorption. Comparing the removal of CIP efficiency at different pH, the adsorption of CIP decreases due to increased pH. pKa value of CIP was 8.7 for the amine group and the value of pKa of CIP was 6.1 for the carboxylic acid group on piperazine moiety [\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e]. Due to the carboxyl group's proton being removed, CIP is present in an anion form [\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e, \u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e]. CIP is a cation that is present in solutions with a pH lower than 6.1, but likewise, CIP is present in solution as a zwitterionic form when the pH of the solution ranges from 6.1 to 8.7. The removal of CIP increased when the pH was less than 6, for the reason that electrostatic charge on the algae surface and CIP [\u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e]. However, CIP removal was significantly reduced at high pH. It may occur due to algae surface charging and the nature of the zwitterion of CIP. High removal efficiencies are the result of ionic interactions between the surface of the adsorbent and CIP in acidic solutions [\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e, \u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e, \u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e]. The opposite charge between the electrostatic charging on the microalgae surface and the CIP causes electrostatic attraction, which leads to high removal efficiency.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec8\" class=\"Section2\"\u003e \u003ch2\u003e3.2 Adsorption isotherm modeling\u003c/h2\u003e \u003cp\u003eThe adsorption isotherm can be used to determine the biosorbent's capability as well as the adsorption behavior required to remove the pollutant [\u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e34\u003c/span\u003e]. The Langmuir, Freundlich, Dubinin-Radushkevich, Baudu, and Fritz-Schlunder biosorption isotherms were used in the current study to investigate the characteristics of each of \u003cem\u003eC. vulgaris\u003c/em\u003e's and \u003cem\u003esynechocystis\u003c/em\u003e's characteristics in the removal of CIP. Adsorption models in a nonlinear form are statistically more dependable compared to models in a linear form [\u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e35\u003c/span\u003e]. To determine the equilibrium adsorption capacity, use the following equation [\u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e36\u003c/span\u003e]:\u003c/p\u003e\u003cdiv id=\"Equa\" class=\"Equation\"\u003e\u003cdiv format=\"TEX\" class=\"mathdisplay\" id=\"FileID_Equa\" name=\"EquationSource\"\u003e\n$${q}_{e}=\\frac{v\\left({C}_{i}-{C}_{e}\\right)}{m}$$\u003c/div\u003e\u003c/div\u003e\u003cp\u003e\u003c/p\u003e \u003cp\u003eWhere q\u003csub\u003ee\u003c/sub\u003e equilibrium adsorption capacity q\u003csub\u003ee\u003c/sub\u003e (mg/g), V refers to the sample's volume (L), C\u003csub\u003ei\u003c/sub\u003e represents the beginning concentration of the solute (mg/L), C\u003csub\u003ee\u003c/sub\u003e is the equilibrium concentration of the solute (mg/L) and m is the quantity of adsorbent used (g). Use the following equation to determine the percentage of contaminant water removal [\u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e37\u003c/span\u003e]\u003c/p\u003e\u003cdiv id=\"Equb\" class=\"Equation\"\u003e\u003cdiv format=\"TEX\" class=\"mathdisplay\" id=\"FileID_Equb\" name=\"EquationSource\"\u003e\n$$\\text{R}\\text{e}\\text{m}\\text{o}\\text{v}\\text{a}\\text{l} \\text{e}\\text{f}\\text{f}\\text{i}\\text{c}\\text{i}\\text{e}\\text{n}\\text{c}\\text{y}=\\frac{{C}_{i}-{C}_{e}}{{C}_{i}}\\times 100\\%$$\u003c/div\u003e\u003c/div\u003e\u003cp\u003e\u003c/p\u003e \u003cp\u003eTen models have been investigated for the biosorption of CIP onto \u003cem\u003eC. vulgaris\u003c/em\u003e and \u003cem\u003eSynechocystis\u003c/em\u003e sp.1 (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e. And Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e.). The results showed that the Freundlich model is\u003c/p\u003e \u003cp\u003ethe best to describe the CIP@ \u003cem\u003eC. vulgaris\u003c/em\u003e where the calculated adsorption capacity is close to the calculated one in addition to a high correlation coefficient (R\u003csup\u003e2\u003c/sup\u003e = 0.944), followed by Dubinin-Radushkevich and Langmuir with q\u003csub\u003emax\u003c/sub\u003e 10.32 and 14.37 mg/g and R\u003csup\u003e2\u003c/sup\u003e = 0.903 and 0.943, respectively [\u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e38\u003c/span\u003e]. The other models are not suitable for describing the CIP@ \u003cem\u003eC. vulgaris\u003c/em\u003e system such as Baudu, Redlich-Peterson, and Khan even with their high correlation coefficients (R\u003csup\u003e2\u003c/sup\u003e = 0.953, 0.948, and 0.948, respectively) where the predicted q\u003csub\u003emax\u003c/sub\u003e according to these models are less than the experimental one. Also, the Sips and Toth models didn’t fit the data well where the calculated values of q\u003csub\u003emax\u003c/sub\u003e according to these models are higher than the experimental one even with their high R\u003csup\u003e2\u003c/sup\u003e values (0.944, and 0.944). Fritz-schlunder, and Langmuir-Freundlich can’t be used for the modeling of CIP@ \u003cem\u003eC. vulgaris\u003c/em\u003e system where R\u003csup\u003e2\u003c/sup\u003e is low (0.82 and 0.832, respectively) and the calculated values of q\u003csub\u003emax\u003c/sub\u003e are far away than the experimental one.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eFor the CIP@ \u003cem\u003eSynechocystis\u003c/em\u003e sp. system, Freundlich is the best model to describe the system with calculated q\u003csub\u003emax\u003c/sub\u003e close to the experimental one and acceptable R\u003csup\u003e2\u003c/sup\u003e (0.80). Followed by Redlich-Peterson (R\u003csup\u003e2\u003c/sup\u003e = 0.805). Baudu, Sips, Langmuir-Freundlich, Toth, Fritz-schlunder, and Kahn failed to describe the CIP system where the predicted q\u003csub\u003emax\u003c/sub\u003e values according to these models are far away from the experimental one. Although Langmuir and Dubinin-Radushkevich yield calculated q\u003csub\u003emax\u003c/sub\u003e close to the experimental, however, R\u003csup\u003e2\u003c/sup\u003e is low 0.748 and 0.726, respectively.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e\u003cdiv class=\"gridtable\"\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\u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c8\" colnum=\"8\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c9\" colnum=\"9\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c10\" colnum=\"10\"\u003e\u003c/div\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\u003eThe parameters of the adsorption isotherm model for CIP@ \u003cem\u003eC. Vulgaris\u003c/em\u003e and CIP@ \u003cem\u003eSynechocystis\u003c/em\u003e sp. systems\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e\u003ccolgroup cols=\"10\"\u003e\u003c/colgroup\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colspan=\"2\" nameend=\"c2\" namest=\"c1\"\u003e \u003cp\u003eAdsorption models\u003c/p\u003e \u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eParameter\u003c/p\u003e \u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003cem\u003eC. Vulgaris\u003c/em\u003e\u003c/p\u003e \u003c/th\u003e\u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u003cem\u003eSyn\u003c/em\u003e. Sp.\u003c/p\u003e \u003c/th\u003e\u003cth align=\"left\" colspan=\"2\" nameend=\"c7\" namest=\"c6\"\u003e \u003cp\u003eAdsorption models\u003c/p\u003e \u003c/th\u003e\u003cth align=\"left\" colname=\"c8\"\u003e \u003cp\u003eParameter\u003c/p\u003e \u003c/th\u003e\u003cth align=\"left\" colname=\"c9\"\u003e \u003cp\u003e\u003cem\u003eC. Vulgaris\u003c/em\u003e\u003c/p\u003e \u003c/th\u003e\u003cth align=\"left\" colname=\"c10\"\u003e \u003cp\u003e\u003cem\u003eSyn\u003c/em\u003e. Sp.\u003c/p\u003e \u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\" morerows=\"8\" rowspan=\"9\"\u003e \u003cp\u003e2- parameters isotherm\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\" morerows=\"2\" rowspan=\"3\"\u003e \u003cp\u003eLangmuir\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eq\u003csub\u003emax\u003c/sub\u003e\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e14.373\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e8.135\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\" morerows=\"19\" rowspan=\"20\"\u003e \u003cp\u003e3-parameters isotherm\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\" morerows=\"3\" rowspan=\"4\"\u003e \u003cp\u003eRedlich-Peterson\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003eK\u003csub\u003eR\u003c/sub\u003e\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e1.567\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e12.0\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eK\u003csub\u003eL\u003c/sub\u003e\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.063\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.303\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003ea\u003csub\u003eR\u003c/sub\u003e\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e0.452\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e4.3\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eR\u003csup\u003e2\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.943\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.748\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003eΒ\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e0.630\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e0.686\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\" morerows=\"2\" rowspan=\"3\"\u003e \u003cp\u003eFreundlich\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eK\u003csub\u003ef\u003c/sub\u003e\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e1.283\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e2.286\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003eR\u003csup\u003e2\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e0.948\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e0.805\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1/n\u003csub\u003eF\u003c/sub\u003e\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.598\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.370\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\" morerows=\"3\" rowspan=\"4\"\u003e \u003cp\u003eSips\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003eQ\u003csub\u003em\u003c/sub\u003e\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e11939.624\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e16276\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eR\u003csup\u003e2\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.944\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.800\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003eKs\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e0.000\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e0.000\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\" morerows=\"2\" rowspan=\"3\"\u003e \u003cp\u003eDubinin-Radushkevich\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eq\u003csub\u003emax\u003c/sub\u003e\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e10.322\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e7.452\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e1/n\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e0.598\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e0.370\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eK\u003csub\u003ead\u003c/sub\u003e\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.001\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.000\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003eR\u003csup\u003e2\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e0.944\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e0.800\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eR\u003csup\u003e2\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.903\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.726\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\" morerows=\"3\" rowspan=\"4\"\u003e \u003cp\u003eLangmuir-Freundlich\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e𝑞\u003csub\u003eMLF\u003c/sub\u003e\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e938.18\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e938.180\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\" morerows=\"4\" rowspan=\"5\"\u003e \u003cp\u003e4-parameters isotherm\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\" morerows=\"4\" rowspan=\"5\"\u003e \u003cp\u003eBaudu\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eq\u003csub\u003em\u003c/sub\u003e\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e1.379\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e2.43\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e𝐾LF\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e9.563\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e9.6E-08\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eb\u003csub\u003e0\u003c/sub\u003e\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e76.783\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e998.2\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e𝑀LF\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e0.372\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e0.372\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003ex\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.574\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.370\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003eR\u003csup\u003e2\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e0.832\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e0.800\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003ey\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e47.678\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e22.71\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\" morerows=\"3\" rowspan=\"4\"\u003e \u003cp\u003eToth\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003eK\u003csub\u003ee\u003c/sub\u003e\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e23362\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e46048\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eR\u003csup\u003e2\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.953\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.86\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003eK\u003csub\u003eL\u003c/sub\u003e\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e45336\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e32002\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\" morerows=\"5\" rowspan=\"6\"\u003e \u003cp\u003e5-parameters isotherm\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\" morerows=\"5\" rowspan=\"6\"\u003e \u003cp\u003eFritz-schlunder\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eq\u003csub\u003emFSS\u003c/sub\u003e\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e67.409\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e84.8\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003en\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e0.401\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e0.629\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eK\u003csub\u003e1\u003c/sub\u003e\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.202\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.254\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003eR\u003csup\u003e2\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e0.944\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e0.800\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eK\u003csub\u003e2\u003c/sub\u003e\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e9.924\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e8.305\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\" morerows=\"3\" rowspan=\"4\"\u003e \u003cp\u003eKahn\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003eQ\u003csub\u003em\u003c/sub\u003e\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e2.705\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e1.169\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003em\u003csub\u003e1\u003c/sub\u003e\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e6.385\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e6.25\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003eb\u003csub\u003eK\u003c/sub\u003e\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e0.486\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e6.695\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003em\u003csub\u003e2\u003c/sub\u003e\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e5.808\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e5.93\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003ea\u003csub\u003eK\u003c/sub\u003e\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e0.512\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e0.62\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eR\u003csup\u003e2\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.953\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.82\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003eR\u003csup\u003e2\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e0.948\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e0.86\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/table\u003e\u003c/div\u003e \u003cp\u003e\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec9\" class=\"Section2\"\u003e \u003ch2\u003eKinetics\u003c/h2\u003e \u003cp\u003eThe kinetic of the adsorption process yields significant insights to design a batch adsorption system and it also provides optimum operating conditions for full-scale operation. Therefore, the experimental results of CIP adsorption onto both microalgae were studied using pseudo 1st order (PFO), Pseudo 2nd order (PSO), Avrami, mixed 1st and 2nd (MFSO) and intraparticle diffusion models, whose results are represented in in Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003e and Tables\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eFour models; PFO, PSO, Avrami, and MFSO can describe the CIP@ \u003cem\u003eC. Vulgaris\u003c/em\u003e system, especially at the higher concentration of CIP following the order: MFSO (R\u003csup\u003e2\u003c/sup\u003e = 0.982) \u0026gt; PFO (R\u003csup\u003e2\u003c/sup\u003e = 0.981) and Avrami (R\u003csup\u003e2\u003c/sup\u003e = 0.981) \u0026gt; PSO (R\u003csup\u003e2\u003c/sup\u003e = 0.979) while in the lower concentration of CIP, MFSO (R\u003csup\u003e2\u003c/sup\u003e = 0.937) and PSO (R\u003csup\u003e2\u003c/sup\u003e = 0.937) are better than PFO (R2 = 0.890) and Avrami (R\u003csup\u003e2\u003c/sup\u003e = 0.890).\u003c/p\u003e \u003cp\u003eOn the other hand, the intraparticle diffusion model is not suitable for this system where the predicted data do not agree with the experimental one as well as R\u003csup\u003e2\u003c/sup\u003e values are low (0.484 − 0.065). For the CIP@Cy Sp., PFO (R\u003csup\u003e2\u003c/sup\u003e = 0.937), PSO (R\u003csup\u003e2\u003c/sup\u003e = 0.937), Avrami (R\u003csup\u003e2\u003c/sup\u003e = 0.937), and MFSO (R\u003csup\u003e2\u003c/sup\u003e = 0.937) can fit the data well with excellent matching between the experimental and the predicted data in addition to high values of R\u003csup\u003e2\u003c/sup\u003e while at lower concentrations, the correlation coefficients decreased to 0.708, 0.631, 0.708 and 0.708 for PFO, PSO, MFSO and Avrami models, respectively. On the other hand, the intraparticle diffusion model is not suitable for CIP@ \u003cem\u003eSynechocystis\u003c/em\u003e sp. at both initial concentrations of CIP.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e\u003cdiv class=\"gridtable\"\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\u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\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\u003eThe parameters of kinetic models describing the adsorption of CIP onto \u003cem\u003eC. vulgaris\u003c/em\u003e and \u003cem\u003eSynechocystis\u003c/em\u003e sp.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e\u003ccolgroup cols=\"6\"\u003e\u003c/colgroup\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eModel\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eParameters\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c4\" namest=\"c3\"\u003e \u003cp\u003e\u003cem\u003eC. vulgaris\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c6\" namest=\"c5\"\u003e \u003cp\u003e\u003cem\u003eSynechocystis\u003c/em\u003e sp.\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eConc. 10 mg/L\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eConc. 20 mg/L\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eConc. 10 mg/L\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003eConc. 20 mg/L\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\" morerows=\"2\" rowspan=\"3\"\u003e \u003cp\u003ePseudo-first-order\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eq\u003csub\u003ee\u003c/sub\u003e [mg/g]\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1.600\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e7.083\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.887\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e15.715\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003ek\u003csub\u003e1\u003c/sub\u003e [L/mg]\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.094\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.478\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.100\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.253\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eR\u003csup\u003e2\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.890\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.981\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.708\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.923\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\" morerows=\"2\" rowspan=\"3\"\u003e \u003cp\u003ePseudo-second-order\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eq\u003csub\u003ee\u003c/sub\u003e [mg/g]\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1.712\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e7.145\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.892\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e16.138\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003ek\u003csub\u003e2\u003c/sub\u003e\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.077\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.349\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.278\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.032\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eR\u003csup\u003e2\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.937\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.979\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.631\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.962\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\" morerows=\"3\" rowspan=\"4\"\u003e \u003cp\u003eThe Mixed 1, 2-order Model\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eq\u003csub\u003ee\u003c/sub\u003e [mg/g]\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1.710\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e7.098\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.887\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e16.124\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eK\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.000\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.175\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.100\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.001\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cem\u003ef\u003c/em\u003e\u003csub\u003e2\u003c/sub\u003e\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.998\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.859\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.998\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eR\u003csup\u003e2\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.937\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.982\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.708\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.962\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\" morerows=\"3\" rowspan=\"4\"\u003e \u003cp\u003eAvrami\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eq\u003csub\u003ee\u003c/sub\u003e [mg/g]\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1.600\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e7.083\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.887\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e15.715\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003ek\u003csub\u003eav\u003c/sub\u003e\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.380\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.854\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.390\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.621\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cem\u003en\u003c/em\u003e\u003csub\u003eav\u003c/sub\u003e\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.249\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.559\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.256\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.407\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eR\u003csup\u003e2\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.890\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.981\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.708\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.923\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\" morerows=\"2\" rowspan=\"3\"\u003e \u003cp\u003eIntraparticle diffusion\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003ek\u003csub\u003eip\u003c/sub\u003e\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.033\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.050\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.003\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.137\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cem\u003ec\u003c/em\u003e\u003csub\u003eip\u003c/sub\u003e\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.826\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e6.200\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.678\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e11.793\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eR\u003csup\u003e2\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.484\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.065\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.020\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.292\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/table\u003e\u003c/div\u003e \u003cp\u003e\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec10\" class=\"Section2\"\u003e \u003cdiv id=\"Sec11\" class=\"Section3\"\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv id=\"Sec12\" class=\"Section2\"\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec13\" class=\"Section2\"\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e"},{"header":"Discussion of the characterization results","content":"\u003ch2\u003eFTIR\u003c/h2\u003e\u003cp\u003eFourier transform infrared spectroscopy (FT-IR ) is a common instrumental tool used for the identification of several functional groups of any organic material (liquids, solids, and gases) by the measurement and determination of its emission spectra or infrared absorption [\u003cspan citationid=\"CR39\" class=\"CitationRef\"\u003e39\u003c/span\u003e]. The impact of CIP adsorption onto \u003cem\u003eC. vulgaris\u003c/em\u003e and \u003cem\u003eSynechocystis\u003c/em\u003e sp. on the change in its chemical structures was detected via FTIR analyses. The results showed that stretching vibration of water molecules owning to the intermolecular bonding of OH- appear at 3293.452 cm\u003csup\u003e− 1\u003c/sup\u003e and 3414.190 cm\u003csup\u003e− 1\u003c/sup\u003e for \u003cem\u003eC. vulgaris\u003c/em\u003e and \u003cem\u003eSynechocystis\u003c/em\u003e sp., respectively [\u003cspan citationid=\"CR40\" class=\"CitationRef\"\u003e40\u003c/span\u003e]. The asymmetrical (-C-H) and stretching (-C-H) vibration have been detected at 2933.767 cm\u003csup\u003e− 1\u003c/sup\u003e and 1400.41 cm\u003csup\u003e− 1\u003c/sup\u003e for \u003cem\u003eC. vulgaris\u003c/em\u003e and 2929.20 cm\u003csup\u003e− 1\u003c/sup\u003e \u003cem\u003eSynechocystis\u003c/em\u003e Sp. [\u003cspan citationid=\"CR41\" class=\"CitationRef\"\u003e41\u003c/span\u003e]. 2933.767 cm \u003csup\u003e− 1\u003c/sup\u003e belonging to CH and CH \u003csub\u003e2\u003c/sub\u003e groups the aliphatic of carbohydrates lipids and proteins. 1646.01 cm\u003csup\u003e− 1\u003c/sup\u003e C = O group amide I band of protein. the band of carbohydrate CO group at1041.408 cm\u003csup\u003e− 1\u003c/sup\u003e. 1535.336 cm\u003csup\u003e− 1\u003c/sup\u003e amide II band. 1539.176 cm\u003csup\u003e− 1\u003c/sup\u003eamide II band [\u003cspan citationid=\"CR42\" class=\"CitationRef\"\u003e42\u003c/span\u003e]. The presence of band 1539.176 cm\u003csup\u003e− 1\u003c/sup\u003e indicates the stretching vibration of N–H of amide II and the bending vibration of C–N. For \u003cem\u003eC. vulgaris\u003c/em\u003e, the characteristic bands appear at 3293.452 cm\u003csup\u003e− 1\u003c/sup\u003e (stretching, N-H of protein) [\u003cspan citationid=\"CR43\" class=\"CitationRef\"\u003e43\u003c/span\u003e, \u003cspan citationid=\"CR44\" class=\"CitationRef\"\u003e44\u003c/span\u003e], 1648.624 cm\u003csup\u003e− 1\u003c/sup\u003e (stretching, C = O of protein and C = C)[\u003cspan citationid=\"CR45\" class=\"CitationRef\"\u003e45\u003c/span\u003e], 1539.176 cm\u003csup\u003e− 1\u003c/sup\u003e (bending, amide (N-H and C-H) and Vibration (C-N) stretching of protein [\u003cspan citationid=\"CR46\" class=\"CitationRef\"\u003e46\u003c/span\u003e] and stretching, C = C) [\u003cspan citationid=\"CR43\" class=\"CitationRef\"\u003e43\u003c/span\u003e], 1400.407 cm\u003csup\u003e− 1\u003c/sup\u003e (stretching, C = C) [\u003cspan citationid=\"CR43\" class=\"CitationRef\"\u003e43\u003c/span\u003e], 1108.482 cm\u003csup\u003e− 1\u003c/sup\u003e (Carbohydrate V (-O-C) of polysaccharides, Nucleic acid, stretching of phosphodiesters Carbohydrate [\u003cspan citationid=\"CR44\" class=\"CitationRef\"\u003e44\u003c/span\u003e] and Alkyl stretching) [\u003cspan citationid=\"CR43\" class=\"CitationRef\"\u003e43\u003c/span\u003e], 1041.408 cm\u003csup\u003e− 1\u003c/sup\u003e (Carbohydrate V(C-O-C) of polysaccharides and alkyl stretching) and 613.338 cm\u003csup\u003e− 1\u003c/sup\u003e (Alkyl stretching). For \u003cem\u003eSynechocystis\u003c/em\u003e Sp., the characteristic bands were detected at 1646.01 cm-1 (C = O highly conjugated [\u003cspan citationid=\"CR47\" class=\"CitationRef\"\u003e47\u003c/span\u003e] and the stretching vibration of amide I in proteins [\u003cspan citationid=\"CR45\" class=\"CitationRef\"\u003e45\u003c/span\u003e], 1535.336 cm\u003csup\u003e− 1\u003c/sup\u003e (Carboxyl group in salt from –COO\u003csup\u003e−\u003c/sup\u003e [\u003cspan citationid=\"CR47\" class=\"CitationRef\"\u003e47\u003c/span\u003e], the stretching vibration of amide II in proteins,.[\u003cspan citationid=\"CR45\" class=\"CitationRef\"\u003e45\u003c/span\u003e] 1400.593 cm\u003csup\u003e− 1\u003c/sup\u003e (CH\u003csub\u003e3\u003c/sub\u003e [\u003cspan citationid=\"CR47\" class=\"CitationRef\"\u003e47\u003c/span\u003e], asymmetrical C-H bending mode of -CO-CH\u003csub\u003e2\u003c/sub\u003e- or CO-CH\u003csub\u003e3\u003c/sub\u003e groups [\u003cspan citationid=\"CR41\" class=\"CitationRef\"\u003e41\u003c/span\u003e], stretching vibration of C = O in the carboxyl group [\u003cspan citationid=\"CR48\" class=\"CitationRef\"\u003e48\u003c/span\u003e, \u003cspan citationid=\"CR49\" class=\"CitationRef\"\u003e49\u003c/span\u003e], 1114.017 cm\u003csup\u003e− 1\u003c/sup\u003e (C-O stretch and O–H bend in phenoxy structures, ethers [\u003cspan citationid=\"CR47\" class=\"CitationRef\"\u003e47\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eAfter the CIP adsorption, there is no significant change in the two spectra of the microalgae except the variation in the intensity of the bands. This may refer to that the adsorption process occurred due to the presence of amide, hydroxyl, carboxyl, and carbonyl groups. The intensity of the bands after CIP adsorption decreased in the case of \u003cem\u003eC. vulgaris\u003c/em\u003e (Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003ea) and increased in the case of \u003cem\u003eSynechocystis\u003c/em\u003e Sp. (Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003ea). This may be attributed to the involvement of various functional groups on \u003cem\u003eC. vulgaris\u003c/em\u003e in the attachment of CIP. and the formation of new bands with higher density in the case of \u003cem\u003eSynechocystis Sp\u003c/em\u003e. which agreed with the SEM results and adsorption isotherm modeling.\u003c/p\u003e\u003ch2\u003eSEM\u003c/h2\u003e\u003cp\u003eThe surface morphology of the two biomasses before and after CIP adsorption was observed using SEM (Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003e). The two biomasses exhibit heterogeneous surfaces and possess small cavities/crakes on their surfaces. Figures\u0026nbsp;(7a) confirms that \u003cem\u003eC. vulgaris\u003c/em\u003e is irregularly shaped, with a close, compact, and smoother structure, and after the biosorption of CIP (Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003eb), it exfoliated which may be attributed to the attachment of CIP to specific functional groups onto the biomass in monolayer form which is agreed with the results of the adsorption isotherm modeling.\u003c/p\u003e\u003cp\u003e \u003cem\u003eSynechocystis\u003c/em\u003e sp., (Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003ec), has an irregular shape. After adsorption, the surfaces of the cells were compact with some roughness. It can be seen also (Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003ed) the aggregation of some attachments onto the surface owing to the precipitation or accumulation of CIP on the cavity on the cell surface which agreed with the modeling results suggesting that Freundlich isotherm is the predominant in CIP@\u003cem\u003eSynechocystis\u003c/em\u003e Sp.\u003c/p\u003e\u003ch2\u003eMapping and EDX\u003c/h2\u003e\u003cp\u003eThe surface morphology of the two biomasses before and after CIP adsorption was observed using SEM (Fig.\u0026nbsp;\u003cspan refid=\"Fig8\" class=\"InternalRef\"\u003e8\u003c/span\u003e, and Fig.\u0026nbsp;\u003cspan refid=\"Fig9\" class=\"InternalRef\"\u003e9\u003c/span\u003e). The two biomasses exhibit heterogeneous surfaces and possess small cavities/crakes on their surfaces. Figures\u0026nbsp;(8a) confirms that \u003cem\u003eC. vulgaris\u003c/em\u003e is irregularly shaped, with a close, compact, and smoother structure, and after the biosorption of CIP (Fig.\u0026nbsp;\u003cspan refid=\"Fig8\" class=\"InternalRef\"\u003e8\u003c/span\u003eb), it exfoliated which may be attributed to the attachment of CIP to specific functional groups onto the biomass in monolayer form which is agreed with the results of the adsorption isotherm modeling. \u003cem\u003eSynechocystis\u003c/em\u003e sp., (Fig.\u0026nbsp;\u003cspan refid=\"Fig9\" class=\"InternalRef\"\u003e9\u003c/span\u003ea), has an irregular shape. After adsorption, the surfaces of the cells were compact with some roughness. It can be seen also (Fig.\u0026nbsp;\u003cspan refid=\"Fig9\" class=\"InternalRef\"\u003e9\u003c/span\u003eb) the aggregation of some attachments onto the surface owing to the precipitation or accumulation of CIP on the cavity on the cell surface which agreed with the modeling results suggesting that Freundlich isotherm is predominant in CIP and \u003cem\u003eSynechocystis\u003c/em\u003e Sp. The EDX analytical data indicated that oxygen, carbon, nitrogen, and iron were present in the microalgae). This result confirmed the successful incorporation of CIP molecules into the \u003cem\u003eC. vulgaris\u003c/em\u003e and \u003cem\u003eSynechocystis\u003c/em\u003e sp. algae[\u003cspan citationid=\"CR50\" class=\"CitationRef\"\u003e50\u003c/span\u003e]. The study showed that applying microalgae successfully removes CIP compounds from contaminated water.\u003c/p\u003e"},{"header":"Conclusion","content":"\u003cp\u003eIn the current study, the removal of CIP was investigated from contaminated water by using microalgae as an adsorbent. The two types of algae used in the current research are \u003cem\u003echlorella vulgaris\u003c/em\u003e and \u003cem\u003eSynechocystis sp.\u003c/em\u003e The effects of several factors on removing CIP by microalgae were tested (e.g., pH, CIP dosage, adsorbent concentrations, contact time, and temperature\u003cb\u003e).\u003c/b\u003e The adsorption of CIP increases with an increase in adsorbent dose and contact time, up to a definite limit. Based on isotherm data, the adsorption of CIP by microalgae follows the Langmiur isotherm model. The kinetic data show that CIP adsorption fits second-order kinetic models depending on R\u003csup\u003e2\u003c/sup\u003e values and the comparison of calculated and experimental q\u003csub\u003ee\u003c/sub\u003e values. The microalgae are from the best biosorbent and the most cost-effective strategies for achieving this goal, in the removal of CIP and wastewater treatment.\u003c/p\u003e"},{"header":"Abbreviations","content":"\u003ctable border=\"0\" cellspacing=\"0\" cellpadding=\"0\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd width=\"29.607843137254903%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eCIP\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"70.3921568627451%\" valign=\"top\"\u003e\n \u003cp\u003eCiprofloxacin\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"29.607843137254903%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eC. vulgaris\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"70.3921568627451%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cem\u003eChlorella Vulgaris\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"29.607843137254903%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eSynechocystis sp.1\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"70.3921568627451%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cem\u003eSynechocystis sp\u003c/em\u003e. PCC6803\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"29.607843137254903%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eFQ\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"70.3921568627451%\" valign=\"top\"\u003e\n \u003cp\u003efluoroquinolones\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"29.607843137254903%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eARB\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"70.3921568627451%\" valign=\"top\"\u003e\n \u003cp\u003eAntibiotic-resistant bacteria\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"29.607843137254903%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eARG\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"70.3921568627451%\" valign=\"top\"\u003e\n \u003cp\u003eAntibiotic-resistant gene\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"29.607843137254903%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eCEC\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"70.3921568627451%\" valign=\"top\"\u003e\n \u003cp\u003eContaminants of emerging concern\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"29.607843137254903%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eFLU\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"70.3921568627451%\" valign=\"top\"\u003e\n \u003cp\u003eFlutamide\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"29.607843137254903%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eSEM\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"70.3921568627451%\" valign=\"top\"\u003e\n \u003cp\u003eScanning Electron Microscope\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"29.607843137254903%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eFTIR\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"70.3921568627451%\" valign=\"top\"\u003e\n \u003cp\u003eFourier-transform infrared spectrum\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"29.607843137254903%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003ePpm\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"70.3921568627451%\" valign=\"top\"\u003e\n \u003cp\u003eparts per million\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"29.607843137254903%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003ePZC\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"70.3921568627451%\" valign=\"top\"\u003e\n \u003cp\u003ePoint of zero charge\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"29.607843137254903%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eXPS\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"70.3921568627451%\" valign=\"top\"\u003e\n \u003cp\u003eX-ray photoelectron spectroscopic\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"29.607843137254903%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u003cem\u003eq\u003c/em\u003e\u003c/strong\u003e\u003cstrong\u003e\u003csub\u003emax\u003c/sub\u003e\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"70.3921568627451%\" valign=\"top\"\u003e\n \u003cp\u003eMaximum adsorption capacity (mg g\u003csup\u003e\u0026minus;1\u003c/sup\u003e)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"29.607843137254903%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003ePFO\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"70.3921568627451%\" valign=\"top\"\u003e\n \u003cp\u003ePseudo-First-Order\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"29.607843137254903%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003ePSO\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"70.3921568627451%\" valign=\"top\"\u003e\n \u003cp\u003ePseudo-Second-Order\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"29.607843137254903%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eMFSO\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"70.3921568627451%\" valign=\"top\"\u003e\n \u003cp\u003eMixed first anf second\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"29.607843137254903%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u003cem\u003eq\u003c/em\u003e\u003c/strong\u003e\u003cstrong\u003e\u003csub\u003ee\u003c/sub\u003e\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"70.3921568627451%\" valign=\"top\"\u003e\n \u003cp\u003eRefers to the amount of adsorbate in the adsorbent at equilibrium (mg g\u003csup\u003e\u0026minus;1\u003c/sup\u003e)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"29.607843137254903%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u003cem\u003eC\u003c/em\u003e\u003c/strong\u003e\u003cstrong\u003e\u003csub\u003e0\u003c/sub\u003e\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"70.3921568627451%\" valign=\"top\"\u003e\n \u003cp\u003eThe \u0026nbsp;initial equilibrium dye concentration (mg L\u003csup\u003e\u0026minus;1\u003c/sup\u003e)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"29.607843137254903%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u003cem\u003eC\u003c/em\u003e\u003c/strong\u003e\u003cstrong\u003e\u003csub\u003ee\u003c/sub\u003e\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"70.3921568627451%\" valign=\"top\"\u003e\n \u003cp\u003eThe equilibrium dye concentration (mg L\u003csup\u003e\u0026minus;1\u003c/sup\u003e)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"29.607843137254903%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eV\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"70.3921568627451%\" valign=\"top\"\u003e\n \u003cp\u003eThe volume of solution, L\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"29.607843137254903%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eW\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"70.3921568627451%\" valign=\"top\"\u003e\n \u003cp\u003ethe mass of adsorbent used, g\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"29.607843137254903%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eK \u003csub\u003eL\u003c/sub\u003e\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"70.3921568627451%\" valign=\"top\"\u003e\n \u003cp\u003eLangmuir isotherm constant (L/mg)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"29.607843137254903%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u003cem\u003eK\u003c/em\u003e\u003c/strong\u003e\u003cstrong\u003e\u003csub\u003ef\u003c/sub\u003e\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"70.3921568627451%\" valign=\"top\"\u003e\n \u003cp\u003eFreundlich adsorption capacity (mg g\u003csup\u003e\u0026minus;1\u003c/sup\u003e)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"29.607843137254903%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u003cem\u003eK\u003c/em\u003e\u003c/strong\u003e\u003cstrong\u003e\u003csub\u003eLF\u003c/sub\u003e\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"70.3921568627451%\" valign=\"top\"\u003e\n \u003cp\u003eLangmuir\u0026ndash;Freundlich equilibrium constant for heterogeneous solids\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"29.607843137254903%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003e1/\u003cem\u003en\u003c/em\u003e\u003csub\u003eF\u003c/sub\u003e\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"70.3921568627451%\" valign=\"top\"\u003e\n \u003cp\u003eFreundlich adsorption intensity\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"29.607843137254903%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003en\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"70.3921568627451%\" valign=\"top\"\u003e\n \u003cp\u003e\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;the empirical constant\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"29.607843137254903%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003ek1\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"70.3921568627451%\" valign=\"top\"\u003e\n \u003cp\u003ethe pseudo-first-order rate constant, min-1\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"29.607843137254903%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003ek2\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"70.3921568627451%\" valign=\"top\"\u003e\n \u003cp\u003eThe rate constant of pseudo-second-order adsorption, g/(mg min)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eAuthor contributions\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe contributions of all authors must be described in the following manner: The authors confirm their contribution to the paper as follows: Khaled N. M. Elsayed (Manuscript writing, Data acquisition, Software analysis, Supervision, Conceptualization, Editing and revision, Methodology, and manuscript preparation);\u0026nbsp;Nabila Shehata (Manuscript writing, Data acquisition, Software analysis, Supervision, Conceptualization, Editing and revision, Methodology, and manuscript preparation);\u0026nbsp;Noha Khedr (Manuscript writing, Data acquisition, Software analysis, Supervision, Conceptualization, Editing and revision, Methodology, and manuscript preparation); Heba Salah (Manuscript writing, Data acquisition, Software analysis, Conceptualization, Methodology, and manuscript preparation). The author confirms sole responsibility for the following: study\u0026nbsp;Manuscript writing, Data acquisition, Software analysis, Supervision, Conceptualization, Editing and revision, Methodology, and manuscript preparation.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eData availability\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAll data generated or analyzed during this study are included in this manuscript. Further data including source data are available from the corresponding author on reasonable request.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eEthics approval and consent to participate.\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNot applicable.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent for publication.\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNot applicable.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting interests\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors declare no competing interests.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding declarations\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe coauthors declare that there is no funding for this manuscript.\u0026nbsp;\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eProsenc F, Piechocka J, \u0026Scaron;kufca D, Heath E, Griessler Bulc T, Istenič D, et al. 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Ecotoxicol Environ Saf. 2019;176:162\u0026ndash;9. \u003c/li\u003e\n\u003cli\u003eSingh S, Verma E, Niveshika, Tiwari B, Mishra AK. Exopolysaccharide production in Anabaena sp. PCC 7120 under different CaCl2 regimes. Physiol Mol Biol Plants. 2016;22:557\u0026ndash;66. \u003c/li\u003e\n\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":"microbial-cell-factories","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"micf","sideBox":"Learn more about [Microbial Cell Factories](http://microbialcellfactories.biomedcentral.com/)","snPcode":"12934","submissionUrl":"https://submission.nature.com/new-submission/12934/3","title":"Microbial Cell Factories","twitterHandle":"@BioMedCentral","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"BMC/SO AJ","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"Contaminants of emerging concern (CEC), Adsorption, Ciprofloxacin, Synechocystis sp. PCC6803, C. vulgaris, Antibiotics","lastPublishedDoi":"10.21203/rs.3.rs-4596545/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-4596545/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003ePharmaceutical residues which are labeled as a new class of environmental contaminants have potentially negative environmental and human health effects. Recently, biosorption is one of the most appealing choices to manage these pharmaceutical wastes in water. However, the environmental limitations of the adsorbent material are an obstacle to the development of this process. Hence, the current study suggested two biosorbents; \u003cem\u003eChlorella vulgaris\u003c/em\u003e and \u003cem\u003eSynechocystis\u003c/em\u003e sp. microalgae to manage Ciprofloxacin (CIP) in water. The experimental results showed that the optimal adsorption conditions are an initial CIP concentration of 4.0 mg L\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e and pH 5 and 3 for \u003cem\u003eSynechocystis\u003c/em\u003e sp. and \u003cem\u003eC. vulgaris\u003c/em\u003e, respectively. The adsorption process fitted well with the pseudo-second-order kinetic model. The main mechanism of biosorption is the complexation of CIP with carboxyl, hydroxyl, carbonyl, and amido groups which was confirmed by Fourier-transform infrared spectroscopy (FTIR), Scanning electron microscopy (SEM), and energy-dispersive X-ray spectrometry (EDX) analyses which represent the presence of CIP on the cyanobacterial cell surface and intracellularly. These results revealed that the adsorption mechanism of CIP by \u003cem\u003eSynechocystis\u003c/em\u003e sp. PCC6803 and \u003cem\u003eC. vulgaris\u003c/em\u003e provide theoretical guidance for insight into the biosorption mechanisms of pharmaceutical residues by other strains.\u003c/p\u003e","manuscriptTitle":"Management of a ciprofloxacin as a contaminant of emerging concern in water using microalgae bioremediation: mechanism, modeling, and kinetic studies","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-07-18 21:50:12","doi":"10.21203/rs.3.rs-4596545/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2024-08-08T19:47:01+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2024-07-19T18:30:52+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2024-07-18T13:25:20+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"154041535429899093110633712716736633866","date":"2024-07-10T16:35:30+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"291654565000832554422639509689613453888","date":"2024-07-09T04:17:01+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2024-07-08T22:30:15+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2024-06-22T19:04:32+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2024-06-22T12:33:08+00:00","index":"","fulltext":""},{"type":"submitted","content":"Microbial Cell Factories","date":"2024-06-18T01:36:16+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"microbial-cell-factories","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"micf","sideBox":"Learn more about [Microbial Cell Factories](http://microbialcellfactories.biomedcentral.com/)","snPcode":"12934","submissionUrl":"https://submission.nature.com/new-submission/12934/3","title":"Microbial Cell Factories","twitterHandle":"@BioMedCentral","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"BMC/SO AJ","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"61c18226-80ea-40f7-b55d-b194338791e3","owner":[],"postedDate":"July 18th, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[],"tags":[],"updatedAt":"2024-12-23T16:06:09+00:00","versionOfRecord":{"articleIdentity":"rs-4596545","link":"https://doi.org/10.1186/s12934-024-02591-y","journal":{"identity":"microbial-cell-factories","isVorOnly":false,"title":"Microbial Cell Factories"},"publishedOn":"2024-12-17 15:58:37","publishedOnDateReadable":"December 17th, 2024"},"versionCreatedAt":"2024-07-18 21:50:12","video":"","vorDoi":"10.1186/s12934-024-02591-y","vorDoiUrl":"https://doi.org/10.1186/s12934-024-02591-y","workflowStages":[]},"version":"v1","identity":"rs-4596545","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-4596545","identity":"rs-4596545","version":["v1"]},"buildId":"qtupq5eGEP_6zYnWcrvyt","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}