Physico-chemical characterisation of selective TiO2 layer on kaolin-based ceramic membranes

Physico-chemical characterisation of selective TiO2 layer on kaolin-based ceramic membranes | 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 Physico-chemical characterisation of selective TiO2 layer on kaolin-based ceramic membranes Svitlana Kyrii, Anna Misevych, Oleh Romaniuk, Mykhail Tereshkov, and 3 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-3687052/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract The selective layer in a ceramic membrane is crucial for separation and filtration processes, as it endows the membrane with specific properties and functions, determining its selectivity and suitability for various applications. This study aimed to investigate the impact of the type of composition used to create a selective layer on low-cost clay ceramic membranes and to determine their physicochemical properties and permeability. In this study, a ceramic membrane substrate based on kaolin was synthesized and characterized using XRD, thermal analysis, and IR spectroscopy, and its mechanical properties were also tested. Selective layers on the ceramic membrane were synthesized with various compositions using spin-coating. They were characterized using IR spectroscopy, diffuse reflectance absorption spectrum, and scanning electron microscopy (SEM). The SEM images of all samples show a dense structure typical of clay materials. These images indicate that the composition and number of layers have minimal impact on the morphology in this case. The obtained ceramic membranes are characterized by a pore size ranging from 50 – 200 μm. The permeability of the ceramic membrane support is 40 cm 3 /min·cm 2 , which decreases with the application of selective layers. Selectivity by turbidity increases from 32% to 66.4%. kaolin-based ceramic membrane TiO2 selective layer spin-coating membrane characterization Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Introduction Membrane technologies, owing to their advantages [ 1 ], are widely used in chemical, pharmaceutical, biotechnological, energy, dairy, and other industrial sectors, as well as in water treatment and purification processes [ 2 ], including emergencies and in field conditions [ 3 , 4 ]. Among existing membrane materials, ceramic membranes are particularly interesting due to their high mechanical strength, good resistance to organic solvents, and stability in various pH or temperature conditions, making them suitable for use in diverse industrial sectors [ 5 , 6 , 7 ]. A ceramic membrane consists of a porous base (support), an intermediate layer, and a top separating (selective) layer [ 8 ]. The membrane support is designed to provide maximum mechanical stability with minimal membrane resistance, typically characterized by large average pore size, pronounced surface roughness, and high void density. Ideally, the membrane substrate should be high-strength, uniform, durable, and provide minimal flow resistance [ 9 – 11 ]. It should also be chemically compatible with the intermediate and selective layers while maintaining mechanical and thermal stability [ 9 ]. The selective layer of a ceramic membrane is often produced using methods such as Chemical Vapor Deposition (CVD) or sol-gel [ 12 ]. This layer requires high variability to meet the demands of separation. Furthermore, the material from which the selective layer is made is significant. Very often, metal oxides such as titanium dioxide (TiO 2 ), zirconium dioxide (ZrO 2 ), alumina (Al 2 O 3 ), silica (SiO 2 ), etc., are used as materials for the selective layer [ 13 – 16 ]. Titanium dioxide (TiO 2 ) is known for its strong photocatalytic properties, chemical inertness, and good thermal stability [ 17 – 19 ]. When used as the selective layer on ceramic membranes, TiO 2 can impart self-cleaning capabilities to the membrane surface due to its photocatalytic properties, and it can also enhance anti-fouling properties, making the membrane more resistant to contaminants [ 20 ]. An example of a potential application of such a membrane is water purification through ultrafiltration and simultaneous photodegradation of small organic molecules remaining in the permeate under the influence of ultraviolet irradiation. Choi et al. reported on titanium-based membranes' anti-fouling and disinfecting effects [ 21 , 22 ]. Suresh and others [ 23 ] synthesized a microfiltration ceramic membrane based on clay and coated it with TiO 2 nanoparticles using a crossflow filtration method. Their study investigated the effect of crossflow conditions (applied pressures and cross-flow velocities) on the treatment of oily wastewater. In another study, a cost-effective ultrafiltration membrane with a selective nano-TiO 2 layer was developed using a dip-coating method. SEM images of the obtained membrane showed that the applied layer was uniform and had high adhesion to the substrate [ 24 ]. Furthermore, modified TiO 2 samples and nanocomposites based on it have gained significant popularity due to their markedly higher efficiency in catalytic systems compared to pure titanium (IV) oxide. Specifically, systems combining SnO 2 or Nb 2 O 5 and TiO 2 have shown great potential in photodegradation of organic and inorganic compounds, deactivation of pathogens, adsorption of heavy metal ions, and their transformation into less toxic compounds [ 25 – 29 ]. These characteristics make TiO 2 perspective for the purification of industrial effluents, especially when combined with a porous matrix. Therefore, titanium compounds and their modifications are extremely promising for creating the selective layer of ceramic membranes. For applying the selective (top) layer onto the support, methods such as dip-coating or spin-coating are most commonly used. Spin-coating is used to apply thin, uniform films onto flat substrates using centrifugal force. The coating solution is applied to the centre of a rotating plate at high speed. The rotation continues until the excess solution separates from the substrate, leaving a film on it. The solvent from the coating solution is partially removed during the spinning process through evaporation and partially by further baking at elevated temperatures. The quality of the thin coating layer mainly depends on the rotation speed [ 30 ], the rate of solvent evaporation [ 31 , 32 ], the viscosity or concentration of the polymer solution [ 33 ], as well as the porous and surface characteristics of the substrate [ 34 ]. Existing publications do not pay significant attention to comparing the compositions of initial solutions for the selective layer; instead, they focus more on the method of solution application or modifications of the active component itself. Therefore, this study aimed to investigate the impact of the selective layer of ceramic membranes on their physicochemical and filtration properties. To achieve this, methods such as X-ray phase analysis, Differential Thermal Gravimetric analysis, Infrared spectroscopy, Scanning Electron Microscopy, determination of transport properties, and turbidity removal were used. Materials and methods Materials The following materials were used to obtain ceramic membranes: kaolin (Al 2 O 3 ·2SiO 2 ·2H 2 O, Glukhovetske deposit, Vinnytsia region, Ukraine), saponite (Ca 0,25 (Mg,Fe) 3 ((Si,Al) 4 O 10 )(OH) 2 ·nH 2 O, Varvarivske deposit, Khmelnytskyi region, Ukraine), silicon carbide (SiC, Zaporizhabrasiv, Ukraine), borax (Na 2 B 4 O 7 , Klebrig, Turkey, pure for analysis), ammonium bicarbonate (NH 4 HCO 3 , China, pure for analysis), and silicon dioxide (SiO 2 , Ukraine, pure for analysis). Starch ((C 6 H 10 O 5 )n in the form of a 10% solution, Vymal, Ukraine) and liquid glass (Na 2 SiO 3 , commercial solution, "Malva", Ukraine) were used as additional components. Kaolin was the main component of the ceramic membranes. NH 4 HCO 3 and starch were used as pore formers. Borax and SiO 2 were used to enhance mechanical properties, while liquid glass served as a binding component. For the synthesis of the selective layer, the following reagents were used: titanium isopropoxide (C 12 H 28 O 4 Ti, China, pure), diethanolamine (C 4 H 11 NO 2 , Taiwan, chemically pure), glycerin (C 3 H 8 O 3 , Germany), and distilled water. Ceramic membrane preparation 1. Support preparation A series of supports (matrices) based on kaolin, saponite, silicon carbide, and silicon dioxide were prepared using a dry pressing method followed by sintering at a temperature of 950°C [ 35 ]. For this purpose, the respective materials were ground, weighed, and mixed in specific proportions. Subsequently, the resulting powder was pressed into a form using a manual hydraulic press (5 minutes at 30 MPa). The obtained ceramic membrane substrate in the form of a disc with a diameter of 4,6 cm and a thickness of 0.5 cm was fired in a programmed furnace with the regime shown in Fig. 1a. The composition of the initial mixtures for the preparation of the ceramic membrane supports is presented in Table 1 . Table 1 Composition of the initial mixture of the ceramic membrane support Sample Kaolin SiC Na 2 B 4 O 7 SiО 2 NH 4 HCO 3 Saponite CМ0 40% 20% 5% 10% 25% - CМS 40% 20% 5% - 25% 10% 2. Synthesis of selective layer Two types of solutions were used to obtain a selective layer. The first solution (Solution 1) was prepared by sequentially mixing diethanolamine (C 4 H 11 NO 2 ), titanium isopropoxide (Ті(ОС 3 Н 7 ) 4 or Ti[OCH(CH 3 ) 2 ] 4 ), isopropyl alcohol (C 3 H 8 O), and diethylene glycol (C 4 H 10 O 3 ) in the following volumetric proportions: 4:4:1:1. To prepare the second solution (Solution 2), diethanolamine (C 4 H 11 NO 2 ), titanium isopropoxide (Ті(ОС 3 Н 7 ) 4 or Ti[OCH(CH 3 ) 2 ] 4 ), and distilled water were mixed in volumetric proportions of 3:4:3. The spin-coating method was used to form the selective layer on the surface of ceramic membrane support. For this, the prepared solution (Solution 1 or Solution 2) was applied dropwise to the support while it was rotating (from 100 to 1000 rpm), using 1 ml of solution for each selective layer. Afterwards, the membrane samples were dried at 100°C for 1 hour, and the following selective layers were applied using a similar procedure. After applying the appropriate number of selective layers, the samples underwent thermal treatment (firing) at a heating rate of 1°C/min-1 at a temperature of 500°C for 1 hour in an air atmosphere (Fig. 1b). The slow heating rate was aimed at gradually removing organic compounds and water to avoid the formation of cracks and defects on the membrane surface. As a result of the synthesis, 6 samples were obtained with two types of applied solutions, and the number of applied layers was 10, 15, and 20 (Table 2 ). Table 2 Characterisation of ceramic membrane samples with a selective layer Sample Type of applied coating solution Number of selective layers applied CM1-10 1 10 CM1-15 1 15 CM1-20 1 20 CM2-10 2 10 CM2-15 2 15 CM2-20 2 20 Membrane support characterization The samples of ceramic membrane supports were investigated using X-ray phase analysis on an Ultima IV X-ray diffractometer (Rigaku, Japan) with Cu Kα radiation (40 kV, 30 mA). The phase composition and average crystallite size were automatically calculated using the PDXL software application based on standard cards (databases ICDD and PDF-2/Release 2011 RDB). Standardised method of DSTU ISO 14704:2006 "High quality ceramics (ceramics and technical ceramics of improved type)" was used to determine the flexural strength. According to the method, the flexural strength of the samples was measured using a three-point scheme (Bending strength tester, BTS 401/3, Netzsch, Germany) with a sample length of 50 mm, width of 10 mm, and height of 2 mm at a load of 1 N. Ceramic membranes with the diameter of 8.4 cm were used to obtain specimens with a given geometry. Morphologies of the prepared ceramic membranes were observed using the Tescan Vega 3 LMU scanning electron microscope (Tescan Brno, Czech Republic). Methods for investigation of support and ceramic membrane with selective layers Determination of transport and selective properties of the ceramic membranes To determine the transport properties, the ceramic membrane support (CM0) and ceramic membranes with an applied selective layer (CM1-10, CM1-15, CM1-20, CM2-10, CM2-15, CM2-20) were preliminarily cleaned in two stages in aqueous and alcoholic solutions in an ultrasonic cleaner. Initially, the samples were placed in distilled water, subjected to ultrasonic cleaning for 5 minutes, and then dried at 110 ºC. Subsequently, the samples were immersed in a 70% alcohol solution, underwent ultrasonic cleaning for 5 minutes, and dried at 110 ºC. The volume of water passing through the membrane per minute was determined using a custom-constructed apparatus, as illustrated in Fig. 2. Distilled water from container 1 was pumped by pump 2 into cell 4, where the previously prepared ceramic membrane was placed. On pressure gauge 3, the pressure at which water was transmitted over the course of 1 minute was recorded, and the water flux was determined. Water sample testing (selectivity) was conducted using the same apparatus for determining permeability, as shown in Fig. 2. Model water containing 20 mg/L of kaolin was used for these studies. The turbidity in water samples was measured using a Turbidimeter CyberScan TB 1000, Netherlands. Results Characterization As a result of sintering, a ceramic membrane support with a diameter of 4.6 mm and a thickness of 5 mm was obtained, as shown in Fig. 3 . The samples of the ceramic membrane supports were analysed by diffraction methods. Figure 4 shows XRD patterns of the CM0 and CMS samples. The thermal stability analysis was performed using a thermogravimetric analyser (Linseis, Germany) in the temperature range from 25°C to 1050°C at a rate of 10°C/min (Fig. 6 ). Selective layers were obtained on the surface of the CM0 support, which contained 10, 15, and 20 layers made of two types of compositions (solution 1 and solution 2, respectively), the characteristics of which are given in Table 2 . Reflectance spectra were taken for these samples (Fig. 6 ). Figure 7 shows the infrared spectra of samples CM0, CM1-10, CM1-20, CM2-10, and CM2-20. The IR spectra were recorded in the wavenumber range from 400 to 4000 cm − 1 using an IRAffinity-1S FTIR spectrometer (Shimadzu, Japan). The morphology and surface structure of the ceramic membranes were studied using a scanning electron microscope. SEM-images of the synthesized ceramic membranes with selective layer are presented in Fig. 6 . Table 3 Transport and selective properties of ceramic membrane samples Sample of ceramic membrane CM0 CM1-10 CM1-15 CM1-20 CM2-10 CM2-15 CM2-20 Р, bar 0 0 0 ≥ 7 0 0 ≥ 7 Pure water permeability, cm 3 /(min·cm 2 ) 40 39 38 - 37 35 - Turbidity removal, % 32 7.2 14.3 - 58.6 68.4 - Discussion As can be seen from Fig. 4 , the CM0 sample was identified as a mixture of Aluminum Silicon Oxide (Al 3.769 Si 0.731 O 7.5 ) (Card ICDD 01-091-0689), Silicon Oxide (SiO 2 ) (Card ICDD 01-086-1560), Silicon Carbide (SiC) (Card ICDD 01-090-2370), and Moissanite (α-SiC) (Card ICDD 01-072-4532). The X-ray diffraction pattern of the CMS sample, containing 10% saponite (Fig. 4 ), showed similar characteristic peaks as CM0, along with additional ones identified as saponite (Card ICDD 00–013–0305). However, after sintering, the CMS support exhibited component stratification, characterized by heterogeneity. The investigated mechanical properties for bending the obtained ceramic membrane substrates CM0 and CMS demonstrated 13 MPa and 9 MPa bending strength values, respectively. According to existing literature, the most desirable bending strength threshold is 10 MPa; therefore, the CM0 sample was chosen for further research. Thermal analysis (thermogram (TG), derivative thermogram (DTG), and high-temperature differential scanning calorimetry (HDSC)), as presented in Fig. 5 for the CM0 sample, was conducted to understand the physicochemical processes occurring during the thermal treatment of the initial mixture of components. The low endothermic peak at a temperature above 60–80°C on the DTG curve and the smooth section on the TG curve is likely due to the starch gelatinization process. The small area of the peak is attributed to the low content of the substance in the initial mixture. Two endothermic peaks at temperatures on the DTG curve and two sharp decreases in mass on the TG curve at 80 and 150°C correspond to the processes of physical moisture loss by the materials. The main contribution to the released moisture comes from kaolin and borax, which are significant components of the mixture. The endothermic peak at 500–520°C on the DTG curve with a sharp decline on the TG curve is likely associated with the dehydration processes of kaolinite structures and their transformation into metakaolin [ 35 ]. From the reflection spectra (Fig. 6 ), it was established that CM0 has no peaks in the 350 nm region, which are typical for metal oxide structures. However, for the membrane samples CM1-10, CM1-20, CM2-10, and CM2-20, characteristic peaks are observed in the 330–360 nm range, indicative of TiO 2 . The infrared (IR) spectra of samples CM0, CM1-10, CM1-20, CM2-10, and CM2-20 (Fig. 7 ) indicate that for the CM0 ceramic membrane matrix sample, there are no characteristic bands for kaolin. This suggests that the thermal treatment at 950°C was sufficient to transform kaolin into Aluminum Silicon Oxide. This finding is consistent with the data obtained from the diffraction analysis method. The bands identified at 1070 cm − 1 correspond to the asymmetric valence vibrations of Si-O bonds, and those at 796 cm − 1 correspond to the vibrations and deformation of Si-C in Si-CH 3 . For the ceramic membrane samples CM1-10, CM1-20, CM2-10, and CM2-20, there is a disappearance of characteristic bands found in CM0. In the CM1-20 sample, additional peaks appear at 798 cm − 1 and 1058 cm − 1 , which may indicate insufficient temperature or duration of thermal treatment for removing organic components of the selective layer precursors. Overall, the samples with an applied selective layer display a typical IR spectrum of titanium oxide [ 36 ] with slight absorption at 1070 cm − 1 . The SEM images of all samples in Fig. 8 show a dense structure typical of clay materials. These images show that the composition and number of layers have a minimal impact on the morphology in this case. As can be seen, the obtained ceramic membranes are characterized by a pore size ranging from 50–200 µm. This explains the relatively high flux ranging from 40 cm 3 /min·cm 2 to 36 cm 3 /min·cm 2 for the CM0 sample and samples containing 10, 15 selective layers on it (Table 3 ). It should also be noted that CM0 samples with 20 selective layers of two different compositions exhibited zero flux at a pressure of 0.7 MPa. At the same time, turbidity removal for the samples CM1-10 and CM1-15 decreased compared to the CM0 support, from 32–7.2% for CM1-10 and 14.3% for CM1-15. CM1-20 exhibited a lack of filtration at pressures up to 0.7 MPa, probable due to the blocking pores of the membrane surface. For the second composition applied on the surface of the CM2-10 and CM2-15 membranes, an increase in selectivity to 58.6% for CM2-10 and 68.4% for CM2-15 was observed. CM2-20 also demonstrated a lack of filtration. The uncharacteristic dependence on turbidity removal needs further research. Conclusions A macroporous ceramic membrane support was synthesized from low-cost clay raw material, specifically kaolin, which demonstrated a high permeability of 40 cm 3 /(min·cm 2 ) and good mechanical properties of 13 MPa. XRD studies revealed the presence of phases such as aluminium silicon oxide, silicon oxide, silicon carbide, and moissanite, which was confirmed by thermal analysis showing the transformation of kaolin into metakaolin. Selective layers (10, 15, and 20) of two different compositions were applied to the surface of the obtained ceramic support using the spin-coating method and characterized. The diffuse reflectance absorption spectrum and IR analysis indicated that the characteristic peaks observed in the 330–360 nm range suggest TiO 2 , which is consistent with the infrared (IR) spectral data. SEM studies indicated that both compositions partially block the pores of the ceramic membrane and are not uniformly distributed across its surface. This finding correlates with the obtained data on permeability, which slightly decreases for the support with 10 and 15 applied layers, while for the substrate with 20 layers, filtration processes did not occur at pressures up to 0.7 MPa. The studied selectivity of ceramic membranes indicates varied character of suspended particle removal. In the case of the first composition, turbidity removal decreased compared to the support, while it increased in the case of the second composition. The uncharacteristic reduction in turbidity can be explained by the peculiarities of the porous structure formation after modification. Further scientific research plans include obtaining an intermediate layer to achieve a more controlled design of the selective layer on the surface of the support made from clay materials. This layer will create the desired architecture and prevent the blocking of the matrix pores. Declarations Author Contribution S.K. conduct research, wrote the main manuscript text;A.M. conduct research, reference design;O.R. conduct research, figures design;M.T. conduct research, describe some experiments;W.K. XRD analysis, checking the article;T.D. work concept design and approving, revised drafted work;All authors reviewed the manuscript. Acknowledgements Authors are grateful to the National Research Foundation of Ukraine for funding the project (project registration number 2020.02/0024). References N. H. Othman, N. H. Alias, N. S. Fuzil, F. Marpani, M. Z. Shahruddin, C. M. Chew, K. M. David Ng, W. J. Lau, A. F. Ismail, A review on the use of membrane technology systems in developing countries, Membranes 12(1), 30 (2021). https://doi.org/10.3390/membranes12010030. T. A. Saleh, V. K. Gupta, An overview of membrane science and technology, in Nanomaterial and polymer membranes (Elsevier, 2016), pp. 1–23. https://doi.org/10.1016/B978-0-12-804703-3.00001-2. S.-L. Loo, A. G. Fane, W. B. Krantz, T.-T. Lim, Emergency water supply: A review of potential technologies and selection criteria, Water Res., 46(10), 3125–3151, (2012). https://doi.org/10.1016/j.watres.2012.03.030 T. Mitchenko, I. Kosogina, S. Kyrii, The local solutions for water security in Ukraine, in Physical and cyber safety in critical water infrastructure (2019), pp. 99–105. https://doi.org/10.3233/NICSP190044. R. Sondhi, R. Bhave, G. Jung, Applications and benefits of ceramic membranes, Membr. Technol. 2003(11), 5–8 (2003). https://doi.org/10.1016/s0958-2118(03)11016-6. C. A. M. Siskens, Chapter 13 Applications of ceramic membranes in liquid filtration, in Membrane science and technology (Elsevier, 1996), pp. 619–639. https://doi.org/10.1016/s0927-5193(96)80016-7. A. Kuzminchuk, A. Burmak, M. Litynska, M., T. Dontsova, New diatomaceous earth and kaolinite ceramic membranes for turbidity reduction in water, Appl. Nanosci. 13, 5335–5343 (2023). https://doi.org/10.1007/s13204-023-02792-8 L. Huang, H. Qin, T. Hu, J. Xie, W. Guo, P. Gao, H. Xiao, Fabrication of high permeability SiC ceramic membrane with gradient pore structure by one-step freeze-casting process, Ceram. Int. 47(12), 17597–17605 (2021). https://doi.org/10.1016/j.ceramint.2021.03.078 G. Rothenberg, V. Gitis, Ceramic Membranes: New Opportunities and Practical Applications (Wiley & Sons, Limited, John, 2016). A. Pierre, G. Christian, Current Status and Prospects for Ceramic Membrane Applications, in Handbook of Membrane Separations (CRC Press, 2008), pp. 159–200. https://doi.org/10.1201/9781420009484-12. P. Maarten Biesheuvel, H. Verweij, Design of ceramic membrane supports: permeability, tensile strength and stress, J. Membr. Sci. 156(1), 141–152 (1999). https://doi.org/10.1016/s0376-7388(98)00335-4. A. Sah, H. L. Castricum, A. Bliek, D. H. A. Blank, J. E. ten Elshof, Hydrophobic modification of γ-alumina membranes with organochlorosilanes, J. Membr. Sci. 243(1-2), 125–132 (2004). https://doi.org/10.1016/j.memsci.2004.05.031. K. Suresh, G. Pugazhenthi, Cross flow microfiltration of oil-water emulsions using clay based ceramic membrane support and TiO 2 composite membrane, Egypt. J. Pet. 26(3), 679–694 (2017). https://doi.org/10.1016/j.ejpe.2016.10.007 T. Meng, R. Xie, X. Ju, C. J. Cheng, S. Wang, P. F. Li, B. Liang, L. Y. Chu, Nano-structure construction of porous membranes by depositing nanoparticles for enhanced surface wettability, J. Membr. Sci. 427, 63–72, (2013). https://doi.org/10.1016/j.memsci.2012.09.051 J. E. Zhou, Q. Chang, Y. Wang, J. Wang, G. Meng, Separation of stable oil–water emulsion by the hydrophilic nano-sized ZrO 2 modified Al 2 O 3 microfiltration membrane, Sep. Purif. Technol. 75(3), 243–248, (2010). https://doi.org/10.1016/j.seppur.2010.08.008 S. K. Hubadillah, M. H. D. Othman, T. Matsuura, A. F. Ismail, M. A. Rahman, Z. Harun, J. Jaafar, M. Nomura, Fabrications and applications of low cost ceramic membrane from kaolin: A comprehensive review, Ceram. Int. 44(5), 4538–4560, (2018). https://doi.org/10.1016/j.ceramint.2017.12.215 T. Dontsova, S. Kyrii, O. Yanushevska, V. Suprunchuk, I. Kosogina, Physicochemical properties of TIO 2 , ZrO 2 , Fe 3 O 4 nanocrystalline adsorbents and photocatalysts, Chem. Pap. (2022). https://doi.org/10.1007/s11696-022-02433-4. A. Kutuzova, T. Dontsova, W. Kwapinski, J. J. Leahy, J. Strunk, Photocatalytic activity to ciprofloxacin and physico-chemical properties of TiO 2 synthesized by different methods, Mol. Cryst. Liq., 1–13 (2022). https://doi.org/10.1080/15421406.2022.2073526. T. A. Dontsova, A. S. Kutuzova, K. O. Bila, S. O. Kyrii, I. V. Kosogina, D. O. Nechyporuk, Enhanced Photocatalytic Activity of TiO 2 /SnO 2 Binary Nanocomposites, J. Nanomater. 1–13 (2020). https://doi.org/10.1155/2020/8349480. Grebenișan, E.; Hegyi, A.; Szilagyi, H.; Lăzărescu, A.-V.; Ionescu, B.A. Influence of the Addition of TiO 2 Nanoparticles on the Self-Cleaning Performance of Cementitious Composite Surfaces. Proc. 63(42), (2020). https://doi.org/10.3390/proceedings2020063042 H. Choi, E. Stathatos, D. D. Dionysiou, Sol–gel preparation of mesoporous photocatalytic TiO2 films and TiO 2 /Al 2 O 3 composite membranes for environmental applications, Appl. Catal. B 63(1-2), 60–67 (2006). https://doi.org/10.1016/j.apcatb.2005.09.012. H. Choi, E. Stathatos, D. D. Dionysiou, Photocatalytic TiO2 films and membranes for the development of efficient wastewater treatment and reuse systems, Desalination 202(1-3), 199–206 (2007). https://doi.org/10.1016/j.desal.2005.12.055. K. Suresh, G. Pugazhenthi, Cross flow microfiltration of oil-water emulsions using clay based ceramic membrane support and TiO 2 composite membrane, Egypt. J. Pet. 26(3), 679–694 (2017). https://doi.org/10.1016/j.ejpe.2016.10.007. A. Bouazizi, M. Breida, B. Achiou, M. Ouammou, J. I. Calvo, A. Aaddane, S. A. Younssi, Removal of dyes by a new nano–TiO 2 ultrafiltration membrane deposited on low-cost support prepared from natural Moroccan bentonite, Appl. Clay Sci. 149, 127–135 (2017). https://doi.org/10.1016/j.clay.2017.08.019. Y. Du, X. Wang, J. Wu, C. Qi, Y. Li, Adsorption and photoreduction of Cr(VI) via diatomite modified by Nb 2 O 5 nanorods, Particuology 40, 123–130 (2018). https://doi.org/10.1016/j.partic.2017.11.005. G. Zhang, Z. Sun, Y. Duan, R. Ma, S. Zheng, Synthesis of nano-TiO 2 /diatomite composite and its photocatalytic degradation of gaseous formaldehyde, Appl. Surf. Sci. 412, 105–112 (2017). https://doi.org/10.1016/j.apsusc.2017.03.198. D. D. Nematov, K. T. Kholmurodov, M. A. Husenzoda, A. Lyubchyk, A. S. Burhonzoda, Molecular Adsorption of H 2 O on TiO 2 and TiO 2 :Y Surfaces, J. Hum., Earth, Future 3(2), 213–222 (2022). https://doi.org/10.28991/hef-2022-03-02-07. S. Kyrii, T. Dontsova, I. Kosogina, V. Podopryhor, A. Serhiienko, Influence of yttrium and niobium oxides modifiers on physicochemical and photocatalytic properties of titanium (IV) oxide, Eastern-European J. Enterp. Technol. 4(6(112)), 67–74 (2021). https://doi.org/10.15587/1729-4061.2021.238347. Y. L. R. L. Fernandes, M. C. L. Silva, R. A. Raimundo, J. Cavalcante, J. B. Q. Tomaz, M. Mashhadikarimi, M. A. Morales, F. V. da Motta, W. Acchar, U. U. Gomes, Development of mesoporous ceramic membranes of Diatomite/TiO 2 /Nb 2 O 5 nanocomposites for the treatment of contaminated water, J. Environ. Chem. Eng. 111161, (2023). https://doi.org/10.1016/j.jece.2023.111161. K. J. Skrobis, D. D. Denton, A. V. Skrobis, Effect of early solvent evaporation on the mechanism of the spin-coating of polymeric solutions, Polym. Eng. Sci. 30(3), 193–196 (1990). https://doi.org/10.1002/pen.760300309. B. T. Chen, Investigation of the solvent-evaporation effect on spin coating of thin films, Polym. Eng. Sci. 23(7), 399–403 (1983). https://doi.org/10.1002/pen.760230706. J. H. Lai, An investigation of spin coating of electron resists, Polym. Eng. Sci. 19(15), 1117–1121 (1979). https://doi.org/10.1002/pen.760191509. L. L. Spangler, J. M. Torkelson, J. S. Royal, Influence of solvent and molecular weight on thickness and surface topography of spin-coated polymer films, Polym. Eng. Sci. 30(11), 644–653 (1990). https://doi.org/10.1002/pen.760301104. J. D. Le Roux, D. R. Paul, Preparation of composite membranes by a spin coating process, J. Membr. Sci. 74(3), 233–252 (1992). https://doi.org/10.1016/0376-7388(92)80064-q. A. O. Serhiienko, T. A. Dontsova, O. I. Yanushevska, V. I. Vorobyova, G. S. Vasyliev, Characterization of ceramic membrane support based on Ukrainian kaolin, Mol. Cryst. Liq. Cryst. 2022, 1–14. https://doi.org/10.1080/15421406.2022.2091279. Interactive IRUG Spectrum, IMP00141 Titanox RA, rutile form. (Infrared and Raman Users Group (IRUG)), http://www.irug.org/jcamp-details?id=920. Accessed 28 November 2023 Additional Declarations No competing interests reported. Cite Share Download PDF Status: Posted Version 1 posted 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. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. 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-3687052","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":255415058,"identity":"01749c8f-3870-4ba3-a84f-2a7b96f59a2e","order_by":0,"name":"Svitlana Kyrii","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAAvklEQVRIiWNgGAWjYBACCRCRwGADJBkbD5CgJSENpKWBBC0MCYfBFHFaJGekP5N4+OO83dr2w0BbamyiCWqRlsgxk0hIuJ287UwiUMuxtNwGQlrkJHKYDUBazA4AtTA2HCZGS/pjoJZzyWbnHxKpRVoiwfBBQsIBO7MbxNoi2fMGqCUtOcHsBtCWBGL8InE8/cHBHzZ29mbn0x8++FBjQ1gLg0ACmEoEq0wgqBwE+A+AKXuiFI+CUTAKRsHIBADRcEefyiblNgAAAABJRU5ErkJggg==","orcid":"","institution":"National Technical University of Ukraine “Igor Sikorsky Kyiv Polytechnic Institute”","correspondingAuthor":true,"submittingAuthor":false,"prefix":"","firstName":"Svitlana","middleName":"","lastName":"Kyrii","suffix":""},{"id":255415060,"identity":"fc516887-2e44-4433-89a6-70e8e3ad7fb0","order_by":1,"name":"Anna Misevych","email":"","orcid":"","institution":"National Technical University of Ukraine “Igor Sikorsky Kyiv Polytechnic Institute”","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Anna","middleName":"","lastName":"Misevych","suffix":""},{"id":255415061,"identity":"30193169-68c7-419a-995e-f3aff7771699","order_by":2,"name":"Oleh Romaniuk","email":"","orcid":"","institution":"National Technical University of Ukraine “Igor Sikorsky Kyiv Polytechnic Institute”","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Oleh","middleName":"","lastName":"Romaniuk","suffix":""},{"id":255415064,"identity":"222a13d6-952a-4664-a280-fe9cdcdbe2f0","order_by":3,"name":"Mykhail Tereshkov","email":"","orcid":"","institution":"National Technical University of Ukraine “Igor Sikorsky Kyiv Polytechnic Institute”","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Mykhail","middleName":"","lastName":"Tereshkov","suffix":""},{"id":255415068,"identity":"2974648a-e73c-4843-b5cf-d4411564811d","order_by":4,"name":"Hlib Ivzhenko","email":"","orcid":"","institution":"National Technical University of Ukraine “Igor Sikorsky Kyiv Polytechnic Institute”","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Hlib","middleName":"","lastName":"Ivzhenko","suffix":""},{"id":255415070,"identity":"810aa06f-9eb3-419b-83c0-a8baac3ea895","order_by":5,"name":"Witold Kwapinski","email":"","orcid":"","institution":"University of Limerick","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Witold","middleName":"","lastName":"Kwapinski","suffix":""},{"id":255415072,"identity":"c104505b-5f97-4929-8402-c1de6b15b61d","order_by":6,"name":"Tetiana Dontsova","email":"","orcid":"","institution":"National Technical University of Ukraine “Igor Sikorsky Kyiv Polytechnic Institute”","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Tetiana","middleName":"","lastName":"Dontsova","suffix":""}],"badges":[],"createdAt":"2023-11-30 13:14:27","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-3687052/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-3687052/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":47708078,"identity":"ac3b4b0d-0fad-41d1-8911-bf6161cfae62","added_by":"auto","created_at":"2023-12-06 13:04:39","extension":"jpg","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":47337,"visible":true,"origin":"","legend":"\u003cp\u003eTemperature conditions for the production of ceramic membranes\u003c/p\u003e","description":"","filename":"1.jpg","url":"https://assets-eu.researchsquare.com/files/rs-3687052/v1/3eb30672af332c6831aa34a9.jpg"},{"id":47708085,"identity":"a5fd3be7-ef00-4b80-96a5-e73c95d2341d","added_by":"auto","created_at":"2023-12-06 13:04:39","extension":"jpg","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":82968,"visible":true,"origin":"","legend":"\u003cp\u003eLaboratory unit of special original design for permeability determination\u003c/p\u003e","description":"","filename":"2.jpg","url":"https://assets-eu.researchsquare.com/files/rs-3687052/v1/cbab8abb36a032240dfacca4.jpg"},{"id":47709461,"identity":"d6c565ee-bea0-48da-bfcc-cd23f371c99d","added_by":"auto","created_at":"2023-12-06 13:12:39","extension":"jpg","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":25680,"visible":true,"origin":"","legend":"\u003cp\u003eThe image of the ceramic membrane substrate after sintering\u003c/p\u003e","description":"","filename":"3.jpg","url":"https://assets-eu.researchsquare.com/files/rs-3687052/v1/dac651cf164c7aafad1e706d.jpg"},{"id":47708082,"identity":"72bbf331-8070-4cbc-9859-6c3a61f31e40","added_by":"auto","created_at":"2023-12-06 13:04:39","extension":"jpg","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":27085,"visible":true,"origin":"","legend":"\u003cp\u003eX-ray image of ceramic membrane supports\u003c/p\u003e","description":"","filename":"4.jpg","url":"https://assets-eu.researchsquare.com/files/rs-3687052/v1/8e93f7187c48342d0a67431a.jpg"},{"id":47708083,"identity":"a8a13897-7953-475b-91fa-faab54d19298","added_by":"auto","created_at":"2023-12-06 13:04:39","extension":"jpg","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":39704,"visible":true,"origin":"","legend":"\u003cp\u003eDerivatogram of a ceramic membrane support CM0\u003c/p\u003e","description":"","filename":"5.jpg","url":"https://assets-eu.researchsquare.com/files/rs-3687052/v1/4c424f8df3794154f7fda0b2.jpg"},{"id":47709462,"identity":"489d3677-2573-4577-ae52-5b714bd691f7","added_by":"auto","created_at":"2023-12-06 13:12:39","extension":"jpg","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":29582,"visible":true,"origin":"","legend":"\u003cp\u003eDiffuse reflectance absorption spectrum of support and ceramic membranes\u003c/p\u003e","description":"","filename":"6.jpg","url":"https://assets-eu.researchsquare.com/files/rs-3687052/v1/425c3e0d8ab0f6d7ec611262.jpg"},{"id":47708080,"identity":"cca7d2f9-b3a9-48f8-be04-609e161ca815","added_by":"auto","created_at":"2023-12-06 13:04:39","extension":"jpg","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":36117,"visible":true,"origin":"","legend":"\u003cp\u003eInfrared spectra for ceramic membranes with a selective layer\u003c/p\u003e","description":"","filename":"7.jpg","url":"https://assets-eu.researchsquare.com/files/rs-3687052/v1/e37118863efdebecbbe376a6.jpg"},{"id":47708084,"identity":"21bb9cb2-dda3-4bbc-92c9-8a4bd6694eb4","added_by":"auto","created_at":"2023-12-06 13:04:39","extension":"jpg","order_by":8,"title":"Figure 8","display":"","copyAsset":false,"role":"figure","size":151304,"visible":true,"origin":"","legend":"\u003cp\u003eSEM images of ceramic membrane samples\u003c/p\u003e","description":"","filename":"8.jpg","url":"https://assets-eu.researchsquare.com/files/rs-3687052/v1/0cedf154231ed5e513abb4a3.jpg"},{"id":47786971,"identity":"a4603e70-75f8-4aa8-8e75-b5d76cd9fa04","added_by":"auto","created_at":"2023-12-07 13:00:07","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":655275,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-3687052/v1/c62b220c-62c5-4b32-ad3a-4219b6a39f8c.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Physico-chemical characterisation of selective TiO2 layer on kaolin-based ceramic membranes","fulltext":[{"header":"Introduction","content":"\u003cp\u003eMembrane technologies, owing to their advantages [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e], are widely used in chemical, pharmaceutical, biotechnological, energy, dairy, and other industrial sectors, as well as in water treatment and purification processes [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e], including emergencies and in field conditions [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e, \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eAmong existing membrane materials, ceramic membranes are particularly interesting due to their high mechanical strength, good resistance to organic solvents, and stability in various pH or temperature conditions, making them suitable for use in diverse industrial sectors [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e, \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e, \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]. A ceramic membrane consists of a porous base (support), an intermediate layer, and a top separating (selective) layer [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]. The membrane support is designed to provide maximum mechanical stability with minimal membrane resistance, typically characterized by large average pore size, pronounced surface roughness, and high void density. Ideally, the membrane substrate should be high-strength, uniform, durable, and provide minimal flow resistance [\u003cspan additionalcitationids=\"CR10\" citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]. It should also be chemically compatible with the intermediate and selective layers while maintaining mechanical and thermal stability [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eThe selective layer of a ceramic membrane is often produced using methods such as Chemical Vapor Deposition (CVD) or sol-gel [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]. This layer requires high variability to meet the demands of separation. Furthermore, the material from which the selective layer is made is significant. Very often, metal oxides such as titanium dioxide (TiO\u003csub\u003e2\u003c/sub\u003e), zirconium dioxide (ZrO\u003csub\u003e2\u003c/sub\u003e), alumina (Al\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e), silica (SiO\u003csub\u003e2\u003c/sub\u003e), etc., are used as materials for the selective layer [\u003cspan additionalcitationids=\"CR14 CR15\" citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eTitanium dioxide (TiO\u003csub\u003e2\u003c/sub\u003e) is known for its strong photocatalytic properties, chemical inertness, and good thermal stability [\u003cspan additionalcitationids=\"CR18\" citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e]. When used as the selective layer on ceramic membranes, TiO\u003csub\u003e2\u003c/sub\u003e can impart self-cleaning capabilities to the membrane surface due to its photocatalytic properties, and it can also enhance anti-fouling properties, making the membrane more resistant to contaminants [\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e]. An example of a potential application of such a membrane is water purification through ultrafiltration and simultaneous photodegradation of small organic molecules remaining in the permeate under the influence of ultraviolet irradiation. Choi et al. reported on titanium-based membranes' anti-fouling and disinfecting effects [\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e, \u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e]. Suresh and others [\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e] synthesized a microfiltration ceramic membrane based on clay and coated it with TiO\u003csub\u003e2\u003c/sub\u003e nanoparticles using a crossflow filtration method. Their study investigated the effect of crossflow conditions (applied pressures and cross-flow velocities) on the treatment of oily wastewater. In another study, a cost-effective ultrafiltration membrane with a selective nano-TiO\u003csub\u003e2\u003c/sub\u003e layer was developed using a dip-coating method. SEM images of the obtained membrane showed that the applied layer was uniform and had high adhesion to the substrate [\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eFurthermore, modified TiO\u003csub\u003e2\u003c/sub\u003e samples and nanocomposites based on it have gained significant popularity due to their markedly higher efficiency in catalytic systems compared to pure titanium (IV) oxide. Specifically, systems combining SnO\u003csub\u003e2\u003c/sub\u003e or Nb\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e5\u003c/sub\u003e and TiO\u003csub\u003e2\u003c/sub\u003e have shown great potential in photodegradation of organic and inorganic compounds, deactivation of pathogens, adsorption of heavy metal ions, and their transformation into less toxic compounds [\u003cspan additionalcitationids=\"CR26 CR27 CR28\" citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e]. These characteristics make TiO\u003csub\u003e2\u003c/sub\u003e perspective for the purification of industrial effluents, especially when combined with a porous matrix. Therefore, titanium compounds and their modifications are extremely promising for creating the selective layer of ceramic membranes.\u003c/p\u003e \u003cp\u003eFor applying the selective (top) layer onto the support, methods such as dip-coating or spin-coating are most commonly used. Spin-coating is used to apply thin, uniform films onto flat substrates using centrifugal force. The coating solution is applied to the centre of a rotating plate at high speed. The rotation continues until the excess solution separates from the substrate, leaving a film on it. The solvent from the coating solution is partially removed during the spinning process through evaporation and partially by further baking at elevated temperatures. The quality of the thin coating layer mainly depends on the rotation speed [\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e], the rate of solvent evaporation [\u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e, \u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e], the viscosity or concentration of the polymer solution [\u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e], as well as the porous and surface characteristics of the substrate [\u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e34\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eExisting publications do not pay significant attention to comparing the compositions of initial solutions for the selective layer; instead, they focus more on the method of solution application or modifications of the active component itself.\u003c/p\u003e \u003cp\u003eTherefore, this study aimed to investigate the impact of the selective layer of ceramic membranes on their physicochemical and filtration properties. To achieve this, methods such as X-ray phase analysis, Differential Thermal Gravimetric analysis, Infrared spectroscopy, Scanning Electron Microscopy, determination of transport properties, and turbidity removal were used.\u003c/p\u003e"},{"header":"Materials and methods","content":"\u003cdiv id=\"Sec3\"\u003e\n \u003ch2\u003eMaterials\u003c/h2\u003e\n \u003cp\u003eThe following materials were used to obtain ceramic membranes: kaolin (Al\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e\u0026middot;2SiO\u003csub\u003e2\u003c/sub\u003e\u0026middot;2H\u003csub\u003e2\u003c/sub\u003eO, Glukhovetske deposit, Vinnytsia region, Ukraine), saponite (Ca\u003csub\u003e0,25\u003c/sub\u003e(Mg,Fe)\u003csub\u003e3\u003c/sub\u003e((Si,Al)\u003csub\u003e4\u003c/sub\u003eO\u003csub\u003e10\u003c/sub\u003e)(OH)\u003csub\u003e2\u003c/sub\u003e\u0026middot;nH\u003csub\u003e2\u003c/sub\u003eO, Varvarivske deposit, Khmelnytskyi region, Ukraine), silicon carbide (SiC, Zaporizhabrasiv, Ukraine), borax (Na\u003csub\u003e2\u003c/sub\u003eB\u003csub\u003e4\u003c/sub\u003eO\u003csub\u003e7\u003c/sub\u003e, Klebrig, Turkey, pure for analysis), ammonium bicarbonate (NH\u003csub\u003e4\u003c/sub\u003eHCO\u003csub\u003e3\u003c/sub\u003e, China, pure for analysis), and silicon dioxide (SiO\u003csub\u003e2\u003c/sub\u003e, Ukraine, pure for analysis). Starch ((C\u003csub\u003e6\u003c/sub\u003eH\u003csub\u003e10\u003c/sub\u003eO\u003csub\u003e5\u003c/sub\u003e)n in the form of a 10% solution, Vymal, Ukraine) and liquid glass (Na\u003csub\u003e2\u003c/sub\u003eSiO\u003csub\u003e3\u003c/sub\u003e, commercial solution, \u0026quot;Malva\u0026quot;, Ukraine) were used as additional components. Kaolin was the main component of the ceramic membranes. NH\u003csub\u003e4\u003c/sub\u003eHCO\u003csub\u003e3\u003c/sub\u003eand starch were used as pore formers. Borax and SiO\u003csub\u003e2\u003c/sub\u003e were used to enhance mechanical properties, while liquid glass served as a binding component.\u003c/p\u003e\n \u003cp\u003eFor the synthesis of the selective layer, the following reagents were used: titanium isopropoxide (C\u003csub\u003e12\u003c/sub\u003eH\u003csub\u003e28\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003eTi, China, pure), diethanolamine (C\u003csub\u003e4\u003c/sub\u003eH\u003csub\u003e11\u003c/sub\u003eNO\u003csub\u003e2\u003c/sub\u003e, Taiwan, chemically pure), glycerin (C\u003csub\u003e3\u003c/sub\u003eH\u003csub\u003e8\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e, Germany), and distilled water.\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003eCeramic membrane preparation\u003c/strong\u003e\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec4\"\u003e\n \u003ch2\u003e1. Support preparation\u003c/h2\u003e\n \u003cp\u003eA series of supports (matrices) based on kaolin, saponite, silicon carbide, and silicon dioxide were prepared using a dry pressing method followed by sintering at a temperature of 950\u0026deg;C [\u003cspan\u003e35\u003c/span\u003e]. For this purpose, the respective materials were ground, weighed, and mixed in specific proportions. Subsequently, the resulting powder was pressed into a form using a manual hydraulic press (5 minutes at 30 MPa). The obtained ceramic membrane substrate in the form of a disc with a diameter of 4,6 cm and a thickness of 0.5 cm was fired in a programmed furnace with the regime shown in Fig.\u0026nbsp;1a.\u003c/p\u003e\n \u003cp\u003eThe composition of the initial mixtures for the preparation of the ceramic membrane supports is presented in Table \u003cspan\u003e1\u003c/span\u003e.\u003c/p\u003e\u0026nbsp;\u003ctable id=\"Tab1\" border=\"1\"\u003e\n \u003ccaption language=\"En\"\u003e\n \u003cdiv\u003eTable 1\u003c/div\u003e\n \u003cdiv\u003e\n \u003cp\u003eComposition of the initial mixture of the ceramic membrane support\u003c/p\u003e\n \u003c/div\u003e\n \u003c/caption\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eSample\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eKaolin\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eSiC\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eNa\u003csub\u003e2\u003c/sub\u003eB\u003csub\u003e4\u003c/sub\u003eO\u003csub\u003e7\u003c/sub\u003e\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eSiО\u003csub\u003e2\u003c/sub\u003e\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eNH\u003csub\u003e4\u003c/sub\u003eHCO\u003csub\u003e3\u003c/sub\u003e\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eSaponite\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eCМ0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e40%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e20%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e5%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e10%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e25%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eCМS\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e40%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e20%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e5%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e25%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e10%\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n\u003c/div\u003e\n\u003cp\u003e\u003cbr\u003e\u003c/p\u003e\n\u003cdiv id=\"Sec5\"\u003e\n \u003ch2\u003e2. Synthesis of selective layer\u003c/h2\u003e\n \u003cp\u003eTwo types of solutions were used to obtain a selective layer. The first solution (Solution 1) was prepared by sequentially mixing diethanolamine (C\u003csub\u003e4\u003c/sub\u003eH\u003csub\u003e11\u003c/sub\u003eNO\u003csub\u003e2\u003c/sub\u003e), titanium isopropoxide (Ті(ОС\u003csub\u003e3\u003c/sub\u003eН\u003csub\u003e7\u003c/sub\u003e)\u003csub\u003e4\u003c/sub\u003e or Ti[OCH(CH\u003csub\u003e3\u003c/sub\u003e)\u003csub\u003e2\u003c/sub\u003e]\u003csub\u003e4\u003c/sub\u003e), isopropyl alcohol (C\u003csub\u003e3\u003c/sub\u003eH\u003csub\u003e8\u003c/sub\u003eO), and diethylene glycol (C\u003csub\u003e4\u003c/sub\u003eH\u003csub\u003e10\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e) in the following volumetric proportions: 4:4:1:1. To prepare the second solution (Solution 2), diethanolamine (C\u003csub\u003e4\u003c/sub\u003eH\u003csub\u003e11\u003c/sub\u003eNO\u003csub\u003e2\u003c/sub\u003e), titanium isopropoxide (Ті(ОС\u003csub\u003e3\u003c/sub\u003eН\u003csub\u003e7\u003c/sub\u003e)\u003csub\u003e4\u003c/sub\u003e or Ti[OCH(CH\u003csub\u003e3\u003c/sub\u003e)\u003csub\u003e2\u003c/sub\u003e]\u003csub\u003e4\u003c/sub\u003e), and distilled water were mixed in volumetric proportions of 3:4:3. The spin-coating method was used to form the selective layer on the surface of ceramic membrane support. For this, the prepared solution (Solution 1 or Solution 2) was applied dropwise to the support while it was rotating (from 100 to 1000 rpm), using 1 ml of solution for each selective layer. Afterwards, the membrane samples were dried at 100\u0026deg;C for 1 hour, and the following selective layers were applied using a similar procedure. After applying the appropriate number of selective layers, the samples underwent thermal treatment (firing) at a heating rate of 1\u0026deg;C/min-1 at a temperature of 500\u0026deg;C for 1 hour in an air atmosphere (Fig.\u0026nbsp;1b). The slow heating rate was aimed at gradually removing organic compounds and water to avoid the formation of cracks and defects on the membrane surface.\u003c/p\u003e\n \u003cp\u003eAs a result of the synthesis, 6 samples were obtained with two types of applied solutions, and the number of applied layers was 10, 15, and 20 (Table \u003cspan\u003e2\u003c/span\u003e).\u003c/p\u003e\n \u003ctable id=\"Tab2\" border=\"1\"\u003e\n \u003ccaption language=\"En\"\u003e\n \u003cdiv\u003eTable 2\u003c/div\u003e\n \u003cdiv\u003e\n \u003cp\u003eCharacterisation of ceramic membrane samples with a selective layer\u003c/p\u003e\n \u003c/div\u003e\n \u003c/caption\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eSample\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eType of applied coating solution\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eNumber of selective layers applied\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eCM1-10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e10\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eCM1-15\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e15\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eCM1-20\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e20\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eCM2-10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e10\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eCM2-15\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e15\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eCM2-20\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e20\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n\u003c/div\u003e\n\u003cp\u003e\u003cbr\u003e\u003c/p\u003e\n\u003cdiv id=\"Sec6\"\u003e\n \u003ch2\u003eMembrane support characterization\u003c/h2\u003e\n \u003cp\u003eThe samples of ceramic membrane supports were investigated using X-ray phase analysis on an Ultima IV X-ray diffractometer (Rigaku, Japan) with Cu K\u0026alpha; radiation (40 kV, 30 mA). The phase composition and average crystallite size were automatically calculated using the PDXL software application based on standard cards (databases ICDD and PDF-2/Release 2011 RDB).\u003c/p\u003e\n \u003cp\u003eStandardised method of DSTU ISO 14704:2006 \u0026quot;High quality ceramics (ceramics and technical ceramics of improved type)\u0026quot; was used to determine the flexural strength. According to the method, the flexural strength of the samples was measured using a three-point scheme (Bending strength tester, BTS 401/3, Netzsch, Germany) with a sample length of 50 mm, width of 10 mm, and height of 2 mm at a load of 1 N. Ceramic membranes with the diameter of 8.4 cm were used to obtain specimens with a given geometry.\u003c/p\u003e\n \u003cp\u003eMorphologies of the prepared ceramic membranes were observed using the Tescan Vega 3 LMU scanning electron microscope (Tescan Brno, Czech Republic).\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec7\"\u003e\n \u003ch2\u003eMethods for investigation of support and ceramic membrane with selective layers\u003c/h2\u003e\n \u003cdiv id=\"Sec8\"\u003e\n \u003ch2\u003eDetermination of transport and selective properties of the ceramic membranes\u003c/h2\u003e\n \u003cp\u003eTo determine the transport properties, the ceramic membrane support (CM0) and ceramic membranes with an applied selective layer (CM1-10, CM1-15, CM1-20, CM2-10, CM2-15, CM2-20) were preliminarily cleaned in two stages in aqueous and alcoholic solutions in an ultrasonic cleaner. Initially, the samples were placed in distilled water, subjected to ultrasonic cleaning for 5 minutes, and then dried at 110 \u0026ordm;C. Subsequently, the samples were immersed in a 70% alcohol solution, underwent ultrasonic cleaning for 5 minutes, and dried at 110 \u0026ordm;C. The volume of water passing through the membrane per minute was determined using a custom-constructed apparatus, as illustrated in Fig.\u0026nbsp;2.\u003c/p\u003e\n \u003cp\u003eDistilled water from container 1 was pumped by pump 2 into cell 4, where the previously prepared ceramic membrane was placed. On pressure gauge 3, the pressure at which water was transmitted over the course of 1 minute was recorded, and the water flux was determined.\u003c/p\u003e\n \u003cp\u003eWater sample testing (selectivity) was conducted using the same apparatus for determining permeability, as shown in Fig.\u0026nbsp;2. Model water containing 20 mg/L of kaolin was used for these studies. The turbidity in water samples was measured using a Turbidimeter CyberScan TB 1000, Netherlands.\u003c/p\u003e\n \u003c/div\u003e\n\u003c/div\u003e"},{"header":"Results","content":"\u003cp\u003eCharacterization\u003c/p\u003e \u003cp\u003eAs a result of sintering, a ceramic membrane support with a diameter of 4.6 mm and a thickness of 5 mm was obtained, as shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e3\u003c/span\u003e.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThe samples of the ceramic membrane supports were analysed by diffraction methods. Figure\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e4\u003c/span\u003e shows XRD patterns of the CM0 and CMS samples.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThe thermal stability analysis was performed using a thermogravimetric analyser (Linseis, Germany) in the temperature range from 25\u0026deg;C to 1050\u0026deg;C at a rate of 10\u0026deg;C/min (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e6\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eSelective layers were obtained on the surface of the CM0 support, which contained 10, 15, and 20 layers made of two types of compositions (solution 1 and solution 2, respectively), the characteristics of which are given in Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e. Reflectance spectra were taken for these samples (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e6\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eFigure\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e7\u003c/span\u003e shows the infrared spectra of samples CM0, CM1-10, CM1-20, CM2-10, and CM2-20. The IR spectra were recorded in the wavenumber range from 400 to 4000 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e using an IRAffinity-1S FTIR spectrometer (Shimadzu, Japan).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThe morphology and surface structure of the ceramic membranes were studied using a scanning electron microscope. SEM-images of the synthesized ceramic membranes with selective layer are presented in Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e6\u003c/span\u003e.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab3\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 3\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eTransport and selective properties of ceramic membrane samples\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"8\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"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 \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 \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSample of ceramic membrane\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eCM0\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eCM1-10\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eCM1-15\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eCM1-20\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003eCM2-10\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c7\"\u003e \u003cp\u003eCM2-15\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c8\"\u003e \u003cp\u003eCM2-20\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eР, bar\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u0026ge;\u0026thinsp;7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e\u0026ge;\u0026thinsp;7\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePure water permeability, cm\u003csup\u003e3\u003c/sup\u003e/(min\u0026middot;cm\u003csup\u003e2\u003c/sup\u003e)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e40\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e39\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e38\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e37\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e35\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTurbidity removal, %\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e32\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e7.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e14.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e58.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e68.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eAs can be seen from Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e4\u003c/span\u003e, the CM0 sample was identified as a mixture of Aluminum Silicon Oxide (Al\u003csub\u003e3.769\u003c/sub\u003eSi\u003csub\u003e0.731\u003c/sub\u003eO\u003csub\u003e7.5\u003c/sub\u003e) (Card ICDD 01-091-0689), Silicon Oxide (SiO\u003csub\u003e2\u003c/sub\u003e) (Card ICDD 01-086-1560), Silicon Carbide (SiC) (Card ICDD 01-090-2370), and Moissanite (α-SiC) (Card ICDD 01-072-4532). The X-ray diffraction pattern of the CMS sample, containing 10% saponite (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e4\u003c/span\u003e), showed similar characteristic peaks as CM0, along with additional ones identified as saponite (Card ICDD 00\u0026ndash;013\u0026ndash;0305). However, after sintering, the CMS support exhibited component stratification, characterized by heterogeneity. The investigated mechanical properties for bending the obtained ceramic membrane substrates CM0 and CMS demonstrated 13 MPa and 9 MPa bending strength values, respectively. According to existing literature, the most desirable bending strength threshold is 10 MPa; therefore, the CM0 sample was chosen for further research.\u003c/p\u003e \u003cp\u003eThermal analysis (thermogram (TG), derivative thermogram (DTG), and high-temperature differential scanning calorimetry (HDSC)), as presented in Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e5\u003c/span\u003e for the CM0 sample, was conducted to understand the physicochemical processes occurring during the thermal treatment of the initial mixture of components. The low endothermic peak at a temperature above 60\u0026ndash;80\u0026deg;C on the DTG curve and the smooth section on the TG curve is likely due to the starch gelatinization process. The small area of the peak is attributed to the low content of the substance in the initial mixture. Two endothermic peaks at temperatures on the DTG curve and two sharp decreases in mass on the TG curve at 80 and 150\u0026deg;C correspond to the processes of physical moisture loss by the materials. The main contribution to the released moisture comes from kaolin and borax, which are significant components of the mixture. The endothermic peak at 500\u0026ndash;520\u0026deg;C on the DTG curve with a sharp decline on the TG curve is likely associated with the dehydration processes of kaolinite structures and their transformation into metakaolin [\u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e35\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eFrom the reflection spectra (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e6\u003c/span\u003e), it was established that CM0 has no peaks in the 350 nm region, which are typical for metal oxide structures. However, for the membrane samples CM1-10, CM1-20, CM2-10, and CM2-20, characteristic peaks are observed in the 330\u0026ndash;360 nm range, indicative of TiO\u003csub\u003e2\u003c/sub\u003e.\u003c/p\u003e \u003cp\u003eThe infrared (IR) spectra of samples CM0, CM1-10, CM1-20, CM2-10, and CM2-20 (Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e7\u003c/span\u003e) indicate that for the CM0 ceramic membrane matrix sample, there are no characteristic bands for kaolin. This suggests that the thermal treatment at 950\u0026deg;C was sufficient to transform kaolin into Aluminum Silicon Oxide. This finding is consistent with the data obtained from the diffraction analysis method.\u003c/p\u003e \u003cp\u003eThe bands identified at 1070 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e correspond to the asymmetric valence vibrations of Si-O bonds, and those at 796 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e correspond to the vibrations and deformation of Si-C in Si-CH\u003csub\u003e3\u003c/sub\u003e. For the ceramic membrane samples CM1-10, CM1-20, CM2-10, and CM2-20, there is a disappearance of characteristic bands found in CM0. In the CM1-20 sample, additional peaks appear at 798 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e and 1058 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e, which may indicate insufficient temperature or duration of thermal treatment for removing organic components of the selective layer precursors. Overall, the samples with an applied selective layer display a typical IR spectrum of titanium oxide [\u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e36\u003c/span\u003e] with slight absorption at 1070 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eThe SEM images of all samples in Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e8\u003c/span\u003e show a dense structure typical of clay materials. These images show that the composition and number of layers have a minimal impact on the morphology in this case. As can be seen, the obtained ceramic membranes are characterized by a pore size ranging from 50\u0026ndash;200 \u0026micro;m. This explains the relatively high flux ranging from 40 cm\u003csup\u003e3\u003c/sup\u003e/min\u0026middot;cm\u003csup\u003e2\u003c/sup\u003e to 36 cm\u003csup\u003e3\u003c/sup\u003e/min\u0026middot;cm\u003csup\u003e2\u003c/sup\u003e for the CM0 sample and samples containing 10, 15 selective layers on it (Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e). It should also be noted that CM0 samples with 20 selective layers of two different compositions exhibited zero flux at a pressure of 0.7 MPa. At the same time, turbidity removal for the samples CM1-10 and CM1-15 decreased compared to the CM0 support, from 32\u0026ndash;7.2% for CM1-10 and 14.3% for CM1-15. CM1-20 exhibited a lack of filtration at pressures up to 0.7 MPa, probable due to the blocking pores of the membrane surface. For the second composition applied on the surface of the CM2-10 and CM2-15 membranes, an increase in selectivity to 58.6% for CM2-10 and 68.4% for CM2-15 was observed. CM2-20 also demonstrated a lack of filtration. The uncharacteristic dependence on turbidity removal needs further research.\u003c/p\u003e"},{"header":"Conclusions","content":"\u003cp\u003eA macroporous ceramic membrane support was synthesized from low-cost clay raw material, specifically kaolin, which demonstrated a high permeability of 40 cm\u003csup\u003e3\u003c/sup\u003e/(min\u0026middot;cm\u003csup\u003e2\u003c/sup\u003e) and good mechanical properties of 13 MPa. XRD studies revealed the presence of phases such as aluminium silicon oxide, silicon oxide, silicon carbide, and moissanite, which was confirmed by thermal analysis showing the transformation of kaolin into metakaolin.\u003c/p\u003e \u003cp\u003eSelective layers (10, 15, and 20) of two different compositions were applied to the surface of the obtained ceramic support using the spin-coating method and characterized. The diffuse reflectance absorption spectrum and IR analysis indicated that the characteristic peaks observed in the 330\u0026ndash;360 nm range suggest TiO\u003csub\u003e2\u003c/sub\u003e, which is consistent with the infrared (IR) spectral data.\u003c/p\u003e \u003cp\u003eSEM studies indicated that both compositions partially block the pores of the ceramic membrane and are not uniformly distributed across its surface. This finding correlates with the obtained data on permeability, which slightly decreases for the support with 10 and 15 applied layers, while for the substrate with 20 layers, filtration processes did not occur at pressures up to 0.7 MPa.\u003c/p\u003e \u003cp\u003eThe studied selectivity of ceramic membranes indicates varied character of suspended particle removal. In the case of the first composition, turbidity removal decreased compared to the support, while it increased in the case of the second composition. The uncharacteristic reduction in turbidity can be explained by the peculiarities of the porous structure formation after modification.\u003c/p\u003e \u003cp\u003eFurther scientific research plans include obtaining an intermediate layer to achieve a more controlled design of the selective layer on the surface of the support made from clay materials. This layer will create the desired architecture and prevent the blocking of the matrix pores.\u003c/p\u003e"},{"header":"Declarations","content":"\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\u003cp\u003eS.K. conduct research, wrote the main manuscript text;A.M. conduct research, reference design;O.R. conduct research, figures design;M.T. conduct research, describe some experiments;W.K. XRD analysis, checking the article;T.D. work concept design and approving, revised drafted work;All authors reviewed the manuscript.\u003c/p\u003e\u003ch2\u003eAcknowledgements\u003c/h2\u003e \u003cp\u003eAuthors are grateful to the National Research Foundation of Ukraine for funding the project (project registration number 2020.02/0024).\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eN. H. Othman, N. H. Alias, N. S. Fuzil, F. Marpani, M. Z. Shahruddin, C. M. Chew, K. M. David Ng, W. J. Lau, A. F. Ismail, A review on the use of membrane technology systems in developing countries, Membranes 12(1), 30 (2021). https://doi.org/10.3390/membranes12010030.\u003c/li\u003e\n\u003cli\u003eT. A. Saleh, V. K. Gupta, An overview of membrane science and technology, in Nanomaterial and polymer membranes (Elsevier, 2016), pp. 1\u0026ndash;23. https://doi.org/10.1016/B978-0-12-804703-3.00001-2.\u003c/li\u003e\n\u003cli\u003eS.-L. Loo, A. G. Fane, W. B. Krantz, T.-T. Lim, Emergency water supply: A review of potential technologies and selection criteria, Water Res., 46(10), 3125\u0026ndash;3151, (2012). https://doi.org/10.1016/j.watres.2012.03.030 \u003c/li\u003e\n\u003cli\u003eT. Mitchenko, I. Kosogina, S. Kyrii, The local solutions for water security in Ukraine, in Physical and cyber safety in critical water infrastructure (2019), pp. 99\u0026ndash;105. https://doi.org/10.3233/NICSP190044.\u003c/li\u003e\n\u003cli\u003eR. Sondhi, R. Bhave, G. Jung, Applications and benefits of ceramic membranes, Membr. Technol. 2003(11), 5\u0026ndash;8 (2003). https://doi.org/10.1016/s0958-2118(03)11016-6.\u003c/li\u003e\n\u003cli\u003eC. A. M. Siskens, Chapter 13 Applications of ceramic membranes in liquid filtration, in Membrane science and technology (Elsevier, 1996), pp. 619\u0026ndash;639. https://doi.org/10.1016/s0927-5193(96)80016-7.\u003c/li\u003e\n\u003cli\u003eA. Kuzminchuk, A. Burmak, M. Litynska, M., T. Dontsova, New diatomaceous earth and kaolinite ceramic membranes for turbidity reduction in water, Appl. Nanosci. 13, 5335\u0026ndash;5343 (2023). https://doi.org/10.1007/s13204-023-02792-8\u003c/li\u003e\n\u003cli\u003eL. Huang, H. Qin, T. Hu, J. Xie, W. Guo, P. Gao, H. Xiao, Fabrication of high permeability SiC ceramic membrane with gradient pore structure by one-step freeze-casting process, Ceram. Int. 47(12), 17597\u0026ndash;17605 (2021). https://doi.org/10.1016/j.ceramint.2021.03.078\u003c/li\u003e\n\u003cli\u003eG. Rothenberg, V. Gitis, Ceramic Membranes: New Opportunities and Practical Applications (Wiley \u0026amp; Sons, Limited, John, 2016).\u003c/li\u003e\n\u003cli\u003eA. Pierre, G. Christian, Current Status and Prospects for Ceramic Membrane Applications, in Handbook of Membrane Separations (CRC Press, 2008), pp. 159\u0026ndash;200. https://doi.org/10.1201/9781420009484-12.\u003c/li\u003e\n\u003cli\u003eP. Maarten Biesheuvel, H. Verweij, Design of ceramic membrane supports: permeability, tensile strength and stress, J. Membr. Sci. 156(1), 141\u0026ndash;152 (1999). https://doi.org/10.1016/s0376-7388(98)00335-4.\u003c/li\u003e\n\u003cli\u003eA. Sah, H. L. Castricum, A. Bliek, D. H. A. Blank, J. E. ten Elshof, Hydrophobic modification of \u0026gamma;-alumina membranes with organochlorosilanes, J. Membr. Sci. 243(1-2), 125\u0026ndash;132 (2004). https://doi.org/10.1016/j.memsci.2004.05.031.\u003c/li\u003e\n\u003cli\u003eK. Suresh, G. Pugazhenthi, Cross flow microfiltration of oil-water emulsions using clay based ceramic membrane support and TiO\u003csub\u003e2\u003c/sub\u003e composite membrane, Egypt. J. Pet. 26(3), 679\u0026ndash;694 (2017). https://doi.org/10.1016/j.ejpe.2016.10.007 \u003c/li\u003e\n\u003cli\u003eT. Meng, R. Xie, X. Ju, C. J. Cheng, S. Wang, P. F. Li, B. Liang, L. Y. Chu, Nano-structure construction of porous membranes by depositing nanoparticles for enhanced surface wettability, J. Membr. Sci. 427, 63\u0026ndash;72, (2013). https://doi.org/10.1016/j.memsci.2012.09.051 \u003c/li\u003e\n\u003cli\u003eJ. E. Zhou, Q. Chang, Y. Wang, J. Wang, G. Meng, Separation of stable oil\u0026ndash;water emulsion by the hydrophilic nano-sized ZrO\u003csub\u003e2\u003c/sub\u003e modified Al\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e microfiltration membrane, Sep. Purif. Technol. 75(3), 243\u0026ndash;248, (2010). https://doi.org/10.1016/j.seppur.2010.08.008 \u003c/li\u003e\n\u003cli\u003eS. K. Hubadillah, M. H. D. Othman, T. Matsuura, A. F. Ismail, M. A. Rahman, Z. Harun, J. Jaafar, M. Nomura, Fabrications and applications of low cost ceramic membrane from kaolin: A comprehensive review, Ceram. Int. 44(5), 4538\u0026ndash;4560, (2018). https://doi.org/10.1016/j.ceramint.2017.12.215 \u003c/li\u003e\n\u003cli\u003eT. Dontsova, S. Kyrii, O. Yanushevska, V. Suprunchuk, I. Kosogina, Physicochemical properties of TIO\u003csub\u003e2\u003c/sub\u003e, ZrO\u003csub\u003e2\u003c/sub\u003e, Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e nanocrystalline adsorbents and photocatalysts, Chem. Pap. (2022). https://doi.org/10.1007/s11696-022-02433-4.\u003c/li\u003e\n\u003cli\u003eA. Kutuzova, T. Dontsova, W. Kwapinski, J. J. Leahy, J. Strunk, Photocatalytic activity to ciprofloxacin and physico-chemical properties of TiO\u003csub\u003e2\u003c/sub\u003e synthesized by different methods, Mol. Cryst. Liq., 1\u0026ndash;13 (2022). https://doi.org/10.1080/15421406.2022.2073526.\u003c/li\u003e\n\u003cli\u003eT. A. Dontsova, A. S. Kutuzova, K. O. Bila, S. O. Kyrii, I. V. Kosogina, D. O. Nechyporuk, Enhanced Photocatalytic Activity of TiO\u003csub\u003e2\u003c/sub\u003e/SnO\u003csub\u003e2\u003c/sub\u003e Binary Nanocomposites, J. Nanomater. 1\u0026ndash;13 (2020). https://doi.org/10.1155/2020/8349480.\u003c/li\u003e\n\u003cli\u003eGrebenișan, E.; Hegyi, A.; Szilagyi, H.; Lăzărescu, A.-V.; Ionescu, B.A. Influence of the Addition of TiO\u003csub\u003e2\u003c/sub\u003e Nanoparticles on the Self-Cleaning Performance of Cementitious Composite Surfaces. Proc. 63(42), (2020). https://doi.org/10.3390/proceedings2020063042 \u003c/li\u003e\n\u003cli\u003eH. Choi, E. Stathatos, D. D. Dionysiou, Sol\u0026ndash;gel preparation of mesoporous photocatalytic TiO2 films and TiO\u003csub\u003e2\u003c/sub\u003e/Al\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e composite membranes for environmental applications, Appl. Catal. B 63(1-2), 60\u0026ndash;67 (2006). https://doi.org/10.1016/j.apcatb.2005.09.012.\u003c/li\u003e\n\u003cli\u003eH. Choi, E. Stathatos, D. D. Dionysiou, Photocatalytic TiO2 films and membranes for the development of efficient wastewater treatment and reuse systems, Desalination 202(1-3), 199\u0026ndash;206 (2007). https://doi.org/10.1016/j.desal.2005.12.055.\u003c/li\u003e\n\u003cli\u003eK. Suresh, G. Pugazhenthi, Cross flow microfiltration of oil-water emulsions using clay based ceramic membrane support and TiO\u003csub\u003e2\u003c/sub\u003e composite membrane, Egypt. J. Pet. 26(3), 679\u0026ndash;694 (2017). https://doi.org/10.1016/j.ejpe.2016.10.007.\u003c/li\u003e\n\u003cli\u003eA. Bouazizi, M. Breida, B. Achiou, M. Ouammou, J. I. Calvo, A. Aaddane, S. A. Younssi, Removal of dyes by a new nano\u0026ndash;TiO\u003csub\u003e2\u003c/sub\u003e ultrafiltration membrane deposited on low-cost support prepared from natural Moroccan bentonite, Appl. Clay Sci. 149, 127\u0026ndash;135 (2017). https://doi.org/10.1016/j.clay.2017.08.019.\u003c/li\u003e\n\u003cli\u003eY. Du, X. Wang, J. Wu, C. Qi, Y. Li, Adsorption and photoreduction of Cr(VI) via diatomite modified by Nb\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e5\u003c/sub\u003e nanorods, Particuology 40, 123\u0026ndash;130 (2018). https://doi.org/10.1016/j.partic.2017.11.005.\u003c/li\u003e\n\u003cli\u003eG. Zhang, Z. Sun, Y. Duan, R. Ma, S. Zheng, Synthesis of nano-TiO\u003csub\u003e2\u003c/sub\u003e /diatomite composite and its photocatalytic degradation of gaseous formaldehyde, Appl. Surf. Sci. 412, 105\u0026ndash;112 (2017). https://doi.org/10.1016/j.apsusc.2017.03.198.\u003c/li\u003e\n\u003cli\u003eD. D. Nematov, K. T. Kholmurodov, M. A. Husenzoda, A. Lyubchyk, A. S. Burhonzoda, Molecular Adsorption of H\u003csub\u003e2\u003c/sub\u003eO on TiO\u003csub\u003e2\u003c/sub\u003e and TiO\u003csub\u003e2\u003c/sub\u003e:Y Surfaces, J. Hum., Earth, Future 3(2), 213\u0026ndash;222 (2022). https://doi.org/10.28991/hef-2022-03-02-07.\u003c/li\u003e\n\u003cli\u003eS. Kyrii, T. Dontsova, I. Kosogina, V. Podopryhor, A. Serhiienko, Influence of yttrium and niobium oxides modifiers on physicochemical and photocatalytic properties of titanium (IV) oxide, Eastern-European J. Enterp. Technol. 4(6(112)), 67\u0026ndash;74 (2021). https://doi.org/10.15587/1729-4061.2021.238347.\u003c/li\u003e\n\u003cli\u003eY. L. R. L. Fernandes, M. C. L. Silva, R. A. Raimundo, J. Cavalcante, J. B. Q. Tomaz, M. Mashhadikarimi, M. A. Morales, F. V. da Motta, W. Acchar, U. U. Gomes, Development of mesoporous ceramic membranes of Diatomite/TiO\u003csub\u003e2\u003c/sub\u003e /Nb\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e5\u003c/sub\u003e nanocomposites for the treatment of contaminated water, J. Environ. Chem. Eng. 111161, (2023). https://doi.org/10.1016/j.jece.2023.111161.\u003c/li\u003e\n\u003cli\u003eK. J. Skrobis, D. D. Denton, A. V. Skrobis, Effect of early solvent evaporation on the mechanism of the spin-coating of polymeric solutions, Polym. Eng. Sci. 30(3), 193\u0026ndash;196 (1990). https://doi.org/10.1002/pen.760300309.\u003c/li\u003e\n\u003cli\u003eB. T. Chen, Investigation of the solvent-evaporation effect on spin coating of thin films, Polym. Eng. Sci. 23(7), 399\u0026ndash;403 (1983). https://doi.org/10.1002/pen.760230706.\u003c/li\u003e\n\u003cli\u003eJ. H. Lai, An investigation of spin coating of electron resists, Polym. Eng. Sci. 19(15), 1117\u0026ndash;1121 (1979). https://doi.org/10.1002/pen.760191509.\u003c/li\u003e\n\u003cli\u003eL. L. Spangler, J. M. Torkelson, J. S. Royal, Influence of solvent and molecular weight on thickness and surface topography of spin-coated polymer films, Polym. Eng. Sci. 30(11), 644\u0026ndash;653 (1990). https://doi.org/10.1002/pen.760301104.\u003c/li\u003e\n\u003cli\u003eJ. D. Le Roux, D. R. Paul, Preparation of composite membranes by a spin coating process, J. Membr. Sci. 74(3), 233\u0026ndash;252 (1992). https://doi.org/10.1016/0376-7388(92)80064-q.\u003c/li\u003e\n\u003cli\u003eA. O. Serhiienko, T. A. Dontsova, O. I. Yanushevska, V. I. Vorobyova, G. S. Vasyliev, Characterization of ceramic membrane support based on Ukrainian kaolin, Mol. Cryst. Liq. Cryst. 2022, 1\u0026ndash;14. https://doi.org/10.1080/15421406.2022.2091279.\u003c/li\u003e\n\u003cli\u003eInteractive IRUG Spectrum, IMP00141 Titanox RA, rutile form. (Infrared and Raman Users Group (IRUG)), http://www.irug.org/jcamp-details?id=920. Accessed 28 November 2023 \u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"kaolin-based ceramic membrane, TiO2 selective layer, spin-coating, membrane characterization","lastPublishedDoi":"10.21203/rs.3.rs-3687052/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-3687052/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eThe selective layer in a ceramic membrane is crucial for separation and filtration processes, as it endows the membrane with specific properties and functions, determining its selectivity and suitability for various applications. This study aimed to investigate the impact of the type of composition used to create a selective layer on low-cost clay ceramic membranes and to determine their physicochemical properties and permeability. In this study, a ceramic membrane substrate based on kaolin was synthesized and characterized using XRD, thermal analysis, and IR spectroscopy, and its mechanical properties were also tested. Selective layers on the ceramic membrane were synthesized with various compositions using spin-coating. They were characterized using IR spectroscopy, diffuse reflectance absorption spectrum, and scanning electron microscopy (SEM). The SEM images of all samples show a dense structure typical of clay materials. These images indicate that the composition and number of layers have minimal impact on the morphology in this case. The obtained ceramic membranes are characterized by a pore size ranging from 50 – 200 μm. The permeability of the ceramic membrane support is 40 cm\u003csup\u003e3\u003c/sup\u003e/min·cm\u003csup\u003e2\u003c/sup\u003e, which decreases with the application of selective layers. Selectivity by turbidity increases from 32% to 66.4%.\u003c/p\u003e","manuscriptTitle":"Physico-chemical characterisation of selective TiO2 layer on kaolin-based ceramic membranes","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2023-12-06 13:04:34","doi":"10.21203/rs.3.rs-3687052/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"5bb57b6b-75ec-4128-b6e3-bf53db380e01","owner":[],"postedDate":"December 6th, 2023","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2023-12-07T12:59:52+00:00","versionOfRecord":[],"versionCreatedAt":"2023-12-06 13:04:34","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-3687052","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-3687052","identity":"rs-3687052","version":["v1"]},"buildId":"rHA-KDH7Qsr4HCuvH75dn","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}