Membrane Casting Solution Research Articles

Experimental investigation and comparison of PBI/MWCNT and PSF/MWCNT membranes for recovering water from RO reject of brackish water by FO

The performances of polybenzimidazole (PBI) and polysulfone (PSF) membranes for recovering water from reverse osmosis (RO) reject of brackish water through forward osmosis (FO) were assessed and compared. Non-functionalised multi-walled carbon nanotubes (MWCNT) were added to the membrane casting solutions, with concentrations ranging from 0 to 3 wt%. The experiment was conducted for eight samples using RO reject of brackish water as the feed solution (FS) and 2 M analytical grade MgCl2 as the draw solution (DS). The hydrophilicity, water permeability, salt rejection rate (Rs), water flux (WF) and porosity of the membranes improved with increasing MWCNT content up to 2 wt%. Also, the structural parameter, salt permeability and reverse solute flux decreased. PBI/MWCNT2 wt% exhibited the best performance among the membranes tested compared with porosity of 70 ± 4 %, structural parameter of 0.36 ± 0.2 μm, and Rs of 93.5 %. In contrast with the pristine PBI membrane, an average water flux enhancement of 15 % and 49 % was observed for the FS and DS sides, respectively, for PBI/MWCNT2 wt%. It is evident from the results that including MWCNT improves the performance of both membranes, with better relative performance for PBI membranes than PSF membranes.

Dormancy and double-activation strategy for construction of high-performance mixed-matrix membranes.

Mixed-matrix membranes (MMMs) have the potential for energy-efficient gas separation by matching the superior mass transfer and anti-plasticization properties of the fillers with processability and scaling up features of the polymers. However, construction of high-performance MMMs has been prohibited due to low filler-loading and the existence of interfacial defects. Here, high MOF-loaded, i.e., 55 wt %, MMMs are developed by a 'dormancy and double-activation' (DDA) strategy. High MOF precursor concentration suppresses crystallization in the membrane casting solution, realizing molecular level mixing of all components. Then, the polymeric matrix was formed with uniform encapsulation of MOF nutrients. Subsequently, double-activation was employed to induce MOF crystallization: the alkali promotes MOFs nucleation to harvest small porous nanocrystals while excessive ligands activate the metal ions to enhance the MOFs conversion. As such, quasi-semi-continuous mass transfer channels can be formed in the MMMs by the connected MOFs nanocrystals to boost the gas permeability. The optimized MMM shows significantly ameliorated CO2 permeability, i.e., 2841 Barrer, five-fold enhancement compared with pristine polymer membrane, with a good CO2 /N2 selectivity of 36. Besides, the nanosized MOFs intensify their interaction with polymer chains, endowing the MMMs with good anti-plasticization behaviour and stability, which advances practical application of MMMs in carbon capture.

Dormancy and double‐activation strategy for construction of high‐performance mixed‐matrix membranes

AbstractMixed‐matrix membranes (MMMs) have the potential for energy‐efficient gas separation by matching the superior mass transfer and anti‐plasticization properties of the fillers with processability and scaling up features of the polymers. However, construction of high‐performance MMMs has been prohibited due to low filler‐loading and the existence of interfacial defects. Here, high MOF‐loaded, i.e., 55 wt %, MMMs are developed by a ‘dormancy and double‐activation’ (DDA) strategy. High MOF precursor concentration suppresses crystallization in the membrane casting solution, realizing molecular level mixing of all components. Then, the polymeric matrix was formed with uniform encapsulation of MOF nutrients. Subsequently, double‐activation was employed to induce MOF crystallization: the alkali promotes MOFs nucleation to harvest small porous nanocrystals while excessive ligands activate the metal ions to enhance the MOFs conversion. As such, quasi‐semi‐continuous mass transfer channels can be formed in the MMMs by the connected MOFs nanocrystals to boost the gas permeability. The optimized MMM shows significantly ameliorated CO2 permeability, i.e., 2841 Barrer, five‐fold enhancement compared with pristine polymer membrane, with a good CO2/N2 selectivity of 36. Besides, the nanosized MOFs intensify their interaction with polymer chains, endowing the MMMs with good anti‐plasticization behaviour and stability, which advances practical application of MMMs in carbon capture.

Fabrication of high permeability and antifouling composite membrane loaded with Fe3O4 nanoparticles via a magnetic field induced phase separation

Membrane fouling increases operational expenses and limits the application of ultrafiltration technology in water treatment. To mitigate the membrane fouling, this study incorporated Fe3O4 nanoparticles (NPs) into the polyethersulfone (PES) membrane casting solution, and developed a non-solvent induced phase separation (NIPS) method assisted by a magnetic field (MGF) to fabricate the Fe3O4 NPs composite ultrafiltration membrane. The combination of MGF and Fe3O4 NPs synergistically enhanced the permeability and separation performance of the composite membrane. The performance of the membrane was determined by its structure. With the involvement of MGF, Fe3O4 NPs were enriched on the surface layer of the membrane, resulting in enhanced hydrophilicity of the composite membrane. The membrane permeability increased to 913.39 LMH·bar−1, and the rejection performance rose to 93 % due to the formation of tiny pores on the membrane surface that facilitated solvent diffusion during phase separation, thereby counteracting the adverse effects of heightened viscosity in the casting solution. Moreover, the Fe3O4 NPs composite membrane fabricated with MGF induction exhibited significantly enhanced antifouling capability in multi-cycle fouling tests, resulting in a 27.5 % increase in specific flux compared to the pure PES membrane. Additionally, the preparation procedures for the matrix membrane were optimized to include 15 wt% PES, 3 wt% PVP, and a pre-treatment time of 30 s. These findings have significant implications for advancing the widespread application of membrane technology.

Fe3O4@Gum Arabic modified polyvinyl chloride membranes to improve antifouling performance and separation efficiency of organic pollutants

Nanofiltration (NF) membranes are promising media for water and wastewater treatment; however, they suffer from their hydrophobic nature and low permeability. For this reason, the polyvinyl chloride (PVC) NF membrane was modified by iron (III) oxide@Gum Arabic (Fe3O4@GA) nanocomposite. First, Fe3O4@GA nanocomposite was synthesized by the co-precipitation approach and then its morphology, elemental composition, thermal stability, and functional groups were characterized by various analyses. Next, the prepared nanocomposite was added to the casting solution of the PVC membrane. The bare and modified membranes were fabricated by a nonsolvent-induced phase separation (NIPS) method. The characteristics of fabricated membranes were assessed by mechanical strength, water contact angle, pore size, and porosity measurements. The optimum Fe3O4@GA/PVC membrane had a 52 L m−2. h−1. bar−1 water flux with a high flux recovery ratio (FRR) value (82%). Also, the filtration experiment exhibited that the Fe3O4@GA/PVC membrane could remarkably remove organic contaminants, achieving high rejection rates of 98% Reactive Red-195, 95% Reactive Blue-19, and 96% Rifampicin antibiotic by 0.25 wt% of Fe3O4@GA/PVC membrane. According to the results, adding Fe3O4@GA green nanocomposite to the membrane casting solution is a suitable and efficient procedure for modifying NF membranes.

Effect of Different Solvents, Pore-Forming Agent and Solubility Parameter Differences on the Properties of PES Ultrafiltration Membrane

In the production of polymeric membranes used in water treatment by the non-solvent-induced phase separation (NIPS) method, the materials used in the membrane casting solution and the interaction of these materials greatly affect the properties and performance of the obtained membranes. In this study, polyethersulfone (PES) membranes are produced by the NIPS method using two different solvents, dimethyl sulfoxide (DMSO) and N-methyl-2-pyrrolidone (NMP), and polyvinylpyrrolidone (PVP) as pore-forming agent. Chemical functional groups and morphologies of the produced membranes are investigated by Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM), respectively. The viscosity of the membrane casting solutions and the hydrophilicity, porosity, mean pore size, and mechanical properties of the membranes are characterized. The pure water flux (PWF) of the membranes is determined at 1 and 3 bar pressures. The Hansen solubility parameters (HSP) of the materials used in membrane production are calculated and the effect of the interactions of DMSO, NMP, and PVP with PES and/or non-solvent (water) on the membrane properties are investigated.

Fabrication and characterization of polymer nanocomposites membrane (Cu-MOF@CA/PES) for water treatment

In present work, the hydrophilic Cu-MOF was synthesized by solvothermal method and incorporated with a cellulose acetate (CA)/polyether sulfone (PES) polymer membrane casting solution using a phase inversion approach to create new mixed matrix membranes of nanocomposite membrane material (Cu-MOF@CA-PES). The physical and chemical characteristics of the prepared materials were examined using different analytical techniques such as, FT-IR, XRD, TGA, XPS, SEM, TEM, AFM, BET and contact angle analysis. The membrane performance was analyzed using pure water flux (PWF), Bovine sirup albumin (BSA) and Humic acid (HA) rejection. The maximum water flux was 28.5 L m−2 h−1 with an 85 % BSA rejection rate and a 79 % HA rejection rate respectively and the contact angle value reduced from 75.27° to 46.02° respectively confirming that the modified membrane material is hydrophilic nature. The presence of Cu-MOF membrane material also exhibited outstanding anti-bacterial properties against pseudomonas aeruginosa, E. coli, Enterococcus faecalis and Staphylococcus aureus for gram positive and gram negative.

Preparation and characterization of polyvinyl chloride membranes decorated with designed novel zinc oxide particles for mitigating uncontrollable agglomeration

The use of nanomaterials in the fabrication of polymeric composite membranes has a great potential for improving separation performance by altering the membrane characteristics. However, homogeneous dispersion of these fillers in the matrix and stability issues have remained major drawbacks to take a step forward for the commercial applications of such membranes. In this study, polyvinyl chloride ultrafiltration membranes were prepared via direct blending of designed zinc oxide (ZnO) powders (MicNo®), that were intentionally agglomerated in hexagonal platelet forms, into the casting solution by immersion precipitation method. The impact of MicNo® loading on the development of membrane microstructure, separation performance and bulk properties were evaluated in comparison to neat PVC and commercial ZnO-doped membranes. Water flux (456 L/m2h) of the 0.05% wt. MicNo® platelets containing membranes had 30.6% and 9% higher values with respect to pristine PVC and 0.5% commercial ZnO (c-ZnO) containing membranes, respectively. Although the amount of MicNo® platelets (0.05%), added to the membrane casting solution was ten times less than c-ZnO nanoparticles (0.5%), rejection and antifouling properties of the membranes were enhanced significantly due to the large active hydrophilic surface area of MicNo® powders. The highest FRR value after SA removal tests was achieved as 89.9% in the case of PVC/0.05 MicNo® membrane with 19% enhancement compared with the pristine membrane. Overall, incorporating MicNo® into PVC-based membrane matrix could be a promising approach to cope with the uncontrolled agglomeration and leaching issues with minimal embedment of fillers.

Preparation and Characterization of a Thin-Film Composite Membrane Modified by MXene Nano-Sheets.

MXene nano-sheets were introduced into a thin-film composite membrane (TFC) to reduce the mass transfer resistance (concentration polarization) and improve the membrane performance. The process entailed dissolving the MXene nano-sheets in a membrane casting solution using the blending method and introducing them into the porous support layer to prepare a modified thin-film composite forward osmosis (TFC-FO) membrane. The results showed that the water contact angle decreased by about 16%, indicating that the hydrophilicity was strengthened, and the O/N ratio of the active selective layer decreased by 13%, indicating an increased degree of crosslinking, thereby demonstrating that the introduction of MXene nano-sheets changed the properties of the membrane and played a positive role in its physicochemical properties. In contrast to the unmodified TFC-FO membrane, the modified membrane had a slightly higher reverse solute flux, while its water flux increased by about 80%. Its specific reverse osmosis flux was also significantly optimized (only 0.63 g/L). In conclusion, adding MXene nanosheets to TFC-FO membranes led to the modified membranes with better mass transfer, lessened internal concentration polarization (ICP), and better osmotic separation.

Polyphenylsulfone/zinc ion‐exchanged zeolite Y nanofiltration mixed matrix membrane for water desalination

AbstractIn the present study, zinc ion‐exchanged zeolite Y (ZnY) was incorporated as a dispersed phase into polyphenylsulfone (PPSU) polymer matrix to prepare PPSU/ZnY porous mixed matrix membranes (MMMs) with enhanced separation properties. Various MMMs with different ZnY contents (0, 0.25, 0.5, 0.75, 1, 1.5, and 3 wt.%) were fabricated using phase inversion method. The morphologies of prepared membranes were characterized by using scanning electron microscopy (SEM) and atomic force microscopy (AFM) analysis. Fourier transform infrared (FTIR) and X‐ray diffraction (XRD) were used to investigate the chemical structures and microstructural properties, respectively. Differential scanning calorimetry (DSC) analysis and tensile test were done to investigate thermomechanical properties of the membranes. Density and dynamic viscosity of membrane casting solutions as well as porosity, mean pore size, contact angle and water content of the prepared membranes were determined to investigate how these parameters affect the morphology of the membranes. Finally, separation performance of the membrane samples was investigated by determining water flux, salt (CuSO4) rejection, and anti‐fouling properties. SEM results showed an increase in top layer pore volumes with the incorporation of ZnY nanoparticles, which offer a higher water flux. AFM images indicated the higher surface roughness for an MMM compared to the pure PPSU membrane. FTIR spectroscopy confirmed the presence of all PPSU and ZnY functional groups in the MMM and showed no existence of chemical bonds at the polymer‐particle interface. XRD patterns exhibited a decrease in the degree of crystallinity by addition ZnY nanoparticles into PPSU matrix. DSC and tensile tests confirmed the XRD analysis and show lower Tg and tensile stress for an MMM compared to the pure PPSU membrane. Porosity measurements showed that the membrane porosity improved by decreasing the polymer concentration in the casting solutions and by incorporation of ZnY nanoparticles. The contact angle measurement indicated that the values decrease upon loading of ZnY nanoparticles. Finally, an enhanced pure water flux of 4.315 L m−2 h−1 bar−1 and a salt rejection of 75%, respectively as compared to 3.591 L m−2 h−1 bar−1 and 81% for pure PPSU membrane, were observed for the MMM with 1 wt.% of ZnY filler.

Photocatalytic Filtration of Zinc Oxide-Based Membrane with Enhanced Visible Light Responsiveness for Ibuprofen Removal

The growing interest in mixed matrix membranes (MMMs) for developing photocatalytic membranes has provided a new direction in the search for efficient methods to concurrently separate and degrade contaminants. In this study, a visible light-responsive photocatalyst was blended into a polyvinylidene fluoride (PVDF) membrane casting solution to prepare PVDF-ZnO/Ag2CO3/Ag2O MMMs using the wet phase inversion method. The potential of ZnO/Ag2CO3/Ag2O as a photocatalytic component that is incorporated into the membrane was explored in detail under various loadings (0.5–2.91 wt%). The membranes were tested under ibuprofen (IBF) aqueous solution to analyze the membrane behavior in the synergistic combination of membrane filtration and photodegradation. The resulting PVDF-ZnO/Ag2CO3/Ag2O membrane with a rougher membrane surface area and excellent light harvesting capability showed higher photocatalytic filtration activity in removing IBF under visible light irradiations. The MMM fluxes demonstrated higher IBF fluxes than their initial fluxes at certain durations. This indicates that the membrane actively responds to light irradiation. The increase in the positive flux could be attributed to the photoinduced hydrophilicity generated by the ZnO/Ag2CO3/Ag2O photocatalyst, resulting in easier water layer formation and rapid transport through membranes. The highest IBF removal was demonstrated by the PVDF-ZAA2 membrane (1.96 wt% loading), with 49.96% of IBF removal within 180 min upon visible light irradiation. The reason for this lower IBF removal is that the UF membrane pores exceed the size of IBF molecules, thereby preventing the size exclusion mechanism. Thus, charge repulsion, hydrophobic adsorption, and photocatalytic activity were considered along with the IBF removal of the photocatalytic membranes. However, the recyclability of the PVDF-ZAA2 photocatalytic membrane showed a great improvement, with 99.01% of IBF removal recovery after three cycles. These results highlight the potential of such hybrid membranes in mitigating membrane fouling by providing a platform for photocatalysts to continuously degrade pollutants present in such wastewaters. Therefore, the hybridization of a photocatalyst and membrane provides insight that could be utilized to improve and retrofit current water effluent treatment methods.

Fabrication of novel anti-fouling poly(m-phenylene isophthalamide) ultrafiltration membrane modified with Pluronic F127 via coupling phase inversion and surface segregation

• PMIA/F127 membrane was prepared via NIPS combining with surface segregation. • DFT calculation was employed for designing membrane casting solution. • Influences of F127 on membrane properties were systematically investigated. • The membrane exhibited good separating performance and high antifouling ability. The novel poly( m -phenylene isophthalamide) (PMIA) ultrafiltration membrane with enhanced anti-fouling performance was successfully designed using amphiphilic block copolymer Pluronic F127 via non-solvent induced phase separation (NIPS) technique combined with induced segregation. The influences of Pluronic F127 on PMIA membrane’s microstructure and properties were systematically conducted by employing a series of characterized methods. Meanwhile, the density functional theory (DFT) calculation was employed to study the intermolecular force among the bulk PMIA, Pluronic F127 additive, solvent, and inorganic agent. Results demonstrated that Pluronic F127, functioning as both a porogen and an induced-segregation additive, could effectively affect membrane structure and property. Specifically, the resultant membrane morphologies of the sublayer gradually altered from the finger-like pore to cavity-like shape, and the pore diameter and porosity displayed a stepwise upward trend via increasing the concentration of Pluronic F127, which further induced the loss of the membrane’s mechanical strength. The filtration experiments demonstrated that the water permeation was enhanced, along with the slightly reduced rejection to bovine serum albumin (BSA) with the increasing concentration of Pluronic F127. Furthermore, the fouling resistance and stability were improved remarkably, which benefited from the enhanced hydrophilicity caused by the migration of polyethylene glycol (PEO) segment of Pluronic F127 toward membrane surface and inner-pore wall. Additionally, DFT calculation confirmed the interaction energy among the dope components, which provided theoretical support on the dope design. In summary, the Pluronic F127/PMIA ultrafiltration membrane demonstrated great potential in the field of water purification and wastewater reclamation.

Hyperbranched polyethylenimine functionalized silica/polysulfone nanocomposite membranes for water purification

Hyperbranched polyethyleneimine functionalized silica (PEI-SiO2) nanoparticles with considerable hydrophilicity were synthesized and incorporated into a polysulfone (PSF)/dimethylacetamide (DMA)/polyvinylpyrrolidone (PVP) membrane casting solution in five different ratios to fabricate PEI-SiO2/PSF nanocomposite membranes using nonsolvent-induced phase separation. The hydrophilic PEI-SiO2 nanoparticles were characterized by TEM, FTIR, TGA, and XPS analyses. Morphology, water contact angles, mean pore sizes, overall porosity, tensile strengths, water flux, antifouling and the dye separation performances of the PEI-SiO2/PSF membranes were also studied. The PEI-SiO2 nanoparticles were uniformly dispersed in the PSF-based membranes, where a fall in the water contact angle was observed from 65.4° to 49.7° by addition of 2 wt% nanoparticles. The fouling resistance parameters of the PEI-SiO2/PSF membranes were declined with an increase in the nanoparticle concentration, suggesting the superior hydrophilic nature of the PEI-SiO2 nanoparticles. The permeability of the nanocomposite membranes was increased from 38.5 to 70 L m−2 h−1 bar−1 by incorporation of 2 wt% PEI-SiO2. Finally, improvements were observed in the flux recovery ratio (95.8%), Reactive Green 19 dye rejection (99.6%) and tensile strengths of the PEI-SiO2/PSF membranes over the neat PSF and SiO2/PSF membranes, which were used as controls. The results of this study demonstrate the promising application of PEI-SiO2 nanoparticles in improving the separation and antifouling performances of the PSF membranes for water purification.

Performance evaluation and modeling study of PC blended membranes incorporated with SDS-modified and unmodified halloysite nanotubes in the separation of oil from water

Due to the destructive environmental effects of oily wastewaters and the required purification of these effluents, novel polycarbonate (PC) based mixed matrix membranes (MMMs) including two various kinds of halloysite nanotubes (HNTs) were fabricated by phase inversion technique. The additive utilized in the preparation of neat membrane was polyvinyl pyrrolidone (PVP), while sodium dodecyl sulfate (SDS) was used for the modification of HNTs. Both SDS-modified and unmodified HNTs were separately impregnated into the membrane matrix with different nanoparticle loadings and the obtained mixed matrix membranes were utilized in the ultrafiltration process of oil/water emulsion. The effects of additive and nanoparticle loadings were evaluated on some properties of the membranes, namely hydrophilicity, functional groups, surface morphology, and mechanical characteristic via contact angle measurement, Fourier transform infrared spectrophotometry (FTIR), field emission scanning electron microscope (FESEM), transmission electron microscopy (TEM), and mechanical strength tests, respectively. Based on the obtained results, the membranes containing SDS-modified nanofillers exhibited more hydrophilicity and mechanical strength than the mixed matrix membranes incorporated with unmodified HNTs. Compared to bare polycarbonate membranes, adding SDS-modified HNTs into the membrane casting solution improved the pure water flux of the synthesized membranes and reduced the filtration time for the acquisition of the complete oil removal yield (100%). As an example, the water flux of the PC-0.75MH MMM was enhanced around 319% in comparison with that of the bare polycarbonate membrane. Evaluation of the membranes antifouling characteristic displayed that the optimized PC-0.75MH membrane had a flux recovery of above 95% after 3 regeneration cycles. Furthermore, the water permeability was analyzed using D-Optimal design response surface methodology. The results of the modeling study showed that the experimental data had about 97.37% proximity with the proposed model.

Temperature resistant cross-linked brominated poly phenylene oxide-functionalized graphene oxide nanocomposite anion exchange membrane for desalination

A new age strategic route to synthesize cross-linked nanocomposite anion exchange membranes (AEMs) from functionalized graphene oxide was reported here. Nanocomposite crosslinking networks were formed by reacting aminopropylsilane graphene oxide (AGO) with brominated poly (2,6-dimethyl-1,4-phenylene oxide) (BPPO). Amine ended functionalized graphene oxide; AGO was synthesized by condensation reaction between graphene oxide and 3-aminopropyltrimethoxysilane. A variety of nano cross-linker; AGO loading was introduced into membrane casting solution and the prepared membranes were explored based on physicochemical and electrochemical properties. The best optimized AEM; PPO/AGO-8 showed ion exchange capacity 2.2 mmol·g−1, water uptake 37.91%, swelling ratio 9.8%, conductivity 8.38 × 10−2 S·cm−1, counter ion transport number (0.97) and 108 A·m−2 limiting current density (Ilim) with maintaining good thermo-mechanical stability due to covalent interaction between polymer and nanofiller. Desalination performances were evaluated on the basis of removal ratio (RRNaCl), current efficiency (η) and energy consumption (EC) over a whole range of temperatures (25 °C to 55 °C). On being applied in ED, the PPO/AGO-8 membrane showed slightly higher RRNaCl (47.23%), η (86.0%) and lower EC (2.85 kWh·kg−1 NaCl) than commercial Fumatech FAB-PK-130 membrane (RRNaCl: 43.8%, η: 82.34% and EC: 3.21 kWh·kg−1 NaCl) under same temperature (55 °C). The superior ED performance of synthesized cross-linked nanocomposite AEM is suggested to be a promising candidate for electrodialytic desalination and temperature based separation and purification processes for industrial applications.

Utilization of used polyethylene terephthalate (PET) bottles for the development of ultrafiltration membrane

Polyethylene terephthalate (PET) bottle is commonly used as a single-use packaging for beverages. The recycling of used PET bottles is very important since the huge amount of used PET bottles creates serious environmental concerns. In this work, used PET bottles were utilized as a raw material to develop ultrafiltration membranes by phase inversion technique. The results of this study revealed that lowering the polarity of the non-solvent by using various types of non-solvents, namely water-ethanol, water-n-propanol, and water-n-butanol, resulted in an increase in the water permeate flux of the membrane. The membranes also exhibited higher water permeate fluxes by increasing the molecular weight and the concentration of the additive for the membrane casting solution. Ultrafiltration experiment using aqueous solution containing Bovine Serum Albumin as a model feed solution showed rejection values of up to 91 %.

Study on thermo-kinetic modeling of green route synthesized inorganic loading on PVDF membrane for Cr(VI) removal and its optimization

Mathematical modeling of a phase inversion membrane was studied to predict the morphology. The effect of different concentrations of TiO2 nanoparticles on the thermodynamic and kinetic properties of polyvinylidene fluoride (PVDF) membrane casting solutions was investigated. The addition of green synthesized TiO2 increases the viscosity, and a sufficient amount results in the formation of two phases. Thermodynamics enhances the demixing rate, whereas kinetics delays the demixing rate; this trade-off between thermodynamic and kinetic parameter will affect the membrane morphology. A quadratic phase diagram for PVDF/ TiO2/solvent/Water system was drawn experimentally at different concentrations of TiO2 using a new method. Synthesized membranes were characterized by the contact angle, porosity, and permeability. Surface morphologies at different compositions were also examined using High Resolution scanning electron microscope (HRSEM). At TiO2 concentration of 2 wt% in the polymer casting solution, thermodynamics parameter dominates kinetics parameter; thus, maximum porosity with enhanced permeability was achieved experimentally. The importance of thermo-kinetic parameters was further assessed using response surface optimization. The study suggested an optimum value of 2.165% of weight% TiO2 at 5.125 pH giving excellent agreement to the experimental data.

Solid‐state ion sensor for on‐chip determination of potassium ion in body fluid

AbstractThis article describes a synthetic route for the fabrication of all‐solid‐state potentiometric ion‐sensing device for on‐chip determination of potassium ion in body fluid. The sensing electrodes comprised of (a) a solid‐state reference electrode made from a Ag/AgCl‐printed electrode covered with a solid‐electrolyte‐embedded membrane made from siloxane polymer and (b) solid‐state ion‐selective electrode as working electrode made by assembling ionophore‐impregnated PVC membrane casting solution over a ion exchanger‐impregnated membrane. The ion exchanger‐impregnated membrane is cast by assembling siloxane–polyindole nanodispersion over working electrode of screen‐printed electrode to yield constant dipolar potential. The screen‐printed electrodes comprising of all‐solid‐state reference and working electrode can be operated under zero current flow to monitor potassium ion in given sample. The configuration of the printed electrodes is designed to fix a microneedle assembly over the working portion of both reference and working electrodes for transdermal ion sensing. The functional alkoxysilanes derived from nanodispersion allow to make solid‐state reference electrode avoiding the use of internal filling solution providing innovation in designing potentiometric sensor. In one aspect, a potentiometric device for detecting analyte in biological fluid that can include a array of hollowed microneedle in which each needle acts as protruded needle structure including an exterior wall forming a hollow interior covering both solid‐state working and reference electrode with an opening at terminal end in such that one microneedle is converted into a potassium ion‐selective electrode.

Stimuli responsive mixed matrix polysulfone ultrafiltration membrane for humic acid and photocatalytic dye removal applications

Current work discusses the synthesis and characterization of a pH and thermo-responsive poly (N-vinylcaprolactam-TiO2-acrylic acid) (VCL-TiO2-AA) polymer nanocomposite in various compositions of TiO2 and application of these nanocomposites for the modification of polysulfone (PSF) membranes. The stimuli responsive nanocomposite was directly blended to the membrane casting solution and this casting solution was used to synthesize membranes by phase inversion method. The modified membranes were analyzed for their hydrophilic, photocatalytic, pH, and thermo-responsive behavior. The membranes were characterized for their morphology by using FESEM. FTIR and FESEM-EDX analysis were carried out to analyze their elemental analysis. Furthermore, the effect of the synthesized stimuli responsive VCL-TiO2-AA polymer nanocomposite was analyzed on the membrane performance in terms of fouling, temperature and pH responsiveness, and photocatalytic removal of MB dye under dark and UV light conditions at different pH values. Furthermore, the ultrafiltration performance and antifouling nature of the modified membranes were investigated and analyzed.

Efficient removal of dyes from aqueous solution: the potential of cellulose nanocrystals to enhance PES nanocomposite membranes

A novel nanocomposite membrane produced with polyether sulfone (PES) and cellulose nanocrystal (CNC) was developed for efficient removal of dye. The nanocomposite membranes were prepared using PES and different contents of CNCs (0.1, 0.3, 0.5, 0.8 and 1.0 wt%). The morphologies, surface properties, permeability, rejection and fouling analysis were carefully examined. The dye solution flux of PES/CNC membrane significantly increased with an increase of CNC content of the membrane casting solution, maximized to 4.13 times higher compared with dye solution flux of pristine PES membrane. Dye rejections were achieved as 95.8 and 93.6% respectively for an addition of 0.5 and 1% of CNCs into membrane casting solution. Moreover, the antifouling properties of PES membranes improved with adding CNCs due to the hydrophilic character of CNCs. Consequently, the obtained results showed that synthesized PES/CNC membranes can be effectively used for the removal of dyes due to their performance. However, the production cost of CNC is main challenge to be addressed for full-scale application.