Nanocomposite Membranes Research Articles

Evaluation of the performance of Fe3O4-NPs/PVDF nanocomposite membrane for removal of BTEX from contaminated water

With the increase in reported cases of toxic organic contaminants such as benzene, toluene, ethylbenzene, and xylene (BTEX) in the aquatic environment, membrane technology offers a viable option for removing BTEX from wastewater. However, hydrophilic modification of the membranes is vital to reduce the rapid accumulation of the BTEX organic contaminants and maintain improved membrane performance in BTEX removal. In this study, biogenically-synthesized Fe3O4-NPs were embedded into a PVDF membrane to endow the membrane with hydrophilicity, which necessitates the reduction in BTEX accumulation on the membrane, consequently maintaining improved membrane performance towards BTEX removal. Different Fe3O4-NPs loadings (0 wt% to 5 wt%) were used for the PVDF modification to establish the optimum blending amount of the Fe3O4-NPs required to achieve the most effective membrane. The water contact angle was reduced from 84.2° (pristine PVDF) to 52° for the membrane modified with 1 wt% of the Fe3O4-NPs. Other membrane features such as porosity, surface roughness, and mechanical strength were also enhanced. Performance evaluation of the membranes revealed that the flux and BTEX rejection of the Fe3O4-NPs/PVDF membrane were improved. The antifouling test results showed a reduction in the total fouling from 52.1 % (pristine membrane) to 36.3 % for the membrane modified with 1 wt% of the Fe3O4-NPs. Our findings provide a strategy utilizing biogenically synthesized Fe3O4-NPs to enhance PVDF membranes' performance for removing BTEX from wastewater.

Tannic acid etched ZIF-8 incorporated thin-film nanocomposite nanofiltration membrane with enhanced performance

Incorporating functionalized nanomaterials in the selective layer of conventional polyamide nanofiltration (NF) membrane is a promising strategy for overcoming the trade-off between permeability and selectivity. Highly hydrodispersible TA/ZIF-8 composite nanomaterials were prepared by etching ZIF-8 with tannic acid, and the thin-film nanocomposite (TFN) NF membranes were prepared by introducing TA/ZIF-8 into the interfacial polymerization aqueous phase solution. The nanomaterials and NF membranes' structure, chemical composition, and hydrophilicity were comprehensively characterized. The influence and mechanism of introducing TA/ZIF-8 into the polyamide layer on the separation performance of the TFN membranes were discussed by separating typical mono- and divalent salts. The optimal TFN membrane had a water flux of 26.59 LMH-bar−1 (increased by 86.6% than that of the TFC-blank membrane) with 94.95% rejection of Na2SO4 while having good antifouling performance and stability. Furthermore, the inverse size exclusion phenomenon of chlorine-contained salts was explored through relevant control experiments. This work is valuable for expanding the application of 3D nanomaterials in membrane separation technology and preparing high-performance TFN nanofiltration membranes.

Effects of Poly(Vinylidene Fluoride-co-Hexafluoropropylene) Nanocomposite Membrane on Reduction in Microbial Load and Heavy Metals in Surface Water Samples

In this work, nanocomposite membranes were prepared using silver nanoparticles (Ag) attached to poly(amidoamine) dendrimer (P)-functionalised multi-walled carbon nanotubes (CNTs) blended with poly(vinylidene fluoride-co-hexafluoropropene) (PVDF-HFP) polymeric membranes (i.e., AgP-CNT/PVDF-HFP) via the phase inversion method. The nanocomposites were characterised and analysed via transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDX), thermal gravimetric analysis (TGA) and Brunauer–Emmett–Teller (BET) analysis. The TEM and EDX analyses confirmed the presence of Ag nanoparticles on the nanocomposites, while the SEM and BET data showed the spongy morphology of the nanocomposite membranes with improved surface areas. The sample analysis of surface water collected from the Sekhukhune district, Limpopo Province, South Africa indicated that the water could not be used for human consumption without being treated. The nanocomposite membranes significantly reduced the physicochemical parameters of the sampled water, such as turbidity, TSS, TDS and carbonate hardness, to 4 NTU, 7 mg/L, 7.69 mg/L and 5.9 mg/L, respectively. Significant improvements in microbial load (0 CFU/mL) and BOD (3.0 mg/L) reduction were noted after membrane treatment. Furthermore, toxic heavy metals such as chromium, cadmium and nickel were remarkably reduced to 0.0138, 0.0012 and 0.015 mg/L, respectively. The results clearly suggest that the AgP-CNT/PVDF-HFP nanocomposite membrane can be used for surface water treatment.

MXene-enhanced sulfonated TFN nanofiltration membranes for improved desalination performance

MXene, a recently identified 2D nanosheet, has drawn interest due to its potential application in the modification of thin film nanocomposite (TFN) membranes for the production of clean water. This study presents the development of MXene-based sulfonated TFN (STFN) nanofiltration membrane for the desalination application and chlorine resistance. A novel amine monomer approach of combination such as 1-(2-aminoethyl)piperazine (APIP) and 2,5-diaminobenzenesulfonic acid (DABSA) was proposed for the interfacial polymerization. The as-prepared MXene displayed a thin-layer nanoflakes-like structure. The surface morphology of the membrane indicated that the MXene bound well on the sulfonated TFN membrane. The hydrophilicity of the membrane was enhanced significantly in the STFN membrane, and the lower contact angle value was decreased up to 24°. The filtration performance showed that the water flux and salt rejection were improved in both sulfonated thin film composite (STFC) and STFN membranes. STFN membranes achieved a higher rejection of >93 % for Na2SO4 and MgSO4. The antifouling and chlorine resistance were also improved in STFC and STFN membranes. This study would be an insight for the development of novel STFN membranes for desalination applications.

GO/AgNW aided sustained release of ciprofloxacin loaded in Starch/PVA nanocomposite mats for wound dressings application

Compared to conventional bandages, which do not meet all wound care requirements, nanofiber wound dressings could provide a potentially excellent environment for healing. In the present research, nanocomposite membrane based on starch (St) - polyvinyl alcohol (PVA) nanofibers containing ciprofloxacin antibiotic drug loaded on graphene oxide‑silver nanowire (GO-AgNWs) hybrid nanoparticles is produced by electrospinning process. Morphological studies showed that the length and diameter of silver nanowires are 21 ± 9.17 μm and 82 ± 10.52 nm, respectively. The contact angle of 57.1° due to the hydrophilic nature of nanofibers, also the swelling degree of 679.51 % and, the water vapor permeability of 2627 ± 56 (g/m2.day) can be expressed as a confirmation of the ability of this wound dressing to manage secretions around the wound. In evaluating the antibacterial activity of these nanocomposite membranes against Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus bacteria, the most potent antibacterial effect is in the case of nanofibers containing a high percentage of starch and nanoparticles carrying ciprofloxacin; with non-growth halos of 47.58 mm and 22.06 mm was recorded. The release of ciprofloxacin drug in vitro was reported to be 61.69 % during 24 h, and the final release rate was 82.17 %. Despite the biocompatibility and cell viability of 97.74 % and the biodegradability rate of 28.51 %, the StP-GOAgNWCip nanocomposite membrane can be introduced as a suitable candidate for wound dressing.

Preparation and adsorption behavior investigation of polypropylene/organically modified saponite nanocomposites fiber membrane with strong oil‐adsorption

AbstractTo improve the adsorption and reusability of polypropylene (PP) fiber membranes, the organically modified saponite (Sap@P(St‐co‐MMA)) was prepared by solution polymerization. Furthermore, PP‐based nanocomposite fiber membranes with strong oil adsorption, thermal stability, and reusability were prepared via melt‐blown technology. The increased specific surface area of PP‐based nanocomposite fiber membranes (PP‐1.5%) provided more active sites for the oil adsorption. Simultaneous rheology and Fourier transform infrared measurements tests showed that Sap@P(St‐co‐MMA) enhanced the crystallinity of PP matrix, promoted the regular arrangement of molecules, and improved the intermolecular interaction force, which was beneficial for the oil adsorption. The adsorption of PP‐1.5% (1.5 wt% addition of Sap@P(St‐co‐MMA)) fiber membrane for xylene and kerosene reached a maximum of 15.84 and 22.84 g g−1, respectively. In the treatment of coal tar wastewater, the removal rate of oil can reach 62.9%, and the removal rate can still reach 51.17% after five cycles of experiments. In summary, PP‐1.5% fiber membrane does not produce secondary pollution to the environment, and is a kind of oil removal material with good application prospect.Highlights PP‐based nanocomposites fiber membrane with strong oil adsorption was prepared. Organically modified saponite had strong heterogenous nucleation for PP matrix. Sap@P(St‐co‐MMA) increased the specific surface area of PP‐based fiber membrane.

A novel ZIF-L/PEI thin film nanocomposite membrane for removing perfluoroalkyl substances (PFASs) from water: Enhanced retention and high flux

Membrane separation technology is widely recognized as an effective method for removing perfluoroalkyl substances (PFASs) in water treatment. ZIF-L, a metal-organic framework (MOF) family characterized by its mat-like cavities and leaf-like morphology, has garnered considerable interest and has been extensively employed in fabricating thin-film nanocomposite (TFN) membranes. In this study, a robust, high-performance TFN membrane to remove PFASs in a nanofiltration (NF) process was created through an interfacial polymerization approach on the surface of polysulfone (PSF), incorporating ZIF-L within the selective layer. The TFN membrane modified by adding 5 wt% ZIF-L (relative to the weight of ethylene imine polymer (PEI)) exhibits 2.3 times higher water flux (up to 47.56 L·m−2·h−1·bar−1) than the pristine thin film composite membrane (20.46 L·m−2·h−1·bar−1), and the rejection for typical PFASs were above 95 % (98.47 % for perfluorooctanesulfonic acid (PFOS) and 95.85 % for perfluorooctanoic acid (PFOA)). The effectiveness of the ZIF-L/PEI TFN membrane in retaining representative PFASs was examined under various conditions, including different pressures, feed concentrations, aqueous environments, and salt ions. Notably, the experiments demonstrated that even after contamination with humic acid (HA), >88 % of the water flux could be restored by washing. Additionally, density functional theory (DFT) calculations were employed to predict the distinct intermolecular interactions between PFASs and ZIF-L as well as PEI. These calculations provide additional insights into the interception mechanism of TFN membranes towards PFASs. Based on this study, TFN membranes incorporating MOF as nanofillers show great potential as an effective method for purifying PFASs from aqueous environments and possess superior environmental sustainability and cost-effectiveness.

The influences of Keggin-type H3PW12O40 nanostructure on Polyurethane microfiltration membrane to reinforce screening organic pollutants from wastewater

Manifestly, unceasing growth industrialization has caused to produce the non-segregated phases, engendering complexity in wastewater remediation. Therefore, we endeavored to construct the electrospun Polyurethane (PU)-based Microfiltration (MF) membrane that the Keggin-type H3PW12O40 (KHPW) nanostructure embedded in it by simplified strategy; after that, the PU/KHPWx (x= 0.5, 1, 1.5, and 2 %wt) nanocomposite membranes executed to purify the emulsifier-stabilized Walnut oil (EWO). Fortunately, perfect wettability, controlled porosity, and high negative charge boosted the values of Permeated Water Flux (PWF) and Oil Rejection Efficiency (ORE), which equaled 2150 L.m−2.h−1 and 100 % for the 1400 mg.L-1 of EWO by the PU/KHPW2 membrane, respectively; after that, the fouling resistance parameter (i.e., the Flux Recovery Ratio (FRR)) improved to 62.18 % in pH = 9. Notably, the MB Removal Efficiency (MRE) surveyed to render the light-driven catalytic activities of KHPW, and the Taguchi method optimized the values of operational parameters. Hence, the MRE astonishingly elevated to 79.3 % by PU/KHPW2 at the ameliorated conditions under UV-light irradiation, conferring the self-cleaning merits to the PU/KHPWx samples. After reviewing previously published articles, these authentic observations about the multifunctional capabilities of PU/KHPW2 elucidated insights towards robust screening water pollutants, which discreetly could utilize it in the pre-treatment units of MF.

CO2-Philic Nanocomposite Polymer Matrix Incorporated with MXene Nanosheets for Ultraefficient CO2 Capture.

The incorporation of two-dimensional (2D) functional nanosheets in polymeric membranes is a promising material strategy to overcome their inherent performance trade-off behavior. Herein, we report a novel nanocomposite membrane design by incorporating MXene, a 2D sheet-like nanoarchitecture known for its advantageous lamellar morphology and surface functionalities, into a cross-linked polyether block amide (Pebax)/poly(ethylene glycol) methyl ether acrylate (PEGMEA) blend matrix, which delivered exceptional CO2/N2 and CO2/H2 separation performances that are critical to industrial CO2 capture applications. The finely dispersed Ti3C2Tx nanosheets in the blend polymer matrix led to an expansion of the free volume within the resultant mixed matrix membrane (MMM), giving rise to a substantially enhanced CO2 permeability of up to 1264.6 barrer, which is 102% higher than that of the pristine polymer. Moreover, these MXene-incorporated MMMs exhibited preferential sorption for CO2 over light gases, which contributed to an exceptional CO2/N2 and CO2/H2 selectivity (64.3 and 19.2, respectively) even at a small loading of only 1 wt %, allowing the overall performance to not only surpass the latest upper bounds but also exceed many previously reported high-performance nanosheet-based nanocomposite membranes. Long-term performance tests have also demonstrated the good stability of these membranes. This composite membrane design strategy reveals the remarkable potential of combining a blend copolymer matrix with ultrathin MXene nanosheets to achieve superior gas separation performance for environmentally important gas separations.

Rational Design of a Necklace-like ZIF-67/Poly(vinylidene fluoride) Electrospun Nanofiber Hybrid Membrane for Simultaneous Removal of PM0.3 and SO2.

Growing concerns over poor air quality, especially in urban and industrial regions, have led to increased global demands for advanced air-purification technologies. However, the stability and airborne pollutant control abilities of the available air-purification materials under diverse environmental conditions are limited. Thus, the advanced development of filtration materials that can effectively control different types of pollutants, such as particulate matter (PM) and gaseous pollutants, simultaneously has attracted attention. The zeolitic imidazolate framework (ZIF), a type of porous metal-organic framework (MOF), is a promising material for capturing weakly acidic toxic gases such as SO2 owing to its excellent adsorption performance and high thermal and chemical stability. In this study, we successfully developed an ultrastable necklace-like multifunctional hybrid membrane via the cetyltrimethylammonium bromide-assisted in situ growth of zeolitic imidazolate framework (ZIF)-67 crystals on electrospun Co2+-doped poly(vinylidene fluoride) nanofibers (70 nm) that can be used in different moisture environments to achieve sustainable air-filtration performance. The hybrid nanocomposite membrane demonstrated excellent performance for the simultaneous control of intractable fine PM0.3 (filtration efficiency, 99.461%) and SO2 (adsorption capacity, 1476.5 mg g-1) under different humidity conditions. This study contributes to the optimal synergistic integration of the advanced metal-organic framework (MOF)-nanofiber nanocomposite membranes and can guide the rational design and conceptualization of a facile and novel membrane for various applications in the environmental science and energy fields.

Distinguishable photorecycling of PVDF nanocomposites membrane for reactive yellow 145 dye and real industrial wastewater treatment by different photocatalytic processes

This paper investigates the photocatalytic performance and recyclability of PVDF-MWCNTs-TiO2 nanocomposite membranes for the treatment of textile wastewater under sunlight irradiation. The nanocomposites were fabricated by incorporating varying weight ratios of MWCNTs-TiO2 (1 %, 3 %, 6 %, and 9 %) into PVDF matrices using a solvent casting method. Optimal loading of MWCNTs-TiO2 at 9 wt% resulted in nanocomposites with enhanced surface area (94.15 m2/g), reduced band gap (2.38 eV), uniform dispersion of nanoparticles, and abundant surface hydroxyl groups. Under Xenon lamp irradiation, the optimized PVDF-9 %(MWCNTs-9 %TiO2) nanocomposite achieved a high apparent reaction rate constant (kapp) of 9.92 × 10−3 s−1 for photocatalytic degradation of the model dye Reactive Yellow 145. Significantly, when tested on-site at a Saudi Arabian textile facility over 6 months, this nanocomposite effectively reduced the chemical oxygen demand (COD) of real wastewater samples to regulatory limits of 1000 ppm under natural sunlight irradiation. The COD values were lowered from an initial 5050–6200 ppm to a final range of 785–945 ppm using the PVDF-9 %(MWCNTs-9 %TiO2) membrane. Furthermore, the optimized nanocomposite exhibited good recyclability, retaining around 87 % of its initial activity after 8 reuse cycles for industrial wastewater treatment. The excellent photocatalytic efficiency and reusability of the MWCNTs-TiO2 modified PVDF nanocomposite under solar irradiation highlight its promise as a sustainable membrane technology for environmental remediation.

Improving dye removal ability and fouling resistance of thin‐film nanocomposite nanofiltration membranes using a new citric acid functionalized FSM‐16 mesoporous

AbstractThe development of superior thin‐film nanocomposite (TFN) membranes with good separation performance and anti‐fouling capacity is required to address the larger‐scale freshwater need. In this study, a new citric acid‐functionalized FSM‐16 (CA‐FSM‐16) mesoporous was successfully synthesized and characterized. Subsequently, it was introduced on the surface of the sodium hydroxide/cyanuric chloride‐activated PES membrane to fabricate the CA‐FSM‐16 TFN membrane. It was investigated how various CA‐FSM‐16 loadings affected the overall physicochemical characteristics and performance of the membrane. The SEM analysis confirmed the TFN structure of the fabricated membranes. All manufactured membranes displayed improved hydrophilicity and flux. For the pristine membrane, the salt (Na2SO4) rejection was measured 73.20 ± 2.10%, whereas for the TFN‐0.08 membrane, it was measured 91.40 ± 1.80%. The dye rejection experiment in cross‐flow filtration showed that the TFN‐0.08 membrane had the maximum licorice retention among the membranes (99.10 ± 2.00%). In addition, the CA‐FSM‐16 TFN membranes demonstrated superior antifouling performance, especially the optimum membrane (TFN‐0.08), which showed a high flux recovery ratio (FRR) of 97.10 ± 1.90% and a low irreversible fouling ratio (DRir) of 2.90%. The introduction of CA‐FSM‐16 on the surface of the PES membrane via the surface modification method was a potentially useful technology to fabricate a high‐performing TFN membrane for water treatment applications.

Lamellar structured GO-Melamine nanocomposite membranes with varying d-spacing for efficient organic solvent nanofiltration (OSN)

There is a lot of research being done on GO lamellar 2D membranes for separating organic solvents and dyes. These membranes are highly sought-after due to their exceptional characteristics. However, existing challenges include inadequate solvent permeability and limited dye rejection capacity due to swelling of membranes. In this study, we proposed a novel technique that employs low-pressure assisted filtration to fabricate nanocomposite membranes using GO and melamine. Remarkably, these composite membranes exhibited outstanding separation performance for dyes (≥99.06 %) in organic solvents, regardless of their positive or negative charges or when present in mixtures. The optimum GO-M0.02 nanocomposite membrane exhibits impressive organic solvent flux (J), attaining a value as high as 50.8 L/m2h (acetone), which is 6.57 times greater than that of the pure GO membrane. Furthermore, these GO-Melamine nanocomposite membranes showed excellent durability against both common and harsh organic solvents, and the flux of solvents through the GO-M0.02 nanocomposite membrane remained almost unchanged even after being immersed in methanol for up to one week. Additionally, the membrane exhibited consistent solvent flux and rejection rates for methyl green during continuous filtration. These results highlight the exceptional stability and immense potential of GO-melamine nanocomposite membranes for real organic solvent nanofiltration.

Affinity-based engineering of carbon nanotube embedded polyamide membranes for simultaneous desalination and boron removal

Reverse osmosis (RO) is the leading technology for obtaining drinking and irrigation water from seawater. Although currently developed RO membranes achieve high salt rejection; several challenges exist, such as permselectivity trade-off, biological/chemical contamination, and insufficient retention of small and neutral molecules like boric acid. Due to its toxicity to living organisms and strictly monitored levels in potable water, removal of boron has gained considerable attention in RO industry. Thin film nanocomposite (TFN) membranes have emerged by incorporating nanomaterials with superior water/salt selectivity into polyamide (PA) layer of composite membranes. For the first time, our group investigated the potential of carboxylated carbon nanotube (CNT) embedding in the selective layer of TFN membranes for boron removal. Within this frame, we hypothesize that embedding fillers with low boron affinity accompanied by high water permeability in the selective layer of TFN membranes improves boron removal without suffering from the permselectivity trade-off. In this study, we investigated the boron removal performance of functionalized CNT (f-CNT) embedded TFN membranes. Initially, CNTs were functionalized with three different functional groups (namely, biotin (BIO), 8-amino caprylic acid (ACA), and zwitterion (ZWT)) to narrow down the tube entrance, provide repulsive electrostatic interactions with boron, and interfere with the hydrogen bonding between water and boric acid molecules. Then, TFN membranes incorporating f-CNTs were fabricated, characterized, and tested. Showing high compatibility with PA, ZWT functionalization has increased water/boron selectivity of TFN membranes by 66% and water permeability by 44%, while maintaining the salt rejection at 98%. Furthermore, we employed molecular dynamics simulations and potential of mean force calculations to elucidate the boron exclusion mechanism in f-CNTs. With its flexible structure and “gate-keeper” ability, ZWT functional group was found to show the highest energy barrier against boron transport. Hence, engineering CNT/PA TFN membranes to promote steric hindrance and decrease solute affinity is promising for efficient removal of detrimental small molecules from seawater.

From environmental issue to purification aid: Novel positively charged functionalized algal biochar as robust modifier of composite nanofiltration membranes

Robust membrane modifiers were achieved for the first time by functionalizing the algal biochar of unique porous structure. The biochar was prepared through the pyrolysis of Cladophora glomerata, the most widespread freshwater macroalga, functionalized by diethylenetriamine and dendrimer poly(amidoamine), and employed to fabricate positively charged composite nanofiltration membranes. The presence of hydrophilic functionalizers of positive charge on the membrane was verified through Fourier transform infrared and energy dispersive X-ray analyses and atomic force microscopy and zeta potential measurements were performed to determine surface roughness and confirm positive charge of the modified membranes. Dispersion of modifiers on the surface and morphology of the were also revealed through field-emission scanning electron microscopy images. It has shown that, compared to the pristine membrane, pure water fluxes were increased by 214% and 185%, and water contact angles were reduced from 66.1° to 39.5° and 43.3° in those modified by biochar functionalized with dendrimer poly(amidoamine) and diethylenetriamine, respectively. More than 90% dye rejections and salt and heavy metals removals were recorded for the membranes possessed 0.6 wt% of modifiers. Finally, a comparative study conducted between the novel modifier introduced in this study and those reported in the literature, indicated that C. glomerata biochar decorated with amine functional groups could be considered as a robust and practical alternative to the common modifiers used to manipulate nanocomposite membranes characteristics.

Metal-organic framework-intercalated graphene oxide nanofiltration membranes for enhanced treatment of wastewater effluents

Graphene oxide membranes (GO) hold immense potential in the field of water purification. However, when applied directly to real wastewater effluents, pure GO membranes suffer from drawbacks such as fouling sensitivity and limited stability. To address these challenges and unlock the full potential of GO membranes, novel nanocomposite membranes have been developed by the intercalation of GO with nanoparticles of ZIF-8 (a type of zeolitic imidazolate framework). The prepared GO/ZIF-8 (GZ) nanocomposite membranes have exhibited enhanced hydrophilicity and exceptional water purification capabilities. Specifically, the GZ membranes have demonstrated a permeance enhancement of over two-fold when compared to the pristine GO reference membrane. This enhancement is coupled with anti-fouling performance and competitive rejection rates for both salts and organic pollutants. GZ membranes have been effectively employed for the purification by cross-flow filtration of 3 industrial wastewater effluents. They have shown improved separation performance compared to the pristine GO reference membrane, and high stability under cross-flow conditions. The origin of the high performances of the GZ membrane has been clarified using structural and morphological analyses. This work highlights the significant progress made in the field of water treatment using graphene-based membranes.

In-situ interfacial polymerization of polyamide TFN membranes by adding a diamino-silane coupling agent: Toward enhanced desalination performance

The primary challenge faced by thin film nanocomposite (TFN) membrane in nanofiltration (NF) process is to effectively resolve the trade-off effect between permeability and selectivity. Herein, a polyamide (PA) TFN membrane with enhanced NF performance was prepared through in-situ interfacial polymerization (in-situ IP) method, using piperazine (PIP) and 3-diamino-methyl-cyclohexyl triethoxysilane (DTES) as co-amine monomers to undergo a reaction with 1,3,5-benzenetricarbonyl trichloride (TMC). This study investigated the effects of DTES on the surface chemical composition, morphologies, hydrophilicity, separation efficiency, and anti-fouling properties of the novel DTES/PIP/TMC TFN membranes. It was found that SiO2 nanoparticles were generated in-situ from the reacted DTES through hydrolysis and self-condensation, resulting in their uniform distribution within the formed PA selective layer with high compatibility and without aggregation. The optimal PA TFN membrane was achieved by adjusting the ration of Si-OH group in formed SiO2 nanoparticles through varying the concentration of DTES concentration. Meanwhile, the induction of SiO2 into the PA layer resulted in an enlargement in membrane pore size and improved surface hydrophilicity. When the concentration of added DTES was 0.333 wt%, the optimal PA TFN membrane (TFN-4) exhibited the highest quantity of formed Si-OH groups, resulting in the excellent performance, including a markedly enhanced water permeability flux of 76.8 L·m−2·h−1 (2-fold larger than that of the pure TFC membrane), a great Na2SO4 rejection of 97.5 %, and a superior Cl−/SO42− permeation selectivity of 46.0. Moreover, the TFN-4 membrane exhibited exceptional stability and superior antifouling properties attributed to its unparalleled hydrophilicity. This work provided a strategy for preparing uniform and high-performance TFN membranes.

Effect of titanium oxide/reduced graphene (TiO2/rGO) addition onto water flux and reverse salt diffusion thin-film nanocomposite forward osmosis membranes

Thin-film nanocomposite (TFN) forward osmosis (FO) membranes have attracted significant attention due to their potential for solving global water scarcity problems. In this study, we investigate the impact of titanium oxide (TiO2) and titanium oxide/reduced graphene (TiO2/rGO) additions on the performance of TFN-FO membranes, specifically focusing on water flux and reverse salt diffusion. Membranes with varying concentrations of TiO2 and TiO2/rGO were fabricated as interfacial polymerizing M-phenylenediamine (MPD) and benzenetricarbonyl tricholoride (TMC) monomers with TiO2 and its reduced graphene composites (TiO2/rGO). The TMC solution was supplemented with TiO2 and its reduced graphene composites (TiO2/rGO) to enhance FO performance and reverse solute flux. All MPD/TMC polyamide membranes are characterized using various techniques such as scanning electron microscopy (SEM), atomic force microscopy (AFM), and contact angle measurements. The results demonstrate that incorporating TiO2/rGO into the membrane thin layer improves water flux and reduces reverse salt diffusion. In contrast to the TFC membrane (10.24 L m−2h−1 and 6.53 g/m2 h), higher water flux and higher reverse solute flux were detected in the case of TiO2and TiO2/rGO-merged TFC skin membranes (18.81 and 24.52 L m−2h−1 and 2.74 and 2.15 g/m2 h, respectively). The effects of TiO2 and TiO2/rGO stacking on the skin membrane and the performance of TiO2 and TiO2/rGO skin membranes have been thoroughly studied. Additionally, being investigated is the impact of draw solution concentration.Graphical

Natural Clay-Modified Piezocatalytic Membrane for Efficient Removal of Coliform Bacteria from Wastewater.

In the modern era, water pollution, especially from industries, agricultural farms, and residential areas, is caused by the release of a large scale of heavy metals, organic pollutants, chemicals, etc., into the environment, posing a serious threat to aquatic ecosystems and nature. Moreover, untreated sewage waste discharged directly into nearby water bodies can cause various diseases to mankind due to the high load of fecal coliform bacteria. This work demonstrates the development of a biocompatible, cost-effective, highly robust, efficient, flexible, freestanding, and reusable membrane using naturally formed biocompatible kaolinite clay-doped poly(vinylidene fluoride-hexafluoropropylene) (PVDF-HFP) for effective piezodynamic destruction of coliform bacteria. In this study, Escherichia coli (E. coli) and Enterococcus faecalis (E. faecalis) have been used to evaluate the mechanical stimulus-responsive antibacterial efficacy of the nanocomposite membrane. The membrane can effectively eradicate nearly 99% viable E. coli and 97% E. faecalis within a span of 40 min under mechanical stimulation (soft ultrasound ∼15 kHz). To further understand the mechanism, an evaluation of reactive oxygen species and bacterial FESEM was performed. These studies revealed that bacterial cells suffered severe visible cell damage after 40 min of piezocatalysis, elucidating the fact that the synthesized membrane is capable of producing a superior piezodynamic antibacterial effect.

Development of eco-friendly microwaved chitosan-based nanocomposite membrane for efficient capturing of cationic dyes from aqueous solution: permeability and fouling studies

Development of eco-friendly microwaved chitosan-based nanocomposite membrane for efficient capturing of cationic dyes from aqueous solution: permeability and fouling studies