Humic Acid Filtration Research Articles

Coconut husk ash and polyethersulfone mixed matrix membrane analysis for textile wastewater and humic acid filtration process

Coconut husk ash and polyethersulfone mixed matrix membrane analysis for textile wastewater and humic acid filtration process

The anti-fouling and mechanism of Fe3O4@PVDF catalytic membrane in-situ coupling Fenton oxidation for organic pollutants removal

Polyvinylidene fluoride (PVDF) membrane is a promising technique for deep treatment of organic wastewater. However, the unavoidable membrane contamination greatly restrictions its field of application. Herein, we successfully prepared Fe3O4@PVDF membrane with excellent anti-fouling and catalytic ability by non-solvent induced phase inversion method. Meanwhile, Fe3O4@PVDF membrane was characterized by SEM, XRD, FTIR, Water contact Angle and membrane aperture analyzer. The properties of separation and anti-fouling were also evaluated by cross flow filtration of humic acid (HA). Compare with pristine membrane, the pure water flux, rejection rate and FRR respectively increase from 556.81 L m-2 h−1, 65.42 %, 68.26 % to 656.96 L m-2 h−1, 99.64 %, 90.17 % under in-situ Fenton reaction condition. In addition, further mechanistic insights by XDLVO theory, 3D-EEM and EPR verified that high anti-fouling mainly attribute to excellent hydrophilicity of Fe3O4@PVDF and in-situ degradation of HA by OH and 1O2· This work provides insights for improving the separation properties and anti-fouling properties of PVDF membrane in the field of treatment organic wastewater.

Green polycaprolactone/sulfonated kraft lignin phase inversion membrane for dye/salt separation

Exploring environmentally friendly, renewable, and cost-effective raw materials is essential in sustainable membrane fabrication. This study presents a facile and scalable method for fabricating a green and biodegradable tight ultrafiltration membrane for dye/salt separation. This involves simply blending biodegradable polycaprolactone (PCL) with the low-cost biobased sulfonated kraft lignin (SKL) additive. Additionally, we employed acetic acid as a green alternative solvent to enhance the sustainability of the membrane fabrication process. The incorporation of hydrophilic SKL into the PCL matrix resulted in increased hydrophilicity (water contact angle changed from 72° to 56°), surface roughness (increased from 29 nm to 43.5 nm), and enhanced negative electrostatic charge of the membrane (−40 mV to −45 mV). The optimized PCL/SKL membrane (M3) exhibited excellent water flux (∼45 LMH) under 40 psi hydraulic pressure coupled with ∼98 % and ∼10 % rejection rates for reactive red (RR) dye and NaCl, respectively. Moreover, the M3 membrane maintained its exceptional dye/salt fractionation performance while separating the mixtures at low salt concentrations. However, with increasing salt concentration (1–50 g/L), the membrane's RR dye rejection declined from ∼90 % to ∼50 %, with a significant reduction in NaCl and Na2SO4 salts rejection (from ∼14 % to ∼1 % and ∼22 % to –∼1 %, respectively). The M3 membrane exhibited remarkable antifouling properties during dye and humic acid filtration with a high flux recovery ratio (>98 %) and low flux decline rate (<7 %). The PCL/SKL membrane also showed excellent stability and maintained consistent separation performance over a long period. Overall, the novel biodegradable PCL/SKL membrane prepared in this study presents a promising avenue toward sustainable membrane fabrication for wastewater treatment applications.

Dynamic relationship between membrane fouling and reverse diffusion of inorganic draw solutes in forward osmosis

Both membrane fouling and reverse diffusion limit the application of forward osmosis (FO), and the combined effects further decrease water generation. Herein, the effects of typical inorganic draw solutes (DSs) were investigated on the dynamic relationship between membrane fouling from two organic pollutants and reverse diffusion. The formation of a membrane fouling layer decreased the amount of Ca2+ ions reverse-diffusing from a CaCl2 DS and increased the amount of NH4+ ions reverse-diffusing from a NH4Cl DS. When sodium alginate was used as the feed solute, reverse-diffused ions from the CaCl2/NH4Cl DS resulted in the formation of a three-dimensional network structure, further exacerbating membrane fouling. Moreover, greater reverse diffusion of NH4+ from the NH4Cl DS resulted in more membrane fouling in comparison with the CaCl2 DS (i.e., water recovery of 246.4 ± 4.7 g), resulting in a lower water recovery value of 151.4 ± 10.6 g. During the filtration of humic acid, the membrane fouling layer caused by the CaCl2 DS led to the formation of a cake filtration layer that was more severe than that formed when the NH4Cl DS was used. This study provides a reliable basis for draw solute optimization to extend the application of FO systems.

Conductive and stable polyphenylene/CNT composite membrane for electrically enhanced membrane fouling mitigation

Nanocarbon-based conductive membranes, especially carbon nanotube (CNT)-based membranes, have tremendous potential for wastewater treatment and water purification because of their excellent water permeability and selectivity, as well as their electrochemically enhanced performance (e.g., improved antifouling ability). However, it remains challenging to prepare CNT membranes with high structural stability and high electrical conductivity. In this study, a highly electroconductive and structurally stable polyphenylene/CNT (PP/CNT) composite membrane was prepared by electropolymerizing biphenyl on a CNT hollow fiber membrane. The PP/CNT membrane showed 3.4 and 5.0 times higher electrical conductivity than pure CNT and poly(vinyl alcohol)/CNT (PVA/CNT) membranes, respectively. The structural stability of the membrane was superior to that of the pure CNT membrane and comparable to that of the PVA/CNT membrane. The membrane fouling was significantly alleviated under an electrical assistance of − V, with a flux loss of only 11.7% after 5 h filtration of humic acid, which is significantly lower than those of PP/CNT membranes without electro-assistance (56.8%) and commercial polyvinylidene fluoride (PVDF) membranes (64.1%). Additionally, the rejection of negatively charged pollutants (humic acid and sodium alginate) was improved by the enhanced electrostatic repulsion. After four consecutive filtration-cleaning cycle tests, the flux recovery rate after backwashing reached 97.2%, which was much higher than those of electricity-free PP/CNT membranes (67.0%) and commercial PVDF membranes (61.1%). This study offers insights into the preparation of stable conductive membranes for membrane fouling control in potential water treatment applications.

Enhanced negative charge of polyamide thin-film nanocomposite reverse osmosis membrane modified with MIL-101(Cr)-Pyz-SO3H

Negatively charged MIL-101(Cr)-Pyz-SO3H nanoparticles (NPs), with several concentrations (0.001–0.02 wt%), were used as a hydrophilic and charge modifier to make a high performance thin-film nanocomposite reverse osmosis membrane (TFC RO) through the interfacial polymerization between 1,3-phenylenediamine (MPD) and trimesoyl chloride (TMC) monomers. Surface analyses revealed smoother surfaces and higher hydrophilicity for the modified membranes. The zeta potential investigation approved rising the negative surface charge of MIL-101(Cr)-Pyz-SO3H NPs embedded RO membranes. The desalination performance displayed that 0.005 wt% MIL/RO indicated the most incredible separation efficiency for NaCl (98.05%). The desalination performance of seawater was also studied. Observations showed that 0.005 wt% MIL/RO means the best separation efficiency for seawater desalination (94.46%). Water flux for the modified membranes improved and reached the maximum value of 41.4 L/m2.h in 0.005 wt% MIL-101(Cr)-Pyz-SO3H TFC RO membrane. The fouling resistance of the membranes was identified by filtration of humic acid (HA)/NaCl solution. The obtained results demonstrated that modified membranes improved fouling resistance, and the highest fouling resistance was recorded for 0.005 wt% MIL-101(Cr)-Pyz-SO3H TFC RO membrane.

Unveiling the Impacts of Sodium Hypochlorite on the Characteristics and Fouling Behaviors of Different Commercial Polyvinylidene Fluoride Hollow Fiber Membranes.

Sodium hypochlorite (NaOCl) is a commonly used cleaning agent for recovering membrane performance in membrane technologies. A thorough understanding of the impacts of NaOCl exposure on membrane properties and fouling behavior is important for optimizing chemical cleaning process and extending membrane lifespan. In this study, three commercial polyvinylidene fluoride (PVDF) hollow fiber ultrafiltration membranes (SMM-1010, MEMCOR® CS II and ZeeWeed 500) were used to systematically explore the effects of NaOCl dose and solution pH (8 and 10) on membrane properties. The results showed that membrane pores increased with exposure time prolonging, and more pores were observed at pH 8 aging condition. The amide group in the Fourier transformation infrared spectra was disappeared, while the carboxylic acid and succinimide groups were formed at pH 10 and pH 8 conditions, respectively. The hydrophilicity and pure water permeability (PWP) of SMM-1010 and MEMCOR® CS II membranes had insignificant changes during NaOCl aging process, whereas the hydrophilicity of ZeeWeed 500 membrane slightly decreased and its PWP increased by 1.4-fold. The antifouling properties of NaOCl-aged SMM-1010 and MEMCOR® CS II membranes were slightly improved, whereas the NaOCl-aged ZeeWeed 500 membrane showed severer flux decline with humic acid filtration. Our findings could provide guidance for practical chemical cleaning process optimization.

Incorporation of amino‐functionalized ZnO nanoparticles into polycarbonate/polyvinyl alcohol thin‐film membrane for enhanced water treatment

AbstractZnO nanoparticles were functionalized with amine groups and incorporated into a thin‐film nanocomposite (TFN) membrane. Polycarbonate (PC) membranes were coated with polyvinyl alcohol (PVA)/ZnO‐NH2 solution using the dip‐coating method. All prepared membranes were applied for the removal of humic acid (HA) in a submerged membrane system at vacuum trans‐membrane pressure (TMP) of 0.3 and 0.6 bar. Attenuated total reflectance‐Fourier transform infrared (ATR‐FTIR) and field‐emission scanning electron microscopy (FESEM) images confirmed the formation of PVA/ZnO‐NH2 top layer on the PC support membrane. The addition of nanoparticles caused the hydrophilicity and surface roughness of TFN membranes to increase. HA filtration experiments revealed that at lower vacuum TMP, the TFN with 0.05 wt.% of ZnO‐NH2 nanoparticles showed higher permeate flux. However, at higher vacuum TMP permeate flux significantly decreased. HA rejection did not change with added nanoparticles. As a final result, when vacuum TMP increased from 0.3 to 0.6 bar, rejection of HA slightly increased from 98.3% to 99.1% and 98.3% to 99.3% for thin film composite and TFN with 0.05 wt.% of nanoparticles, respectively.

Design and manufacturing of a novel thin-film composite membrane based on polyamidoamine-grafted graphene nanosheets for water treatment

Graphene oxide polyamidoamine (GO-PAMAM) was incorporated into polyamide network via interfacial polymerization to prepare novel membranes. Several characterization techniques were applied to investigate the changes in the membrane morphological features, roughness profiles, the interactions between the polymer and molecules, and elemental compositions of the modified membrane surface. The results confirmed the successful incorporation of GO-PAMAM into the membrane surface and showed the enhanced hydrophilicity and the smoother surface of the treated composite membrane. Filtration experiments were performed to examine the permeability, chlorine resistance, antifouling property, and separation capacity of the fabricated composite membrane against salts, heavy metals, and organic contaminants. The GO-based membrane showed an excellent water permeability of roughly 62 Lm−2 h−1 and 0.95 fouling index after 3 h of humic acid filtration. An outstanding rejection of 100% against 100 mg/L of heavy metals and organic pollutants was achieved and about 92% and 87% for (SO4, Mg) and (Ca, Cl) salts' ions. The decrease in contact angle indicates the improvement of hydrophilicity which enhances the water flux. Under chlorine exposure test, only a minor decline in the membrane's rejection was observed, which indicates the membrane has high chlorine resistance. The outstanding permeability, stable removal efficiency, and excellent antifouling and chlorine resistance put the produced GO-PAMAM thin film composite membrane as a superb option for water treatment.

Surface tuned polyethersulfone membrane using an iron oxide functionalized halloysite nanocomposite for enhanced humic acid removal.

Nanomodification of ultrafiltration (UF) membranes has been shown to be a simple and efficient technique for the preparation of high-performance membranes. In this work, an iron oxide functionalized halloysite nanoclay (Fe-HNC) nanocomposite was prepared and used as a nanofiller for polyethersulfone (PES) membranes. The effect of Fe-HNC concentration on the filtration performance of the membrane was investigated by varying the nanocomposite dosage (0-0.5wt%) in the casting dope. Various characterization studies showed that the incorporation of Fe-HNC nanocomposites improved the membrane morphology and enhanced the surface properties, thermal stability, mechanical strength, hydrophilicity, and porosity. The permeability to pure water and filtration of humic acid (HA) were significantly improved by incorporating Fe-HNC into the PES membranes. The membrane with Fe-HNC loading of 0.1wt% exhibited the highest pure water permeability (174.3L/(m2h bar)) and removal of HA (90.1%), which were 1.8 times and 29% higher, respectively than the pristine PES membrane. Moreover, fouling studies showed the enhanced antifouling ability of the Fe-HNC nanocomposites modified PES membranes, especially against irreversible fouling. Continuous membrane regeneration-based fouling removal studies from HA showed that the PES/0.1wt% Fe-HNC membrane exhibited a high fouling recovery of 70.4% with very low reversible and irreversible fouling resistance of 9.61% and 14.78%, respectively, compared to the pristine PES membrane (fouling recovery: 40.4%; reversible fouling: 21.7%; irreversible fouling: 20.1%). Overall, the Fe-HNC nanocomposite proved to be an effective nanomodifier for improving the permeability of PES membranes and the antifouling ability to treat HA polluted aqueous streams.

A Contrastive Study of Self-Assembly and Physical Blending Mechanism of TiO2 Blended Polyethersulfone Membranes for Enhanced Humic Acid Removal and Alleviation of Membrane Fouling.

In this study, membrane fabrication was achieved by two different methods: (i) self-assembly and (ii) physical blending of TiO2 in PES membrane for humic acid filtration. The TiO2 nanoparticles were self-assembled by using TBT as the precursor and pluronic F127 as triblock copolymers around the membrane pores. This was achieved by manipulating the hydrolysis and condensation reaction of TBT precursors during the non-solvent induced phase separation (NIPS) process. On the other hand, the TiO2 was physically blended as a comparison to the previous method. The characteristic of the membrane was analysed to explore the possibility of enhancing the membrane antifouling mechanism and the membrane flux. The membrane morphology, pore size, porosity, and contact angle were characterised. Both methods proved to be able to enhance the antifouling properties and flux performance. The HA rejection increased up to 95% with membrane flux 55.40 kg m−2 h−1. The rejection rate was not significantly improved for either method. However, the antifouling characteristic for the self-assembly TiO2/PES membrane was better than the physically blended membrane. This was found to be due to the high surface hydrophilicity of the MM membrane, which repelled the hydrophobic HA and consequently blocked the HA adsorption onto the surface.

Fabrication of Polyvinylidene Difluoride Membrane with Enhanced Pore and Filtration Properties by Using Tannic Acid as an Additive.

Potential use of tannic acid (TA) as an additive for fabrication of polyvinylidene difluoride (PVDF) membrane was investigated. The TA was introduced by blending into the dope solution with varying concentrations of 0, 1, 1.5, and 2 wt%. The prepared membranes were characterized and evaluated for filtration of humic acid (HA) solution. The stability of the membrane under harsh treatment was also evaluated by one-week exposure to acid and alkaline conditions. The results show that TA loadings enhanced the resulting membrane properties. It increased the bulk porosity, water uptake, and hydrophilicity, which translated into improved clean water flux from 15.4 L/m2.h for the pristine PVDF membrane up to 3.3× for the TA-modified membranes with the 2 wt% TA loading. The flux recovery ratio (FRR) of the TA-modified membranes (FRRs = 78–83%) was higher than the pristine one (FRR = 58.54%), with suitable chemical stability too. The improved antifouling property for the TA-modified membranes was attributed to their enhanced hydrophilicity thanks to improved morphology and residual TA in the membrane matric.

Evaluation of membrane tailored with biocompatible halloysite‒polyaniline nanomaterial for efficient removal of carcinogenic disinfection by‒products precursor from water

Humic acid (HA) is the main component of natural organic matter that generates carcinogenic by‒products during disinfection and its removal from water resources is challenging. Biocompatible halloysite (HNTs) nanomaterial decorated with polyaniline (HNTs‒PANI) was synthesized via polymerization technique. HNTs‒PANI was added to prepare polyethersulfone mixed matrix membranes (MMMs). The influence of HNTs‒PANI concentration on HA removal efficiency was studied by varying the HNTs‒PANI (0.5, 1 and 1.5 wt%). The characterization studies of MMMs revealed that the addition of HNTs‒PANI improved the morphology of the membranes, surface properties, chemical stability and thermal property. The amine and hydroxyl groups within the MMMs improved the membrane wettability. The addition of HNTs‒PANI within the MMMs had significantly enhanced the pure water flux and HA filtration. YHP2 MMM with 1 wt% of HNTs‒PANI demonstrated sieving coefficient of 0.10 and the highest HA removal efficiency of 91% greater than the neat PES membrane. Furthermore, the antifouling property of the MMMs was studied using HA as foulant. 1 wt% of HNTs‒PANI added MMM showed a high flux recovery ratio (94.9%) with low total fouling of 12% and low irreversible fouling of 5%, respectively. Thus, HNTs‒PANI was an efficient nanomaterial for enhancing the pure water flux, removal efficiency and antifouling property to treat water contaminated with HA.

Development of a photocatalytic zirconia-titania ultrafiltration membrane with anti-fouling and self-cleaning properties

A photocatalytic Ce-Y-ZrO2/TiO2 ultrafiltration membrane was successfully prepared on a ZrO2/SiC support by a modified sol-gel process. The top active layer is 2 µm thick, uniform and defect-free. The membrane presented a molecular weight cut-off (MWCO) of 19 kDa (equivalent to a pore size of 6 nm) and a high pure water permeability, 160 Lm−2h−1bar−1. The high hydrophilicity and negative surface charge of the membrane favoured its great retention of proteins (bovine serum albumin, whey protein, and hemoglobin), indigo dye, and humic acid. The membrane was effective in photodegrading phenol and humic acid under simulated sun light irradiation. During humic acid filtration tests, the membrane presented better anti-fouling properties (smaller flux decline) and higher permeate flux under irradiation compared to the filtration in the dark. Moreover, self-cleaning properties were observed by irradiating the membrane, which enabled recovering up to 97% of the original flux. Consequently, a longer operation without chemical cleaning is possible, reducing costs and the process footprint. Further investigation would allow the development of innovative treatments for dinking and wastewaters by combining filtration and advanced oxidation processes for the abatement of contaminants of emerging concern in the presence of natural organic matter.

Effect of coagulation treatment on antifouling properties of PVC nanocomposite membrane in a submerged membrane system for water treatment

A submerged membrane system was used in this work to investigate the effect of the polyaluminum chloride (PAC) coagulant on the antifouling performance of the polyvinyl chloride/alumina (PVC/Al2O3) nanocomposite membrane. The prepared nanocomposite membranes were characterized with field emission scanning electron microscopy (FE-SEM), atomic force microscopy, contact angle, porosity measurement, and pure water flux. The results revealed that the membrane containing Al2O3 nanoparticles (the mass ratio of PVC to Al2O3 was 98.5/1.5) had a higher hydrophilicity, porosity, and pure water flux than other membranes. The FE-SEM images showed that when Al2O3 nanoparticles were present in the PVC membrane, large pores and macrovoids formed on the surface and cross-section of the membrane. The fouling behavior of membranes was investigated through the filtration of humic acid (HA) solution with and without the PAC coagulant. Without PAC addition, the PVC/Al2O3 membrane significantly decreased the irreversible fouling ratio from 60.7% to 19.4% and showed a high HA removal efficiency of approximately 90.5%. The Hermia model confirmed that the cake formation mechanism best described the experimental data for the neat PVC and nanocomposite membranes with the presence and absence of the PAC coagulant. This confirms that the PAC coagulant can significantly mitigate fouling and improve HA removal in the submerged membrane system.

Enhancing the antifouling and rejection properties of PVDF membrane by Ag3PO4-GO modification

Ultrafiltration is an environmentally friendly water treatment technology, but membrane fouling significantly impacts membrane performance and service life. Photocatalytic modification of membrane is regarded as an effective way for membrane fouling control. In this study, graphite oxide (GO), Ag3PO4 and Ag3PO4-GO nanomaterials were applied in polyvinylidene fluoride (PVDF) ultrafiltration membranes modification, and the membranes was denoted as P-GO, P-AgP and P-AgP@GO, respectively. Filtration of humic acid (HA) at different operating conditions was adopted in evaluation of membrane performance. Among them, P-AgP@GO had the best permeation, rejection and antifouling performances, and could maintain excellent properties when operation conditions (HA concentration, operation pressure, pH and ionic strength) were changed. Furthermore, the effect of photocatalysis on the self-cleaning performance and its mechanism were revealed. The overall performance of P-AgP@GO could be enhanced by visible light irradiation, and extending the visible illumination time during the filtration was conducive to the reusability.

Novel polycarbonate membrane embedded with multi-walled carbon nanotube for water treatment: a comparative study between bovine serum albumin and humic acid removal

Flat sheet polycarbonate/multi-walled carbon nanotube (PC/MWCNT) nanocomposite membranes with different nanoparticle contents were prepared by applying the phase inversion method. The characteristics of the prepared membranes were analyzed by field emission scanning electron microscopy (FE-SEM), atomic force microscopy (AFM), water contact angle, porosity, pure water flux (PWF), and mechanical properties. The performance of the membranes was evaluated in a submerged membrane system for two cycles and also for the filtration of humic acid (HA) and bovine serum albumin (BSA). The obtained results revealed that nanocomposites containing 0.1 wt% of MWCNTs showed better hydrophilicity, porosity, PWF, and mechanical properties. The FE-SEM images from surface indicated that the density and pore size of membrane increased from 0 to 0.1 wt% of MWCNTs. Moreover, according to AFM images, the PC/MWCNT-0.1 membrane showed a smoother surface than other samples. The antifouling performance of the membranes in a submerged membrane system revealed that the BSA solution flux for all membranes was lower than that of the HA solution due to the pore blocking of membranes occurring in the initial filtration of BSA. Apart from that addition of the 0.1 wt% of MWCNTs led to significant improvement in the fouling recovery ratio in the filtration of both HA and BSA because of the lower roughness and high hydrophilicity of the membrane surface. The rejection results revealed that the neat PC membrane had the highest value in the removal of HA and BSA with respect to other samples due to the formation of a thicker and denser cake layer on the membrane surface.

Surface Modification of Polyamide Ultrafiltration Membrane by Plasma Polymerisation of Acrylic Acid

Increase in hydrophilicity of the filtration membrane could attribute to the fouling reduction and overall filtration performance. In this study, we employ a surface modification on polyamide (PA) membrane by using plasma polymerization with acrylic acid as the precursor by varying the deposition time from 1 to 10 min to induce hydrophilic surface of the membrane without changing the bulk properties of PA membrane. Cross-flow filtration of humic acid using the modified PA membrane was conducted to measure permeates flux and rejection. We calculate the fouling tendencies of each membrane and the result indicates the best performance from sample with 7 min deposition time in terms of permeate flux, rejection and the lowest fouling tendencies. Therefore, this proposed technique could be useful to further improve the commercial filtration membrane; without changing the membrane fabrication process.

Toward tailoring nanofiltration performance of thin-film composite membranes: Novel insights into the role of poly(vinyl alcohol) coating positions

Nanofiltration (NF)-based purification technology has been considered as an efficient approach for providing freshwater due to its excellent feasibility and selectivity for treating saline water. However, the preparation of high-performance NF membranes with simultaneously high water permeance and fouling resistance still remains a bottleneck in the practical fabrication process. To provide new insights into the fabrication of highly permeable and fouling resistant TFC membranes, two NF membranes were fabricated via a gutter- and coating layer-assisted strategy using poly(vinyl alcohol) (PVA). The surface morphologies, chemical structures, and filtration performances were systematically evaluated. The PVA gutter-layered NF membrane (PA-TFC-I) showed a much rougher and higher negatively charged surface, reaching an outstanding water permeability of 28.2 ± 0.3 L m−2 h−1 bar−1 with excellent rejection to Na2SO4 (99.8 ± 0.1%). In contrast, superior antifouling performance was observed for the PVA-coated membrane (PA-TFC-P), presenting an ≥ 80.0% flux recovery ratio after each physical cleaning process during three cycles filtration of humic acid. Compared to the control NF membrane, the PVA coating rendered the PA-TFC-P membrane with excellent antifouling performance without sacrificing its rejection performance, while the PVA gutter-layered strategy endowed the PA-TFC-I membrane with ultrahigh water permeance and enhanced salt rejections. Therefore, a double modification strategy integrating the PVA-coating and guttering may be a hopeful avenue for developing highly-efficient NF membranes with both high water flux and outstanding antifouling properties.

A novel strategy based on magnetic field assisted preparation of magnetic and photocatalytic membranes with improved performance

Membrane fouling problem is the bottleneck for commercial applications of separation membranes. The current study offered a first report on preparation and performance of the magnetic and photocatalytic poly (vinylidene fluoride) (PVDF)-Ni-ZnO composite membranes for the antifouling purpose. Magnetic Ni–ZnO particles (NZPs) was firstly prepared via an in-situ reduction reaction. Thereafter, the NZPs were attracted onto a PVDF membrane surface through a magnetic force effect. The PVDF-NZPs composite membrane displayed magnetic property, photocatalytic property and obviously higher antifouling performance than that of bare PVDF membrane. Particularly, the flux recovery rates (FRR) of the optimal PVDF-NZPs membrane reached to 100%, 100%, 83% and 83% for filtration of humic acid (HA), sodium alginate (SA), bovine serum albumin (BSA) and yeast solutions, respectively, which are comparable or much better than most of the literature data. In addition, it was found that acid-based (AB) interaction of the extended Derjaguin-Landau-Verwey-Overbeek (XDLVO) results played the predominant role during the fouling process. The ultrahigh FRR of the modified PVDF-NZPs membrane mainly stemmed from its in-situ and persistent photocatalytic activities. The current work not only offered a novel membrane modification method, but also presented the modified membranes with enhanced performance for water treatment.