Investigating the effect of zirconium-based and titanium-based metal–organic frameworks nanoparticles on the performance of polysulfone hollow fiber mixed matrix membrane for dialysis application

This study aims to investigate polysulfone (PSF) mixed matrix membranes (MMMs) properties containing zirconium-based and titanium-based metal–organic frameworks (MOFs). for hemodialysis application. The nanoparticles were synthesized, and the membranes were produced by the phase inversion method. Membrane characterization conducted by attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR), field emission Scanning electron microscope (FE-SEM), energy-dispersive x-ray analysis (EDX), transmission electron microscopy (TEM), x-ray diffraction (XRD), and atomic force microscopy (AFM) confirmed the presence of MOF nanoparticles. Also, the evaluation of the specific surface area of nanoparticles was done by BET. The water contact angle reduced from 64.4° to 51.2°, indicating the hydrophilicity improvement, enhancing the pure water flux from 46.8 L/m²h for the pristine membrane to 76.7 L/m2h for the pristine membrane M₄. The total fouling resistance decreased from 30% to 21%, and the bovine serum albumin (BSA) adsorption of modified membranes was lower than that of the pristine membrane. Urea and creatinine were cleared significantly for modified ones, up to 82.6% and 72.1%, respectively, and all membranes showed BSA retention of more than 93%. A comparison between MMMs that contained UIO-66-NH₂ and MIL-125-NH₂ showed that the former had a better effect on the performance. M₄ had better results, indicating high water flux, the lowest fouling resistance, high porosity, lower BSA adsorption, proper clearance for urea and creatinine, and 94.2% BSA retention.     

Inorganic nanoparticles incorporated in polyacrylonitrile-based mixed matrix membranes for hydrophilic,ultrafast, and fouling-resistant ultrafiltration

Mixed matrix membrane (MMM) structures and performances are greatly affected by the distribution of nanoparticles in the polymeric matrix. Until now, there has been little research on the effects of nanoparticle distribution states on polyacrylonitrile (PAN)-based MMM structures and performances. In this paper, different intermolecular interactions between nanoparticles and PAN molecules were generated by in situ fabricated amino-functionalized SiO₂ and TiO₂ nanoparticles to create absolutely different distribution states of nanoparticles in a PAN matrix. The results indicated that, due to the strong interactions between amino and cyano groups, SiO₂ is distributed in the PAN membranes homogeneously, while most of the TiO₂ migrates to the membrane's top surfaces or the walls of pores or even escape from the membranes during the nonsolvent index phase separation (NIPS) process. PAN-TiO₂ MMMs have more hydrophilic top surfaces, higher porosity, larger mean pore size, and stronger antifouling performances than pure PAN and PAN-SiO₂ membranes. The PAN-TiO₂ MMMs have an ultrahigh water flux of 1204.6 L/(m² h), which is more than 44 times that of PAN membranes. And the good pore structures and hydrophilicity of the membranes derived from special interactions between in situ TiO₂ nanoparticles and PAN molecules can give high-performance PAN-based ultrafiltration membranes a bright future. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47902.     

A polyvinyl alcohol-based mixed matrix membrane with uniformly distributed Schiff base network-1 for ethanol dehydration

In this study, Schiff base network (SNW)-1 nanoparticles with high hydrophilicity and large specific surface area were used to prepare polyvinyl alcohol (PVA)-based mixed matrix membranes (MMMs), which were evaluated for ethanol dehydration. Because of the low difference of density between SNW-1 and PVA, the as-prepared nanoparticles can be uniformly distributed into the PVA active layer. The effects of SNW-1 loading, feed temperature, and water concentration on pervaporation (PV) performance were further studied. The results showed the MMM with 10 wt% of SNW-1 loading exhibited a separation factor of 1,501 and a permeation flux of 187 g m⁻² h⁻¹ for feeding 95 wt% ethanol/water binary solution at 75°C. Overall, the SNW-1/PVA MMMs showed great prospect in ethanol dehydration via PV.     

Separation of heavy metal and protein from wastewater by sulfonated polyphenylsulfone ultrafiltration membrane process prepared by glycine betaine enriched coagulation bath

This work deals with a simple and eco-friendly approach for the development of ultrafiltration membranes for the separation of environmentally hazardous substances from the water source. Polysulfone and sulfonated polyphenylsulfone blend ultrafiltration membranes were fabricated by the non-solvent induced phase inversion technique. Prepared membranes were characterized for their morphology, hydrophilicity, porosity, filtration and antifouling properties. The blend membranes with 15 wt% of sPPSU demonstrated the best performance with water flux of 190.33 Lm^?2h^?1 and flux recovery ratio of 86.56%. The effect of aq. glycine betaine (GB) coagulation bath on the membrane property and performance was studied and compared with commonly used additives such as NaCl and NMP. The GB in coagulation bath exhibited better flux and performance with protein rejection of 66.3%, 74.0% and 91.2% for trypsin, pepsin, and bovine serum albumin, respectively, and heavy metal rejection of 75.2% and 87.6% for polymer enhanced ultrafiltration of Cd²⁺ and Pb²⁺ ions, respectively.     

The influence of solvent properties on the performance of polysulfone/β‐cyclodextrin polyurethane mixed‐matrix membranes

This study investigates the effect of solvent properties on the structural morphology and permeation properties of polysulfone/β‐cyclodextrin polyurethane (PSf/β‐CDPU) mixed‐matrix membranes (MMMs). The membranes were prepared by a modified phase‐inversion route using four different casting solvents [dimethyl formamide (DMF), dimethyl sulfoxide (DMSO), dimethyl acetamide (DMA), and N‐methyl‐2‐pyrrolidone (NMP)]. While DMSO‐based membranes demonstrated particularly high permeability (ca 147 L/m²h.bar), their crystallinity was low compared to MMMs prepared using DMA, DMF and NMP due to the formation of thin active layers on their surfaces. Cross‐sectional morphology revealed that the MMMs have a dense top skin with finger‐like inner pore structures. Membranes prepared using NMP displayed the highest hydrophilicity, porosity, and crystallinity due to the low volatility of NMP; DMF membranes exhibited superior mechanical and thermal stability due to its (DMF) high hydrogen bonding (δH) values. Thus, the morphological parameters, bulk porosity, and flux performance of MMMs have a significant inter‐relationship with the solubility properties of each solvent (i.e., δH, density, volatility, solubility parameter). © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 2005–2014, 2013     

Removal of heavy metals from wastewater by membrane processes: a comparative study

Wastewater containing copper and cadmium can be produced by several industries. The application of both reverse osmosis (RO) and nanofiltration (NF) technologies for the treatment of wastewater containing copper and cadmium ions to reduce fresh water consumption and environmental degradation was investigated. Synthetic wastewater samples containing Cu²⁺ and Cd²⁺ ions at various concentrations were prepared and subjected to treatment by RO and NF in the laboratory. The results showed that high removal efficiency of the heavy metals could be achieved by RO process (98% and 99% for copper and cadmium, respectively). NF, however, was capable of removing more than 90% of the copper ions existing in the feed water. The effectiveness of RO and NF membranes in treating wastewater containing more than one heavy metal was also investigated. The results showed that the RO membrane was capable of treating wastewater with an initial concentration of 500 ppm and reducing the ion concentration to about 3 ppm (99.4% removal), while the average removal efficiency of NF was 97%. The low level of the heavy metals concentration in the permeate implies that water with good quality could be reclaimed for further reuse.     

Carbon-encapsulated magnetic nanoparticles as separable and mobile sorbents of heavy metal ions from aqueous solutions

Carbon-encapsulated magnetic nanoparticles (CEMNPs) are studied as mobile sorbents for removal of heavy metal ions (Cu²⁺, Co²⁺, Cd²⁺) from aqueous solutions. The ion uptakes achieve 95% for cadmium and copper. CEMNPs-based sorbents also have excellent adsorption capacities (between 1.23 and 3.21 mg/g), which are considerably higher than the capacities of activated carbons (between 0.37 and 0.39 mg/g).     

Preparation of blend polyethersulfone/cellulose acetate/polyethylene glycol asymmetric membranes for oil–water separation

Blend PES/CA hydrophilic membranes were prepared via a phase-inversion process for oil–water separation. PEG-400 was introduced into the polymer solution in order to enhance phase-inversion and produce high permeability membranes. A gas permeation test was conducted to estimate mean pore size and surface porosity of the membranes. The membranes were characterized in terms of morphology, overall porosity, water contact angle, water flux and hydraulic resistance. A cross-flow separation system was used to evaluate oil–water separation performance of the membranes. From FESEM examination, the prepared PES/CA membrane presented thinner outer skin layer, higher surface porosity with larger pore sizes. The outer surface water contact angle of the prepared membrane significantly decreased when CA was added into the polymer solution. The higher water flux of the PES/CA membrane was related to the higher hydrophilicity and larger pore sizes of the membrane. From oil–water separation test, the PES/CA membrane showed stable oil rejection of 88 % and water flux of 27 l/m² s after 150 min of the operation. In conclusion, by controlling fabrication parameters a developed membrane structure with high hydrophilicity, high surface porosity and low resistance can be achieved to improve oil rejection and water productivity.     

Preparation and characterization of polyzwitterionic hydrogel coated polyamide-based mixed matrix membrane for heavy metal ions removal

A novel polyzwitterionic hydrogel coated mixed matrix membrane (MMM) was successfully prepared, characterized and used for Cu²⁺, Mn²⁺, and Pb²⁺ heavy metal ions removal from water. Hydrophilic and porous covalent organic framework (COF) nanoparticles (NP) as filler were synthesized from melamine and terephthalaldehyde, and then incorporated into polyamide (PA) thin film composite (TFC) membrane. The hydrogel coating was applied by using a tailored cross-linkable polymer system in combination with concentration polarization enabled cross-linking. The effects of COF NP loading into PA layer and polyzwitterionic hydrogel coating on the membrane morphology and separation performance were studied using different analyses. The MMM prepared with a COF NP loading of 0.02 wt/wt% in the hexane dispersion used for NP deposition during PA layer formation (leading to 0.42 g/m²) exhibited an increased pure water permeability of around 200% compared with the neat PA TFC membrane while the Mn²⁺ ion rejection maintained above 98%. Scanning electron microscopy surface images and zeta potential profiles showed that the hydrogel was successfully deposited on the membrane surface. Furthermore, the hydrogel coating could decrease net surface charge of membranes but did not significantly influence the heavy metal ions rejections under nanofiltration conditions. The results of filtration experiment with protein solution indicated that the hydrogel coated membranes exhibited superior antifouling property, as shown by higher flux recovery ratio after washing with water, compared with neat PA TFC membrane and not coated MMM, respectively.     

Preparation of novel Polyvinylidene fluoride/boehmite composite membrane made using nonsolvent induced phase separation method for arsenate ion removal from water

Polyvinylidene fluoride/boehmite composite membranes with hydrophilic surfaces were prepared using the nonsolvent induced phase inversion technique (NIPS) method to remove arsenate ions from water. The nanoparticles were added with different boehmite filler content. The contact angle of the bare membrane is 85⁰, and it is reduced to 53⁰, imparting hydrophilicity due to the presence of boehmite nanoparticles. The mechanical characteristics of the membranes have significantly improved. The BET and SEM results have shown that the average pore diameter gets reduced with boehmite addition, and surface area increases. Additionally, the use of nanoparticles enhanced the membranes' thermal stability. The nanofiltration unit is used to filter the arsenic-contaminated water. The transmembrane pressure of ~4 bar is applied to all the membranes, and arsenic rejection; the flux of the membranes was calculated. The membrane has shown the highest rejection of 55% with a flux of 3.5659 L/m².h.     

Cellulose acetate ultrafiltration membranes customized with copper oxide nanoparticles for efficient separation with antifouling behavior

Cellulose acetate (CA) nanocomposite ultrafiltration membranes are fabricated with copper oxide (CuO) nanoparticles with the aim of improving efficient protein separation and antifouling performance. CuO nanoparticles are synthesized from cupric nitrate using a wet precipitation method and characterized by FTIR and XRD. CA/CuO nanocomposite membranes fabricated using 0.5, 1.0, and 1.5 wt% of CuO nanoparticles individually by simple phase inversion technique. The CA nanocomposite membrane with 0.5 wt% of hydrophilic CuO exhibited enhanced PWF of 118.6 Lm⁻² h⁻¹ due to the improvement in porosity and water uptake. This is in good agreement with the enhanced hydrophilicity of the CA/CuO nanocomposite membranes results observed in surface contact angle and morphological investigations. Further, 95.5% of BSA separation and 94.7% of flux recovery ratio (FRR) indicates its superior antifouling potential caused due to the presence of the hydration layer at the CA/CuO membrane surface. Among all the fabricated membranes, the CA-0.5 nanocomposite membrane with 0.5 wt% of CuO exhibited superiorly improved hydrophilicity, water permeation, BSA separation, and antifouling performance indicates its potential use in water and wastewater treatment applications.     

Effects of polyethylene glycol on the structure and filtration performance of thin-film PA-Psf composite forward osmosis membranes

In forward osmosis, internal concentration polarization is related to the properties (e.g., hydrophilicity, porosity, structural resistant) of membrane support layer. In this work, polyethylene glycol with a low molecular weight of 400 Da was introduced as a support layer additive during the fabrication of thin-film polyamide-polysulfone composite forward osmosis membranes. The forward osmosis performances including water flux and reverse salt flux of the membranes were tested in the mode of AL-FS where the membrane active layer faced toward feed solution. Results showed that the addition of polyethylene glycol would reduce internal concentration polarization and improve membrane performance in forward osmosis by means of enhancing membrane hydrophilicity and changing pore morphologies of membrane support layer. The membrane prepared with 6 wt.% polyethylene glycol was found to exhibit the highest water flux of 47.4 Lm^?2h^?1 with a reverse salt flux of 7.6 gm^?2h^?1 when using DI water and 2.0 M NaCl as the feed and the draw solution, respectively, indicating an optimal polyethylene glycol dosage of 6 wt.% in this work.     

Synthesis of poly(4, 4′-biphenylene sulfonyl succinamide)-polysulfone blend membranes for removal of toxic metal ions from water

A novel polymer poly(4,4′-biphenylene sulfonyl succinamide) (PBSS) was synthesized via polycondensation reaction. Succinyl chloride and 4-aminophenyl sulfone were used as reactive monomers and anhydrous AlCl₃ was used as a catalyst. Both polysulfone (PSf) and PBSS were dissolved in N-methyl-2-pyrrolidone (NMP) at different compositions to obtain a homogeneous solution to fabricate PSf-PBSS blend membranes. The structure of PBSS was characterized by ATR-IR and ¹H-NMR spectroscopy. Thermal properties of PBSS were analyzed by TGA-DTA. Mechanical properties and morphology of blend membranes were analyzed by universal testing machines and field emission scanning electron microscope, respectively. The hydrophilicity of blend membranes with respect to the concentration of PBSS was studied by contact angle and water uptake studies. Upon blending, the hydrophilicity of PSf-PBSS membranes drastically increased due to the presence of large number of amide and sulfonyl groups in the matrix. The blend membranes exhibited significant increase in water flux from 100 L m⁻² h to 650 L m⁻² h⁻¹, and rejection of 100% for Pb(II) and 80% for both Cd(II) and As(III) toxic heavy metal ions. The hydrophilic nature of  CO NH and inter and intramolecular hydrogen bonding among PBSS polymer chains dispersed within rigid PSf matrix imparts softness, amide and sulfonyl groups enhance interconnected porosity and hydrophilicity of blend membranes. Hence, PBSS may serve as a low-cost novel polymeric additive for water purification and separation membrane applications. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 48254.     

Influence of copper oxide nanomaterials in a poly(ether sulfone) membrane for improved humic acid and oil–water separation

In this study, self‐synthesized copper(I) oxide (Cu₂O) nanoparticles were incorporated in poly(ether sulfone) (PES) mixed‐matrix membranes (MMMs) through the phase‐inversion method. A cubic arrangement and crystallite size of 28 nm was identified by transmission electron microscopy and X‐ray diffraction (XRD) for the as‐synthesized Cu₂O particles. The pristine PES membrane had a higher contact angle value of 88.50°, which was significantly reduced up to 50.10° for 1.5 wt % PES/Cu₂O MMMs. Moreover, XRD analysis of the Cu₂O‐incorporated PES membrane exhibited a new diffraction pattern at 36.46°. This ensured that the Cu₂O nanoparticles were distributed well in the PES matrix. Interestingly, the water permeability progressively improved up to 66.72 × 10^?9 m s^?1 kPa^?1 for 1.5 wt % PES/Cu₂O MMMs. Furthermore, the membrane performances were also evaluated with different feed solutions: (1) bovine serum albumin, (2) humic acid, and (3) oil–water. The enhanced rejection and lower flux reduction percentage were observed for hybrid membranes. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43873.     

Modification of cellulose acetate: Its characterization and application as an ultrafiltration membrane

The development of cellulose acetate blend membranes using a commercial grade Mycell cellulose acetate and cellulose diacetate with suitable pore structure is discussed. These membranes were characterized in terms of resistance of the membrane, pure water flux, the molecular weight cutoff, water content, pore size, and porosity. The removal of copper metal ions by this blend membrane using polyethyleneimine as a chelating agent was studied. The effects of copper ion concentration and casting solution composition on separation are also discussed. A possible correlation between feed and permeate concentration of copper ion is evaluated. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 67:1939–1946, 1998     

EAA及致孔剂PEG400改性PVDF膜的结构及其渗透性能

为了调控聚偏氟乙烯(PVDF)膜的孔状结构和性能,以EAA(聚乙烯丙烯酸)作为添加剂,以PEG400作为致孔剂,通过浸入沉淀相转换法制备了一系列PVDF/EAA复合超滤膜,通过扫描电镜、红外、水接触角、黏度表征、孔隙率、纯水通量、牛血清蛋白(BSA)截留率、通量恢复率和污染率等测试手段,研究了不同的EAA含量和不同的致孔剂PEG400含量对复合膜性能的影响。结果表明,EAA的添加改善了膜表面的亲水性,致孔剂PEG400的加入提高了铸膜液和凝固浴之间的亲和性,加快了成膜速度,从而在膜表面形成更多的孔洞,其中E-3膜的纯水通量和BSA截留率分别达到了271.57 L.m_?2^.h_?1^和64.83%,相对于纯PVDF膜分别提高了约486.29%和116.10%;通量恢复率和总污染率分别为75.97%和46.51%,相对于纯PVDF膜分别提升了19.37%和降低了26.92%。而P-3膜的孔隙率为53.33%,平均孔径为4.55 nm,相对于未加致孔剂的P-0膜的孔隙率和平均孔径分别提高了约33.33%和88.02%;因此,本研究中提到EAA作为添加剂,及 PEG400作为致孔剂的方法可以显著改善PVDF膜结构和渗透性能。     

Binary metal oxides incorporated polyethersulfone ultrafiltration mixed matrix membranes for the pretreatment of seawater desalination

In this study, an attempt was made to pretreat seawater using polyethersulfone (PES) mixed matrix membranes (MMMs) incorporated with titania-based binary metal oxides. Two different titania-based binary metal oxides were prepared, namely titania-zirconia (TiZr) and titania-zinc oxide (TiZn). The influence of hydrophilic and negatively charged sulfonated poly(ether ether ketone) (SPEEK) polymer as additive of PES MMMs was also studied. Morphological and elemental analysis revealed that both ZrO₂ and ZnO were well dispersed in the as-prepared binary metal oxide TiZr and TiZn, respectively._. Thermogravimetry analysis indicated the good compatibility of TiZr and TiZn with the SPEEK/PES polymer. The binary metal oxide incorporated SPEEK/PES MMMs exhibited improved hydrophilic properties with a low water contact angle of 57° ± (0.6). SPEEK/PES MMMs incorporated with 0.5 wt% TiZr exhibited the highest permeability of 3.11 × 10⁻⁷ ± (0.2) m/s·kPa. Seawater pretreatment performance of membranes evaluated using natural organic matters containing high salinity feed water. TiZr and TiZn incorporated SPEEK/PES MMMs exhibited 95% rejection for humic acid. SPEEK/PES MMMs loaded with 0.5 wt% TiZr also showed the highest water flux and 87% water recovery within 90 min of seawater filtration. Both PES/SPEEK/TiZr and PES/SPEEK/TiZn MMMs exhibited superior antibacterial activity.     

Fabrication of polysulfone/zinc oxide nanocomposite membrane: Investigation of pore forming agent on fouling behavior

The aim of this research was to synthesize a polysulfone/Zinc oxide nanocomposite membrane (PSf/ZnO NCM) in order to mitigate membrane fouling. ZnO nanoparticles with an approximate size of 20 nm were blended with PSf matrix. To fabricate an efficient PSf/ZnO NCM, polyethylene glycol and polyvinyl pyrrolidone were used as pore former agent, based on which PEG-NCMs and PVP-NCMs were fabricated. The effect of the type of pore former and concentration of nanoparticles was evaluated on the structure and performance of nanocomposite membrane. According to SEM images, with the increase in the concentration of nanoparticles, membrane porosity grew as well. AFM analysis confirmed increased roughness with contact angle measurement showing enhanced hydrophilicity. The filtration performance implied that the presence of ZnO nanoparticles improves water flux. Moreover, ZnO nanoparticles elevated humic acid rejection up to 99.7% and 94.2% and decreased total filtration resistance up to 89% and 30% for PEG-NCMs and PVP-NCMs, respectively.     

Treatment of dye and cadmium solutions using asymmetric kaolin porous tubular support

Kaolin porous support ceramic was prepared from kaolin. The characterization of the porous properties and structure of the support synthesis was carried out by scanning electron microscopy (SEM), absorption rate, shrinkage rate and Hg-porosimetry methods. The pore size distribution showed a unimodal pore size distribution with an average pore size of about 0.9 µm. The reliability of support was measured by filtration tests and removal of heavy metals.Filtration studies using porous tubular supports were performed for solutions containing methylene blue and Evans blue. The study of the liquid filtration and flow through these supports showed that the methylene blue rejection rate was 99% while the Evans blue rate reached 90% for a 90 minute filtration time under a pressure of 2 bar. We beforehand tested the flow rate for each support with distilled water and the results show that the support of kaolin gave a flux for distilled water of 31.0 L/h at the pressure of 2 bar. At a pressure of 3.5 bar an increase in the distilled water flux through the support was observed.The rejection rate of cadmium ions was more significant. A rejection rate of 99.99% using a 10^− 4 mol/L solution of this heavy metal for two-hour treatment time was obtained.     

Performance evaluation of modified fabricated cotton membrane for oil/water separation and heavy metal ions removal

Preparation of effective membrane with special surface treatment for oil/water separation having promising future and low manufacturing cost. The suggested membrane was fabricated by a simple treatment via increasing the hydrophilicity of the cotton fabric surface. The cotton fabric was impregnated in poly(acrylic acid-co-N-methylol acrylamide), poly(AA-co-NMA), where NMA acts as bonding agent. Sodium hypophosphite (SHP) was added to the modification solution to enhance the bonding between the cotton fabric and the PAA. The modified fabric was thermally dried and cured at different temperatures. It was found that, the presence of 3.5% NMA and addition of 5% SHP to the modification solution then curing at 190°C gave the highest amount of bonded PAA to the cotton fabric. The success of the modification process was confirmed by scanning electron microscope, Fourier transformer infrared and the increase in the contact angle of the cotton fabric after modification. Furthermore, the prepared membrane was evaluated for oil (n-hexane, toluene, and petroleum ether)/water separation and also for heavy metal ions removal (Cd²⁺ and Co²⁺). Neutralization of the produced membrane with ammonium hydroxide resulting in a higher contact angle and consequently higher separation efficiency for oil/water mixtures and higher performance for heavy metal ions removal compared to the unneutralized one.