Bovine Serum Albumin Rejection Research Articles

Synthesis, characterization, and performance of MXene-modified PVC membranes for organic and inorganic separation

This study explores the transformation of polyvinyl chloride (PVC) flat sheet membranes for the first time using MXene, a hydrophilic two-dimensional (2D) nanosheet, to enhance ultrafiltration (UF) performance for wastewater treatment. The loading of MXene in the PVC solution was adjusted from 0 to 0.5 g in order to create modified membranes. The properties and performance of these membranes were thoroughly analyzed using field emission scanning electronmicroscopy (FESEM), contact angle (CA) measurements, Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), water permeation flux, Bovine serum albumin (BSA) rejection, and Pb metal ions removal tests. Among the developed membranes, the N2-modified PVC membrane, with 0.4 g of MXene, exhibited the most favorable characteristics, including a contact angle of 65.77° and a porosity of .84.8 %. This membrane achieved the highest clean water permeation flux of 201.3 LMH, along with a 99.9 %, 91.03 % BSA and Pb metal ions rejection rate respectively, and a flux recovery ratio (FRR) of 90.2 %. The incorporation of MXene nanosheets significantly enhanced membrane efficiency compared to neat PVC membranes, demonstrating the promising capabilities of MXene-modified PVC membranes for effective wastewater treatment.

1-(3-Aminopropyl) imidazole (APIm) modified ultrafiltration (UF) membrane for mitigating alginate fouling caused by calcium

UF is widely used as a wastewater treatment and recycling technology. However, membrane fouling is still an important factor affecting the wide application. In this study, APIm with positive amino group was adsorbed to the surface of the carboxylated polyacrylonitrile (PAN) membrane by electrostatic force to reduce the fouling of sodium alginate (SA) caused by Ca2+. The results show that 1 v/v% APIm was selected as the optimal dosage, accompanied by the highest water flux of 330.5 L·m-2h−1 bar−1 and bovine serum albumin (BSA) rejection rate of 91.0 %. When the concentration of Ca2+ was increased to 10 mM, the Ca2+ catch amount increased to 48.25 mg/cm2. The main anti-fouling mechanism was that APIm captured a certain amount of Ca2+ in situ, destroyed the complex structure of sodium alginate (SA) and Ca2+. Then the fouling layer was easy to be removed by physical cleaning. At the concentration of 10 mM Ca2+, the membrane flux recovery rate of 1 v/v% APIm membrane was increased to 80.1 %. This study demonstrates a fouling control strategy for in-situ removal of Ca2+ bound SA fouling, providing a new approach for the future development of UF membrane.

Enhancement of antifouling and separation properties of poly(m-phenylene isophthalamide) hybrid ultrafiltration membrane using highly crystalline poly(heptazine imide) nanosheets

A highly crystalline phase g-C3N4, namely poly (heptazine imide) (PHI) was synthesized using molten salts. A high-performance ultrafiltration membrane was prepared by blending PHI nanosheets with Poly(m-phenylene isophthalamide) (PMIA) to obtain casting solution, and further prepared by phase conversion method. Hybrid PMIA membranes were prepared by incorporating 0.02–0.10 wt% of PHI, which were further characterized by SEM, AFM, XRD, FTIR, XPS, TGA and surface zeta potential. The hydrophilicity, water flux, and rejection of bovine serum albumin (BSA) of the membrane significantly increased. For instance, the water permeability of M4 (264.6 Lm−2h−1bar−1) was about 2.3 times that of bare PMIA membrane (113.6 Lm−2h−1bar−1), while maintaining a BSA rejection of 94.7 % for a 1000 mgL−1 BSA feed solution. Moreover, the M4 membrane showed excellent antifouling performance with a flux recovery rate of up to 88.7 % and lower irreversible fouling of 11.3 %. This study may provide reference for the modulation of highly crystalline g-C3N4 structure and its application in membrane fabrication for water treatment.

Microplastics and dye removal from textile wastewater using MIL-53 (Fe) metal-organic framework-based ultrafiltration membranes

Microplastics (MPs) and other organic matters in textile wastewater have posed a formidable challenge for treatment processes, particularly in the primary stages such as ultrafiltration (UF). UF plays a crucial role in preventing the entry of pollutants into subsequent treatment steps. However, the performance efficiency of UF membranes is compromised by the potential fouling of membrane pores by MPs, dyes and other organic pollutants such as bovine serum albumin (BSA). This study focuses on enhancing UF membrane performance, specifically its antifouling properties, through the development of high-performance membranes using MIL-53(Fe) metal-organic framework (MOF) particles (noted as MIL-53 here). Various concentrations of the MIL-53 (0.05, 0.1, 0.2, and 0.5 wt%) were integrated into the membrane structure through phase inversion process. Streaming zeta potential results confirmed the negatively charged surface of the membranes and their high hydrophilicity was validated through contact angle analysis. FTIR, SEM, EDS, and XRD confirmed the presence of MIL-53 particles on the surface of membranes. The developed membranes were tested for 24 h to assess their antifouling properties, with a subsequent 30-min hydraulic flush to measure their flux recovery ratios. Methylene Blue (MB) dye was used as a cationic dye present in textile wastewater to evaluate the efficiency of the developed membranes in dye removal and the synergistic effects of dye rejection in the presence of organic matters (i.e., MPs and BSA). Since previous studies have not fully addressed the combination of dyes and organic matter, this study thoroughly investigated the effect of particle-type foulants (MPs) and their interactions with dye (MB), as well as water soluble protein-type foulants (BSA) and their interaction with MB. The results indicated that the developed membranes exhibited higher MB rejection when the dye was present with either MP or BSA, along with improved antifouling properties. The optimised UF membrane integrated with 0.1 wt% MIL-53 demonstrated nearly 96% BSA rejection and around 86% MB rejection in the mixed foulant case (BSA-MB). The modified membrane exhibited a substantial increase in water flux from 176 L m−2.h−1 to 327 L m−2.h−1. The findings of this research show the potential of iron-based MOFs in improving the performance of UF membranes and provide a platform for future studies on significant areas such as long-term stability studies and testing with other pollutants found in textile wastewater.

A 5,5’‐Thiobis(thiazol‐2‐amine)‐based dithiocarbamate polymer: Straightforward synthesis and application in PVC membrane modification to enhance cadmium and dye removal

AbstractA novel dithiocarbamate polymer (TTDP) derived from bis(2‐aminothiazole) sulfide was synthesized through a straightforward process. The synthesis involved the initial conversion of 2‐aminothiazole into its bis(sulfide), subsequent reaction with chloroacetyl chloride, and final copolymerization with disodium ethylene bisdithiocarbamate. TTDP boasts a high percentage of functional groups containing sulfur, nitrogen, and oxygen, contributing to its hydrophilicity, strong chelation capacity with metal cations, and compatibility with other polymers. Therefore, it was used as a strong candidate for making membranes in water media. According to this, TTDP was blended in ratios 1, 2, 5, and 10 wt% with polyvinyl chloride (PVC; 15 wt%), 2 wt% of polyethylene glycol 4000 in N,N‐dimethylacetamide as polymeric membranes for water‐based applications. The blended membranes were prepared using the casting and immersion precipitation method. The blended membrane showed high fluxes, up to 1052 L/m2 h for 2 wt% of TTDP (in comparison to the bare membrane's 459 L/m2h). Notably, they demonstrated an excellent protein solution flux of 222–269 L/m2 h at 3 bar with 96%–98% bovine serum albumin rejection. Furthermore, these membranes showed remarkable efficacy in removing cadmium ions (up to 98.96% for 5 and 10 wt% TTDP) and synthetic dye methyl orange (up to 84.03% for 2 wt% TTDP).

Maltodextrin-modified graphene oxide composite membrane applied to the enantioseparation of amino acids

The separation of enantiomers using chiral membranes has garnered much research interest. In this study, the enantioseparation of amino acids using chiral membranes, namely graphene oxide-ethylenediamine-maltodextrin (GO-EDA-MD) and GO-EDA-hydroxypropyl-MD (GO-EDA-HP-MD), was evaluated. HP-MD and MD were investigated as chiral selectors due to their inherent chirality. Various characterization techniques, including atomic force microscopy, Fourier transform infrared spectrometry, field emission scanning electron microscopy, water contact angle analysis, tensile properties, and thermal gravimetric analysis were employed to analyze the membrane structures. The evaluation of enantioseparation performance was conducted by employing tryptophan, phenylalanine, and tyrosine enantiomers. Optimal conditions for enantiomer separation were achived using a GO-EDA-HP-MD chiral composite (1.75 wt%), a feed concentration of 10 mg/L for each enantiomer, a separation time of 15 min, and a membrane effective surface area of 1.0 cm2. Also, the bovine serum albumin rejection was 90.0 %, and the water flux reached 37.1 L m−2 h−1. The highest enantiomeric excess (ee.%) values were 46.33 %, 76.97 %, and 73.04 % for tryptophan, phenylalanine, and tyrosine, respectively. The impact of voltage on ee.% and substance flux was also explored. This membrane was able to separate enantiomers successfully.

Modification of polyvinylidene fluoride membrane with ciprofloxacin to improve the bacteriostatic performance

The common polyvinylidene fluoride (PVDF) membrane itself is susceptible to membrane fouling, especially biofouling, which is a serious threat. In this study, PVDF membrane was modified with ciprofloxacin (CIP) through co-blending to investigate the filtration properties, bacterial inhibition and fouling resistance. Modified membranes were prepared by adding 0.3 g (MC0.3), 0.6 g (MC0.6), 0.9 g (MC0.9) and 1.2 g (MC1.2) CIP per 100 g casting solution. Among these modified membranes, MC0.6 showed the best filtration performances, with the pure water flux stabilized at about 416.67 L/(m2·h) and bovine serum albumin (BSA) rejection of 92.0% at a trans-membrane pressure of 0.1 MPa. The pore size was reduced, the average roughness was reduced to 29.4 nm, the contact angle was lowered to 68.9°, and the hydrophilicity was greatly improved. The width of the inhibition circle produced by MC0.6 was 0.35–0.45 mm, and the modified membrane showed good inhibition of non-specific bacteria and algal removal during urban river water filtration. The rejection of BSA was increased by 16.32% compared to the base membrane and the adsorption rate for BSA was reduced by 68.45%. In addition, the removal of conventional pollutants in urban river water by the modified membranes for was also improved. Compared with that of the base membrane, the removal of TN, NH3–N, TP and COD by MC0.6 was increased by 10.58%, 12.45%, 15.44% and 13.53%. The results showed that CIP co-blending modified PVDF membrane could effectively improve membrane performances and has good value for water treatment.

Effects of a dual functional filler, polyethersulfone-g-carboxymethyl chitosan@MWCNT, for enhanced antifouling and penetration performance of PES composite membranes

Ultrafiltration technology, separating water from impurities by the core membrane, is an effective strategy for treating wastewater to meet the ever-growing requirement of clean and drinking water. However, the similar nature of hydrophobic organic pollutants and the membrane surface leads to severe adsorption and aggregation, resulting unavoidable membrane degradation of penetration and rejection. The present study presents a novel block amphiphilic polymer, polyethersulfone-g-carboxymethyl chitosan@MWCNT (PES-g-CMC@MWCNT), which is synthesized by grafting hydrophobic polyethersulfone to hydrophilic carboxymethyl chitosan in order to suspend CMC in organic solution. A mixture of hydrophilic carboxymethyl chitosan and hydrophobic polymers (polyethersulfone), in which hydrophilic segments are bonded to hydrophobic segments, could provide hydrophilic groups, as well as gather and remain stable on membrane surfaces by their hydrophobic interaction for improved compatibility and durability. The resultant ultrafiltration membranes exhibit high water flux (198.10 L m−2·h−1), suitable hydrophilicity (64.77°), enhanced antifouling property (82.96%), while still maintains excellent rejection of bovine serum albumin (91.75%). There has also been an improvement in membrane cross-sectional morphology, resulting in more regular pores size (47.64 nm) and higher porosity (84.60%). These results indicate that amphiphilic polymer may be able to significantly promote antifouling and permeability of ultrafiltration membranes.

Preparation and performance study of waste plastic blended ultrafiltration membrane

Waste plastic packaging bags (rPVC) and waste milk tea straws (rPLA) were used as membrane materials to prepare ultrafiltration (UF) membranes by the non-solvent induced phase separation (NIPS) method. The study aimed to investigate the influence of various factors, including different rPVC contents (10 wt%-20 wt%), membrane fractions (rPVC/rPLA), additive fractions (Pluronic F-127/PVP-K30), and different additive contents (0.5 wt%-3.0 wt%), on the performance of the membranes. The permeability, morphology, hydrophilicity, chemical composition, thermal stability, and antifouling properties of the blended UF membranes were thoroughly investigated. The experimental results revealed that the presence of rPLA and Pluronic F-127 increased the porosity, water absorption, pore size, and hydrophilicity of the blended UF membranes. Furthermore, the introduction of rPLA enhanced the thermal stability of the blended UF membranes. Additionally, the incorporation of Pluronic F-127 further improved the overall performance of the blended UF membranes. Specifically, it was found that the blended UF membranes achieved a pure water flux (PWF) of 192.50 L·m−2·h−1, while maintaining a bovine serum albumin (BSA) rejection rate of 95.20%. These results were obtained using a content ratio of rPVC/rPLA (90/10) at 14 wt% and an additive content of Pluronic F-127 at 2.5 wt%. By comparing with the blended UF membranes without introducing additives into the casting solution, the roughness (Ra) was reduced by 40.3%, the water contact angle (WCA) was reduced by 7.5%, the flux recovery rate (FRR) was increased by 80.5%, and the fouling resistance was enhanced.

Microstructure and performance modification of PVDF ultrafiltration membrane via adjusting the composition of coagulation Bath

AbstractIn this paper, the effect of the composition of a nonsolvent bath on the physicochemical properties of the polyvinylidene fluoride (PVDF) ultrafiltration membranes were comprehensively investigated using the nonsolvent‐induced phase separation method. Three additives (ethanol, glycerol, or NaCl) were added to the water coagulation bath respectively to obtain different membranes. It was found that the microstructure of the membranes changed from finger‐like structure to the sponge‐like structure with the increase of additives concentration, which successfully improved the retention and mechanical properties of the membranes. In addition, the membrane surface became smoother and more hydrophilic. The membrane fabricated in 30 wt% glycerol bath exhibited outstanding comprehensive properties of retention and anti‐fouling, with a water flux of 243.5 L/(m2 h), a bovine serum albumin rejection of more than 90%, and a flux recovery rate of 97%. From mechanism analysis, the addition of ethanol, glycerol, or NaCl to the coagulation bath altered the thermodynamic stability of the polymer system, and slowed down the rate of solvent and nonsolvent diffusion from a kinetic perspective. This research provides important clues for optimizing the membrane properties, such as flux, rejection, and strength.

A novel polyethersulfone ultrafiltration membrane with enhanced permeability and antifouling ability via melamine-modified metal-organic framework

The trade-off between permeability and selectivity, as well as membrane fouling remains a major challenge in membrane application, impacting the performance and lifespan. Herein, a novel approach has been proposed, involving the incorporation of melamine-modified Metal-Organic Frameworks (MOFs) into Polyethersulfone (PES) ultrafiltration membranes. The modified MOFs exhibit stable anchoring to the membrane surface through hydrogen bonding, forming a hydration layer that enhances resistance to foulants. Moreover, the MOF framework channels facilitate water transport via providing additional pathways. The optimized melamine-MOF modified membranes achieve a permeability of 50 L/m2.h and a 97.8 % bovine serum albumin (BSA) rejection. The antifouling experiment demonstrates an 87 % fouling recovery ratio (FRR) for the modified membrane. A computational study has been conducted to investigate the interaction between UiO-66 and melamine using molecular dynamics (MD) simulations. The simulations validated the formation of hydrogen bonds and confirmed previous findings. Overall, the melamine-modified MOF exhibits high permeability and antifouling ability due to its excellent hydrophilic properties, which offer promising application prospects in wastewater reclamation.

Development and Study of Novel Ultrafiltration Membranes Based on Cellulose Acetate.

Recently, increasing attention of researchers in the field of membrane technology has been paid to the development of membranes based on biopolymers. One of the well-proven polymers for the development of porous membranes is cellulose acetate (CA). This paper is devoted to the study of the influence of different parameters on ultrafiltration CA membrane formation and their transport properties, such as the variation in coagulation bath temperature, membrane shrinkage (post-treatment at 80 °C), introduction to casting CA solution of polymers (polyethylene glycol (PEG), polysulfone (PS), and Pluronic F127 (PL)) and carbon nanoparticles (SWCNTs, MWCNTs, GO, and C60). The structural and physicochemical properties of developed membranes were studied by scanning electron and atomic force microscopies, Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy, and contact angle measurements. The transport properties of developed CA-based membranes were evaluated in ultrafiltration of bovine serum albumin (BSA), dextran 110 and PVP K-90. All developed membranes rejected 90% compounds with a molecular weight from ~270,000 g/mol. It was shown that the combination of modifications (addition of PEG, PS, PL, PS-PL, and 0.5 wt% C60) led to an increase in the fluxes and BSA rejection coefficients with slight decrease in the flux recovery ratio. These changes were due to an increased macrovoid number, formation of a more open porous structure and/or thinner top selective, and decreased surface roughness and hydrophobization during C60 modification of blend membranes. Optimal transport properties were found for CA-PEG+C60 (the highest water-394 L/(m2h) and BSA-212 L/(m2h) fluxes) and CA-PS+C60 (maximal rejection coefficient of BSA-59%) membranes.

Zeolite-Based Poly(vinylidene fluoride) Ultrafiltration Membrane: Characterization and Molecular Weight Cut-Off Estimation with Support Vector Regression Modelling.

Zeolite serves as a promising additive for enhancing the hydrophilicity of polymeric membranes, yet its utilization for bolstering the mechanical strength of the membrane remains limited. In this study, poly(vinylidene fluoride) (PVDF) membranes were modified by incorporating various concentrations of zeolite (0.5-2 wt%) to improve not only their mechanical properties, but also other features for water filtration. Membranes with and without zeolite incorporation were fabricated via a dry-wet phase inversion technique, followed by the application of a series of characterization techniques in order to study their morphological structure, mechanical strength, and hydrophilicity. The membrane filtration performance for each membrane was evaluated based on pure water flux and Bovine Serum Albumin (BSA) rejection. Field-Emission Scanning Electron Microscopy (FESEM) images revealed a dense, microvoid-free structure across all of the PVDF membranes, contributing to a high pristine PVDF membrane tensile strength of 14 MPa. The addition of 0.5 wt% zeolite significantly improved the tensile strength up to 19.4 MPa. Additionally, the incorporation of 1 wt% zeolite into PVDF membrane yielded improvements in membrane hydrophilicity (contact angle of 67.84°), pure water flux (63.49% increase), and high BSA rejection (95.76%) compared to pristine PVDF membranes. To further improve the characterization of the zeolite-modified PVDF membranes, the Support Vector Regression (SVR) model was adopted to estimate the molecular weight cut off (MWCO) of the membranes. A coefficient of determination (R2) value of 0.855 was obtained, suggesting that the SVR model predicted the MWCO accurately. The findings of this study showed that the utilization of zeolite is promising in enhancing both the mechanical properties and separation performance of PVDF membranes for application in ultrafiltration processes.

Investigation of the effect of permeation and antifouling characteristics of hybrid poly(vinylidene fluoride) membranes tailored with ZIF‐67 metal–organic frameworks

AbstractHerein the ZIF‐67, a hydrophilic cobalt‐based zeolitic imidazolate framework is synthesized and incorporated with a poly(vinylidene fluoride) (PVDF) to fabricate hybrid ultrafiltration membranes by phase inversion method. The characteristics of PVDF/ZIF‐67 membranes are examined using different analytical techniques such as Fourier‐transform infrared spectroscopy, X‐ray diffractometer, scanning electron microscope, atomic force microscope, and contact angle analysis. The membrane performance is probed using pure water flux (PWF), bovine serum albumin (BSA), and humic acid (HA) rejection. The maximum water flux of 162.5 Lm2 h−1 with BSA and HA rejection of 97% and 98.2%, respectively, exhibited by 1.5 wt% ZIF‐67. The contact angle value is reduced from 83.5 to 58.6° indicating the increase in hydrophilic nature of PVDF membranes by the addition of ZIF‐67. The presence of ZIF‐67 in the PVDF membrane matrix showed outstanding anti‐bacterial properties against Escherichia coli and Staphylococcus aureus. Overall, the PVDF/ZIF‐67 ultrafiltration membranes demonstrate the potential for water treatment applications.

Preparation of novel zwitterionic polysulfone ultrafiltration membranes for the dual-enhanced antifouling and antibacterial properties by in-situ one pot crosslinking reaction

Zwitterionic polysulfone (PSf) ultrafiltration membranes were fabricated by non-solvent phase separation (NIPS) method. Herein, a casting solution at 45 °C was developed by using chloromethylated polysulfone (CMPSf), N, N-dimethylacetamide (DMAc) as a solvent, 4-amino-benzenesulfonic acid monosodium salt (ABS) as a cross-linking agent, and Na2CO3 as an acid binder. Simultaneously, the occurrence of the electrophilic substitution reaction between ABS and CMPSf caused the formation of ABS grafting CMPSf (CMPSf-g-ABS). After a specific reaction time, the casting solution was applied to cast membranes, which were subsequently submerged in coagulation bath. A zwitterionic ultrafiltration (ZUF) membrane was obtained using NIPS following the treatment of hydrochloric acid (HCl) solution (1 M mol). Because of the formation of cross-linked CMPSf-g-ABS, the results revealed that the casting solution's viscosity increased sharply from 425.4 mPa s at the initial stage (0 h) to 4810.8 mPa s (22 h). Interestingly, the morphology of the membranes with an asymmetric finger-like structure at 0 h gradually transformed to a gradient sponge-like structure after 22 h. Specifically, the ZUF membrane (M22-H) with the gel fraction of 72.1% procured after the reaction of 22 h demonstrated a low water contact angle (40.17°) and a high pure water permeance (420.4 L m−2 h−1 bar−1). The M22-H also exhibited a high flux recovery rate (FRR) (90.2%), bovine serum albumin (BSA) rejection (>95%), and Escherichia coli (E. coli) antibacterial rate (96.2%). The surface of the ZUF membrane with numerous zwitterionic groups enhances the hydration layer's energy (i region <16 nm) and creates a thick hydration layer (ii region >16 nm), causing a significant improvement in the antifouling performance. This research opens new avenues for preparing zwitterionic functional membranes.

Manufacturing supported loose-nanofiltration polymeric membranes with eco-friendly solvents on an R2R System

In this study, loose nanofiltration membranes made of polysulfone dissolved in co-solvents PolarClean and gamma-Valerolactone were prepared via slot die coating (SDC) on a roll-to-roll (R2R) system by directly coating them onto a support layer or free standing. A solution flow rate of 20 mL/min, substrate speed of 17.1 mm/s, and coating gap of 0.1 mm resulted in the formation of membranes without structural defects. Pre-wetting the support layer with dope solution minimized shrinkage of membrane layer thickness and improved interfacial adhesion. Membrane samples produced using SDC exhibited properties and performance consistent with bench-scale doctor blade extruded samples; pre-wetted and uncompressed samples (SDC-3) exhibited the highest rejection of bovine serum albumin (99.20% ± 1.31%) and along with adequate mean permeability during filtration (70.5 ± 8.33 LMH/bar). This study shows that combining sustainable materials development with SDC provides a holistic approach to membrane separations to bridge materials discovery and membrane formation.

Synthesis and characterization of enhanced polysulfone-based mixed matrix membranes containing ZSM-5 zeolite for protein and dye removal

In this paper, polysulfone (PSf)-based ultrafiltration (UF) mixed matrix membranes (MMMs) embedded with ZSM-5 zeolite nanoparticles were synthesized via the NIPS method. The membranes were characterized by FESEM, ATR-FTIR, AFM, and tensile analyses, along with contact angle, porosity, and mean pore size measurements. The FESEM images indicated that the addition of hydrophilic ZSM-5 nanoparticles has led to formation of more and larger finger-like macrovoids. Moreover, hydrophilicity and pure water flux (PWF) values were consequently augmented, which was also approved by water contact angle reduction. The maximum PWF was equal to 394.7 L m-2h−1 at 3 bar for the optimum MMM, containing 1 wt% ZSM-5 which is 125.4 % greater than the value for the bare membrane. In addition, filtration of the bovine serum albumin (BSA) protein and aqueous solutions of two organic dyes were carried out. The highest BSA flux value was obtained 217.9 L m-2h−1 for the optimum membrane, where the BSA rejection values were all greater than 98 %. Furthermore, the optimum MMM displayed the highest flux recovery ratio (FRR%) of 60.1 % as well as the dyes rejection values equal to 95.5 % and 74.1 % for reactive black 5 (RB 5) and reactive yellow 160 (RY 160), respectively, representing its great potential to be applied in various wastewater treatment applications.

Study on preparation and properties of polyacrylonitrile/jute microcrystalline cellulose ultrafiltration membranes

AbstractPolyacrylonitrile (PAN) is widely used in the preparation of ultrafiltration membranes. However, the hydrophilicity, thermal, and mechanical properties of the PAN ultrafiltration membrane are poor, limiting the applications in water treatment technology. In this study, the hydrophilic jute microcrystalline cellulose (MCC) is utilized as the modifier for the PAN membrane aiming to develop the ultrafiltration membrane with improved performance. The PAN/jute MCC ultrafiltration membranes with varying jute MCC contents are prepared using the phase inversion method and their structure and properties are systematically characterized. The results demonstrate that the hydrophilicity and thermal stability of the PAN membrane are enhanced. Under optimal conditions, compared with pure PAN membrane, the tensile strength and elongation at break of the membrane increase by 22.64% and 9.84%, respectively, and the water flux can reach 88 L/(m2 h), with the bovine serum albumin rejection ratio of 85%. The above results support that jute MCC can improve the performance of the PAN membrane significantly.

Porous organic polymer nanosheets doped multistage water channel ultrafiltration membrane: Accelerated phase inversion process and in-situ covalent crosslinking strategy

Mixed matrix membranes (MMMs) have attracted significant interest in the field of water treatment owing to their capability to integrate the scalability and processability of polymers with the selectivity of fillers. Despite the numerous advantages demonstrated by emerging nanofillers, currently developed MMMs are still limited by such as insufficient hydrophilicity, susceptibility to additive loss, and poor filler compatibility.To address these challenges, we developed a series of polyethersulfone (PES)-based MMMs featuring a hydrophilic surface and multistage water transport channels, thereby minimizing additive loss, and enhancing efficiency in water treatment processes. Through interfacial azo-coupling polymerization, we synthesized a series of hydrophilic and porous two-dimensional sulfonic acid-functionalized porous organic polymer nanosheets (NS-sPOPs) to be used as additives in the MMMs. Owing to the exceptional hydrophilicity and favorable dispersibility of NS-sPOPs in water, the nanosheets influenced phase inversion through an accelerated phase separation process, resulting in the formation of multistage channels. Polyphosphoric acid (PPA) was used for the post-crosslinking treatment of the PES/NS-sPOP membrane. Consequently, the NS-sPOPs were immobilized within the polymer matrix to ensure stable performance in subsequent use. The prepared PES/NS-sPOP membrane exhibited outstanding water permeability (pure water flux) of 493 L·m−2·h−1·bar−1, and a high bovine serum albumin rejection rate of 99.3 %. Furthermore, it exhibits consistent performance throughout a 48 h long-term stability test. Overall, the blending and crosslinking strategy of hydrophilic nanofillers enables the realization of superhydrophilic 2D nanosheet-doped multistage-water-channel MMMs with exceptional permeability and high selectivity for water purification and organic pollutant removal.

Bovine Serum Albumin Rejection by an Open Ultrafiltration Membrane: Characterization and Modeling.

The classic application of ultrafiltration (UF) is for the complete retention of proteins, and in that situation, the transport behavior is well established. More open membranes with fractional retention are used when separating different proteins. However, protein transport has not been well documented yet in the literature. The bovine serum albumin (∼69 kDa) observed rejection ranges from 0.65 to 1 using a 300 kDa molecular weight cut-off membrane at different pH, ionic strength, and pressure. We demonstrated that, especially with open UF, the transport of proteins through the membrane is dominated by advection, with insignificant diffusion effects (p value > 0.05). We showed that with open UF, retention is not only caused by size exclusion but also to a large extent by electrostatic interactions and oligomerization of the proteins. Mass transfer in the polarization layer was relatively independent of the pH and ionic strength. It was underestimated by common Sherwood relations due to a relatively large contribution of the reduction in the flow turbulence near the membrane by the removal of fluid through the membrane. We propose a model that allows relatively quick characterization of the rejection of proteins without prior knowledge of the pore sizes and charges based on just a limited set of experiments. Therefore, protein rejection with the open UF system can be targeted by tuning the processing conditions, which might be useful for designing protein fractionation processes.