Congo Red Rejection Research Articles

SWCNTs-channeled MOF nanosheet membrane for high-efficient organic solvent nanofiltration

Organic solvent nanofiltration (OSN) has become increasingly important in petrochemical and pharmaceutical industries, demanding superior and robust membranes. 2D MOF nanosheets hold great promise in the preparation of OSN membrane. Nevertheless, the fabrication of defect-free 2D MOF membranes with robust mechanical strength is hampered due to the weak interlamellar interactions between MOF nanosheets. Herein, 2D MOF composite membrane for high-performance OSN application is fabricated through the assembly of copper 1,4-benzene dicarboxylate (CuBDC) nanosheets and NH2-SWCNTs. Within this composite configuration, NH2-SWCNTs can shelter the defects between the adjacent CuBDC nanosheets, rendering CuBDC/CNTs composite membranes precise molecular sieving ability. Meanwhile, the nanochannels created by NH2-SWCNTs with low frictional coefficients on the internal surface promote the permeation of organic solvents. Moreover, the multiple interactions between CuBDC and NH2-SWCNTs improve the mechanical strength of composite membranes. Accordingly, the composite membranes display excellent rejections of dye molecules on the basis of size-sieving mechanism with superior methanol permeance of 1260 L m−2h−1 bar−1, as well as steady congo red rejection at high trans-membrane pressure of 5 bar, demonstrating good pressure resistance of composite membranes. Moreover, the composite membranes exhibit outstanding stability against high-concentration feeds and long-term operation for 50 h, confirming excellent practicality in the purification of dyes from organic solvents. The design approach in this work may inspire the fabrication of other nanosheet-based membranes for high-efficient OSN.

Facile and sustainable fabrication of carbon membranes through mechanical rubbing for efficient nanofiltration

Although having shown great promise in gas separation, reverse osmosis, and nanofiltration, preparation of carbon membranes, which commonly involves elaborate high-temperature pyrolysis or exfoliation-reassembly, still suffers from complicated fabrication procedure and/or high production cost. In this study, we pioneered the preparation of continuous asymmetric carbon membrane through facile mechanical rubbing of a pencil graphite. Among them, 2B-type pencil with 64 wt% graphite exhibited superior nanofiltration performance (Congo Red rejection rate of 99.4% and water flux of 21.91 L·m−2·h−1·bar−1). Long-time operation confirmed its excellent stability. Of particular note, the spent membrane could be facilely recovered by erasing, resulting in not only zero pollutant discharge but also full recovery and reutilization of the substrate. The above protocol is anticipated to pave an avenue for facile and sustainable production of versatile carbon membranes with superior separation performances.

High permeance nanofiltration membrane for harsh organic solvent based on spiral-ring polyesters

Currently, many polymeric membranes are poorly tolerated in harsh (strong polar aprotic) solvents like dimethylformamide (DMF) and N-methylpyrrolidone (NMP) and are not applicable to organic solvent nanofiltration (OSN). In this study, we combined the oxidized poly (arylene sulfide sulfone) (OPASS) supports with excellent organic solvent resistance and the spiral-ring polyester interfacial polymerization (IP) layer together to fabricate ultra-resistant and high permeance membranes for OSN. The tetramethyl-1,1′-spirobisindane-6,6′diol (SBI), a contorted diphenol monomer with a spiral-ring structure, was preferentially selected from six types of polyphenols based on molecular simulations and experimental results. It was conducted to react with trimesoyl chloride (TMC) via interfacial polymerization to yield a polyester separation layer of thin film composites (TFC). Investigating the different alkali ratios and types revealed that the alkali added in the aqueous phase to improve the solubility of the SBI could cause hydrolysis of the polyester layer generated by IP, which led to increased membrane permeance and reduced rejection, and the more alkali and the stronger the alkali used, the more severe the hydrolysis. Besides, DMF activation treatment to the TFC membrane improved the ethanol permeance by at least four times while maintaining high congo red rejection. As a result, combining the effects of alkali and DMF activation, the representative TFC membranes fabricated in our work exhibited excellent permeance of 21.5±1.3, 9.0±1.1 L m−2 h−1 bar−1 for DMF and NMP, respectively, and high rejection rates (≥ 93%) for congo red (Mw 696.7 Da), higher than the earlier reports. This research presents a new and straightforward approach to developing TFC membranes with high-efficiency filtration capabilities, suitable for harsh organic solvent separation applications.

MXene/ZIF-L co-stacking membranes with high water permeation for solute-tailored selectivity

Herein, we design a composite MXene membrane with high permeability and stability by introducing highly porous two-dimensional ZIF (zeolitic imidazolate framework)-L sheets. On the one hand, the ZIF-L sheets provide additional nanochannels in the vertical direction, which shorten and enrich the mass transport pathways of the MXene membrane. On the other hand, a moderate increase in interlayer spacing of Ti3C2TX nanosheets is detected after introducing ZIF-L. Additionally, the Ti-O-Zn/Ti-F-Zn chemical bonds between Ti3C2Tx and ZIF-L nanosheets provide structural stability to the composite membrane. When applied in nanofiltration, the optimal co-stacking membrane with a ZIF-L mass fraction of 9.10 % exhibits an ultrahigh pure water flux of 287.29 L m-2h−1 bar−1, which is ∼ 2.41 times higher than the pristine MXene membrane (124.98 L m-2h−1 bar−1). Meanwhile, the composite MXene/ZIF-L membrane shows an excellent dye/salt separation efficiency, as indicated by the high Congo Red rejection (99.2 %) and the low MgCl2 rejection (1.58 %) in a mixing dye/salt system. This work provides a promising strategy for constructing a two-dimensional membrane with high permeation for dye/salt separation.

Preparation of novel (MgCoNiCuZn)O high-entropy ceramic membrane and its dye separation

(MgCoNiCuZn)O high entropy ceramic (HEC) membrane was prepared successfully by phase inversion and calcination, and was used to remove Congo red. Raman spectra and XRD measurements showed complete transformation to single rock salt phase, and EDS exhibited uniform distribution of five metals. The hydrophilicity of HEC membrane became weak due to low free energy which was attributed to the high configuration entropy. The porosity of HEC membrane decreased and densification took place as the temperature enhanced, yielding the increase of bending strength. When the HEC membrane was calcined at 1040 ℃, the pure water flux and Congo red rejection reached 881.5 L/(m2·h) and 99.35%, respectively. The HEC membrane exhibited good long-term stability. When continuous filtration was performed for 10 h, the pure water flux ranged from 857.5 to 879 L/(m2·h), while Congo red rejection changed from 98.85% to 99.32%. The HEC membrane showed good chemical stability under weakly acidic and strong alkaline conditions.

Recycling the High-Salinity Textile Wastewater by Quercetin-Based Nanofiltration Membranes with Minimal Water and Energy Consumption.

Effective recovery of dyes and salts from textile wastewater by nanofiltration (NF) remains a serious challenge due to the high consumption of water and energy caused by the limited performance of the available membranes. Herein, a novel strategy is described to prepare loose polyester NF membranes by using renewable quercetin as the aqueous monomer for fractionation of high salinity textile wastewater with minimal water and energy consumption. Compared with NF270, taken as the reference membrane, the QE-0.2/TMC-0.2 membrane significantly improved the efficiency for dye/salt fractionation by 288%. The water consumption was also decreased by 42.9%. The efficiency is attributed to an ultrahigh water permeance of 198 ± 2.1 L-1 m-2 h-1 bar-1 with a high selectivity of 123 (extremely low NaCl rejection of 1.6% and high Congo red rejection of 99.2%). The optimal quercetin-based membrane had an ultrathin separation layer of about 39 ± 1.2 nm with good hydrophilicity and negative charge density. Moreover, this work includes a novel method of comparison with a theoretically ideal membrane, which shows that both the energy and water consumption are near their theoretical minimum. This strategy is expected to save energy and minimize carbon emissions for membrane-based wastewater treatment systems.

Pore structure design and optimization of electrospun PMIA nanofiber membrane

BackgroundPoly (m-phenylene isophthalamide) (PMIA) has been widely used in many applications due to its excellent thermal stability, flame resistance and mechanical properties. MethodsIn this study, PMIA nanofiber membranes were fabricated by electrospinning method, and then, the solvent welding was used to optimize the pore structure and mechanical strength. Effects of solvent concentration (volume fraction of solvent) and welding temperature on the PMIA nanofiber membranes’ morphology, pore structure and mechanical properties were investigated, respectively. Significant findingsThe mechanical strength and pore size was simply controlled by solvent welding and heat pressing. And the process of solvent welding and heat pressing was classifiable regulation. In addition, the separation accuracy of nanofiber membrane was controllable in the range of ultrafiltration. The mechanical strength of PMIA nanofiber membrane raised from 5.5 MPa to 99.0 MPa, while the mean pore size decreased from 459.1 nm to 33.6 nm after post-treatment. The Congo red rejection rate of PMIA nanofiber membrane after heat pressing increased from 4.9% to 94.7%, which showed excellent ultrafiltration performance.

ZIF-8 modified poly (m-phenylene isophthalamide) (PMIA) hybrid membrane for dye wastewater treatment

The separation of dye/salt through the separation membranes is a great significance for the treatment of dye wastewater. In this study, a novel PMIA hybrid membrane was fabricated via nonsolvent induce phase separation (NIPS) method, in which porous zinc imidazolate framework-8 (ZIF-8) was utilized as a filler. The effect of ZIF-8 content on the structure and performance of PMIA/ZIF-8 membrane was investigated. The results showed that the structure and performance of the PMIA/ZIF-8 membrane could be controlled by changing the content of ZIF-8. The proper content of ZIF-8 was 0.45 wt% in this study. To further enhance the water flux of PMIA/ZIF-8 membrane, the concept of creating nanovoids within the ZIF-8 nanoparticle via wet-chemical etching method was explored in this study. The additional pore of ZIF-8 nanoparticles after wet-chemical etched endows PMIA/ZIF-8 membrane with additional pathways for water molecules. Hence, the PMIA/ZIF-8 membrane after wet-chemical etching showed higher separation performance for dye wastewater. The optimized PMIA/ZIF-8 membrane showed a water permeance of 104.7 L·m−2·h−1 and Congo red rejection of 98% at 0.1 MPa. The water permeance was about 1.5 times than that of the pristine PMIA/ZIF-8 membrane while the Congo red rejection was well maintained. Moreover, the PMIA/ZIF-8 membrane showed good thermal stability during the filtration process. These results indicated that PMIA/ZIF-8 membrane has potential application in dye wastewater treatment.

In-situ fabricated covalent organic frameworks-polyamide hybrid membrane for highly efficient molecular separation

Covalent organic frameworks (COFs) membranes fabricated via interfacial polymerization typically present high permeance but relatively low selectivity for small molecules. To address this issue, COFs-polyamide hybrid membranes were in-situ fabricated onto polyacrylonitrile (PAN) substrate via interfacial polymerization for highly efficient molecular separation. Specifically, P-phenylenediamine (Pa) or benzidine (BD) as the aqueous monomer was reacted with a mixture of 2,4,6-trihydroxybenzene-1,3,5-tricarbaldehyde (Tp) and trimesoyl chloride (TMC) to generate COFs-polyamide hybrid structure, comprising the imide-linked COFs and the amide-linked polyamide. Since the TMC could react with the residual unreacted amine groups after COFs formation, the COFs-polyamide hybrid structure exhibited few defects and excellent stability. The as-prepared TpPaTMC/PAN or TpBDTMC/PAN hybrid membranes presented excellent performance for dye rejection and dye desalination with pure water permeances of 84∼95 L·m-2·h-1·bar-1, congo red rejection of ∼99%, acid red 66 rejection of 85%∼92%, and Na2SO4/CR separation factor of 65∼86. Moreover, the separation performance of COFs-polyamide hybrid membranes could be easily tunable by adjusting the TMC contents in the organic phase during the membrane fabrication, and the optimized membranes could be applied for dye rejection or dye desalination. The COFs-polyamide hybrid membranes also showed excellent anti-fouling performance and chemical stability. Therefore, the convenient and efficient in-situ fabrication of high-performance COFs-polyamide hybrid membrane would provide novel insight into the structure, property and application prospects of COFs membrane.

Engineering hierarchical nanochannels in graphene oxide membranes by etching and polydopamine intercalation for highly efficient dye recovery

• Chemical etching of GO generates nanopores and increases water permeance. • Polydopamine (PDA) cross-links GO nanosheets and stabilizes GO membranes. • Integrating GO etching and PDA intercalation improves dye desalination performance. • PDA/HGO exhibits superior water and salt permeance and dye/salt selectivity. Graphene oxide (GO) membranes have been extensively investigated for dye removal from wastewater, and they are often reduced or cross-linked to improve their stability, which, however, decreases water permeance. This study demonstrates an effective approach to enhance both durability and water permeance and retain dye rejection by synergistically integrating chemical etching using H 2 O 2 and intercalation with polydopamine (PDA) to create hierarchical nanochannels. The nanopores on the holey GO (HGO) shorten the diffusion path, while the PDA intercalation increases the channel sizes and stabilizes the GO nanosheets. Optimized membranes exhibit water permeance of 70–120 LMH/bar (much higher than state-of-the-art commercial polyamide membranes) and a Congo Red rejection of 98.5%, better than GO membranes reported in the literature. Moreover, a membrane with water permeance of 70 LMH/bar exhibits stable performance in a 3-day continuous crossflow filtration test. The versatile approach reported here may be applied to other two-dimensional materials to create hierarchical nanochannels for desired separations.

Ultrathin and high-performance covalent organic frameworks composite membranes generated by oligomer triggered interfacial polymerization

The practical application of covalent organic frameworks (COFs) membrane still faces major challenges emanated from harsh fabrication condition, non-uniform performance and high production cost. To address these issues, oligomer triggered interfacial polymerization (OT-IP) was proposed to fabricate COFs/PSf composite membranes, in which two reactive monomers having extremely low concentration (0.6 mM) were in advance pre-mixed in n-hexane to generate oligomers with planar structure, which was then subsequently grew under the catalysis of acetic acid to form an ultrathin and continuous COFs layer. The as-prepared TpPa/PSf (OT-IP), TpBd/PSf (OT-IP) and TpDp/PSf (OT-IP) composite membranes exhibited superior permeability of 52–85 L·m−2·h−1·bar−1 and congo red rejection of 93–99%, precisely in consistent with the pore sizes of COFs. The OT-IP technique would not only inspire the fabrication of COFs/PSf composite membranes with a greater variety but also make their scale-up and application feasible and economical.

Engineering of macroscale graphene oxide quantum dots skeleton membrane via electrostatic spraying method

In order to construct an efficient separation channel of graphene oxide quantum dots (GOQDs) membrane, a novel macroscale GOQDs skeleton membrane with the ethylenediamine (EDA) as the bridging agent was prepared for the first time by uniformly covering GOQDs nanosheets (∼2.78 nm) and EDA on the surface of the substrate membrane via electrostatic spraying method. The structure of the membrane was further optimized by post-crosslinking with trimesoyl chloride (TMC), and obtained the c-GOQDs skeleton membrane. The effects of spraying time and post-crosslinking on the structure and properties of as-prepared membranes were studied. The results showed that the obtained macroscale GOQDs skeleton membrane exhibited excellent separation effect for salt and dye. The introduction of EDA reconstructed the structure of the GOQDs skeleton separation layer, which made the separation layer structure loose and contributed to accelerating the water transmission speed. Thus, the permeation flux of GOQDs skeleton membrane (M-2, 155.6 L m−2 h−1, 3 bar) with similar dye rejection and lower bivalent salt rejection, was near 5 times than that of pure GOQDs membrane. Moreover, post-crosslinking could further improve the Congo Red rejection of c-GOQDs skeleton membrane (99.5%) with the higher salt/dye selectivity, which also showed high long-term operation stability and presented a potential application in dye desalination field.

Comprehensive Analysis of Spinel-Type Mixed Metal Oxide-Functionalized Polysulfone Membranes toward Fouling Resistance and Dye and Natural Organic Matter Removal.

Nanostructured polymeric membranes are of great importance in enhancing the antifouling properties during water filtration. Nanomaterials with tunable size, morphology and composition, surface modification, and increased functionality provide considerable opportunities for effective wastewater treatment. Thus, in this work, an attempt has been made to use spinel-structured MnCo2O4 as a nanofiller in the fabrication of nanostructured polysulfone (PSF) mixed matrix membranes and is investigated in terms of morphology, hydrophilicity, permeability, protein and natural organic matter separation, dye removal, and, finally, antifouling properties. The MnCo2O4 nanomaterials are synthesized and characterized via X-ray diffraction and field emission scanning electron microscopy and are loaded into a membrane matrix with varied concentrations (0 to 1.5 wt %). PSF nanocomposite membranes are prepared via a nonsolvent-induced phase-separation process. The results show an enhancement in hydrophilicity, porosity, and permeability with respect to the modified nanocomposite membranes because of oxygen-rich species in the membrane matrix, which increases affinity toward water. It was also found that the modified membranes display remarkably greater pure water flux (PWF) (220 L/m2 h), higher Congo red rejection coefficient (99.86%), higher humic acid removal (99.81%), higher fouling resistance, and a significant flux recovery ratio (FRR) (88%) when tested with bovine serum albumin protein when compared to a bare PSF membrane (30 L/m2 h PWF and 35% FRR). This is because the addition of MnCo2O4 nanoparticles into the polymeric casting solution yielded tighter PSF membranes with a denser skin layer and greater selectivity. Thus, the enhanced permeability, greater rejection coefficient, and antifouling properties show the promising potential of the fabricated PSF-spinel nanostructured membrane to be utilized in membrane technology for wastewater treatment.

Large-pore covalent organic frameworks for ultra-fast tight ultrafiltration (TUF)

Tight ultrafiltration (TUF) membranes featuring specific pore sizes are increasingly developed to bridge the gap between nanofiltration and ultrafiltration. So far, a wealth of efforts has been devoted to tackle the limitation found in TUF, but there still lacks a facile accessibility to upgrade TUF membranes with simultaneously improved permeance and selectivity. Herein, we report a large-pore covalent organic framework (LP-COF) as the building material to prepare ultra-permeable TUF membranes for fast separations. The LP-COF layers with an exceptionally large aperture size of up to ~3.6 nm are synthesized on macroporous substrates through a unidirectional diffusion method. The resultant LP-COF layers show a moderate crystallinity and low thickness down to ~60 nm, and allow ultrafast water permeation. Surprisingly, the optimal LP-COF membrane exhibits an unprecedented water permeance of ~3147 L m−2 h−1 MPa−1 with a high Congo red rejection (~92.6%), which is basically unchanged after several cycles of filtration. Moreover, the large-pore channels enable an unimpeded pass of ions, thus affording the membrane an excellent dye/salt separation competence, and largely exceeding state-of-the-art membranes. Therefore, this work opens up a new opportunity in producing high-performance TUF membranes by large-pore COFs for rapid and precise separations.

Highly permeable carbon nanotubes/polyamide layered membranes for molecular sieving

Traditional nanofiltration membranes (NFMs) formed by interfacial polymerization (IP) present relatively low water permeance due to the limitation of polymer-based supports. This work reports high-performance carbon nanotubes-polyamide (CNTs-PA) NFMs with interlayer and functional layer covalently coupled. These membranes feature an interpenetrating network structure, which leads to an extremely high Congo red rejection of 99.47%. The water permeance of the optimal membrane (48.98 L m-2h−1 bar−1) is much higher than most membranes with similar Congo red rejection. Meanwhile, the obtained membranes show an excellent selectivity to NaCl/dye mixed solution (the selectivity of NaCl/CR is 150.32). Moreover, this work comprehensively demonstrates the aggregation kinetics of dye molecules under different pH environments, which strongly affects the dye rejection of the CNTs-PA membrane. The membrane exhibits a switchable CR release property that the CR rejection is severely disabled (2.12%) under a strong alkaline environment and immediately re-effective (99.38%) after neutralization. Building on these findings, our work expands the possibilities of NFMs in ultrafast molecular sieving and pH-responsive separation.

Covalent organic framework membranes with limited channels filling through in-situ grown polyaniline for efficient dye nanofiltration

Due to the high porosity and ordered channels, covalent organic framework (COF) membranes with ultrathin selective layer and high permeance have gained increasing attention in the field of nanofiltration (NF). However, it remains a challenge to fabricate ultrathin and dense COF NF membranes with both high permeance and high rejection. This work presents a facile and efficient method to fabricate COF membrane with limited channel filling through in-situ growth of polyaniline (PANI) layer. Specifically, interfacial polymerized COF-TpPa membrane was fabricated with ~ 1.8 nm pore channel, and then the in-situ grown PANI layer could fill the partial of channels and reduce the effective pore size of COF-TpPa. The obtained PANI-TpPa composite membrane exhibited excellent performance with pure water permeance up to 85.2 L·m−2·h−1·bar−1, congo red rejection above 99.4%, and acid fuchsin rejection above 81.0%. The whole membrane fabrication just cost 3 h and took place at room temperature, which was much more efficient than other membranes with similar performance. Besides, the PANI-TpPa composite membrane showed excellent stability in acidic environment and organic solvent, and maintained great performance in long-term test.

Oligomer-Induced Ultrathin Covalent Organic Frameworks Composite Membranes Generated by Catalysis-Interfacial Polymerization

The practical application of covalent organic frameworks (COFs) membrane still faces major challenges emanated from harsh fabrication condition, non-uniform performance and high production cost. To address these issues, catalysis-interfacial polymerization (catal.IP) was proposed to fabricate oligomer-induced COFs composite membranes , in which two reactive monomers having extremely low concentration (0.6 mM) were in advance pre-reacted to generate oligomers with planar structure and then subsequently grew under the catalysis of acetic acid to form an ultrathin and continuous COFs layer. The as-prepared TpPa (catal.IP), TpBd (catal.IP) and TpDp (catal.IP) membranes exhibited superior permeability of 52~85 L·m-2·h-1·bar-1 and congo red rejection of 93~99%, precisely in consistent with the pore sizes of COFs. The catal.IP technique would not only inspire the fabrication of COFs composite membranes with a greater variety but also make their scale-up and application feasible and economical.

Fine-tuning the architecture of loose nanofiltration membrane for improved water flux, dye rejection and dye/salt selective separation

Herein, loose nanofiltration membranes were prepared using non-solvent induced phase separation (NIPS) method. In NIPS, the non-solvent controls the morphology of the skin layer of the asymmetric membranes formed, while the solvent tunes the morphology of the lower layer. The membranes were made from polyethersulfone in n-methyl pyrrolidone (NMP) with the addition of dicarboxylic acids (glutaric acid, azelaic acid). Aliphatic alcohols (1-butanol, 1-octanol) were added to the solvent to tailor the skin layer pore morphology. Cross-sectional electron microscope images revealed the acids created nano-voids and shorter micro-voids. The addition of alcohols extended the micro-voids and improved symmetry. Pore size distribution results showed that the addition of the alcohols did indeed reduce the pore size as hypothesised. The performance of the modified polyethersulfone membranes was greatly improved in terms of pure water flux and salt passage without sacrificing the dye rejection. The loose nanofiltration membranes prepared in this study showed good dye/salt separation capability compared to most of the results reported in literature. The membranes were compacted with de-ionised water at an applied pressure of 4 bar for 5 h and rejections tests were done at 2 bar. It is hereby reported that the membranes achieved a high salt passage (Na2SO4 rejection varying between <3% and ~12%), as well as sustainable high Congo red rejection of 97%.

Fabrication of thin-film composite nanofiltration membranes with improved performance using β-cyclodextrin as monomer for efficient separation of dye/salt mixtures

Complete separation of dye/salt mixtures through nanofiltration (NF) membranes is of great significance for the sustainable development of salt-containing dye wastewater treatment. Herein, a novel hydrophilic thin-film composite NF membrane was fabricated using β-cyclodextrin (β-CD) and trimesoyl chloride (TMC) via interfacial polymerization on a commercial ultrafiltration membrane. The performance of the resultant β-CD/TMC membranes was optimized by altering the variables. The results showed that the optimized β-CD4.0/TMC membrane (4.0 wt% β-CD, 0.2 wt% TMC, and 0.5 mol L-1 NaOH) possessed a pure water flux of 207.8 L m-2h−1 at 2.0 bar. Meanwhile, the membrane exhibited efficient dye/salt separation with high rejection of dyes (e.g. 100.0% for congo red and 99.1% for rose bengal) and low salt rejection (e.g. 8.5% for NaCl). Congo red/NaCl mixtures achieved similar removal rates to those of dye or salt solutions (the congo red rejection over 99.0% and the rejection of NaCl was below 10.6%). Furthermore, the membrane showed desirable stability, the flux remained at 82.9% of the initial value after filtration for 16 h. We believe that the fabricated NF membrane has a great potential for application in the treatment of salt-containing dye wastewater with improved selectivity for dye/salt separation.

Development of iron oxide decorated graphene oxide (Fe3O4/GO) PSf mixed-matrix membrane for enhanced antifouling behavior

Water pollution is a severe issue to the environment globally. The removal of the pollutant from the water sources are unavoidable and it can be achieved through new generation types of membrane, generally known as mixed-matrix membrane (MMM). However, the stability of single nanomaterials in mixed-matrix membrane remains as a major obstacle to obtain a stable membrane performance. Hence, the goal of the study is to investigate the effect of nanohybrid towards the enhancement of MMM followed by optimizing nanohybrid concentration that required to produce the desire membrane. First, graphene oxide (GO) and iron oxide decorated graphene oxide nanohybrid (Fe3O4/GO) were synthesized using modified Hummer’s method and co-precipitation in the presence of GO prior to the incorporation into polysulfone (PSf) matrix while the membranes were fabricated via phase inversion method. The optimal membrane, M5-0.6 (0.6 wt% Fe3O4/GO nanohybrid concentration) showed that, the hydrophilicity of the modified membrane increased by 11.42 % from 78.8° to 69.8° attributed to the presence of hydrophilic nanohybrid that favor the transport water molecules across the membrane. Associated with this, M5-0.6 membrane showed better permeation flux of 87.01 L/m2.h and Congo red rejection of 98 % as compared to neat membrane at 51.82 L/m2.h and 87 %. Additionally, the M5-0.6 membrane also experience better antifouling properties at high flux recovery ratio (FRR) of 95 % while the neat membrane showed lower FRR of 87 %. Besides, M5-0.6 membrane also showed better stability as indicated by the lower flux decline at 23 % as compare to neat membrane at 41 %.