Flux Recovery Ratio Research Articles

Algal biochar of unique structure as a robust alternative to manipulate mixed-matrix membranes performance and fouling resistance

A new application has been introduced for Cladophora glomerata, the most abundant and one of the most harmful filamentous algae widely distributed in fresh waters. Biochar of unique filter-like structure was synthesized through the pyrolysis of C. glomerata and after being fully characterized, was incorporated for the first time in the structure of mixed matrix membranes to manipulate the dominant characteristics of the membranes. At different amounts, the biochar was incorporated in polyethersulfone to prepare the novel biochar-amended mixed matrix membranes. The permeate water flux, antifouling, flux recovery ratio, and the salt and dye rejections were assessed for the bare and biochar-amended membranes to verify the effect of biochar on membrane performance. It has been shown that, the higher the amount of biochar, the lower the contact angle and the more the hydrophilicity of the membrane surface. The mean pore radius and porosity of the modified membranes were significantly increased compared to that of the bare PES membrane, and consequently, pure water fluxes were increased by more than 63% in biochar-amended membranes. Based on the obtained results, 0.5 wt% was determined as the optimum amount of biochar leading to the best biochar-amended mix matrix membrane performance.

Modified-graphene quantum dot thin-film nanocomposite membrane for enhanced nanofiltration performance and antifouling properties: Minimal incorporation

Nitrogen-doped graphene quantum dot (NGQD) with both oxygen-containing and amine functional groups was employed in this work to enhance the surface chemistry of thin film nanocomposite (TFN) membrane and cross-linking degree of polyamide (PA) layer for real wastewater treatment. The incorporation of NGQD has enhanced the hydrophilicity of all TFN membranes, as reflected by the decreased water contact angle (WCA) from 44.5 to 31.1°. Besides, the incorporation of NGQD interfered the interfacial polymerization (IP) reaction, and at the same time affected the surface tension between aqueous and organic phase, which caused the formation of thinner and rougher PA. The increase in hydrophilicity and surface roughness resulted in 17.5–65.5 % improvement of water permeability for TFN membrane which was attributed to the encouragement of water molecules attachment and transportation by incorporating hydrophilic NGQD. The membrane incorporated with minimal concentration (0.01 wt%) of NGQD (TFN2) has shown the optimum results. The TFN membranes fabricated displayed enhanced divalent salt (Na2SO4) rejection at above 95 %, especially TFN2 has shown 3.4 % higher rejection than unmodified thin film composite (TFC) membrane. For humic acid (HA) and congo red (CR) antifouling test, the flux recovery ratio (FRR) was improved by 3–14.4 %, while flux decline rate (FDR) was reduced by 5.4–22.1 % even after 3 cycles of filtration (FRR3). For real wastewater, aerobically-treated palm oil mill effluent (AT-POME) antifouling test, TFN2 has achieved the highest FRR3 at 75 % compared to TFC and commercial NF2001. With minimal incorporation of NGQD, antifouling properties were enhanced due to the increase of PA cross-linking degree and surface negativity by both its amine groups and oxygen-containing functional groups that repel and prevent the deposition of pollutants on the membrane surface.

Methylene blue rejection and antifouling properties of different carbonaceous additives-based polyvinylidene fluoride membrane

In the present study, various polyvinylidene fluoride (PVDF)-based membranes were successfully fabricated via non-solvent induced phase separation (NIPS) method utilising different carbon-based materials as additive. The incorporation of reduced graphene oxide (rGO), multi-walled carbon nanotubes (MWCNTs) and GO-MWCNTs hybrid along with titanium dioxide (TiO2) definitely affect the fabricated membrane’s morphology, hydrophilicity, porosity, filtration performance and antifouling properties. Based on dead-end filtration measurement, rGO-based PVDF/TiO2 membrane presented excellent pure water flux (2446.887 L/m2h) with membrane permeability of 1143.850 L/m2hMPa compared to other membranes. Furthermore, the inclusion of rGO and TiO2 also resulted in the highest methylene blue (MB) dye rejection rate (∼92%) compared to MWCNTs (62.22%) and GO-MWCNTs (86.69%). It was believed that steric hindrance effect played a major role in enhancing dye rejection performance of PVDF@rGO/TiO2 membrane. Interestingly, in terms of antifouling properties, PVDF@GO-MWCNTs/TiO2 possessed better antifouling properties as indicated by its higher flux recovery ratio (FRR) value of 95.30%. The existence of hydration layer on membrane surface endowed by oxygen-functional groups prevents the contaminant accumulation thus resulted high FRR value.

Green Synthesis of Polyvinylidene Fluoride using Xanthan Gum Biopolymer and Dimethyl Sulfoxide Green Solvent

The usage of conventional solvent during the membrane fabrication could cause undesirable negative impact to the environment. Associated with this, greener alternative to membrane synthesis has grab the attention of researchers globally. Therefore, this study explored on the green synthesis of polyvinylidene fluoride (PVDF) membrane by adopting the natural ingredient Xanthan Gum (XG) biopolymer together with green solvent dimethyl sulfoxide (DMSO) to form a new generation PVDF membrane. The membrane was prepared by phase inversion method with different XG concentration ranging from 0 wt% to 1.5 wt% while maintaining the constant PVDF and DMSO concentration. Several membrane performance tests were done which included water flux test, Congo red (CR) rejection, and flux recovery ratio (FRR). In this study, the incorporation of XG in membrane shown enhancement in membrane hydrophilicity with a noticeably reduction of wettability from 48.67o to 42.15o. The results shown that membrane embedded with 0.5 wt% XG appeared as the optimum XG concentration. As for the membrane performance, it achieved the pure water flux and FRR of 182.87 L/m2.h and 91.25%, respectively. According to the overall performance evaluation, the incorporation of XG promoted the performance of membrane.

Removal of Manganese Ion Using Integral Membrane Incorporated with Rice Husk Ash

Wastewater treatment is a method of ensuring that the water supply is clean and free from contaminants. Manganese is a pollutant that needs to be removed from the water as it is harmful and usually triggers concern about water quality and water distribution system issues. Besides the adsorption method, membrane technology is efficient due to its mild and environmentally friendly process. This research focused on the production of integral membranes from a blend of polyvinyl alcohol/chitosan/polysulfone/polyethylene glycol cross-linked with silica extracted from rice husk ash (RHA) by using the phase inversion method. The silica was incorporated into the membrane formulation through a sol-gel reaction. The goal of this research was to determine the potential utilization of silica from RHA in the membrane’s formulation to remove manganese ions from various concentrations of manganese solutions. The loadings of RHA were varied at 2, 3 and 5 % wt./wt. polymer. The formulated membranes were then characterized in terms of thermal stability by Thermogravimetric analysis, functional group by Fourier Transform Infrared Spectroscopy, and surface morphology by Scanning Electron Microscopy. The performances of the membranes were tested through filtration of manganese ions solutions and antifouling analysis. The results showed that all membranes including membranes from the polymer blend were able to remove more than 94 % manganese ions. However, the membrane incorporated with 2 % RHA portrayed the best performance in terms of obtaining the highest flux for both water and manganese as feed solution respectively, which also resulted in the highest relative flux recovery ratio at 62.50 % from the antifouling analysis. These findings have proven the successful incorporation of RHA in the form of silica powder, which shows the potential utilization of RHA in membrane fabrication.

Construction of antifouling zwitterionic coatings on polypropylene microporous membranes via N-hydroxyphthalimide(NHPI) catalysis

Developing polyolefin microporous membranes with good antifouling ability and high separation efficiency is an important and urgent work. Herein, polypropylene microporous membranes (PP (mm)) containing zwitterionic polymer was prepared by grafting poly (sulfobetaine methacrylate) (PSBMA) onto the membrane via N-hydroxyphthalimide(NHPI) catalysis and activators regenerated by electron transfer atom transfer radical polymerization (ARGET-ATRP) for the first time. The structure, morphology, hydrophilicity and antifouling ability of PP (mm)-g-PSBMA was systematically studied. Water contact angle of the modified membrane could be sharply reduced at a proper grafting degree (GD), and it exhibited extraordinary hydrophilicity. The PP (mm)-g-PSBMA membrane also showed excellent protein antifouling ability and higher water flux compared to that of pristine PP membrane. Flux recovery ratio (FRR) of PP (mm)-g-PSBMA was increased to 93.1 % and relative flux reduction ratio (RFR) was decreased to 25.3%. This work presents a controllable and high efficiency strategy to polyolefin separation membrane for high value products.

Single-Step Surface Hydrophilization on Ultrafiltration Membrane with Enhanced Antifouling Property for Pome Wastewater Treatment

High organic materials in palm oil mill effluent (POME) can result in serious water pollution. To date, biological treatment has been used to reduce the environmental risks of these effluents prior of their discharge into water streams. However, the effluents’ dark brownish colour remains as a significant issue that must be addressed, as it affects the overall quality of water. Although membrane technology has been frequently used to address these difficulties, membrane fouling has become a serious limitation in POME treatment. On the other hand, zwitterions with balanced charge groups have received growing interest in the fabrication of antifouling membranes due to their hydrated nature. The development of a simple and efficient covalent bonding technique to improve the stability of zwitterions on membrane surfaces remains a challenge. By grafting and co-depositing polyethylenimine (PEI)-based zwitterion (Z-PEI) with super hydrophilic polydopamine (PDA) on the surface of a commercial polysulfone (PSf) ultrafiltration membrane at ambient temperature, a new zwitterionic surface with a neutral surface charge was created (PDA/Z-PEI). This study aims to investigate the effect of different loading ratios of PDA/Z-PEI (1:1, 1:2, and 1:3) and evaluate their performance on treating brownish coloured anaerobically treated POME (AT-POME). SEM and FTIR analysis showed the successful incorporation of the PDA/Z-PEI membrane while the zwitterionic feature is indicated by zeta potential analysis. Water flux analysis demonstrated that a lower water flux was achieved for M-ZPEI membranes as compared to the PSf and PSf-MDPA membranes, attributed by the tight skin layer of PDA-ZPEI. In the development of a tight hydration layer on the membrane surface by zwitterions, zwitterionic membranes demonstrated excellent antifouling capabilities, particularly PDA/Z-PEI with a loading ratio of (1:2) with a flux recovery ratio of around 84% and colour rejection of 81.75%. Overall, this research contributes to the development of a unique coating with improved stability and antifouling properties by altering the membrane surface in a simple and reliable manner.

Fabrication of cellulose nanocrystal (CNC) from waste paper for developing antifouling and high-performance polyvinylidene fluoride (PVDF) membrane for water purification

Waste papers are used as a source of raw material to fabricate cellulose nanocrystals (CNCs), a highly valued product with a high degree of crystallinity. Rod-shaped CNCs with an average diameter of 53 ± 9 nm and an average length of 234 ± 42 nm were obtained with a crystallinity of around 78%. Polyvinylidene fluoride (PVDF) thin composite membrane was developed by adding CNCs into the PVDF matrix in different amounts (0, 0.5, 1, 1.5, 2, 3 wt%). Porous finger-like structures in the membrane increased with an increase in CNC content. The FTIR measurement and high-resolution FESEM image of the membranes verified the presence of CNCs in the composite membranes. 48% high pure water flux (PWF) was obtained for PVDF/CNC as compared to pristine PVDF membrane with the addition of 3% CNCs at a pressure of 1 kg−1cm−2. Water contact angle (WCA) also decreased from 85° to 69° with increasing the wt% of CNCs in the dope solution, which signifies improved hydrophilicity. Further, the PVDF/CNCs membrane showed a high bovine serum albumin (BSA) rejection of 93% and a flux recovery ratio (FRR) of 76.76 %, whereas the pristine PVDF membrane showed BSA rejection of 70.86% and a FRR of 40.82 %, respectively.

Fabrication and characterization of different braid‐reinforced PVC hollow fiber membranes to use in membrane bioreactor for wastewater treatment

AbstractIn this research, polyvinyl chloride (PVC) polymer was applied for the first time in the fabrication of braid‐reinforced hollow fiber membranes for ultrafiltration applications. Different concentrations of PVC solutions were cast on tubular braids and coagulated by the phase inversion method in a pure water bath to produce membranes with various porosities and pore sizes. The characterizations such as scanning electron microscopy, overall porosity, contact angle and mean pore size were done to understand membrane morphology. The antifouling property of membranes was explained using bovine serum albumin (BSA). The contact angles of membranes were increased from 64.9° ± 2.2 to 72.8° ± 2.1, while the overall porosity decreased from 43.8 ± 1.2% and 19.6 ± 3.3% for 11 wt% and 17 wt% PVC membranes, respectively. Permeate flow decreased due to decreased pore size of membranes as a result of increased PVC content. Besides, the flux recovery ratio, reversible and irreversible fouling studies showed that better antifouling characteristics observed with increasing of PVC content. A high removal efficiency of 87.2% for BSA was also demonstrated by the optimal membrane (15 wt% PVC), along with an increased flux recovery ratio of 96.6%. After investigating the rejection of COD in a membrane bioreactor setup, all membranes revealed that they were higher than 98%.

Studies in nanofiltration of dyes industry effluent

ABSTRACT A large number of chemicals are being produced in the industries, which resulted in accumulation in the effluent stream. The impact of these effluents on the environment is very adverse, if it released directly without treatment. Nowadays, the treatment of the effluent before discharge is very important due to strict norms imposed by various government agencies. In our study, the effluent from a local effluent treatment plant (effluent from dyes factory) was procured and treated with hydrophilic polymeric and ceramic nanofiltration membranes. The membrane characterisation was done based on flux, permeability, flux recovery ratio, and flux decline ratio. The effluent received from ETP and treated effluent was characterised in terms of pH, total dissolved solids (TDS), Chemical Oxygen Demand (COD), Conductivity, Turbidity, and Osmolality. From our experimental study, more encouraging results were obtained. More than 50% COD reduction was observed in the process. The membrane flux was recovered by the physical (by using backwashing) and chemical process (by using sodium hypochlorite solution). The different range was used for optimising the appropriate process for recovery of membrane flux. About 95% membrane flux was recovered by physical process on both ceramic and polymeric membranes.

Antimicrobial and antifouling performance of modified membrane during UF of sugarcane juice

In the present study, nanofiller (polypyrrole and chitosan (CPY) composite) incorporated polysulfone (PSF) based hollow fiber was synthesized to address the membrane fouling in ultrafiltration of sugarcane juice. The CPY was incorporated within the PSF matrix at varied concentrations (0.25, 0.5 and 1 wt%). The synergy between CPY and PSF was examined by X-ray diffraction and Fourier transform infrared spectroscopy. Morphological results confirmed the augmented porous nature of the modified membrane. The optimized membrane (MHCPY_0.5) displayed improved membrane properties along with the rejection of polyphenoloxidase enzyme (71.2%) and bacteria (5.4 log reduction). The antifouling nature of the selected modified membrane was evaluated in terms of resistances and flux recovery ratio and the same was compared with that of unmodified membrane. The MHCPY_0.5 exhibited remarkable antibacterial properties confirmed from halo zone, shake flask, anti-adhesion, live dead staining assays studies. • Composite HF membrane was tested for anti-fouling and anti-microbial properties. • Membrane permeability was increased 4 times by 0.5% chitosan-polypyrrole composite. • 71% PPO rejection was obtained using the modified membrane. • FRR of the modified membrane was 72% compared to 54% of the unmodified one. • The modified membrane showed remarkable antimicrobial property.

Anti-scaling covalent organic framework membranes with custom-tailored nanochannels for efficient lithium extraction

Covalent organic framework membranes (COFMs) with well-defined nanochannels have infinite potential in efficient separation. However, unsuitable pore size and easily contaminated surface hamper the application of COFMs for ion separation. Herein, we report a custom-tailored nanochannels strategy for forming COF nanosheets (COFNs) with positively charged, narrowed and lithiophilic channels. The obtained COFNs can be easily assembled into free-defect and oriented COFMs via vacuum-assisted filtration method. Charged and narrowed channels augment entrance resistance of divalent cation, meanwhile, lithiophilic groups promote transport of Li+ in channels. Besides, positively charged surface disturbs the crystallization of scaling. Thus, the optimal COFM exhibited excellent water permeance of 32.1 L m−2 h−1 bar−1 and high Li+/Mg2+ separation factor of 30.2 in simulated salt-lake brine. After running in the gypsum solution, the anti-scaling COFMs showed low flux decline ratio (FDR) and the flux recovery ratio (FRR) was nearly 10% higher than NF90. This study may provide a facile regulation method for nanochannels and surface properties of COFMs, and the obtained membranes could be applied to efficient lithium extraction.

A highly durable and hydrophilic PVDF- MoS2/WO3-PVA membrane with visible light driven self-cleaning performance for pollutant-burdened natural rubber wastewater treatment

Recently, the unification of photocatalytic degradation and hydrophilic properties has received a remarkable attention in membrane-based operation. In this study, the PVDF membrane was tailored by the incorporation of MoS2/WO3 recognized as MSW photocatalyst material with a cross-linked PVA. The filtration process was conducted with and without visible-light irradiation, and the properties of the clean and fouled membrane were identified using a scanning electron microscope (SEM), infrared spectroscopy (FTIR), and X-ray diffraction (XRD) analysis. The characterization results confirmed the successful blending of the composite material in the PVDF membrane. The PVDF-MSW-PVA membrane exhibited convincing performances with a high-photodegradation efficiency and excellent self-cleaning ability. The PVDF-MSW-PVA membrane achieved an initial flux of 100.66 L.m−2.h−1 and exhibited 98.77 % of chemical oxygen demand (COD), 94.30 % of total dissolved solid (TDS), and 96.66 % of ammonia nitrogen (NH3-N) rejection under visible-light illumination. The excellent antifouling and self-cleaning ability of the membrane was confirmed by the unnoticeable decrease of permeate flux after 5 cycle photo-filtration process, the highest flux recovery ratio of 96.93 %, and a decrease of total fouling retention of the membrane with the higher Rr than that of Rir. The modified membrane also demonstrated good reusability for long term-used upon 10 h of usage for the filtration process under visible-light irradiation. These results suggest the synergetic use of photocatalytic and hydrophilic material for the treatment of pollutant-burdened natural rubber wastewater via a combined degradation and filtration process.

Enhanced Antifouling in Flat-Sheet Polyphenylsulfone Membranes Incorporating Graphene Oxide-Tungsten Oxide for Ultrafiltration Applications.

In this study tungsten oxide and graphene oxide (GO-WO2.89) were successfully combined using the ultra-sonication method and embedded with polyphenylsulfone (PPSU) to prepare novel low-fouling membranes for ultrafiltration applications. The properties of the modified membranes and performance were investigated using Fourier-transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), contact angle (CA), water permeation flux, and bovine serum albumin (BSA) rejection. It was found that the modified PPSU membrane fabricated from 0.1 wt.% of GO-WO2.89 possessed the best characteristics, with a 40.82° contact angle and 92.94% porosity. The permeation flux of the best membrane was the highest. The pure water permeation flux of the best membrane showcased 636.01 L·m-2·h-1 with 82.86% BSA rejection. Moreover, the membranes (MR-2 and MR-P2) manifested a higher flux recovery ratio (FRR %) of 92.66 and 87.06%, respectively, and were less prone to BSA solution fouling. The antibacterial performance of the GO-WO2.89 composite was very positive with three different concentrations, observed via the bacteria count method. These results significantly overtake those observed by neat PPSU membranes and offer a promising potential of GO-WO2.89 on activity membrane performance.

Removal of diclofenac sodium and cefixime from wastewater by polymeric PES mixed-matrix-membranes embedded with MIL101-OH/Chitosan

Regarding the presence of residual active drug compounds in the municipal effluents and the effluents of pharmaceutical factories, the removal of these compounds increases the resistance of microorganisms, and environmental hazards, such as genetic disorders in the aquatic reproduction and possible damage to human health is necessary. In recent years, using the Mixed-Matrix-Membranes (MMMs) for their high removal efficiency was considered. In the present study, polyether sulfone (PES) membranes, and composite membranes with MIL10-OH/Chitosan (CS), were synthesized and characterized. SEM analysis shows that with the addition of MOF modified with CS, the number and size of micropores and porosity increase compared to the PES membrane. By adding 0.05 wt % of MIL101-OH and MIL101-OH/CS to the PES membrane, the pure water flux increased from 5.1 kg/m2 h to 9.2 and 9.9 kg/m2 h. Increased porosity in the membranes led to a decrease in the resistance of flowing water, and ultimately increased the membrane's permeability. Increased membrane hydrophilicity, as well as membrane surface roughness, reduced membrane clogging. By adding MOF with CS to the PES membrane, the flux recovery ratio increased from 45 % to 95 % in terms of the increase of hydrophilic functional groups of membrane. Furthermore, reversible fouling increases and irreversible fouling in MMMs significantly decreased. Diclofenac sodium (DCF) was separated better than cefixime (CFX). Thus, the removal percentage for DCF was 95 % and for CFX drug is 90 %. By comparing the removal percentage, it can be seen that the performance of MMMs with MIL101-OH/CS was better than MMMs with MIL101-OH, and adding CS to MOF and PES membrane improved membrane performance to remove DCF and CFX.

Amphiphilic Grafted Polymers Based on Citric Acid and Aniline Used to Enhance the Antifouling and Permeability Properties of PES Membranes

Water treatment technology based on ultrafiltration (UF) faces the problem of severe membrane fouling due to its inherent hydrophobicity. The use of amphiphilic polymers that possess both hydrophobic and hydrophilic chain segments can be advantageous for the hydrophilic modification of UF membranes due to their excellent combination in the membrane matrix. In the present study, we examined a novel amphiphilic CA-g-AN material, constructed by grafting citric acid (CA) to aniline (AN), as a modified material to improve the hydrophilicity of a PES membrane. This material was more compatible with the polymer membrane matrix than a pure hydrophilic modified material. The polyethersulfone (PES) membranes modified by amphiphilic CA-g-AN demonstrated a higher water flux (290.13 L·m-2·h-1), which was more than eight times higher than that of the pure PES membrane. Furthermore, the flux recovery ratio (FRR) of the modified membrane could reach 83.24% and the value of the water contact angle (WCA) was 76.43°, demonstrating the enhanced hydrophilicity and antifouling ability of the modified membranes. With this study, we aimed to develop a new amphiphilic polymer to improve the antifouling property and permeability of polymer-based UF membranes to remove organic pollutants from water.

Fabrication of a superhydrophilic/underwater superoleophobic PVDF membrane via thiol–ene photochemistry for the oil/water separation

The direct discharge of oily wastewater into the environment is considered one of the greatest threats to the ecological environment. Membrane technology is considered as an efficient strategy to treat oily wastewater. However, the membrane fouling caused by oil adsorption has intensively impeded its practical utilization in oil/water separation. This work aims to fabricate an anti-oil-fouling membrane for the effective separation of oil/water emulsions. The PEGylated poly(vinylidene fluoride) (PVDF) membrane was synthesized via thiol–ene photochemistry with poly(ethylene glycol) diacrylate (PEGDA) and 3,6-dioxa-1,8-octanedithiol (DOT) as the modifiers. The results of scanning electron microscopy (SEM) and energy-dispersive X-ray (EDX) mapping analysis revealed that the PEGylated layers show uniform distribution on the membrane surface by regulating the feed PEGDA concentration. The superhydrophilic and underwater superoleophobic characteristics of the PEGylated membrane provided oil-adhesion resistance to the membranes. The membrane grafted with a high amount of PEGylated layers shows a low pure water flux, due to the pore blockage. The PEGylated membrane possesses the stable surface wettability and permeation performance of emulsion. The separation efficiency of PEGylated membranes for multiple emulsions is greater than 99%, and the highest rejection value is as high as 99.9%. After the three-cycle filtration of emulsified pump oil solution, the flux recovery ratio of membranes still reaches 90%, indicating an outstanding fouling resistance to emulsified oily matters. This work provides a feasible strategy to prepare the antifouling PVDF membrane used for the oil/water separation.

Outstanding Separation Performance of Oil-in-Water Emulsions with TiO2/CNT Nanocomposite-Modified PVDF Membranes

Membrane filtration is an effective technique for separating micro- and nano-sized oil droplets from harmful oil-contaminated waters produced by numerous industrial activities. However, significant flux reduction discourages the extensive application of this technology; therefore, developing antifouling membranes is necessary. For this purpose, various titanium dioxide/carbon nanotube (TiO2/CNT) nanocomposites (containing 1, 2, and 5 wt.% multi-walled CNTs) were used for the modification of polyvinylidene fluoride (PVDF) ultrafilter (250 kDa) membrane surfaces. The effects of surface modifications were compared in relation to the flux, the filtration resistance, the flux recovery ratio, and the purification efficiency. TiO2/CNT2% composite modification reduced both irreversible and total filtration resistances the most during the filtration of 100 ppm oil emulsions. The fluxes were approximately 4-7 times higher compared to the unmodified PVDF membrane, depending on the used transmembrane pressure (510, 900, and 1340 L/m2h fluxes were measured at 0.1, 0.2, and 0.3 MPa pressures, respectively). Moreover, the flux recovery ratio (up to 68%) and the purification efficiency (95.1-99.8%) were also significantly higher because of the surface modification, and the beneficial effects were more dominant at higher transmembrane pressures. TiO2/CNT2% nanocomposites are promising to be applied to modify membranes used for oil-water separation and achieve outstanding flux, cleanability, and purification efficiency.

Renewed physiognomies of titanium nanotubes for implementation in the polysulfone membrane matrix for desalination

An innovative modification approach is attempted to fine-tune the physiognomies of titanium nanotubes (TNT) for amalgamation in the polysulfone (PSf) membrane matrix, which is employed in the salt rejection studies. The novel modified titanium nanotubes (m-TNT) are integrated in the PSf nanocomposite membranes by the phase inversion process. The synthesized m-TNTs and the nanotube composite membranes are analyzed with a range of characterization techniques and are studied for divalent and monovalent salt rejection studies. The results revealed that the m-TNT as a nanofiller in the membranes decreased contact angle, increased surface charge and hydrophilicity thereby improving the membrane perviousness. The m-TNT/PSf nanotube composite membrane with 2 wt% composition of nanotubes (M2) exhibits a flux of 12.17 LMH and salt rejection efficiency of 76.6 % for MgCl2, 59.9 % for Na2SO4 and 48.6 % for NaCl. The membranes also display superior antifouling behavior with 93.5 % flux recovery ratio and a very meagre 15.9 % of total fouling for the M2 membrane. The fabricated membranes exhibit a good rejection efficiency for the NaCl salt solution, provide appreciable productivity and display enhanced antifouling susceptibility thereby proving to be a prominent material in membrane desalination applications.

ZIF-67 blended PVDF membrane for improved Congo red removal and antifouling properties: A correlation establishment between morphological features and ultra-filtration parameters

Dye effluents from various sectors have constantly imperilled the environment and ecosystem. Nano-composite membrane technology incorporating metal-organic frameworks (MOFs) has shown tremendous potential for toxic pollutant remediation. This study details the impact of ZIF-67 MOF nanoparticles on the structural properties of polyvinylidene fluoride (PVDF) ultrafiltration membrane during the non-solvent induced phase separation (NIPS) process. In order to outline the properties that determine the performance parameters in a MOF-modified mixed matrix membrane, the corresponding changes in mean pore size (MPS), surface porosity, solvent viscosity, and hydrophilicity have been discussed with appropriate surface characterization analysis. The suitability of ZIF-67 as filler nanoparticles were established based on polymer compatibility, dispersibility, and water stability studies. The ZIF-67 incorporated PVDF mixed matrix membranes (MMM) showed 99.5% CR dye removal with 2.6 times DI water permeability than the neat. The flux recovery ratio (FRR) improved by 1.9 times and the membranes were found suitable for up to 5 filtration cycles. Based on the overall results, a correlation analysis between the MMM surface properties and membrane performance parameters were established to determine the key performance parameters. It was observed that in comparison to MPS, surface porosity was more correlated to Jd/Jw (r = 0.96) and FRR (r = 0.95).