Performance Of Polysulfone Membranes Research Articles

Facile Preparation of Dense Polysulfone UF Membranes with Enhanced Salt Rejection by Post-Heating.

Polysulfone (PSf) membranes typically have a negligible rejection of salts due to the intrinsic larger pore size and wide pore size distribution. In this work, a facile and scalable heat treatment was proposed to increase the salt rejection. The influence of heat treatment on the structure and performance of PSf membranes was systematically investigated. The average pore size decreased from 9.94 ± 5.5 nm for pristine membranes to 1.18 ± 0.19 nm with the increase in temperature to 50 °C, while the corresponding porosity decreased from 2.07% to 0.13%. Meanwhile, the thickness of the sponge structure decreased from 20.20 to 11.5 μm as the heat treatment temperature increased to 50 °C. The MWCO of PSf decreased from 290,000 Da to 120 Da, whereas the membrane pore size decreased from 5.5 to 0.19 nm. Correspondingly, the water flux decreased from 1545 to 27.24 L·m-2·h-1, while the rejection ratio increased from 3.1% to 74.0% for Na2SO4, from 1.3% to 48.2% for MgSO4, and from 0.6% to 23.8% for NaCl. Meanwhile, mechanism analysis indicated that the water evaporation in the membranes resulted in the shrinkage of the membrane pores and decrease in the average pore size, thus improving the separation performance. In addition, the desalting performance of the heat-treated membranes for real actual industrial wastewater was improved. This provides a facile and scalable route for PSf membrane applications for enhanced desalination.

Characterization of Polysulfone Membrane with Variation of Ethanol Concentrations in Coagulation Bath for Ultrafiltration Membrane

The aim of this research is to study influence of ethanol concentrations in coagulation bath to charecteristic of physical properties and polysulfone membrane performance. Ethanol concentrations that used is 0; 40; 50; 60 ; 70; 80; 90 %. Process of making for polysulfone ultrafiltration membrane is prepared with phase inversion technique. Polysulfone membrane is made from polysulfone solved in N,N- dimetilacetamida (DMAc) and additive poly(ethylene glikol) (PEG) 600 in proportion 18 %: 77 %: 5 %. The result showed that increasing ethanol concentrations causes the increasing of density and increase concentrations from 0 - 50 % causes increasing swelling degree, but decreasing swelling degree from concentrations 60 - 90 %. However influence of ethanol concentration in coagulation bath to membrane performance is increasing of water flux, permeability coefficient, and rejection coefficient to dextran. It based on of result that polysulfone membrane with ethanol concentrations 80 dan 90 % included membrane classification ultrafiltration by rejection coefficient value above 90 %.

Modification of Thin Film Composite Pressure Retarded Osmosis Membrane by Polyethylene Glycol with Different Molecular Weights.

An investigation of the effect of the molecular weight of polyethylene glycol (PEG) on thin-film composite (TFC) flat sheet polysulfone membrane performance was conducted systematically, for application in forward osmosis (FO) and pressure retarded osmosis (PRO). The TFC flat sheet PSf-modified membranes were prepared via a non-solvent phase-separation technique by introducing PEGs of different molecular weights into the dope solution. The TFC flat sheet PSf-PEG membranes were characterized by SEM, FTIR and AFM. The PSf membrane modified with PEG 600 was found to have the optimum composition. Under FO mode, this modified membrane had a water permeability of 12.30 Lm−2h−1 and a power density of 2.22 Wm−2, under a pressure of 8 bar in PRO mode, using 1 M NaCl and deionized water as the draw and feed solutions, respectively. The high water permeability and good mechanical stability of the modified TFC flat sheet PSF-PEG membrane in this study suggests that this membrane has great potential in future osmotically powered generation systems.

Synthesis and application of ZIF-67 on the performance of polysulfone blend membranes

Sodium nitrate and sodium sulfate are used to study the effect of ZIF-67 on the performance of polysulfone membranes. Zeolitic imidazolate frameworks (ZIFs) have a high surface area, thermally and chemically stable than any other metal–organic frameworks (MOFs) due to the presence of transition metals like cobalt. In this study, the concentration of ZIF-67 was varied from 0, 1, 3, 5 to 7 wt% in polysulfone membranes. It was observed that pure water flux was enhanced from 2.94 L/m2 h (using a pure polysulfone membrane) to 35.39 L/m2h for the membrane with 7 wt% ZIF-67 at 10 kgf/cm2. Also, at a high concentration of ZIF-67 in the membrane, due to aggregation of MOFs, rejection of salts and permeate collected slightly decreased. Hence, 5 wt% ZIF-67 is used as the optimum concentration for better performance in polysulfone membranes.

A novel gold nanocomposite membrane with enhanced permeation, rejection and self-cleaning ability

The trade-off relationship between permeability, selectivity, and antifouling capability of nanocomposite membranes is the focal point of effective membrane technology. This study introduces a new gold nanocomposite membrane with enhanced antifouling behavior and permeability, as well as improved rejection capability for water treatment. Different (0.5, 1 and 2 wt%) concentrations of citrate-stabilized (coating) gold nanoparticles (CT-GNPs) having a core size of 50 nm were embedded into the polysulfone (PSF) membranes by the phase inversion method, resulting in alterations on PSF membrane performance. The intrinsic physicochemical properties and operational ability of all gold nanocomposite membranes were evaluated with regard to the self-cleaning, flux and selectivity criteria for water purification process. The PSF/0.5% GNPs demonstrated the optimal pore structure, morphology, and electrochemical surface properties among the gold nanocomposite and pure PSF membranes. The negative surface charge and the super hydrophilic functional group of CT-GNPs enhanced the permeation (at least three times in comparison with pure PSF membranes) and rejection ability of nanocomposite membranes. In addition, CT-GNPs showed digestive behavior towards humic acid (HA), a natural foulant, that significantly enhanced the antifouling ability (FRR = 95%) of the gold nanocomposite membranes by degrading the HA formed cake layer on the membrane surface and fragmenting the large HA aggregates that blocked the pores. The degradation of HA compounds by the embedded CT-GNPs occurred during the filtration process at room temperature and under the regular visible light. The stability of embedded GNPs into the polymeric matrix of membranes was evaluated at static and dynamic conditions for several days, and no release of CT-GNPs was observed.

Modified Polysulfone Ultrafiltration Membrane for Humic Acid Removal During Peat Water Treatment

In this research, UF membrane was prepared by blending polysulfone (PSf) in DMAc with the addition of PEG400 and low concentration of acetone as additives. The effect of PSf/PEG400 and polymer/solvent ratio on the performance of PSf membrane was investigated during two hours of peat water filtration. The results showed that the increase of ratio PSF/PEG400 from 1:1 to 1:2.5 improved the membrane hydrophilicity. It was indicated by a decrease of water contact angle from 62° to 33° and increased water content in membrane structure from 65 to 74,5%. In addition, the pure water flux also increased up to 200 times. A stable flux is achieved when the ratio PSf/PEG is 1:2 and resulted in 84% rejection of humic acid. The increase of polymer concentration in the membrane solution reduced the pure water flux but increased the rejection of humic acid. Higher polymer concentration in membrane solution reduced fouling tendency towards the membrane surface. It showed that flux decline was reduced from 60% to 40% when the ratio of polymer/solvent concentration was changed from 40/60 to 50/50.

Antifouling polysulfone ultrafiltration membranes with sulfobetaine polyimides as novel additive for the enhancement of both water flux and protein rejection

In this study, the preparation and properties of polysulfone (PSf) ultrafiltration (UF) membranes with sulfobetaine polyimides (PIs) as blending additive were reported. Three molecular weights sulfobetaine PIs were synthesized and blended with PSf to fabricate UF membranes via non-solvent induced phase separation process. It was proved that membrane hydrophilicity, porosity and antifouling properties were significantly enhanced due to the introduction of sulfobetaine PI. More importantly, these sulfobetaine PI/PSf blend membranes exhibited extraordinary thermal stability. It showed that surface hydrophilicity and chemical structures of the blend membranes remain stable after being kept in 90°C water bath for 3h. Experimental results indicated that the addition of sulfobetaine PI substantially promoted the overall performances of PSf membranes, such as pure water fluxes (PWF) (270.2 vs. 140.4Lm−2h−1), bovine serum albumin (BSA) rejection (95.2% vs. 86.9%), flux recovery ratio (FRR) (93.3% vs 60.4%), etc.

Influence of ZnO Nanoparticle Size and Concentration on the Polysulfone Membrane Performance

The activity of using membrane technology has developed fast in the treatment of wastewater, drinking water and process water production. The main challenges in membrane filtration are fouling reduction, permeability increase and high efficiency in retention. The best example of membrane enhancement is increasing hydrophilicity. Nanoparticles have been proven that their presence in the membrane matrix increases the water affinity significantly. Although the zinc oxide nanoparticles have a positive effect over the membrane performance, the influence of zinc oxide (ZnO) nanoparticle size has not been studied enough. Two sizes of nanoparticle of ZnO and three concentrations were used for the preparation of composite polysulfone ultrafiltration membranes. The effects of the ZnO nanoparticles in the membrane matrix on the permeation properties, flux stability and retention were tested. SEM, EDX, porosity and contact angle measurement were conducted in this article, also. The experimental results indicated that ZnO-PSf composite membranes exhibits significant differences in the membrane properties due to nanoparticle addition and regardless of their size it leads to an increase in hydrophilicity, flux, permeability, retention and porosity. Decreasing the nanoparticle size leads to an increase in membrane performance.

The effect of air gap on the morphological properties of PSf/PVP90 membrane for hemodialysis application

Membrane morphology plays an important role in achieving high flux and excellent uremic toxin removal for efficient hemodialysis therapy. Hemodialysis membrane morphology correlates to spinning parameters applied during fabrication of membrane. The effect of air gap on the morphology and liquid separation performance of the polysulfone (PSf) hemodialysis membrane is investigated. PSf hollow fibre membranes were prepared via dry-wet spinning process from dope solution comprises of 18 wt% PSf and 4.8 wt% polyvinylpyrrolidone in Nmethyl- 2-pyrrolidone. The membrane morphology was characterised using a scanning electron microscope (SEM) before tested with the ultrafiltration system to measure the pure water flux (PWF) and protein rejection using bovine serum albumin (BSA). SEM analysis revealed that the air gap does change the structure of the membranes due to the elongation stress because of the gravitational pull on the PSf hollow fibres. At low air gap (3 cm), the lower average pore size on the outer surface reduced the PWF while at high air gap (50 cm), the larger average pore size of membranes permitted water molecules to pass through easier and faster. It was observed that the PWF of the membrane increased significantly with air gap due to the increasing pore size. Membrane fabricated at 50 cm air gap obtained better PWF (28.45 Lm-2h-1) and protein rejection (94.47 %) compared to the membranes fabricated at 3 and 30 cm air gap. The effect of air gap enhanced the morphology and the performance of PSf membrane for hemodialysis application.

Improvement in performance of polysulfone membranes through the incorporation of chitosan-(3-phenyl-1h-pyrazole-4-carbaldehyde)

Pure polysulfone membranes are known to exhibit poor permeability, and high fouling. This study was conducted to explore the possibility of improving the permeation characteristics of polysulfone membranes by using a chitosan derivative as an additive. Polysulfone membranes blended with chitosan derivative 3-phenyl-1H-pyrazole-4-carbaldehyde (ChD) were prepared by the method of wet coagulation. The hydroxyl, amine and the imine functional groups present in the ChD evidently increased the hydrophilicity of the surface of the blended membranes which was confirmed by contact angle measurements. The contact angle of the blended membrane having 2 wt.% ChD was 62 ± 1 as compared to 70 ± 1 of neat polysulfone membrane. The SEM analysis of the blended membranes revealed a highly porous structure with a very thin surface skin layer, finger like projections in the sub-layer with a macro void structure at the base. The blended membranes also showed significant improvement in pure water flux of 351 L m−2 h−1 at 0.8 MPa trans membrane pressure (TMP) as compared to 24 L m−2 h−1 of neat polysulfone membrane at the same TMP. The anti-fouling test using bovine serum albumin exhibited improved anti-fouling characteristic of blended membranes with a maximum flux recovery ratio (FRR) of 57%. The heavy metal rejection study revealed that membrane P-1 showed maximum 36 and 29% rejection for Pb and Cu respectively.

Preparation and characterization of polysulfone membrane incorporating cellulose nanocrystals extracted from corn husks

Cellulose nanocrystals (CNCs) extracted from corn husks were used as additive to modify the hydrophilicity and anti-fouling properties of polysulfone (PSf) membrane. The PSf/CNCs blend membranes were prepared via an immersion phase inversion method. The influence of CNCs content on the morphology, structure, and performances of PSf membrane were carefully investigated by SEM, TG, DTG, DSC, break strength, elongation-at-break, Young modulus, contact angle and filtration experiment. The results showed that the isolated CNCs from corn husks were a promising additive for modifying the properties of PSf membrane. CNCs can improve mechanical property, thermal stability, hydrophilicity and anti-fouling performance of the pure PSf membrane. The PSf/CNCs blend membrane reached optimal properties at 2 wt% CNCs content, which was 2.76 and 1.57 times in pure water flux and FRR values respectively as compared to pure PSf membrane. Meanwhile, PSf-2 also can maintain a relatively high BSA rejection.

Influence of UV curing on morphology and performance of polysulfone membranes containing acrylates

UV cross-linked polysulfone (PSU) based membranes containing additives with different number of acrylate groups were prepared via UV curing and nonsolvent induced phase separation (NIPS). The resulting membranes had good solvent resistant nanofiltration (SRNF) performance with superior chemical resistance. The impact of the UV irradiation as well as the presence of the acrylate cross-linkers and the photoinitiator with respect to membrane morphology, chemical stability, and SRNF performance was investigated. Membranes with a cross-linker and a photoinitiator in their matrix had a macrovoid-like morphology. By decreasing the membrane wet thickness from 200 to 50µm to enhance the depth-curing, a sponge-like structure was achieved. The same macrovoid-free structure was found when 150 and 200µm thick membranes were treated in the reverse order, i.e. first UV irradiated and then immersed in water (UV/NIPS instead of NIPS/UV). Addition of an acrylate cross-linker decreased the contact angle of the membranes (typically from 76° to 61°). Addition of a penta-acrylate cross-linker to the PSU membrane resulted in a 10-fold higher permeance (3.3Lm−2h−1bar−1) in comparison to a reference PSU membrane without acrylate additive with still a 94% retention for Rose Bengal (RB) in IPA. However, after UV curing, the same membrane showed a permeance of only 0.07Lm−2h−1bar−1 and a retention of 96%. By reversing the synthesis sequence to UV/NIPS, an increase of permeances up to a value of 1.2Lm−2h−1bar−1 and retentions up to 94% were achieved.

Characterisation techniques for organic foulants adsorbed onto flat-sheet UF membranes used in abattoir effluent

Ultrafiltration and microfiltration membranes used in clarification of abattoir effluent were found to be subject to fouling by proteins and lipids. The extent of fouling and its consequences on polysulfone membrane performance and character was determined in a static system. Protein was solubilised from the membranes using sodium dodecyl sulfate and analysed using a conventional quantitative as well as a novel qualitative colorimetric method. Lipid was solubilised using a hexane:isopropanol treatment and quantified gravimetrically. Rapid fouling of the membranes by proteins and lipids in the initial stages of contact with effluent was observed, followed by multilayer adsorption. The water contact angle and pure water flux were significantly affected by both foulants, especially in the initial stages of fouling.