Polyethersulphone Membrane Research Articles

Towards continuous wine fining: Materials characterisation and crossflow performance testing of polymer–bentonite mixed matrix membranes

AbstractThis study investigates the feasibility of using bentonite‐embedded mixed matrix membranes to perform wine fining on white wines to eliminate protein instability. Membranes made using polyethersulphone or polyvinylidene fluoride were fabricated using the wet phase inversion technique and used to filter unfined New Zealand Sauvignon Blanc wine in a crossflow filtration system.The morphologies of all the fabricated membranes were characteristic of asymmetric phase inversion membranes. Confocal laser scanning microscopy analysis on the membranes suggests that the two major mechanisms of protein removal are adsorption by the embedded bentonite particles and size exclusion via the membrane morphology. Polyethersulphone membranes were found to produce wine of similar levels of protein stability (around 90% protein removal) and polyphenol content as polyvinylidene fluoride membranes of the same membrane composition and operating conditions but with as much as 80% higher flux. Stabilising wine in one filtration pass was possible with polyethersulphone membrane with 25 wt% bentonite while maintaining high flux. These promising results show that the tested process has the potential to replace the current batch‐wise fining process with continuous crossflow membrane filtration with benefits such as increased processing speed and reduced wine loss.

Enhanced Hydrophilic and Antipollution Properties of PES Membrane by Anchoring SiO2/HPAN Nanomaterial

In this paper, a hydrophilic SiO2/hydrolyzed polyacylonitrile (HPAN)/polyethersulphone (PES) hybrid membrane was fabricated by blending PES with a series of SiO2/HPAN nanoparticles, which were prepared by hydrolyzing PAN and ethyl orthosilicate (TEOS) synchronously. During the phase inversion processing to fabricate the membrane, SiO2/HPAN would blend into the matrix and anchor on the surface of the membrane. By tuning the hydrolyzing time of the HPAN/SiO2 and the content of HPAN/SiO2, water flux and antifouling properties of the SiO2/HPAN/PES hybrid membrane improved significantly in the ultrafiltration process. The experiment demonstrated that, when blending with 10% content of SiO2/HPAN-1.5h, the SiO2/HPAN/PES hybrid membrane could achieve optimal performance: the water contact angle decreased to 42.08°, the water flux increased to 354 L/m2 h, the bovine serum albumin (BSA) flux increased to 144 L/m2 h, and the BSA rejection increased to 94.2%. Besides, the water flux remained at 250 L/m2 h after fouli...

Synthesis of Fe-Ag/f-MWCNT/PES nanostructured-hybrid membranes for removal of Cr(VI) from water

Abstract This work describes the synthesis of Fe-Ag/functionalized-multiwalled carbon nanotube (f-MWCNT)/polyethersulphone (PES) nanostructured-hybrid membranes via a modified phase inversion method and its permeability properties. As-synthesized MWCNTs were first treated with acid and then Fe and Ag nanoparticles (Fe-Ag NPs) were uniformly dispersed on the surface of the f-MWCNTs using a microwave-assisted polyol method prior to addition to the PES polymer matrix. The addition of Fe-Ag/f-MWCNTs into the PES polymer increased the surface roughness of PES membranes and resulted to a higher hydrophilicity. Thermal stability and crystallinity properties of PES were significantly improved. The Fe-Ag/f-MWCNTs enhanced the surface charge density of the PES membranes and were found not to leach from PES. Performance evaluation studies revealed that the addition of Fe-Ag/f-MWCNTs into the PES polymer matrix increased water flux from 26.5 to 36.9 L/m 2 h and improved the rejection of Cr 6+ ions (up to 94%) in a cross-flow system. Furthermore, the addition of Fe-Ag/f-MWCNTs improved fouling resistance of PES membranes. The improved properties of these hybrid membranes make the ideal for use as either point-of-use or end-of-use water purification system for production of potable water.

High-throughput β-glucan analyses and their relationship with beer filterability

Beer filterability is strongly related to the amount and molar mass distribution of β-glucan. Different commercial quantification methods yield different β-glucan concentrations and beer filterability. In order to acquire detailed information on the measureable molar mass and its impact on beer filtration, six high-throughput methods were developed and analysed. These methods involve three calibration standards (Skandinavisk Bryggeri Laboratorium standard, SBL; Megazyme standard for continuous flow analyser, CFA; and 650 kDa standard) and two dyes (Calcofluor and Congo red). Significant correlation was observed between cellulose nitrate membrane filtration and fluorometrically determined β-glucan content (SBL calibration: r = 0.604, P < 0.001; CFA calibration: r = 0.687, P < 0.001). However, no correlation was observed with the colorimetric methods. Polyethersulphone membrane filtration correlated significantly with specific viscosity (r = 0.710, P < 0.001) and fluorometrically determined β-glucan content (CFA calibration: r = 0.586, P < 0.001). However, there was no correlation between the filtration performance of diatomaceous earth and the established beer properties. No correlation between the developed colorimetric and fluorometric methods was found using the SBL and CFA standards. However, a significant correlation was observed with the 650 kDa standard (r = 0.836, P < 0.001). A wide variation, especially between the dyes, was observed in the measurable β-glucan molar mass distribution determined using field-flow fractionation. Our results demonstrate the impact of method parameters on β-glucan concentration. Thus, known β-glucan thresholds regarding filterability must be reconsidered. We conclude that a valid β-glucan quantification method can provide reliable information on beer filterability.

Removal of fine iron-oxide particles after post-filtration in local potable water using an electrophoretic method

Potable water from several residential areas on the east coast of Malaysia was filtered using a polyethersulphone (PES) membrane to separate the coarse and fine iron-oxide particles inside the pipelines. The as-received samples consisted of a wide distribution of particle sizes, ranging from 5μm to 400nm. The concentration of fine iron-oxide particles inside a distribution system was extremely low. Hence, a specific method is necessary to concentrate and separate the fine particles from the coarse ones. To study the fine particles from the bulk, excess pressure was applied to the membrane filter so that the clogged particles were released into the permeate. A 100kDa PES membrane was used to separate the particles, because the samples consisted of a wide molecular-weight cut-off range from 89g/mol goethite (α-FeOOH) to 231g/mol hematite (Fe2O3). After the filtration process, the size distribution of permeated particles reduced to 550–400nm. Through X-ray diffraction analysis, numerous polymorphs such as α-FeOOH, Fe3O4, Fe2O3 and maghemite were detected from the samples. The zeta potential value of the permeated particles changed from −18.5 to −13mV, suggesting that the dispersity of permeated iron-oxide particles became unstable, but remained adequate for electrophoretic deposition (EPD). The fibrous carbon electrode used in the EPD process, could remove up to 87% of the permeated iron-oxide particles compared to solid carbon electrodes (<56%). A high-surface-area, porous electrode and a moderate applied voltage were preferred in order to minimise gas formation, reduce the electro-osmosis effect and increase the deposition efficiency.

The Application of Ultrafiltration for Preliminary Treatment of Liquid Waste Streams Generated in Gasification Process

Gasification is regarded as one of the most promising technology for generation of energy using renewable and alternative fuels. Nevertheless, in order to obtain process gas of desired quality, a range of processes for removal of pollutants present in a raw gas stream needs to be performed. One of the most problematic side stream formed during gas cleaning operations is highly loaded wastewater. It is a mixture of organic and inorganic contaminants, which usually appears as a tar-aqueous condensate. It is assumed that the amount of wastewater corresponds to ca. 30-50% of the amount of fuel introduced to gasification. In the presented study membrane ultrafiltration process was proposed as the method of preliminary treatment of wastewater formed during gasification of alternative fuels. Three types of polyethersulphone membranes, which differed in cut off, were used. The goal of the process was to separate raw wastewater into a condensate enriched with organic compounds, which could be reused to the gasification process as a fuel remoistening agent, and a permeate, which had to be undergone to further treatment. The impact of undesired phenomena accompanying membrane filtration i.e., fouling and concentration polarization was determined. The process capacity and efficiency of contaminants removal was evaluated.

Treatment of model oily produced water by combined pre-ozonation–microfiltration process

Oily wastewaters are one of the major environmental pollutants in aquatic systems. This is due to the emission of a variety of industrial oily wastewaters from sources such as crude oil mining (production), refineries, petrochemical plants and transportation. The aims of this work were to investigate the treatment of oil-contaminated wastewaters with a pre-ozonation/microfiltration combined system and the effect of pre-ozonation on the microfiltration parameters. The results demonstrated that ozone pre-treatment modified the chemical nature (pH and conductivity) of oil-in-water emulsion, resulting in higher wettability of the polyethersulphone membrane. In case of salt-containing model emulsions compared to pure oil emulsions, ozone treatment was found to be more effective for membrane resistance reduction and in chemical oxygen demand retention.

Comparison between hydrophilic and hydrophobic metal nanoparticles on the phase separation phenomena during formation of asymmetric polyethersulphone membranes

Inorganic nanoparticles have been applied as additive in membrane synthesis for improving different properties from the base polymer such as hydrophilicity, fouling resistance or permselectivity. To investigate the changes caused by the presence of the inorganic nanoparticles in the formation of the membrane structure, two different metallic compounds with opposite hydrophilicity were used as additives: hydrophilic zinc oxide (ZnO) and hydrophobic tungsten disulphide (WS2). For this purpose, the effect of these metal nanoparticles at ultra-low concentrations (0.05 and 0.25wt% metal nanoparticles/polymer ratio) in the preparation of flat-sheet membranes based on polyethersulphone (PES) by immersion-precipitation method was investigated. N-methyl-2-pyrrolidone (NMP) was used as solvent. The influence of both metal nanoparticles on the characteristics and permselective properties of PES membranes was studied with microscopic observations, contact angle measurements, and filtration experiments. Although the incorporation of metal nanoparticles could turn the system into thermodynamically unstable, the demixing process during formation of membranes was slightly delayed, suppressing the macrovoid formation (remarkably using WS2). Regardless the nature of the metal nanoparticles, results showed an overall improvement in membrane hydrophilicity and permselectivity by adding metal nanoparticles compared to the control PES membrane, demonstrating that the behaviour of both metal nanoparticles at ultra-low concentrations was very similar.

English

Palm oil mill effluent (POME) treatment has developed in the last decade. Due to the characteristic and volume of POME, it needed a complete treatment to reduce the pollutant content. Three pre-treatments method, ultrafiltration, adsorption and decantation were applied prior to nanofiltration (NF) membrane. The polyethersulphone membrane, montmorillonite as the adsorbent and modern decanter was investigated in this research. Two types of NF membrane, named NF-1 and NF-ASP30 were used after pre-treatment. The removal of four important parameters were determined i.e. COD, TSS, colour and turbidity. The results showed that the adsorption and UF is better than decantation pre-treatment. The ultrafiltration and adsorption can reduce POME content more than 80% for all parameter while decantation varied between 40 and 80%. The combination of ultrafiltration and adsorption with both of NF membrane can removed almost all the parameter. But the decantation can only remove the turbidity but not for the rest of the parameters. Besides the POME content, the flux decline for both of NF membrane was also investigated. The flux of NF-1 membrane was higher than NF-ASP30 membrane but NF-ASP was more relative stable for the flux decline. Overall, NF-1 has better performance in flux decline.

Microfiltration and ultrafiltration as a post-treatment of biogas plant digestates for producing concentrated fertilizers

Biogas plant digestate liquid fractions can be concentrated by microfiltration and ultrafiltration. Two types of microfiltration membranes (polysulphone (PS) and surface-modified polyvinylidene fluoride (PVDF)) were used to process digestate liquid fractions, and to assess their applicability in the recovery of particulate phosphorus, compared to an ultrafiltration membrane (polyethersulphone (PES)). Results show that membrane material, operational conditions, and pore diameter influenced the permeate flux pattern during microfiltration. The PS membranes initially had a higher tendency to foul than PVDF membranes. However, during the filtration process, as fouling built up, the permeate flux behavior of the two membranes became very similar. During the concentration of digestate liquid fractions, the microfiltration PS membrane and the ultrafiltration PES membrane achieved the highest phosphorus rejection (80% w/w), suggesting that there was a correlation between the membrane material and both the fouling trend and phosphorus rejection. A two-step basic-acidic cleaning was unable to recover the initial water flux for the fouled microfiltration membranes. In conclusion, the PS microfiltration membranes might be a good strategy for recovering phosphorus from digestate liquid fractions. Further research leading to adequate cleaning procedures, for microfiltration PS and PVDF membranes treating digestate liquid fractions though, are needed.

Removal of heavy metals from aqueous solution by polyacrylic acid enhanced ultrafiltration

One of the recently developed water treatment processes is the polyelectrolyte-enhanced ultrafiltration (PEUF). This technique combines a membrane filtration process (ultratfiltration) and a cation–polyectrolyte complexation technique. PEUF is shown to be an efficient technology for the removal of heavy metals from liquid effluents even at low concentrations. In this proposal, the removal of three heavy metals (cadmium, copper and zinc) from aqueous solutions by PEUF process was investigated. The poly(acrylic acid) (PAA) with an average molecular weight 100 kDa was used as complexing agent. The ultrafiltration experiments were performed using a tangential cell system equipped with a polyethersulphone membrane having a 10.000 molecular weight cut-off (MWCO). To improve the retention of the heavy metal ions, the effect of some operating parameters and solution characteristics were studied. For different PAA concentrations, this study showed that all permeate fluxes increased linearly by increasing transmembrane pressure. For the three studied metals, the best retentions were observed at 2 × 10–3 mol L–1 PAA concentration, 3 bar transmembrane pressure and pH above 5. The removal of cadmium, copper and zinc exceeded, respectively, 80, 93 and 70%.

Characterization and modeling of radial flow membrane (RFM) module in ultrafiltration

Design, characterization and modeling of a novel radial flow membrane (RFM) module is reported in the present study. The module has been investigated in ultrafiltration of bovine serum albumin (BSA) with a 30kDa polyethersulphone (PES) membrane under steady state. The proposed semi-empirical, steady state model was validated under different parametric conditions of transmembrane pressure and bulk concentration. The model may be viewed as an extension of the well known osmotic pressure model in conjugation with Spiegler–Kedem black box model and a system specific, steady state solute balance equation. Model empiricity was introduced primarily to account for unknown entrance–exit effects and effects of membrane roughness on hydrodynamic profile. The empirical parameter was evaluated by minimizing a global objective function. The maximum absolute deviation of the model with respect to the experimental data of permeate flux was found to be well within 7%.

Chemical cleaning of fouled polyethersulphone membranes during ultrafiltration of palm oil mill effluent

Fouling is one of the critical factors associated with the application of membrane technology in treating palm oil mill effluent (POME), due to the presence of high concentration of solid organic matter, oil, and grease. In order to overcome this, chemical cleaning is needed to enhance the effectiveness of membranes for filtration. The potential use of sodium hydroxide (NaOH), sodium chloride (NaCl), hydrochloric acid (HCl), ethylenediaminetetraacetic acid (EDTA), and ultrapure water (UPW) as cleaning agents have been investigated in this study. It was found that sodium hydroxide is the most powerful cleaning agent, the optimum conditions that apply are as follows: 3% for the concentration of NaOH, 45°C for temperature solution, 5 bar operating pressure, and solution pH 11.64. Overall, flux recovery reached 99.5%. SEM images demonstrated that the membrane surface after cleaning demonstrated similar performance to fresh membranes. This is indicative of the fact that NaOH solution is capable of removing almost all of the foulants from PES membranes.

Concentration and purification of galacto‐oligosaccharides using nanofiltration membranes

SummaryThis study was aimed at using nanofiltration to purify the galactooligosaccharides (GOS) found in a commercial mixture containing lactose, glucose and galactose, whose compositions were similar to that obtained through transgalactosylation reactions catalysed by β‐galactosidase from Kluyveromyces marxianus CCT 7082. NP030 polyethersulphone membrane was selected for the purification processes, once it differed statistically from other membranes due to the higher purification factor and permeate flux under the optimised temperature and pressure conditions of 35 °C and 3 MPa, respectively. Results indicate that NP030 membrane can be employed as a preliminary technique for the GOS purification with approximately 61% (w/w) of recovery.

Enzime recovery by ultrafiltration from broth

Recycling waste products of food industry is important: one side because of the environmental aspects and the other side because of the economic reasons. The one of the most preferred basic material for second generation bio-fuels might be the tobacco (Ábel et al. 2011). The cost of the process depends on the cost of the hydrolysis of cellulose/lignocelluloses i.e. and the cost of the enzymes. These enzymes are very expensive and that is why it is so important to find a good enzyme recovery method. In my research the membrane separation was used for enzyme recovery. Different polyether-sulphone membranes with cut-off value of 7 kDa (PES7) and 10 kDa (PES10) were used for separation the hydrolyzate.

Modeling and Simulation of Rotating Disk-Membrane Module in Ultrafiltration of Bovine Serum Albumin

A dynamic mass transfer model, coupled with transient back transport flux for a Rotating Disk-Membrane (RDM) module has been developed in the present study. The simulation algorithm is capable of predicting the permeate flux (J), membrane surface concentration (cm), and permeate concentration (cp) under different parametric conditions of transmembrane pressure (TMP), feed concentration (c0), stirrer speed (Ω2), and membrane speed of rotation (Ω1). The key feature of the proposed model is the analytical solution of the governing component balance equation. Additionally, the well-known osmotic pressure model and the Spiengler-Kedem black box model were used to describe the solvent transport through membrane. The proposed model was validated with the experimental results obtained in ultrafiltration of bovine serum albumin (BSA)/water solution conducted in a standard RDM module, fitted with polyethersulphone (PES) membrane of 30 kDa molecular weight cut-off (MWCO). The maximum absolute deviation of the model predictions with respect to the experimental results was observed to be well within 5%.

Reversible and irreversible compaction of ultrafiltration membranes

This study evaluates differences in reversible (after relaxation) and irreversible compaction and the effect of compaction on the performance of three different ultrafiltration membranes. The evaluation is based on results from both off-line and on-line measurements of compaction. The on-line measurements were done with an ultrasonic time-domain reflectrometry (UTDR) tool with improved resolution compared to tools used in earlier studies.The results reveal that the regenerated cellulose membrane compacted significantly more than the tested polyethersulphone membranes. This dissimilarity originates from the different membrane materials used and from significant differences in the membrane structures. It is also found that measurements of membrane compaction, whether made on-line or off-line, are not predictive for membrane performance. For instance, compaction of the UH030 membrane was negligible but its permeability decrease and retention increase due to the compaction were significant. Compaction decreased the cut-off values of the 30kDa membranes to lower than 8kDa. The results thus indicate that the skin layers of the membranes compact significantly causing remarkable changes in membrane performance. Thickness changes occurring in the scale of skin layer thicknesses are out of the resolution limits of methods thus far available for monitoring of membrane compaction in real-time. Real-time measured information on compaction phenomena is further needed to be able to distinguish flux decrease caused by concentration polarization and the effects of reversible compaction.

Development of an Eastern Blotting Technique for the Visual Detection of Aristolochic Acids in Aristolochia and Asarum Species by Using a Monoclonal Antibody Against Aristolochic Acids I and II

Aristolochic acids (AAs) are naturally occurring nephrotoxicants and human carcinogens. Aristolochic acid I (AA-I) and aristolochic acid II (AA-II) are two important AAs with clear toxicity. To obtain a monoclonal antibody (MAb) recognising AA-I and AA-II and develop an Eastern blotting technique for the specific visualisation and easy determination of AA-I and AA-II in plant extracts or tissues of Aristolochia and Asarum species. A hybridoma secreting MAb against AAs was prepared by cell fusion with splenocytes derived from a mouse immunised with AA-I-keyhole limpet haemocyanin (KLH) conjugate and the myeloma cell line SP2/0-Ag14. AA-I and AA-II were separated by thin-layer chromatography (TLC) and then blotted onto a positively charged polyethersulphone (PES) membrane using a modified carbodiimide method. The resulting membrane-bound AA-protein conjugates were linked to the newly prepared MAb and then to the secondary antibody labelled with peroxidase. 4-Chloro-1-naphthol was then added as the peroxidase substrate for staining. MAb 2A10-10B showed a high specificity for AA-I (100%) and AA-II (69.3%) and low cross reactivity (≤ 2.2%) toward analogues that may disrupt detection of AA-I and AA-II in plants. An established Eastern blotting method was applied to the immunohistolocalisation of AA-I and AA-II in dry plant tissues, and this analysis showed that the phelloderm, cortex and phloem of Aristolochia manshuriensis stem may contain higher amounts of total AA-I and AA-II as compared with the pith and xylem. This method was extremely useful for the visual screening of AA-I and AA-II among easily mistaken herbal medicines.

Enhanced membrane filtration of wood hydrolysates for hemicelluloses recovery by pretreatment with polymeric adsorbents

In this study adsorption of foulants from birch and pine/eucalyptus wood hydrolysates on two polymeric adsorbents was studied aiming to reduce the membrane fouling. The effect of the pretreatment of hydrolysate on polyethersulphone membrane performance was studied in dead-end filtration experiments. Adsorption pretreatment improved significantly filtration capacity and decreased membrane fouling. Especially high-molecular weight lignin was efficiently removed. A multistep adsorption pretreatment was found to reduce the amount of adsorbent required. While large adsorbent amount was shown to increase flux in filtration, it was found also to cause significant hemicellulose losses.

Soluble Microbial Products Removal Profile and Morphological Assessment of Submerged Ultrafiltration Membrane

Performance of ultrafiltration membranes were investigated with submerged membrane in terms of removal of soluble microbial products (SMP) (as proteins and carbohydrates) and fouling mechanisms. Cellulose (UC) and polyethersulphone (UP) membranes with different molecular weight cut off (MWCO) (5, 10, 30 kDa for UC and 5, 10, 20 kDa for UP) were tested in the bioreactor. The quality of permeate was compared in terms of SMP and COD. There was no significant difference in the total SMP removal effectives for both the UC and UP membranes with different MWCO characteristics. However, UP membranes were relatively more effective in removing soluble carbohydrates, while UC membranes were more effective in removing soluble proteins. The submerged membrane bioreactor achieved organic removal efficiencies ranging from 98.1±0.2% to 99.2±0.3% based on the soluble COD levels. Analysis of the membrane performance data by resistances-in-series model indicated that cake fouling was the dominant membrane fouling mechanisms. Increasing the MWCO was resulted in higher membrane flux but lower SMP removal. Morphological examination of the membranes by SEM and AFM showed significant accumulation of organisms on the membrane surface.