Humic Acid Flux Research Articles

Improvement of polyvinylidene fluoride membrane performance by combination of polyethylene glycol and dragon blood resin through coordination reaction with Fe3+ ions

Fouling on hydrophobic membranes can be eliminated by modification with hydrophilic additives such as dragon blood resin (DBR: bio-polymer) and polyethylene glycol (PEG: non-bio-polymer). In this study, the surface modification of polyvinylidene fluoride (PVDF) membranes with bio/non-bio polymeric additives and their coordination reaction with Fe3+ ions was investigated. Five types of membranes with different compositions were prepared by immersion precipitation phase inversion method. The result showed that membrane M–PD (PVDF/PEG/DBR) improved the membrane hydrophilicity, resulting in high pure water flux (98.7 L.m−2.h−1) and humic acid rejection (99.08 %). However, the coordination reaction with PEG and Fe3+ as well as PEG/DBR and Fe3+ resulted in reduced water and humic acid flux. Coordination reaction successfully increased membrane stability as evidenced by FRR < 100 %. These results will be useful in the design of PVDF-based membranes with bio- or non-biopolymer additives.

Photocatalytic TiO2@MIL-88A (Fe)/polyacrylonitrile mixed matrix membranes: Characterization, anti-fouling properties, and performance on the removal of natural organic matter.

Photocatalytic membrane reactors (PMRs), coupling photocatalysts and membranes in a single system, have shown a considerable potential to reduce membrane fouling, which is one of the major drawbacks of using membranes to treat water and wastewater. In this study, the visible light-activated photocatalysts were incorporated into the polyacrylonitrile (PAN) casting solution to synthesize the photocatalytic composite membranes. The physicochemical properties and the morphology of the membranes and photocatalysts were characterized by attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), X-ray diffraction analysis (XRD), ultraviolet-visible diffuse reflectance spectroscopy (UV-visible DRS), photoluminescence (PL), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), atomic force microscopy (AFM), Brunauer-Emmett-Teller (BET), porosimetry, and contact angle analyses. The performance of the synthesized photocatalytic mixed matrix membranes (MMMs) in treating water containing humic acid, as one of the major components in natural organic matter (NOM) existing in drinking water sources, was investigated. Under visible light irradiation, the PAN/TiO2@MIL-88A (Fe) MMMs simultaneously adopted photocatalysis and membrane separation in the PMR and thereby enhanced humic acid removal and anti-fouling properties. The best synthesized photocatalytic membrane could remove 92.4% of the humic acid once exposed to visible light. The optimum membrane had suitable water permeability, a high flux recovery ratio (99.5%), and a 13.5% decline in the humic acid flux after a 10-h run, considerably lower compared to the corresponding decline of the pristine membrane (37.5% over the same period). The remarkable properties of the PAN/TiO2@MIL-88A (Fe) membrane, including its high anti-fouling specification, confirm the appropriateness of the synthesized MMM for treating water involving humic acid.

Juxtaposition of PES based hollow fiber membrane: Antifouling and antibacterial potential of LiCl mediated PVA–ZnO blend

New dope formulation was synthesized to fabricate an antibacterial and antifouling hollow fiber (HF) membrane using polyvinyl alcohol (PVA)–zinc oxide (ZnO) blend, mediated by lithium chloride (LiCl). Study was done between neat polyethersulfone (PES), PES–ZnO, PES–PVA, and PES–PVA–ZnO membrane samples. The addition of PVA improved the antifouling properties with the lowest recorded relative humic acid flux (HAF) above 0.95. On the other hand, PVA–ZnO incorporation improved the humic acid rejection up to 96.03±1.07%. Minimal bacterial formation was found on ZnO present sample surfaces, suggesting superior antibacterial properties.

Optimization of PES/ZnO mixed matrix membrane preparation using response surface methodology for humic acid removal

The application of response surface methodology (RSM) in preparation and optimization of membranes is important in order to reduce the effort and time needed to achieving an optimum performance. RSM was used to develop an optimum polyethersulfone (PES)/ZnO mixed matrix (MM) membrane for humic acid removal. The MMs were synthesized by dispersing various amounts of hydrophilic ZnO nanoparticles (NPs) into a solution containing PES, polyvinylpyrrolidone (PVP) and dimethylacetamide (DMAc). Flat sheet MM membranes were prepared via the phase inversion method using the central composite design (CCD). The effects of four preparation parameters, such as PES, ZnO, PVP weight percentages and solvent evaporation time, were investigated. Pure water flux (PWF), humic acid flux (HAF) and humic acid rejection (HAR) were selected as a model responses. It was shown that PES and PVP were mainly affected on both PWF and HAF. Furthermore, the interaction effect between PES and ZnO-NPs shows a significant effect on PWF, while the quadratic effects of both solvent’s evaporation time and ZnO-NPs weight percentage coupled with the interaction effect between PES and PVP weight percentage shows the most significant parameters that affects HAR. The optimization method was subjected to maximize all of the PWF, HAF and HAR. It was also determined that the optimized membrane can be synthesized from a solution containing 17.25 wt% PES, 3.62 wt% ZnO and 3.75 wt% PVP with 15 s of solvent evaporation time. The optimum values of PWF, HAF and HAR were 222.3 (L/m2 h), 94.7 (L/m2 h), and 96.34%, respectively. Thus, it can be concluded that the CCD technique is capable of optimizing PES-ZnO membrane performance.

Preparation and Characterization of Polyethersulfone Membrane Containing Zinc Oxide Nanoparticles and Polyvinylpyrrolidone

Flat sheet polyethersulfone (PES) ultrafiltration membranes were fabricated by a dry/wet induced phase inversion process. Various ranges of ZnO concentrations (from 0 –5 wt. %) were utilized in conjunction with 16.5 and 2.5 wt. % of polyethersulfone and polyvinylpyrrolidone (PVP), respectively. The prepared membranes were characterized using scanning electron microscope (SEM), contact angle (CA), and flux/rejection performance. The modified membranes were tested on humic acid removal. The hydrophilicity of PES membrane was improved after addition of zinc oxide nanoparticles in the casting solution. Highest pure water flux was obtained at 5 wt.% ZnO nanoparticles. The modified membranes with 2.5 wt. % of zinc oxide exhibited higher humic acid flux and rejection.

Effects of clay on the fouling by organic substances in potable water treatment by ultrafiltration

In water treatment by ultrafiltration, effects of clay on the fouling due to organic matter in cross-flow ultrafiltration were evaluated by fouling model materials and clay. Fouling model materials selected were BSA (Bovine serum albumin, MW68,000), Dextran (MW70,000), and humic acid (MW8,000-200,000) at a size larger than molecular weight cut-off (MWCO 50,000, polysulfone) and alpha-lactalbumin, Dextran (MW9,300), fulvic acid (MW8,000) for smaller size than and that kaolin was selected as a clay material. The flux of BSA, Dextran (MW70,000) increased with an increase in the amount of kaolin, and the flux of alphalactalbumin, Dextran (MW9,300), fulvic acid did not increase with kaolin. In contrast, the flux of humic acid decreased with an increase in the quantity of kaolin. It was found that in the direct ultrafiltration of river water clay materials did not affect the flux decline, and could contribute to the prevention of fouling due to organic matter. It seemed that the pore size of membrane plays an important role in the effect of clay on the fouling due to organic matter.