To increase the surface hydrophilicity of PVDF membranes, in this paper, an electric enhancing method was adopted to treat PVDF nascent membranes during the phase inversion process. It was found that when PEG 600 was taken as the additive, the surface water contact angle of the PVDF membrane treated under 2 kV electric field was decreased from 84.0º to 65.7º. The reason for the surface elements change of the PVDF membranes prepared under the electric field was analyzed in detail with the dielectric parameters of the polymer dope solutions. Results from BSA adsorption experiment showed that the antifouling ability of the external electric field-treated membranes was distinctly enhanced when compared with that of the untreated membranes. The amount of BSA adsorbed by the treated membranes was lower by 38-43%. Compared with the common chemical reaction methods to synthesize hydrophilic additives or membrane materials, the electric field-assisted processing method did not involve any additional chemical synthesis process and it was capable of realizing better hydrophilicity.
PVDF; ultrafiltration; anti-fouling
Polymer Membrane Laboratory, College of Science, Northeast Forestry University, Harbin, Heilongjiang 150040, China.
Herein, the preparation of anion exchange membrane (AEM) from brominated poly(2,6-dimethyl 1,6-phenylene oxide) BPPO and dimethylaniline (DMA) by phase-inversion process is reported. Anion exchange membranes (AEMs) are prepared by varying the DMA contents. Prepared AEMs show high thermal stability, water uptake (WR) around 202% to 226%, dimensional change ratios of 1.5% to 2.6% and ion exchange capacities (IECs) of 0.34 mmol/g to 0.82 mmol/g with contact angle of 59.18° to 65.15°. These membranes are porous in nature as confirmed by SEM observation. The porous property of membranes are important as it could reduce the resistance of transportation of ions across the membranes. They have been used in diffusion dialysis (DD) process for recovery of hydrochloric acid (HCl) from the mixture of HCl and ferrous chloride (FeCl2). Presence of ¯N+(CH3)2C6H5Br &$175;as a functional group in membrane matrix facilitates its applications in DD process. The dialysis coefficients of hydrochloric acid (UH) of the membranes are in range of 0.0016 m/h to 0.14 m/h and the separation factors (S) are in range of 2.09 to 7.32 in the HCl/FeCl2 system at room temperature. The porous membrane structure and presence of amine functional group are responsible for the mechanism of diffusion dialysis (DD).
Polyvinyl chloride (PVC) ultrafiltration membrane was prepared by blending 12 wt.% of PVC in N, N-dimethylacetimide (DMAc) with polyethylene glycol 400 (PEG400) as an additive. The influence of PEG400 concentration on the PVC membrane morphology, permeability, fouling and rejection were investigated. Fouling and rejection of the PVC membrane were characterized by dextran T-100 filtration. The results showed that membrane water flux was increased up to 682 Lm-2h-1 when 28 wt.% of PEG400 was added into the PVC membrane solution. The best membrane performance with a low fouling and a high selectivity was achieved by adding 12 wt.% concentration of PEG400, which resulted in 90% rejection of dextran and 90% of flux recovery ratio. At further addition of PEG400 concentration, irreversible fouling was starting to increase. A 90% of irreversible fouling was formed in the PVC membrane when more than 22 wt.% of PEG400 is added.
ultrafiltration; PVC membrane; additive; hydrophilic; fouling
(1) P.T.P. Aryanti, R. Yustiana, I.G. Wenten:
Chemical Engineering, Institut Teknologi Bandung, Jl. Ganesha 10, Bandung 40116, Indonesia;
(2) R.E.D. Purnama:
Production Division, PT Asahimas Chemical, Ds Gunung Sugih, Jalan Raya Anyer Km-122, Cilegon 42447, Indonesia.
Zinc and lead pollution are public environmental issues that have attracted lots of attention for a long time. Landfill leachate contains heavy metals, such as Zn(II) and Pb(II), which are usually related to thepollution of groundwater, especially in developing countries. Bentonite has been proven to be effective in enhancing the membrane property of clay, by which landfill liners can have better barrier performance towards the migration of contaminants. In this study, 5% sodium bentonite amended with locally available Fukakusa clay was utilized to evaluate the membrane behavior towards the heavy metals zinc and lead. The chemico-osmotic efficiency coefficient, ω, was obtained through Zn(II) and Pb(II) solutions with different concentrations of 0.5, 1, 5, 10, and 50 mM. According to the results,
(1) Qiang Tang:
School of Urban Rail Transportation, Soochow University, China;
(2) Takeshi Katsumi, Toru Inui:
Graduate School of Global Environmental Studies, Kyoto University, Japan;
(3) Zhenze Li:
Department of Civil Engineering, University of Ottawa, Canada.
Membrane modification by different concentrations of acrylic acid has been described. Grafting of acrylic acid to the surface of a polypropylene membrane was obtained by a Fenton-type reaction. Membrane permeability seemed to have been dependent on the value of pH in the solution. To explain tendency, a simple theoretical model was developed. The model incorporates explicitly statistical conformations of a polyacid chain grafted onto the pore surface. The charged capillary model with a varying diameter for porous membranes was then used to evaluate the permeability of the membrane. It has been shown both theoretically and experimentally that the permeability of a grafted membrane depends on the pH of the solution.
(1) Jakub M. Gac, Marta Bojarska, Izabela Stępniewska, Wojciech Piątkiewicz, Leon Gradoń:
Faculty of Chemical and Process Engineering, Warsaw University of Technology, ul. Waryńskiego 1, 00-645 Warszawa, Poland;
(2) Marta Bojarska, Wojciech Piątkiewicz:
PolymemTech Sp. z o.o., al. NiepodlegŁości 118/90, 02-570 Warszawa, Poland.
Polyvinylidene fluoride/fullerene nanoparticle (PVDF/C60) composite microfiltration (MF) membranes were fabricated by a non-solvent induced phase separation (NIPS) using N,N-dimethylacetamide (DMAc) as solvent and deionized water (DI) as coagulation solution. Polyvinylpyrrolidone (PVP) was added to the casting solution to form membrane pores. C60 was added in increments of 0.2% from 0.0% to 1.0% to produce six different membrane types: one pristine PVDF membrane type with no C60 added as control, and five composite membrane types with varying C60 concentrations of 0.2, 0.4, 0.6, 0.8 and 1.0%, respectively. The mechanical strength, morphology, pore size and distribution, hydrophilicity, surface property, permeation performance, and fouling resistance of the six membranes types were characterized using respective analytical methods. The results indicate that membranes containing C60 have higher surface porosity and pore density than the pristine membrane. The presence of numerous pores on the membrane caused weaker mechanical strength, but the water flux of the composite membranes increased in spite of their smaller size. Initial flux and surface roughness reached the maximum point among the composite membranes when the C60 concentration was 0.6 wt.%.
(1) Kyung Hee Kim, Ju Sung Lee, Hyun Pyo Hong, Jin-Won Park, ByoungRyul Min:
Department of Chemical and Biomolecular Engineering, Yonsei University, 262 Seongsanno, Seodaemun-gu, Seoul 120-749, South Korea;
(2) Jun Young Han:
Fuel Cell Research Center, Korea Institute of Science and Technology, 39-1 Hawolgok-dong, Sungbuk-gu, Seoul 136-791, Republic of Korea.