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ABSTRACT: In this work, the surface characteristics of poly(N-vinyl-2-pyrrolidone) (PNVP)-modified nonwoven fabric (NWF) membranes and the effects of the surface characteristics on the membranes antifouling properties were investigated. Effects of grafting time, grafting temperature, and monomer concentration on the grafting degree of PNVP were systematically investigated. The effect of grafting degree on the surface characteristics was also investigated. Scanning electron microscopy (SEM) was used to characterize the structural and morphological changes on the membrane surface. The water contact angles decreased from 113±1.2° to 52±3°, which means that the hydrophilicity of the modified NWF was enhanced with increasing PNVP grafting degree. The surface free energy was calculated, which showed an increase after modification. Static bovine serum albumin (BSA) adsorption experiments were carried out, which showed a decrease of 82.5%. Permeation experiments of water and supernatant solution of active sludge were carried out to determine the antifouling characteristics against the extracellular polymeric substance. Results demonstrated that the modified NWF had higher permeation fluxes and lower flux loss in comparison with the original NWF. Bacterial adhesion on the membrane surface was largely suppressed after the introduction of PNVP.
Journal of Colloid and Interface Science 02/2011; 357(2):273-9. · 3.07 Impact Factor
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ABSTRACT: To prepare a high flux and antifouling filtration membrane used for submerged membrane bioreactors, non-woven fabric (NWF) was modified by coating chitosan (CS) on both internal and outer surface. Chemical structural and morphological changes were characterized. The changes of surface free energy were monitored by dynamic contact angle, which showed an increase after modification. The CS/NWF composite membranes were found to be with high flux, high effluent quality and excellent antifouling property. The results of fouling resistance distribution indicated that irreversible fouling resistance was decreased by coating CS. Especially, there were fewer gel layers existing on the outer surface. The adsorption of EPS on the NWF membrane internal surface decreased after being coated with CS. Modification improved filtration performance, and made fouling less troublesome and membrane regeneration efficient.
Bioresource technology 03/2010; 101(14):5469-74. · 4.25 Impact Factor
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ABSTRACT: Ultrafiltration (UF) pretreatment and reverse osmosis (RO) were used to treat the blowdown water from circulating cooling water system. The UF product water meets the requirements as RO feed water. To optimize the operation of cooling water system with UF–RO and to ensure a satisfactory cooling water quality within the JRA (Japan Refrigeration and Air Conditioning Industry Association) water standard, a reasonable concentration factor was determined. The results suggest that when the concentration factor was maintained at 1.3, the cooling water could meet the JRA water standard, and the makeup tap water rate was minimal. Calculated Langelier saturation index (LSI) and electrochemical measurements indicate that cooling water had a very slight scaling tendency, and would not cause corrosion. Finally, a comparative cost analysis between applying UF–RO treatment and adding chemical inhibitors in cooling water system was carried out, it is concluded that applying UF–RO in air conditioning circulating cooling water system is more economical.
Desalination 02/2010; · 2.59 Impact Factor
