[Preparation and characterization of polyvinyl alcohol microsphere pre-coated dynamic membranes]

To alleviate membrane fouling and reduce the price of membrane module, polyvinyl alcohol microsphere pre-coated dynamic membranes (PVA-MS/PCDMs) were investigated detailedly. It was prepared when the polyvinyl alcohol microsphere of the pre-coated reagent deposited on the surface and entered the pores of porous substrate common filter cloth which was low-cost by means of circulatory filtration. The morphology and structure of PVA-MS/PCDMs were examined using scanning electron microscope (SEM), and approximate maximal separated aperture, water contact angle, pure water permeation resistance and relative Zeta potential of the membrance surface were also determined. The results showed that pure water permeation resistance of PVA-MS/PCDMs was between 0.64 x 10(10) m(-1) and 3.84 x 10(10) m(-1) and the approximate maximal separated aperture reached microfiltration level. The hydrophilicity of PVA-MS/PCDMs increased with increasing PVA-MS pre-coated mass. The relative Zeta potential of the PVA-MS/PCDMs, which were measured using 0.01 mol x L(-1) KCl solution, pH 8.0 +/- 0.2 and at 20 degrees C, reached a peak value of -36.4 mV with pre-coated mass of 15.7 g x m(-2) PVA-MS on the membrance surface. In addition, evolutions of PVA-MS/PCDMs flux versus time were investigated using a 4 hours short-term filtration experiment at 9.5 kPa in an SMBR and the permeability coefficient of PVA-MS/PCDMs were measured by the extracellular polymeric substances (EPS) diffusion experiments. Results indicated that the PVA-MS/PCDMs presented dramatically high anti-fouling characteristics when the pre-coated mass of PVA-MS was 23.9-61.9 g x m(-2).