Preparation Of Polyvinyl Alcohol Nanospheres (PVA-NS) And Performance Research Of Modified Membranes

The membrane Bioreactors (MBR) have become a kind of new waste water treatment and reuse technology, which have comprehensive and potential applications. However, the high cost of membrane module, short lifetime of usage and the severity of pollution have limited the wide applications of MBR. Therefore, developing low-priced membrane material will be important for membrane running long and effectively and wide extension.This paper introduces an approach for preparation of polyvinyl alcohol nano-spheres (PVA-NS) using micro-emulsion polymerization. Polypropylene non-woven fabric (NWF) was used as original membrane, then prepared two kinds of hydrophilic membranes by deposition and self-assembly. The preparation conditions, characterization and antifouling property of deposited and self-assembly membranes were investigated. Results are shown as follows:(1) The performance of prepared PVA-NS:the smallest size is 225nm, the static contact angle is 0°, Zeta potential is-51.4mV.(2) The preparation condition of PVA-NS:HLB=8.38, the ratio of Span 80 and OP-10 was 6:4, the mass fraction of surfactant was 20% and the aimed cross-linking degree was 80%.(3) The Zeta potential value of HTAB/PVA-NS self-assembly membrane under the comdition of pH 8±0.2 was the maximum,-22.4mV. The results of dynamic contact angle indicated:the dynamic contact angle of PVA-NS deposited and HTAB/PVA-NS self-assembly membranes were less than original membrane, which indicated PVA-NS could improve the hydrophilic performance of NWF evidently.(4) BSA static adsorption experiment investigated the membrane fouling circumstance of membrane surface and protein interaction. Compare with original membrane, BSA static adsorption amount of deposited and self-assembly membranes reduced 52.84% and 79.73%, respectively. After the modification of PVA-NS, NWF could restrain the adsorption of BSA effectively and improve the anti-fouling performance of NWF largely.In the experiment of activated sludge filtration, RFR has reduced to 87.71% and 79.87% of deposited and self-assembly membranes from 98.89% of original membrane, which indicated the anti-fouling performance of PVA-NS modified membrane has been improved. The reversible part of RFR (RFRr) of modified membrane took large proportion and the irreversible part (RFRir) took small proportion, which illustrated the flux decrease was prone to recover.FRR of modified membranes were larger than original one, self-assembly membrane after backwashing by deionized water was susceptible to recover, which indicated the anti-fouling performance of self-assembly membrane was strongest.(5) In the backwash experiment of modified membranes, both pure water flux and dynamic contact angle didn't have significant change, which indicated the stability of self-assembly membrane was better than deposited one.