Synthetic polymer delivery system. Sustained release of persulfate during the photo-oxidation of an azo-dye

A synthetic delivery system based on the copolymer ethylene vinyl-acetate ( from now on EVA-polymer) and the carrier, bovine serum albumin (from now on BSA) were prepared by polymer dissolution in the presence of persulfate. T his system acted as a long-term polymer release device, cleaning aqueous so lutions containing Orange II under visible light irradiation. The polymer a nd the carrier used were found to be inert and the observed oxidation was o nly due to persulfate. As expected, the higher initial loadings of persulfa te deliver a higher amount of oxidant, leading to a faster photo-degradatio n of Orange II. The decoloration of Orange II by persulfate only occurred u nder visible light irradiation suggesting a dye sensitized process. The per sulfate release during the reaction was sufficient to decolore amounts of O range II, usually found in large water bodies (similar to 50 mg C/l). Disks of EVA-persulfate were used in conjunction with light increasing the relea se performance of the synthetic delivery system. The addition of BSA can be selective in order to regulate the release of persulfate in the delivery s ystem. The synthetic polymer delivery system was reused over many cycles, s ince, the polymer delivery system could be retrieved after each cycle. The repetitive use of the persulfate based disks have implications for the long -term detoxification of contaminated water, opening the way for new applica tions that are not possible by simple addition of persulfate-ions in homoge neous solutions. (C) 2000 Elsevier Science S.A. All rights reserved.