Comparison of two photosensitizers Al(III) phthalocyanine chloride tetrasulfonic acid and meso-tetrakis(4-sulfonatophenyl)porphyrin in the photooxidation of n-butylparaben

A visible light-sensitized oxidation of endocrine disrupter–n-butylparaben (BP) in the presence of Al(III) phthalocyanine chloride tetrasulfonic acid and meso-tetrakis(4-sulfonatophenyl)porphyrin photosensitizers was studied. The major role of singlet oxygen in BP degradation was proved by the experiments performed in the presence of hydroxyl radicals scavengers and singlet oxygen quenchers. Direct interactions between BP and triplet state of both were investigated using time resolved technique. The rate constants of singlet oxygen quenching by BP in D2O buffer (pD 7, 9 and 10.8) for TPPS4 and AlPcS4 were determined. The efficiencies of BP photodegradation applying both photosensitizers were compared under various process parameters i.e. initial photosensitizer concentration, oxygen content and pH of reaction solution.