Evaluation of methylene blue and rose bengal for dye sensitized solar water treatment

The experimental work described in this paper evaluated the efficacy of dyes as sensitizing agents for solar photochemical detoxification and disinfection of water Methylene blue and rose bengal were evaluated as photosensitizing agents. While neither dye was effective for detoxification, methylene blue showed some efficacy,for photodisinfection over natural sunlight. In all sunlight experiments, methylene blue effected a coliform reduction ranging from 96% at pH 7 and lower methylene blue concentrations, to 99.5% for all concentrations at pH 10 and the 10 mg/L concentration for pH 7. The 99.5% reduction at pH 7 is comparable to 74% reduction at the same pH using sunlight alone. Significant coliform reduction was also observed in dark experiments with 10 mg/L of methylene blue.