Treatment of wastewater contaminated with ionic dyes: Liquid-liquid extraction induced by reversed micelle followed by photodegradation

The main focus was the improvement of clarification of the wastewater effluent contaminated with dyes by liquid-liquid extraction induced by reverse micelle followed by phototreatment. Methylene blue as model of cationic dye and sodium dodecyl sulphate as anionic surfactant in isoamyl alcohol (immiscible organic solvent toward water) were used. The operation conditions were studied with statistic methodologies. Percentage efficiency and rate of the clarification were used as response. The main experimental parameter was the proportion of alcohol:water, however above 33% of alcohol the responses were not so different. It is reached more than 96% of water clarification with t(1/2) of 46 min. The presence of alcohol remaining in the clarified water was eliminated by photodegradation as demonstrated by GC MS and by Artemia salina test. One of the key achievements was the recovery of the isoamyl alcohol after the clarification. This dyed alcohol isolated from clarified water was treated using small amount of inorganic acid. This recycled organic solvent was successfully reused to treat new wastewater and this cycle of clarification/recycling was repeated several times. This dye extraction from wastewater by reversed micelles is already described however the present work improves the overall processes making it economically and environmentally attractive.