Spent caustic treatment using hydrophobic room temperatures ionic liquids

Two hydrophobic room temperature ionic liquid (IL), tetrahexylammonium dihexyl-sulfosuccinate (IL1) and trioctylmethylammonium salicylate (IL2), have been employed for the treatment of spent caustic (SC) wastewater by liquid-liquid extraction at room temperature and pressure. The concentrations of phenols, thiols and benzaldehyde were reduced to below their detection limits and the chemical oxygen demand (COD) levels were reduced from 64166 ± 3880 mg/l to 63.0 ± 9.0 mg/l. This represents an outstanding reduction in pollutant and COD levels to well below the discharge limits for industrial effluents as set by U.S.A. Environmental Protection Agency (EPA) regulations, thus eliminating the need for any further treatment before discharge.