Removal of Reactive Red 195 dye from textile industry wastewater with Deep Eutectic Solvent-based green extraction

Abstract

High water usage, considerable environmental pollution, and toxicity to humans associated with textile dyeing and resulting wastewater effluent has led to the development of various environmentally-sustainable alternatives to current effluent treatment approaches. One of the biodegradable and low-cost emulsion liquid–liquid microextraction (ELLM) techniques is Deep Eutectic Solvents (DES). Herein, the removal efficiency of the Reactive Red 195 (RR195) dye from aqueous solutions by a choline chloride and phenol-based deep eutectic solvent was evaluated. The influence of relative amounts of solvent, sample, and emulsifier were tested alongside that of dye concentration, pH, and addition of various salts typically found in effluent. At optimal conditions of 25 µL of chloroform emulsifier and 600 µL of deep eutectic solvent per 5 mL of sample, the dye removal efficiency exceeded 99 % and was unaffected by dye concentration (up to 20,000 mg L−), salt addition (chloride, sulphate, and nitrate salts), and variations in pH (from 2 to 10). © 2024 Elsevier B.V.