A FUNDAMENTAL STUDY ON SOLUBILITY OF HEAVY METAL OXIDES IN AMMONIUM AND PHOSPHONIUM BASED DEEP EUTECTIC SOLVENTS

Water pollution has become increasingly prevalent in our daily lives and has caused a serious threat at a global level. Among the various pollutants that exist, heavy metal pollution has become an issue of great concern due to their high toxicity, greater bioaccumulation in human body and food chain, non-biodegradability nature, and carcinogenic effects to humans. This study aims to address the heavy metal ion contamination in wastewater by providing a low cost and efficient removal technique using DESs. In this investigation, the solubility of CuO and ZnO heavy metal oxide ions with concentration of 20g/L was studied in ammonium and phosphonium based DESs. The samples were left to stir at 250 rpm at 28, 45 and 65 degrees C respectively for four hours in an incubator orbital shaker and the solubility of the heavy metal ions were analysed using Atomic Absorption Spectrometer (AAS) using serial dilution technique. Phosphonium based DES which contain Methyl Triphenyl Phosphonium Bromide (MTPB) showed higher solubility of CuO and ZnO ions. Based on the results obtained, DES 6 (MTPB: Glycerol) has the highest solubility of CuO, 0.197 mg/L at 65 degrees C and the solubility of ZnO was found to be the highest in DES 7 (MTPB: Glycerol), 1.225 mg/L at 65 degrees C. Higher solubility was observed in samples containing ZnO as they are more ionic compared to CuO.