Green removal of low and high levels of Cu(II) and Cr(III) cations from concentrated saline chloride medium achieved by a mixture of N,N′-bis(salicylidene)-thiocarbohydrazide-TritonX-100 micellar system via cloud point extraction process

Abstract In this work, we performed the cloud point extraction with low and high concentrations of Cu(II) and Cr(III), two particularly toxic metallic pollutants, that have been shown to have adverse effects on human health and the environment. Removal of the metal ions was achieved in the presence of Triton X-100 as a non-ionic surfactant and N,N′-bis(salicylidene)-thiocarbohydrazide as a chelating ligand in concentrated chloride medium. The behavior of the Schiff base was initially investigated in homogeneous DMSO-water and micellar Triton X-100-water media. The obtained values of the acid constants show that the extractant is more acidic in micellar media than in pure aqueous medium. The recorded cloud point temperatures of Triton X-100 are significantly impacted by the sodium chloride concentration, the surfactant concentration, and the Schiff base ligand. Under the optimised experimental conditions, a quantitative extraction of Cu(II) and a maximum extraction rate of 74 % of Cr(III) were obtained. The reduction of the metal concentration from 10−3 mol L−1 to 10−6 mol L−1 resulted in a reduction of the temperature by 10 °C and a reduction of the contact time from 10 h to 3 h.