Removal of Cu(Ⅱ) from water using colloidal liquid aphrons containing amine extractants

Abstract

In this study, Cu(II) was removed from water using colloidal liquid aphrons (CLAs) made out of Trioctylamine (TOA) and Trioctylmetylammonium chloride (Aliquat 336) diluted with kerosene. Cu(II) held by complexing agent like EDTA (Ethylenediaminetetraacteic acid) was treated by CLAs containing Aliquat 336 and non-complexing Cu(II) was removed by CLAs containing TOA. Mass transfer rate of Cu(II) was enhanced by CLAs containing amine extractants. The effect of anionic surfactant Sodium Dodecyl Benzene Sulfonate (SDBS) on solute transfer from the pregnant phase to amine extractants-core was also investigated. Anionic surfactant SDBS had no significant effect on solute transfer in case of CLAs containing Aliquat 336. But, it had considerably influenced solute transfer in case of CLAs containing TOA. Especially, mass transfer rate of Cu(II) in PDSE using TOA CLAs was enhanced by both the adsorption of Cu(II) on surfactant SDBS and the increase of stability of TOA CLAs in the pregnant phase. To optimize CLAs-based process, the stability of CLAs containing Aliquat 336 in the continuous phase was investigated by UV spectrometer measurements for dilute CLAs and visual inspection for concentrated CLAs. Addition of NaCl brings about destabilization of CLAs and then the size of individual aphrons increases through coalescences and such CLAs moves upward due to the difference of density between organic solvents and surrounding medium. Therefore, the reduction of turbidity in UV measurements is related to coalescence of CLAs. Stability ratio was obtained from initial coagulation rate. Critical coagulation concentration that has no energy barriers on collisions was obtained from the plot of stability ratio with NaCl concentration. Break-up of concentrated CLAs in the continuous phase was estimated by measuring released organic solvent with time. The plot of released organic solvent with time follows second order kinetic model. The effect of pH, NaCl concentration, ionic streng...