Electrodialytic extraction of zinc(II) by the di(2-ethylhexyl)phosphoric acid – based liquid membranes
A novel process for the removal of zinc(II) ions by the liquid membranes during galvanostatic electrodialysis accompanied by electrodeposition of the metal in the catholyte is studied. Solutions of di(2-ethylhexyl)phosphoric acid (D2EHPA) with admixtures of tri-n-octylamine (TOA) in 1,2-dichloroethane were used as the liquid membranes. The effects of electrodialysis current density, composition of the aqueous solutions and organic liquid membranes on the metal ion extraction, transfer and electrodeposition rates were studied. The fine-grained zinc electrodeposits were obtained when deposited from hydrochloric, sulphuric, perchloric and acetic acid solutions. It is shown that a practically complete (> 99.9%) extraction of zinc(II) ions from the feed solution containing 0.01 М ZnSO4 by the liquid membranes is achieved during 1 – 2.5 h of electrodialysis. The maximum stripping degree of 98% and the maximum electrodeposition degree of 78% were obtained. It is demonstrated that the shape of the voltage – time diagrams can be used to evaluate the completeness of the zinc(II) removal from the feed solution.
Date
01.11.2018.
Keywords
zinc, liquid membrane, electrodialysis, electrodeposition, di(2-ethylhexyl)phosphoric acid
