Effect of Complexing Agents on Extractive Separation of Cd(II) and Ni(II) from Acidic Sulfate Solution Using D2EHPA

探討添加錯合劑對以D2EHPA溶劑淬取分離硫酸水溶液中鎘鎳離子之影響

林素霞(Su-Hsia Lin) ； 黃建璋(Chian-Chang Huang)

《桃園創新學報》 33期 (2013/12) Pp. 389-406

摘要

Extractive separation of Cd^(2+)/Ni^(2+) from aqueous sulfate solutions with water-soluble complexing agents of ethylenediaminetetraacetic acid (EDTA), iminodiacetic acid (IDA) and citrate using di-2-ethylhexyl phosphoric acid (D2EHPA) in kerosene was experimentally studied at 303 K. Experiments were carried out as a function of initial aqueous pH (2.0-6.0), the concentration ratio of complexing agent to the metal (0.5-1.5), the concentration of extractant and stripping acidities. It was shown that the extraction selectivity strongly depended on solution pH and was not completely related to the affinity of any metal with the complexing agents. When a certain level of complexing agent was present, highly effective separation could be achieved at an appropriate pH range, e.g., pH 4-5.5 with EDTA). The co-extraction of nickel was highly reduced by adding EDTA with α≥1. The application potential of this method was highlighted for the separation of Cd^(2+) from binary mixtures in the presence of trace amount of Ni^(2+) due to its high selectivity and the smaller amount of the complexing agents needed.

關鍵字

萃取分離 ； 錯合劑 ； 萃取劑D2EHPA ； 鎘鎳離子分離

並列摘要

Extractive separation of Cd^(2+)/Ni^(2+) from aqueous sulfate solutions with water-soluble complexing agents of ethylenediaminetetraacetic acid (EDTA), iminodiacetic acid (IDA) and citrate using di-2-ethylhexyl phosphoric acid (D2EHPA) in kerosene was experimentally studied at 303 K. Experiments were carried out as a function of initial aqueous pH (2.0-6.0), the concentration ratio of complexing agent to the metal (0.5-1.5), the concentration of extractant and stripping acidities. It was shown that the extraction selectivity strongly depended on solution pH and was not completely related to the affinity of any metal with the complexing agents. When a certain level of complexing agent was present, highly effective separation could be achieved at an appropriate pH range, e.g., pH 4-5.5 with EDTA). The co-extraction of nickel was highly reduced by adding EDTA with α≥1. The application potential of this method was highlighted for the separation of Cd^(2+) from binary mixtures in the presence of trace amount of Ni^(2+) due to its high selectivity and the smaller amount of the complexing agents needed.

並列關鍵字

Separation Extraction ； Complexing Agents ； D2EHPA ； Cd(II) and Ni(II) ； EDTA