摘要
采用界面积恒定的连续搅拌萃取池,研究在乳酸存在条件下,以用Petrofin 稀释的二-2-乙基己基磷酸(DEHPA)作萃取剂从硝酸盐介质中萃取分离La(Ⅲ)与Ni(Ⅱ)的动力学。考察搅拌速度、界面积、pH 值、乳酸浓度、萃取剂浓度、金属离子浓度和温度对萃取速率的影响。结果表明,该萃取体系是受扩散控制的,界面反应为速率控制步骤。两种金属离子的萃取速率均与pH 值无关。La(Ⅲ)和Ni(Ⅱ)的萃取速率与乳酸浓度和金属离子(La(Ⅲ)或Ni(Ⅱ))浓度呈线性关系。La(Ⅲ)的萃取速率与DEHPA 浓度呈线性关系,而Ni(Ⅱ)的萃取速率则与DEHPA 浓度的1.5 次方呈线性关系。在低界面积和低搅拌速度的条件下,从硝酸盐溶液中分离La(Ⅲ)和Ni(Ⅱ)是可行的。
The kinetics of extractive separation of La(Ⅲ) and Ni(Ⅱ) from nitrate medium in the presence of lactic acid (HLac) using di-2-ethylhexyl phosphoric acid (DEHPA) diluted in petrofin was investigated using a cell with constant interfacial area and continuous stirring. The effects of stirring speed, interfacial area, pH, HLac concentration, extractant concentration, concentrations of metal ions and temperature on the extraction rate were examined. Results suggested that the extraction regime is diffusion-controlled. The reaction which occurred at the interface was found to be the rate-determining step. The extraction rates of both metal ions are found to be independent of pH. The extraction rates of La(Ⅲ) and Ni(Ⅱ) are first-order dependent with respect to lactic acid and metal ions (La(Ⅲ) and Ni(Ⅱ)) concentrations. The extraction rate of La(Ⅲ) is first-order dependent on DEHPA concentration and for Ni(Ⅱ), it varies to the power of 1.5. The separation of La(Ⅲ) and Ni(Ⅱ) from nitrate solution is possible at low interfacial area and low stirring speed.
基金
DST, Govt. of India for the award of INSPIRE fellowship
