研究了萃取剂二壬基萘磺酸(DNNSA)从磷酸介质中萃取Mg(II)的性能。考察了萃取时间、水相P2O5浓度、萃取剂浓度、初始镁离子浓度、萃取温度等因素对萃取的影响。研究表明:当萃取剂浓度为0.5mol·L-1时,混合40min后,萃取率E基本保持不变,可视为萃取过程达到平衡;该萃取过程为阳离子交换反应,磷酸浓度越高萃取越难,该法适用于低浓度磷酸的净化;萃取反应为吸热反应,计算得到了DNNSA从磷酸介质中萃取Mg(II)的过程热效应(△H1)为37.04kJ·mol-1;萃取分配比随萃取剂浓度的增加而增大,这说明萃取的镁离子不是简单地增溶入DNNSA的反胶团,而是与反胶团发生了化学反应。用Levenberg-Marquardt算法进行非线性回归拟合确定了萃合物的组成为MgD2·6HD,萃取的表观平衡常数(K)为59.60。
The solvent extraction of magnesium from phosphoric acid with dinonylnaphthalene sulfonic acid (DNNSA) as extractant was proposed, and the effects of extraction temperature and time, concentration of phosphoric acid and initial magnesium concentration on the extraction were studied. It was found that the extraction mechanism of DNNSA is a cation exchange reaction, and the magnesium ions are not simply solubilized into the water pools in the DNNSA reverse micelles. There are chemical reactions occurring betw...