萃取净化废水中镉的动力学研究

Study on kinetics of extraction of cadmiun from wastewater

采用恒界面池研究了二壬基萘磺酸(简称DNNSA或HD)-煤油体系萃取废水中镉离子的动力学。考察了搅拌转速、二壬基萘磺酸浓度、镉离子浓度和温度对萃取速率的影响,并得到了DNNSA萃取废水中镉离子的萃取动力学方程。实验结果表明,镉离子的萃取速率在200 r/min时出现与搅拌强度无关的化学反应动力学"坪区",FT-IR结果表明,反应产物为磺酸盐;在动力学"坪区",镉离子萃取速率随着萃取剂浓度、水相中的镉离子浓度增加而增加;随着温度升高,萃取速率增加,萃取活化能为11.8 kJ/mol。

Kinetics of Cd （ Ⅱ ） extraction by dinonylnaphthalene sulfonic acid （DNNSA） in kerosene from wastewater were investigated using a Lewis Cell. The different parameters affecting the extraction rate such as stirring speed, DNNSA concentration, Cd （ Ⅱ ） concentration and temperature were separately studied. An ex- traction rate equation was put forward. When stirring speed is more than 200 r/min, there is a chemical reaction kinetic region where the extraction rate of Cd （Ⅱ ） is independent of the stirring speed. The experimental results demonstrate that the extraction rate of Cd （ Ⅱ） is controlled by a chemical reaction at the interface rather than in the bulk phase. IR spectra results confirm that cadmium ions reacted with dinonylnaphthalene sulfonic acid and formed the sulfonates. In the kinetic region, the rate of Cd （Ⅱ） extraction is apparently proportional to the con- centration of Cd （ Ⅱ） and DNNSA. Moreover, the extraction rate also increases with the increase of extraction temperature. The activation energy of extraction was calculated to be 11.8 kJ/mol.