Selective separation of Hg(II) and Cd(II) from aqueous solutions by complexation-ultrafiltration process.
Complexation-ultrafiltration process was investigated to separate selectively Hg(II) and Cd(II) from binary metal solutions by using poly (acrylic acid) sodium salt as a complexing agent. Effects of operating parameters on selective separation factors (beta(Cd/Hg)) of the both metals have been examined in detail. Results indicated that loading rate, pH, concentration of salt added and low-molecular competitive complexing agent affect significantly beta(Cd/Hg) value. Further, a concentration experiment was carried out according to the previous optimum parameters. Rejection coefficient of mercury is close to 1, while that of cadmium is about 0.1. The experiment was characterized by good effectiveness, and enabled the rapid linear increase of mercury concentration and very slow increase of cadmium concentration in the retentate. Then, a diafiltration technique was applied to separate further the both metals. Cadmium concentration in the retentate declines sharply with the diafiltration volume, whereas for mercury it is the contrary.
Zeng
Jian Xian
JX
College of Chemistry and Chemical Engineering, Hunan University of Science and Technology, Xiangtan 411201, PR China. zengjianxian@163.com
Ye
Hong Qi
HQ
Huang
Nian Dong
ND
Liu
Jun Feng
JF
Zheng
Li Feng
LF
D000180:Acrylic Resins / Q000737:chemistry; D001667:Binding, Competitive; D002104:Cadmium / Q000737:chemistry / Q000302:isolation & purification*; D006863:Hydrogen-Ion Concentration; D008628:Mercury / Q000737:chemistry / Q000302:isolation & purification*; D012492:Salts / Q000737:chemistry; D012996:Solutions; D013379:Substrate Specificity; D014462:Ultrafiltration; D014867:Water / Q000737:chemistry*
D000180:Acrylic Resins; D012492:Salts; D012996:Solutions; D002104:Cadmium; D014867:Water; C006903:carbopol 940; D008628:Mercury