title: Selective separation of Hg(II) and Cd(II) from aqueous solutions by complexation-ultrafiltration process.
abstract: 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.
authors.affiliation: College of Chemistry and Chemical Engineering, Hunan University of Science and Technology, Xiangtan 411201, PR China. zengjianxian@163.com
authors.forename: Jian Xian
authors.initials: JX
authors.lastname: Zeng
authors.forename: Hong Qi
authors.initials: HQ
authors.lastname: Ye
authors.forename: Nian Dong
authors.initials: ND
authors.lastname: Huang
authors.forename: Jun Feng
authors.initials: JF
authors.lastname: Liu
authors.forename: Li Feng
authors.initials: LF
authors.lastname: Zheng
mesh_terms: 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*
chemical_list: D000180:Acrylic Resins; D012492:Salts; D012996:Solutions; D002104:Cadmium; D014867:Water; C006903:carbopol 940; D008628:Mercury