The extractant tri-n-octylamine （TOA） was encapsulated in calcium alginate （CaALG） xerogel polymer matrices and the selective separation of Au（III） ions in HCI solution was investigated. The features of the TOA ...The extractant tri-n-octylamine （TOA） was encapsulated in calcium alginate （CaALG） xerogel polymer matrices and the selective separation of Au（III） ions in HCI solution was investigated. The features of the TOA microcapsules （TOA-MCs） were examined using DM, SEM/EDS and EPMA. The adsorption and elution properties of Au（III） were studied by the column method using spherical and highly porous TOA-MCs. The uptake properties of precious metals （Au（IIl）, Pt（IV）, and Pd（II）） were examined by the batch method using TOA-MCs in different concentrations of hydrochloric acid （HCI） solution. The order of uptake （%） of the precious metals was Au（III） 〉 Pt（IV） 〉 Pd（II）. TOA-MCs have strong affinity towards Au（III） in HCI solution. The uptake （%） of Au（III） by TOA-MCs was estimated to be -100% and equilibrium was attained within 1 hour. The breakthrough and elution behaviors of Au（III） were examined by varying the Au（III） concentration in the feed, flow rate, reaction temperature, and eluent concentration. The Au（IlI） in 1 M HCI solution was effectively extracted with TOA-MCs in the column operation. The breakthrough curve showed the S-shaped profile and no dislodgement of TOA from the matrices of CaALG. The breakthrough curve rose steeply and the uptake of Au（IIl） was fairly fast, which indicated a relatively high uptake rate of Au（III） in TOA-MCs. The break point （5% breakthrough） and breakthrough capacity （B. T. Capacity） were estimated to be 82 cm3 and 0.60 mmol/g, respectively. The total capacity （T. capacity） was estimated to be 1.30 mmol/g, which was considerably larger than those of conventional resins. The elution properties of Au（Ill） were studied by varying the concentration of thiourea （0.025 M-1 M） in 1 M HC1 solution. The retention volume （VR, cm3） tended to decrease with the increase in thiourea （TU） concentration. The loaded Au（III） ions were successfully eluted （- 100%, total elution percentage） by the eluent of TU （0.5 M） in HC1 （1 M） solution. The alginate gel microcapsules enclosing TOA extractant were thus effective for the selective separation and recovery of Au（IIl） ions in HCI solution.展开更多
文摘The extractant tri-n-octylamine （TOA） was encapsulated in calcium alginate （CaALG） xerogel polymer matrices and the selective separation of Au（III） ions in HCI solution was investigated. The features of the TOA microcapsules （TOA-MCs） were examined using DM, SEM/EDS and EPMA. The adsorption and elution properties of Au（III） were studied by the column method using spherical and highly porous TOA-MCs. The uptake properties of precious metals （Au（IIl）, Pt（IV）, and Pd（II）） were examined by the batch method using TOA-MCs in different concentrations of hydrochloric acid （HCI） solution. The order of uptake （%） of the precious metals was Au（III） 〉 Pt（IV） 〉 Pd（II）. TOA-MCs have strong affinity towards Au（III） in HCI solution. The uptake （%） of Au（III） by TOA-MCs was estimated to be -100% and equilibrium was attained within 1 hour. The breakthrough and elution behaviors of Au（III） were examined by varying the Au（III） concentration in the feed, flow rate, reaction temperature, and eluent concentration. The Au（IlI） in 1 M HCI solution was effectively extracted with TOA-MCs in the column operation. The breakthrough curve showed the S-shaped profile and no dislodgement of TOA from the matrices of CaALG. The breakthrough curve rose steeply and the uptake of Au（IIl） was fairly fast, which indicated a relatively high uptake rate of Au（III） in TOA-MCs. The break point （5% breakthrough） and breakthrough capacity （B. T. Capacity） were estimated to be 82 cm3 and 0.60 mmol/g, respectively. The total capacity （T. capacity） was estimated to be 1.30 mmol/g, which was considerably larger than those of conventional resins. The elution properties of Au（Ill） were studied by varying the concentration of thiourea （0.025 M-1 M） in 1 M HC1 solution. The retention volume （VR, cm3） tended to decrease with the increase in thiourea （TU） concentration. The loaded Au（III） ions were successfully eluted （- 100%, total elution percentage） by the eluent of TU （0.5 M） in HC1 （1 M） solution. The alginate gel microcapsules enclosing TOA extractant were thus effective for the selective separation and recovery of Au（IIl） ions in HCI solution.
