Synthesis of rhodanine-bonded silica gel and its application in the preconcentration and separation of noble metals

A silica gel based sorbent containing rhodanine as functional group (RDSG) was prepared. Its adsorption and separation characteristics for Ag(I), Au(I II) and Pd(II) were studied by flow-injection (FI) on-line preconcentration . Influence of different experimental parameters such as acidity, eluent, c o-existing ions were investigated. Trace amounts of Ag, Au and Pd could be efficiently adsorbed by rhodanine-bonded silica gel from acidic solution an d eluted with thiourea solution. Common co-existing ions exhibited virtuall y no interference to the preconcentration and determination. The adsorption capacity of RDSG was 0.0352, 0.107 and 0.122 mmol/g for Ag, Au and Pd, res pectively. Detection limits of 0.004, 0.022 and 0.019 mu g/mL for Ag, Au an d Pd, respectively, were achieved with a sampling time of 60 s at a flow ra te of 5.0 mL/min. The relative standard deviation were 0.5%, 0.9% and 1.7% for 0.040 mu g/mL Ag, 0.200 mu g/mL Au and 0.300 mu g/ mt Pd. The sorption property did not change after 1000 cycles of sorption-desorption. The conte nts of Ag and Au in three national certified ore samples and Pd in a second ary nickel alloy, an anode slime and a CoCl2 electrolytic solution were det ermined. The results showed good agreement with the certified values.