Preparation of xylenol orange functionalized silica gel as a selective solid phase extractor and its application for preconcentration—separation of mercury from waters

摘要

A new selective solid phase extractor was prepared from silica gel modified with xylenol orange (SGMXO). The solid phase extractor is stable in 6 mol L~(-1) HCl, common organic solvents, and pH 1.0-9.0 buffer solutions. In the batch experiments, Hg(Ⅱ) can be adsorbed on SGMXO at pH 1.0 with 90.0% retention, whereas the retention of other common coexisting metal ions such as Cd(Ⅱ), Pb(Ⅱ), Cu(Ⅱ), Ni(Ⅱ), Co(Ⅱ), Mn(Ⅱ), Zn(Ⅱ), and Fe(Ⅲ) is less than 4.1%.. The adsorption equilibration for Hg(Ⅱ) was achieved within 3 min. At optimum conditions, the adsorption capacity of the extractor is 18.26 μmol g~(-1) of dry modified silica gel, and the preconcentration factor is as high as 333. The recovery is still higher than 95% for the preconcentration of 10 ng mL~(-1) Hg(Ⅱ). The new solid phase extractor has been used for the preconcentration of low level of Hg(Ⅱ) in surface water, tap water in chemistry laboratory and student's dormitory and a simulated sea water samples, recoveries of 98.2-100.6% were obtained. It is showed that low level of Hg(Ⅱ) can be effectively preconcentrated by this new selective solid phase extractor.