Synthesis Of Some New Inorganic Sorbents And Their Adsorption Properties For Trace Heavy Metals

In recent years, the pollution caused by heavy metals which attracts wide public concern have become more and more serious. The rapid and sensitive determination is needed to monitor the amount of heavy metals in environmental samples. Although the optical spectroscopy has been widely used for its high sensitivity, the direct analysis is still difficult because of the high complexity of samples and severe interference caused by matrix effects. So, a pre-treatment procedure is necessary before the more accurate measurement by ICP-AES. In this paper, we mainly described the preparation of several adsorption materials based on the preconcentration and separation of trace components. The adsorption behaviors of these materials have been studied systematically and detailedly. The more detailed novelty of this research can be categorized as following:1. A new sorbent S-benzyldithiocarbazate (SBDTC) modified activated carbon was prepared and studied for preconcentration of trace Hg(Ⅱ). The experimental conditions were optimized with respect to different experimental parameters (pH, shaking time, flow rate etc.) using both bath and column procedures in details. The maximum static adsorption capacity and the detection limit of the sorbent under optimum conditions was found to be 0.55mmol g-1 and 0.09 ng mL-1. Compared with other sorbents, the more significant characteristics of SBDTC are the higher adsorption capacity and the short time equilibrating. The procedure was validated by analyzing the certified reference river sediment material (GBW 08301), the results obtained were in good agreement with standard values. This sorbent was successfully employed in the separation and pre-concentration of trace Hg(Ⅱ) from the natural water samples.2. Anew sorbent of 8-((1-methyl-2-aminoethylamino)methyl)quinoline modified activated carbon was synthesized and investigated for selective solid-phase extraction of trace Cu(Ⅱ) and Fe(Ⅲ) in solution samples. Under the optimum column conditions (pH 4, flow rate 2.0 mL min-1), Cu(Ⅱ) and Fe(Ⅲ) were adsorbed, then quantitatively eluted by 2 mL of 1 mol L-1 HNO3 and determined by ICP-AES. The adsorption capacity and the detection limit of Cu(Ⅱ) and Fe(Ⅲ) were 12.1,67.1 mg g-1 and 0.27, 0.47μg L-1, respectively. The proposed method has been validated by analyzing a certified material and applied successfully to the proconcentration and determination of Cu(Ⅱ) and Fe(Ⅲ) in actual samples with satisfied results.3. S-benzyldithiocarbazate-functionalized silica gel (SBDTC) was prepared simply, and used for separating trace Au(Ⅲ) from sample solution. Its adsorptivity was investigated from pH, eluent condition, interference, adsorption capacity, accuracy and precision and so on in detail, and optimized the conditions simultaneously. The adsorption capacity and the detection limit was found to be 0.45 mmol g-1 and 0.11 ng mL-1, respectively. The adsorption was used for selective solid-phase extraction of trace Au(Ⅲ) in aqueous solution, and the result was satisfactory.