Preparation Of Novel Adsorbents For The Adsorption Of Heavy Metal Ions

In this paper, a series of studies were conducted, which were mainly about thepreconcentration and determination of heavy metals with adsorption. With the rapiddevelopment of modern industry, environmental pollution caused by heavy metal ionsis increasingly serious. Their toxic properties and bio-accumulation in the food chainmay deteriorate inhabited environment and endanger human health. Thedetermination of trace heavy metals plays an important role in the environmentalpollution monitoring. Because the samples are often complex, there is a considerableneed for the separation and preconcentration of trace elements before their analysis.Among the several methods, the adsorption process is considered as one of the mosteconomical and efficient techniques in the viewpoint of simple design andenvironmental friendly. In this study, two novel adsorption materials were synthesizedin order to preconcentrate and separate trace heavy metal ions. The effects ofexperimental variables were investigated. The detailed items are as followings.1. Graphene-TiO₂（GN-TiO₂） composites were synthesized and employed for theadsorption of Pd（II） from an aqueous solution. Parameters affecting theadsorption of Pd（II）, including the mass ratio of TiO₂and GN, sample pH,adsorbent amount, and ion strength, were studied in detail. The adsorptionisotherm, kinetics, and thermodynamics were also studied.2. GN-TiO₂was used as a sorbent and coupled with graphite furnace atomicabsorption spectrometry （GFAAS） for the adsorption and determination of Pb（II）and Cd（II） from samples. Parameters affecting the adsorption capacity, includingsample pH, adsorbent amount, and ion strength, were studied in detail. Theadsorption kinetics and thermodynamics were also studied. The method was used for the determinations of Pb（Ⅱ） and Cd（Ⅱ） in tea samples.3. Fe₃O₄@SPEK was one-step prepared with hydrothermal method and used for themicrocolumn filler material. The packed microcolumn was hyphenated to flameatomic absorption spectrometry （FAAS） to determinate chromium. The adsorptionof Cr（Ⅲ） and Cr（Ⅵ） was compared at different pH values. Several experimentalparameters which affect the retention and elution of Cr（Ⅲ）, such as sampleloading time, sample flow rate, eluent concentration, and eluent flow rate, wereaslo investigated and optimized. In addition, the developed procedure wassuccessfully employed to the determination of trace chromium in capsule shellsamples.