Study On Adsorption Properties And Application Of Nanocomposite Material TiO₂/SiO₂for Trace Lead, Cadmium, Copper

On the basis of numerous references, nanocomposites TiO₂/SiO₂were preparedby sol-gel method and modified by dithizone （DZ）. We used it as solid phaseadsorbent, with flame atomic absorption spectrometry as determination method, theperformance of adsorption for the trace lead, cadmium and copper was systematicallystudied. A new simple, rapid and accurate with high efficiency and sensitivity methodfor determination of trace harmful element was developed. The major contentsdescribed as follows:1. This paper summarized the practical significance of the determination of traceheavy metals lead, cadmium and copper. It also introduced the determination methodof heavy metals, and the materials and methods of separation/preconcentration oftrace heavy metals. The application of separation/preconcentration by nano-titaniumdioxide and its composites were also described. Nanocomposites TiO₂/SiO₂asseparation/preconcentration material of solid-phase extraction was propose.2. Nanocomposites TiO₂/SiO₂was prepared by sol-gel method. Then thecharacterization of the synthesized material was performed by SEM, IR and Nitrogenadsorption-desorption. The adsorption behavior of trace lead ions on nanocompositesTiO₂/SiO₂was studied and the adsorption mechanism was also discussed. The staticsaturated adsorption capacity was4.8mg/g. The detection limit （3σ） of this methodwas22.9μg/L and the RSD was1.2%. The proposed method was applied todetermination of trace lead in slag samples with satisfactory results.3. With dynamic conditions through the self-made separation column, a methodwas developed for enrichment and determination of trace cadmium usingnanocomposites TiO₂/SiO₂as stationary phase and flame atomic absorptionspectrometry （FAAS） as determination. The dynamic saturated adsorption capacitywas30.0mg/g. The detection limit was15.2μg/L （3σ, n=11） and the RSD was2.6%.Under the optimized experimental conditions, the proposed method was applied todetermination for trace cadmium in environmental waters with recoveries between96.0%and106.5%.4. Modified nanocomposites TiO₂/SiO₂was prepared by surface modificationwith dithizone （DZ）. Based on these separation/preconcentration materials, a newmethod for determination of trace copper with FAAS was proposed. The experiment conditions were discussed. The static saturated adsorption capacity was6.1mg/g. Thelinear range for trace copper was0.05⁵.0mg/L, detection limit （3σ） of this methodwas1.06μg/L. The RSD was1.8%. The proposed method was applied todetermination of trace copper in Chinese herbal medicine samples with satisfactoryresults.5. Flow injection preconcentration with FAAS hyphenated technique, theadsorption behavior of trace lead was studied using a micro-column packed withmodified nanocomposites TiO₂/SiO₂. The optimal conditions of adsorbing anddesorbing on this material for lead ions were investigated. The method was applied tothe determination of trace Pb²⁺in environmental water samples with satisfactoryresult.