| Hexavalent chromium (Cr(â…¥)) has been regard as one of the highly toxic heavy metals. In recent years, with the development of human mining, smelting, processing and commercial manufacturing and other industrial activities, large amounts of chromium was introduced into water and organism through the migration, transformation and enrichment etc. in the ecosystems. Chromium which infiltrates cells in the form of chromate, can cause many kinds of pathological changes, such as organism deformity and cancer et al. It was listed as the priority pollutants in the aquatic environment by U.S. EPA and the high risk heavy metal pollutant in the Chinese "125"programming. Therefore, it has become a global important topic to deal with the problem of chromium pollution in water.Compared with other methods, adsorption has attracted a consider attention due to simple operation, good selectivity, low cost, wide adsorbent sources and recyclable etc.. The porous materials of silicon based micro/nano materials have been widely concerned because of their large specific surface area and adsorption capacity, and are often used as catalysts and adsorption carriers. In addition, amine modified materials have been used as heavy metal adsorbent, and the adsorption capacity is improved significantly compared with the former. The survey found, current research is mainly through static batch experiments to research the adsorption isotherm and adsorption kinetics of powdered material, but due to the powdered material is difficult to recycle and reuse, easy to create secondary pollution and the restricted in practical application. In this study, the SiO2 was used as the material matrix by from market, CTAB as the active component, using impregnation method make the amino groups grafted to the silica, and to investigate the performance of Cr(â…¥) removal form static and dynamic experiments.The results of static experiments showed that the removal performance of Cr(â…¥) by amine functional SiO2 was greatly influenced by the initial pH of the solution, and the adsorption effect was best when pH=2. The adsorption capacity of Cr(â…¥) decreased with the increase of pH due to the degree of the protonation decreased with the increase of pH on the material surface.Cr(â…¥) adsorption properties of amine functionalized SiO2 influenced of coexisting ions. The degree of inhibitionthe of the coexistences cations and coexistences anions on the Cr(â…¥) removal followed by Ni2+<Zn2+< Mg2+< Ca2+< Cu2+ and Cl-<PO43-<CO32-< SO42-<NO3-<F-separately.When the adsorption equilibrium was in accordance with the Langmuir adsorption isotherm model, the maximum monolayer adsorption capacity was calculated as 27.78mg/g; the process followed the pseudo-second-order equation model, which indicated that the "surface reaction" was the main control step. Adsorption thermodynamics shows that the adsorption of Cr (â…¥) on amine functionalized SiO2 is a spontaneous endothermic reaction. In addition, we have a preliminary discussion on the adsorption mechanism of the adsorbent.Combination of characterization results showed that the adsorption mechanismof adsorbent was couple of adsorption and chemical reduction.The results of fixed bed adsorption experiments shows that, The dynamic adsorption process was influenced with the initial Cr(â…¥) concentration, bed height, flow rate, pH, etc.Breakthrough curve can be well fitting Thomas model (R2> 0.99), shows that the reaction rate control steps is not the the surface diffusion and internal diffusion of adsorbent. Material regeneration process shows that the amino functional SiO2 showed good regeneration performance after three times in alkaline conditions.
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