Preconcentration and Separation of Cr(VI) Coupled with Controllable Synthesis of Nano γ-Al2O3 Materials

Abstract

The γ-alumina nano materials were acquired through hydrothermal method of controllable synthesis. Optimized methods were used to change the hydrothermal parameters on the synthesis of nano γ-Al2O3. The preconcentration performance of chromium(VI) was explored comparing with SDS and CTMAB in the presence of precursors which were prepared via Al(NO3)3·9H2O and CO(NH2)2. 170 °C was selected as reaction temperature and SDS was chosen as surfactant. TEM images indicated that the average particle size of granular γ-Al2O3 was between 100 nm to 400 nm whose dispersion tended to be good. After centrifugation, a certain volume of 2 mol·L-1 hydrochloric acid was used as eluent. At the same time, chromium(VI) adsorbed in granular γ-Al2O3 aggregation was analyzed by inductively coupled plasma mass spectrometry. It was showed that the effect of branch type was not better than the granule type. The adsorption limit of Cr(VI) in γ-Al2O3 synthesized by SDS was higher than that of CTMAB. Further experiments of the interfering elements showed that Sb, As, total Cr, Se in granular γ-Al2O3 had higher adsorption rate, which could reach to 90% or more. When eight migrating elements shared some adsorption sites with Cr(VI), the adsorption rate and limitation reduced. The competitive adsorption effect of Ba, Cd, Pb and Hg had little impact on Cr(VI). As a result, this established method had reached the requirements of Cr(VI) combined with separation and detection in environmental sewage which could be used for analysis of other heavy metals.