Improving the removal of chromium by polymer epichlorohydrin-dimethylamine functionalized mesoporous silica

The cationic polymer epichlorohydrin-dimethylamine (EPI-DMA) was first employed as the modifier for preparing the SiO2@EPI-DMA by sonochemical in situ modification. The functionalized mesoporous silica (SiO2@EPI-DMA) was then used for removing Cr(VI) from the aqueous environment. The result showed that EPI-DMA had been grafted to a certain extent, improving the positive charge of SiO2. The adsorption capacity of SiO2@EPI-DMA for Cr(VI) was improved by electrostatic attraction. The XPS results also indicated that the Cr(VI) was partially reduced to Cr(III), which indicated that the redox reaction also contributed to the Cr(VI) removal. The Langmuir isotherm model was suitable to describe Cr(VI) adsorption equilibrium data by SiO2@EPI-DMA, and the adsorption kinetics data were depicted quite well by the pseudo-second-order. The maximum mono-layer adsorption capacity of SiO2@EPI-DMA was about 102.7 mg g(-1), which was greatly higher than that of neat SiO2. It indicates that the EPI-DMA is a promising functional reagent available.