Removing Cd(II) from Aqueous Solution by Inverse Opal Hybrid SiO2

A hybrid adsorbent with inverse opal (IO) structure was prepared for removing Cd(II) from aqueous solution. The functional polymeric chains were grafted from the pore wall of IO silica to prepare the porous hybrid material by surface-initiated atom-transfer radical polymerization. Furthermore, the amidation reaction was carried out to obtain diethylenetriamine-modified hybrid adsorbent (IO SiO 2 -g-PAA-DETA). Batch adsorption of removing Cd(II) onto IO SiO 2 -g-PAA-DETA was studied as the effect of solution pH, adsorbent doses, contact time, ionic concentration, and temperature. When the grafted amount was 73%, the maximum adsorption capacity was obtained. The optimum adsorbent dose and pH value for adsorbing Cd(II) were found to be 5 g/L and 0.5 g/L, respectively. The adsorption capacity was almost unaffected by Na + at low concentrations. The adsorption data was depicted by the corresponding models and the results displayed that adsorbing Cd(II) on IO SiO 2 -g-PAA-DETA followed the Freundlich and pseudo-first-order model. In addition, after six adsorption–desorption cycles, IO adsorbent could remain above 80% of the first adsorption ability while it was washed using 0.025 M EDTA.