Effect of sulfate on Cu(II) sorption to polymer-supported nano-hydrated ferric oxides: Experimental and modeling studies

Incorporating of hydrous ferric oxide (HFO) inside porous supports with large sizes has become an effective way to decontaminate the water from heavy metals. Ubiquitous anions like sulfate are usually present in high concentrations in water, and might greatly affect adsorption behavior of hybrid HFO. Here, a polymer-based HFO-CPS was fabricated by encapsulating nano-HFO inside a chloromethylated polystyrene polymer (CPS) and the reactivity of HFO-CPS with Cu(II) was evaluated in the presence of sulfate ions. Surface complexation theory was firstly employed to describe the effect of sulfate on Cu(II) adsorption edges of hybrid HFO-CPS, where constant capacitance model (CCM) was adopted. The available weak adsorption site Fe(2)OH of hybrid HFO-CPS was found to decrease from 20% Fe to 5% Fe, which might be caused by the pore plugging effect after HFO encapsulation. With the assumption that a ternary complex was formed, the effect of sulfate on Cu(II) adsorption by HFO-CPS were successfully described by CCM using the optimized Fe(2)OH site under different sulfate concentrations (1 or 10 mmol.L-1) and Cu/Fe ratios (0.0042 or 0.0252). It is confirmed that the formation of FeOHCuSO4 ternary surface complexes played an important role in enhancing Cu(II) adsorption on HFO-CPS in the presence of sulfate. (C) 2020 The Chemical Industry and Engineering Society of China, and Chemical Industry Press Co., Ltd.. Published by Elsevier Ltd. All rights reserved.