Metal oxides as dual-functional adsorbents/catalysts for Cu2+/Cr(VI) adsorption and methyl orange oxidation catalysis

摘要

The LDO, calcined product of the Mg/Al-CO3 hydrotalcite, was used as a dual-functional adsorbent/catalyst material for the removal of binary heavy metal ions and the catalytic degradation of methyl orange (MO). The adsorption properties for Cu2+ cations and Cr(VI) anions were investigated in depth in single and co-adsorption systems. The results showed that the LDO demonstrated 0.80 and 2.90 mmol/g adsorption capacities in single Cu2+ (1.6 mmol/L) and Cr(VI) (4.0 mmol/L) systems, respectively. In co-adsorption system, Cu-2(OH)(3)Cl precipitation, isomorphic substitution of Mg2+ sites by Cu2+ and intercalation of CrO42- into the interlayers played important roles. On the LDO, Cu2+ and Cr(VI) presented synergetic effect, resulting in an increase in both Cu2+ and Cr(VI) adsorption capacities. In addition, the spent adsorbents were employed as a catalyst for methyl orange (MO) degradation. The Cr-Cu-RLDO, a calcined product of the spent adsorbent in the co-adsorption system, indicated the high activity with 86.5% degradation rate of MO in the presence of H2O2. The existence of Cu and Cr elements in the catalyst was one of the causes of the enhanced degradation of MO. (C) 2015 Taiwan Institute of Chemical Engineers. Published by Elsevier B.V. All rights reserved.