Hierarchically mesoporous mixed copper oxide/calcined layered double hydroxides composites for iodide high-efficiency elimination

Highlights: • Hierarchically mesoporous Cu₂O/CuO@CLDH were synthesized via facile pyrolysis method. • Iodide adsorption capacity by Cu₂O/CuO@CLDH reached up to 120.9mg/g. • The adsorption property was enhanced by the decomposition of HKUST-1 into Cu₂O/CuO. • The reconstruction of CLDH and the chemical interaction between Cu2O and I– were responsible for its high-efficiency removal. The leakage of iodide (I⁻)-containing wastewater into environment could cause water pollution owing to the toxicity and radioactivity of iodine isotopes. Therefore, multifunctional adsorbents with high-efficiency removal toward iodide are in high demanded. In the present research, the hierarchically mesoporous mixed copper oxide anchored on calcined layered double hydroxide (Cu₂O/CuO@CLDH) materials were synthesized by direct pyrolysis of Cu-BTC metal-organic framework @ layered double hydroxide (HKUST-1@LDH) under N₂. Subsequently, the resultant materials were characterized and applied to remove iodide from simulated wastewater. The batch adsorption experiments showed a high I⁻ adsorption amount of 120.9mg/g with relatively fast kinetic removal process as well as good selectivity, and wide working pH range. The adsorption behavior, with spontaneity and exothermic, matched well with the Langmuir isotherm and pseudo-second-order kinetic models, which suggests a homogenous monolayer adsorption and chemisorption characteristics of the as-fabricated materials toward iodide. The outstanding adsorption performance of Cu₂O/CuO@CLDH could be attributed to the reconstruction of the layered structures of CLDH and the strong chemical interaction between Cu₂O and I⁻. This study proposes a promising material for iodide elimination.