Al–Mg–Ca-Layered Double Oxides for Efficient Removal of As(V) from Water: The Role of Amides

Abstract

Al–Mg–Ca-layered double oxides (LDO) were synthesized by solvothermal process at 160 °C/24 h in the presence of formamide (F), dimethylformamide (DMF), and diethylformamide (DEF), followed by calcination at 500 °C. The role of different amides for the formation of Al–Mg–Ca LDOs in terms of their microstructural behaviors, textural properties, and surface elemental analysis toward the removal of As­(V) from groundwater was investigated. Microstructural analysis shows chrysanthemum flower-like morphology (2–4 μm) with orderly arrangement of nanorod/petal-like particles (10–15 nm). DEF-modified Al–Mg–Ca LDO exhibited the highest surface area of 251 m2/g, resulting in the maximum As­(V) adsorption capacity of 100 mg/g. The XPS study shows peak shifting of Al–O and Mg–O to a higher binding energy after adsorption of As­(V), indicating the change in chemical environment, i.e., sharing of elements with the neighboring atoms. The effects of different parameters, like contact time, dose concentration, pH, and temperature, were investigated for As­(V) adsorption. The synthesized Al–Mg–Ca LDOs were used for the removal of As­(V) (0.7 ppm) from the groundwater collected from the lower Indo-Gangetic plain area (Hariharpara block at Murshidabad district in West Bengal of India) down to <10 ppb.

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