Controllable synthesis of Mg–Fe layered double hydroxide nanoplates with specific Mg/Fe ratios and their effect on adsorption of As(v) from water

Abstract

Layered double hydroxides (LDHs) have been studied comprehensively for adsorptive application due to their outstanding ability to exchange anions. An easy thermal method is presented to synthesize Mg–Fe LDH nanoplates with the controlled Mg/Fe molar ratios (3 : 1, 4 : 1, 5 : 1). Their ability to remove arsenate from water is investigated. Through comparative analysis, the results indicate that the Mg/Fe molar ratio strongly affects adsorption of As(V) on the as-prepared LDHs. The LDHs with a Mg/Fe molar ratio of 4 : 1 exhibited the fastest adsorption rate and the highest adsorption capacity among the LDHs with three different Mg/Fe molar ratios, which was attributed to the higher BET surface area and metastable iron ions in the brucite-like sheets of the LDHs.