Adsorptive removal of fluoride using hierarchical flower‐like calcined Mg–Al layered double hydroxides

Abstract

Fluoride is the naturally occurring groundwater contaminant around the world, and has been the focus of extensive research efforts in the past few decades. Among various fluoride removal technologies, adsorption was the most attractive because it was highly efficient, cost‐effective, and suitable for small communities. A facile synthetic approach was presented for hierarchical flower‐like Mg–Al‐layered double hydroxides (MgAl‐LDO) via the simple hydrothermal method, followed by a subsequent calcination at 500°C for 4 h in air. The resulting calcined MgAl‐LDO were studied for their adsorption performance in removing fluoride from aqueous solutions. The results showed that the flower‐like sphere of hierarchical calcined MgAl‐LDO was synthesized by a simple hydrothermal method using urea as precipitating agent. Batch adsorption experiments demonstrated that the kinetic adsorption could be described by a pseudo‐second‐order model very well. The adsorption of fluoride on MgAl‐LDO was strongly dependent on pH value. The Freundlich model fitted the adsorption isotherms of fluoride better than the Langmuir model at three different temperatures of 25, 45, and 65°C. They were demonstrated to be reusable with the efficiency of fluoride removal up to 80% at the fourth cycle. we successfully fabricated flower‐like spherical structures MgAl‐LDO by a facile hydrothermal method without any templates. It was envisioned that the synthesized samples using this facile synthetic approach were very promising for the removal of fluoride from aqueous solutions. © 2016 American Institute of Chemical Engineers Environ Prog, 2016 © 2016 American Institute of Chemical Engineers Environ Prog, 35: 1420–1429, 2016