Basic aluminum sulfate@graphene hydrogel composites: preparation and application for removal of fluoride

Abstract

Porous composites based on basic aluminum sulfate and graphene hydrogel (BAS@GHG) were prepared via homogeneous precipitation of BAS in GHG, and used as adsorbents for fluoride removal from water. The BAS@GHG composites have a porous structure with a chemically converted graphene three dimensional network coated by a thin layer of amorphous BAS. These composites showed high adsorption capacities of up to 33.4 mg g⁻¹ at equilibrium fluoride concentrations of 10.7 mg L⁻¹ and temperatures of 298 K, higher than those of previously reported graphene and aluminum-based adsorbents. The adsorption kinetics and isotherm were analyzed by fitting experimental data with pseudo-first-order kinetics, the Weber–Morris model and Langmuir equations. The effects of temperature, pH value, and co-existing anions on the adsorption of fluoride were also investigated.