Kinetic and thermodynamic aspects of arsenate adsorption on aluminum oxide modified palygorskite nanocomposites

Abstract

Nanocomposed aluminum oxide modified palygorskite was prepared and some of methods such as X-ray diffraction (XRD), N2 adsorption technique surface area and pore size, and scanning electron microscopic (SEM) with energy dispersive X-ray spectroscopy (EDS) were used to characterize analysis. Compared with aluminum oxide particles, acid activated palygorskite and natural palygorskite clay, aluminum oxide modified palygorskite shows better arsenate adsorption capacity. The effects of adsorption time, temperature, acidity and co-existing anions such as fluorine, bromide, chloride, sulfate, phosphate, nitrite and nitrate on the removal of arsenate from water were investigated. The adsorption thermodynamics was conducted, which shows that the adsorption of arsenate on aluminum oxide modified palygorskite can be better simulated by Redlich–Peterson model and the adsorption is an endothermic and spontaneous process. Kinetics studies show the adsorption is a pseudo-second-order process, which is controlled by surface diffusion at the beginning and then controlled by intraparticle diffusion.