Arsenic Removal from Aqueous Solution by Using Alumi-num-Zirconium Bimetal Oxide: Adsorption Characteristics and Mechanisms

Kun Wu, Qinbin Huang, Xue Yang, Ting Liu



The adsorption properties of arsenate(As(V))were investigated by using aluminum-zirconium bimetal oxide (AZBO) as an adsorbent. The adsorption kinetic results illustrated that AZBO exhibited a fast adsorption rate towards As(V), and the equilibrium of As(V) adsorption could be achieved within 2 h. The kinetic data of As(V)adsorption could be well fitted by the pseudo-second-order model, thus indicating the occurrence of chemisorption. According to the adsorption isotherm results, the maximum amount of As(V) adsorbed onto AZBO at pH = 7.0 was determined to be 115.53 mg/g via the Langmuir isotherm model. Meanwhile, the Freundlich model was perfectly applicable to the equilibrium data, which also suggested that the removal of As(V) is a chemisorption process. The optimal performance for As(V)removal was achieved at pH =6.0 approximately, and As(V)adsorption was depressed at alkali conditions (pH >7). The adsorption of As(V) was also inhibited in the presence of some anions, which can compete with arsenate for adsorption sites on the adsorbent surface. In addition, the spectroscopic analysis results of Fourier transform infrared spectroscopy and X-ray photoemission spectroscopy demonstrated that the removal mechanisms of As(V) primarily include the adhesion to surface hydroxyl groups and the ligand exchange with impregnated sulfate anions on the surface of AZBO.

Keywords: Arsenic; adsorption; aluminum oxide; zirconium oxide