Abstract:
In order to explore the adsorption of As(V) by different goethite crystal faces, this study prepared two kinds of goethite with different proportions of {021}/{110} crystal faces. Through isothermal adsorption and adsorption kinetics experiments, the differences of the adsorption of As(V) by the two kinds of goethite under the influence of different initial As(V) concentrations, pH and competitive anions were studied. The results show that the adsorption of As(V) on the goethite surface is more consistent with Freundlich and pseudo-second-order kinetic model. According to the normalization of specific surface area, it is found that the surface of Goe-B containing a higher proportion of {021}/{110} crystal plane has better adsorption performance. At pH=4, the adsorption capacity reaches 0.304 mg/m
2, which is 1.57 times of that of Goe-A. pH will affect the adsorption of goethite, and the adsorption amount decreases with the increase of pH, but the adsorption capacity of Goe-B is stronger under alkaline conditions. With the increase of As(V) concentration, the point competition effect caused by the adsorption of a large number of ligands is greater than the electrostatic force effect caused by the change of pH. The changes of XRD before and after adsorption indicate that As(V) is mainly adsorbed on the surface of goethite, rather than binding to the crystal structure of goethite. However, FTIR and XPS analysis showed that As(V) formed a new complex (Fe-O-As) by exchanging with Fe-OH ligand and adsorbed on the surface of goatee. Studies have shown that goethite with a higher proportion of {021}/{110} crystal planes has better adsorption performance and is an ideal adsorbent for environmental remediation of arsenic pollution.