Adsorption and photoreduction of Cr(VI) via diatomite modified by Nb2O5 nanorods

We report the design and synthesis of Nb2O5@diatomite composite materials. The composite materials are prepared by the hydrothermal conversion of raw diatomite and activated niobic acid powder in ammonium oxalate aqueous solution, with various hydrothermal reaction durations. The specific surface area of the diatomite modified by Nb2O5 nanorods reaches a maximum of 153 m(2)/g, which is almost five times higher than that of raw diatomite. Insights are gained into the function of sodium dodecyl benzene sulfonate and the mechanism of loading Nb2O5 on diatomite in the solution phase. The controllable growth dynamics allow the morphology and production of the Nb2O5@diatomite structure to be controlled. Adsorption experiments indicate that the diatomite modified by Nb2O5 nanorods is an effective adsorbent for quickly removing Cr(VI) from wastewater at room temperature. The maximum adsorption capacity is 115 mg/g. The Cr(VI) removal capacity is further improved under ultraviolet light irradiation, owing to the synergistic effect of surface adsorption and Nb2O5 photoreduction. The composite therefore has potential practical application. (C) 2018 Chinese Society of Particuology and Institute of Process Engineering, Chinese Academy of Sciences. Published by Elsevier B.V. All rights reserved.