Electric-Field-Enhanced Photocatalytic Removal of Cr(VI) under Sunlight of TiO2 Nanograss Mesh with Nondestructive Regeneration and Feasible Collection for Cr(III)

Rutile TiO2 nanograss was synthesized by a hydrothermal method on Ti mesh. The nanograss is composed of thin TiO2 nanorods with abundantly exposed {110} facets. The TiO2 nanograss on Ti mesh (TNTM) shows an excellent photocatalytic removal of Cr(VI) ions from plating wastewater under sunlight, and the removal capacity can reach as high as 143.8 mg/g. It was found that an external electric field can greatly enhance the removal efficiency of the TNTM, in which the electrons provided by the electric field can effectively neutralize the photoholes and inhibit the recombination of photoelectrons and photoholes. The TNTM can be easily removed after photocatalytic reaction and can be nondestructively regenerated by an electrolyzing process. The Cr(III) ions on the TNTM can be collected by the electrolyzation, effectively avoiding secondary pollution.