An All-in-One Photocatalyst: Photocatalytic Reduction of Cr(Vi) and Anchored Adsorption of Cr(Iii) Over Mesoporous Titanium-Sulfonated Carbon Hollow Hemispheres

Abstract

Completely removing chromium (Cr) from contaminated water with simultaneous reduction of Cr(VI) and sequestration of Cr(III) is an efficient strategy to restrain its migration in natural water. Herein, sulfonated carbon hemisphere (Labeled as CHS, Inner diameter: 150 nm) worked as supporter to hold mesoporous TiO2 (MT) nanoparticles (Diameter: 10 nm), constructing a bifunctional catalyst with photocatalytic activity and adsorption capacity. During a typical Cr removal process, efficient photocatalytic reduction Cr(VI) performed alongside the utter adsorption of the generated Cr(III) on the sulfonated CS by ion exchange for the grafted -SO3H+ there. Resultantly, no residual Cr was determined in the treated water. Controlled research revealed that the highest removal efficiency was achieved when the mass ratio of carbon and TiO2 hemispheres is 0.62%. Three factors contributing to the exceptional reduction efficiency include improved electron-hole separation efficiency endowed by the CHS conductive framework, sensitive light absorption, and sulfonic acid group (-SO3H+) grafted on CHS that can immobilize Cr(III) by ion exchange. In essence, the resulting TiO2-C-SO3H performs like a unique photocatalyst-resin, which realizes the total removal of Cr(VI) or Cr(III) and utterly restrains the possible hazardous influence.

Keywords: Mesoporous TiO2, Carbon hemispheres, Cr(VI), Resin-like photocatalyst