title: Photocatalytic removal of hexavalent chromium by newly designed and highly reductive TiO2nanocrystals.
abstract: Hexavalent chromium Cr(VI), a highly toxic oxyanion, widely occurs in drinking water supplies. This study designed and synthesized a new type of highly reductive TiO2nanocrystals for photochemical Cr(VI) removal, via the thermal hydrolysis of TiCl4in the presence of diethylene glycol (DEG). Surface analyses and hydroxyl radical measurements suggested that DEG was chemically bonded on TiO2surface that resulted in an internal hole-scavenging effect and a high electron-releasing capacity, making it advantageous to conventional TiO2materials. Upon UV irradiation, the synthesized TiO2photocatalyst exhibited fast Cr(VI) reduction kinetics in diverse water chemical conditions. Fast elimination of Cr(VI) was achieved on a time scale of seconds in drinking water matrices. The removal of Cr(VI) by reductive TiO2exhibited a three-stage kinetic behavior: an initial fast-reaction phase, a lag phase resulting from surface precipitation of Cr(OH)3(s),and a final reaction phase due to surface regeneration from oxidation-reduction induced ripening process. The lag phase disappeared in acidic conditions that prevented the formation of Cr(OH)3(s). The catalyst exhibited extremely high electron-releasing capacity that can be reused for multiple cycles of Cr(VI) removal in drinking water treatment.
authors.affiliation: Department of Chemical and Environmental Engineering, University of California, Riverside, CA, 92521, USA; UCR Center for Catalysis, University of California, Riverside, CA, 92521, USA.
authors.forename: Gongde
authors.initials: G
authors.lastname: Chen
authors.affiliation: UCR Center for Catalysis, University of California, Riverside, CA, 92521, USA; Department of Chemistry, University of California, Riverside, CA, 92521, USA.
authors.forename: Ji
authors.initials: J
authors.lastname: Feng
authors.affiliation: UCR Center for Catalysis, University of California, Riverside, CA, 92521, USA; Department of Chemistry, University of California, Riverside, CA, 92521, USA.
authors.forename: Wenshou
authors.initials: W
authors.lastname: Wang
authors.affiliation: UCR Center for Catalysis, University of California, Riverside, CA, 92521, USA; Department of Chemistry, University of California, Riverside, CA, 92521, USA.
authors.forename: Yadong
authors.initials: Y
authors.lastname: Yin
authors.affiliation: Department of Chemical and Environmental Engineering, University of California, Riverside, CA, 92521, USA; UCR Center for Catalysis, University of California, Riverside, CA, 92521, USA. Electronic address: haizhou@engr.ucr.edu.
authors.forename: Haizhou
authors.initials: H
authors.lastname: Liu
mesh_terms: D002384:Catalysis; D002857:Chromium / Q000737:chemistry; D053758:Nanoparticles; D010084:Oxidation-Reduction; D010777:Photochemistry; D014025:Titanium / Q000737:chemistry; D014874:Water Pollutants, Chemical / Q000737:chemistry*; D018508:Water Purification
chemical_list: D014874:Water Pollutants, Chemical; D002857:Chromium; D014025:Titanium
keywords: Diethylene glycol; Hexavalent chromium; Hole scavenger; Photocatalytic reduction; Titanium dioxide