Simultaneous removal of Cr(VI) and 4-chlorophenol through photocatalysis by a novel anatase/titanate nanosheet composite: Synergetic promotion effect and autosynchronous doping

• Published in: Journal of hazardous materials 2016-11, Vol.317, p.385-393
• Main Authors: Liu, Wen, Sun, Weiling, Borthwick, Alistair G.L., Wang, Ting, Li, Fan, Guan, Yidong
• Format: Article
• Language: English
• Subjects: Autosynchronous doping; Combined pollution; Photocatalysis; Synergetic promotion; Titanate nanosheet
• ISSN: 0304-3894; 1873-3336
• DOI: 10.1016/j.jhazmat.2016.06.002

[Display omitted] •TNS composed of anatase and titanate synthesized via a facile one-step method.•Cr(VI) and 4-CP can be simultaneously removed by TNS through photocatalysis.•Photocatalytic efficiencies of Cr(VI) and 4-CP greatly enhanced when coexisting.•Synergetic promotion effect occurs due to separation of electron-hole pairs.•Autosynchronous doping after Cr(III) adsorption leads to narrowed energy gap. Clean-up of wastewaters with coexisting heavy metals and organic contaminants is a huge issue worldwide. In this study, a novel anatase/titanate nanosheet composite material (labeled as TNS) synthesized through a one-step hydrothermal reaction was demonstrated to achieve the goal of simultaneous removal of Cr(VI) and 4-cholophenol (4-CP) from water. TEM and XRD analyses indicated the TNS was a nano-composite of anatase and titanate, with anatase acting as the primary photocatalysis center and titanate as the main adsorption site. Enhanced photocatalytic removal of co-existent Cr(VI) and 4-CP was observed in binary systems, with apparent rate constants (k1) for photocatalytic reactions of Cr(VI) and 4-CP about 3.1 and 2.6 times of that for single systems. In addition, over 99% of Cr(VI) and 4-CP was removed within 120min through photocatalysis by TNS at pH 7 in the binary system. Mechanisms for enhanced photocatalytic efficiency in the binary system are identified as: (1) a synergetic effect on the photo-reduction of Cr(VI) and photo-oxidation of 4-CP due to efficient separation of electron-hole pairs, and (2) autosynchronous doping because of reduced Cr(III) adsorption onto TNS. Furthermore, TNS could be efficiently reused after a simple acid-base treatment.