Role of self-assembly coated Er3+: YAlO3/TiO2 in intimate coupling of visible-light-responsive photocatalysis and biodegradation reactions

• Published in: Journal of hazardous materials 2016-01, Vol.302, p.386-394
• Main Authors: Dong, Shanshan, Dong, Shuangshi, Tian, Xiadi, Xu, Zhengxue, Ma, Dongmei, Cui, Bin, Ren, Nanqi, Rittmann, Bruce E.
• Format: Article
• Language: English
• Subjects: Intimate coupling; Phenol; Self-assembly; Self-regulation mechanism; Visible-light-responsive photocatalysis
• ISSN: 0304-3894; 1873-3336
• DOI: 10.1016/j.jhazmat.2015.10.007

[Display omitted] •First study on intimate coupling of photocatalysis & biodegradation by visible light.•Self-assembly was used to coat Er3+: YAlO3/TiO2 on the sponge carriers.•Fewer accumulated intermediates & higher phenol removal for VPCB than VPC or B alone.•Self-regulation in VPCB contributes to the high degradation efficiency. Conventionally used ultraviolet light can result in dissolved organic carbon (DOC) increasing and biofilm damage in intimate coupling of photocatalysis and biodegradation (ICPB). Visible-light-responsive photocatalysis offers an alternative for achieving ICPB. In this study, composite-cubes were developed using self-assembly to coat a thin and even layer of visible-light-responsive photocatalyst (Er3+: YAlO3/TiO2) on sponge-type carriers, followed by biofilm cultivation. The degradations of phenol (50mgL−1) were compared for four protocols in circulating beds: adsorption (AD), visible-light-responsive photocatalysis (VPC), biodegradation (B), and intimately coupled visible-light-responsive photocatalysis and biodegradation (VPCB). The phenol and DOC removal efficiencies using VPCB in 16h were 99.8% and 65.2%, respectively, i.e., higher than those achieved using VPC (71.6% and 50.0%) or B (99.4% and 58.2%). The phenol removal of 96.3% could be obtained even after 3 additional cycles. The 6.17-min intermediate detected by HPLC, continuously accumulated for VPC, appeared at 1–6h and then was completely removed for VPCB in 10h. ICPB was further illustrated in that most of the biofilm was protected in the carrier interiors, with less protection on the carrier exterior in VPCB. A self-regulation mechanism that helped photocatalyst exposure to visible-light irradiation was identified, promoting the combined photocatalysis and biodegradation.