Enhanced degradation of methylene blue by three-dimensional ordered ceria and strontium titanate composite heterojunction visible photocatalyst activated peroxymonosulfate.

Recently, visible-light-driven persulfate-based advanced oxidation processes (AOPs) employing heterogeneous catalysts to generate sulfate radicals (SO4·−) from peroxymonosulfate (PMS, HSO5−) have been extensively investigated in the field of water remediation, to remove organic contaminants. In this study, CeO2/2.0STO visible light photocatalyst with pore structure was synthesized by sol–gel method and impregnation method for photocatalytic methylene blue (MB) degradation via PMS activation. The MB degradation efficiency exhibited a high level at a broad pH range 2–12, and the presence of various organic matter and natural inorganic ions had no significant impact. When the PMS dosage was at 0–0.1 mM, the MB degradation efficiency still reached 100% within 40 min, indicating that the photocatalyst has high PMS utilization rate. The catalyst has high catalytic degradation efficiency on several typical dyes. Reused for 5 cycles, the catalytic activity, crystal form and three-dimensionally ordered macroporous (3DOM) structure of the photocatalyst without change significantly, and the leaching ratios of Sr, Ti and Ce were just under 0.1%. CeO2/2.0STO hole confinement effects and the synergistic effect between strontium titanate (SrTiO3) and ceria (CeO2) result in the excellent photocatalytic performance. The catalyst surface abundant pores absorb MB molecules into its interior, shortening the diffusion path of ROSs and improving contact efficiency. The formation of SrTiO3 and CeO2 heterojunction, which enhanced the separation of photogenerated electron/hole pairs. Experimental results confirmed that 1O2, SO4−·, ·O2− and ·OH all contributed to the MB degradation. [ABSTRACT FROM AUTHOR]