Mesoporous reduction state cobalt species-doped silica nanospheres: An efficient Fenton-like catalyst for dual-pathway degradation of organic pollutants

• Published in: Journal of colloid and interface science 2020-09, Vol.576 (C), p.59-67
• Main Authors: Zhang, Xuejian, Liang, Junrong, Sun, Yong, Zhang, Fagen, Li, Chenwei, Hu, Chun, Lyu, Lai
• Format: Article
• Language: English
• Subjects: Co-containing catalyst; Dual-pathway degradation; Electron donation of pollutants; Heterogeneous Fenton; Water purification
• ISSN: 0021-9797; 1095-7103
• DOI: 10.1016/j.jcis.2020.05.007

[Display omitted] •Mesoporous reduction state cobalt species-doped silica nanospheres are first prepared.•Excellent activity is realized in mp-RSCo-SiO2 NSs/H2O2 system.•Efficient dual-pathway degradation of pollutant is achieved in Fenton-like process.•Pollutants replace H2O2 as electron donors for the mp-RSCo-SiO2 NSs system.•A new interfacial Fenton-like reaction mechanism involving pollutants is proposed. A novel heterogeneous Co-containing Fenton-like catalyst consisting of mesoporous reduction state cobalt (RSCo)-doped silica (SiO2) nanospheres (mp-RSCo-SiO2 NSs) was prepared by an enhanced hydrothermal process. The catalyst exhibited very high activity and stability for a series of refractory pollutant degradation in a very wide pH range of 3.1–10.9. The Fenton-like reaction rate constant of this Co-containing catalyst was approximately 290 times higher than that of Co3O4 for pollutant degradation under the neutral and mild conditions. Based on the characterization, the catalyst possessed a porous nanosphere morphology, and the reduction state cobalt species, including nano-zero-valent cobalt (nZVCo) and Co2+, were found to be generated in the SiO2 framework through forming CoOSi bonds. During the Fenton-like reaction, the electron donation effect of organic pollutants was successfully realized through the interaction of “Pollutants → Co2+/0-SiO2”. The obtained electrons from pollutants were transferred to the catalyst surface and captured by H2O2, resulting in the generation of hydroxyl radicals (OH). Therefore, a dual-pathway degradation of the pollutants was realized: (I) oxidation and degradation as the electron donors for the system and (II) attacking and destruction by OH radicals. This work provided a new perspective on the effective utilization of the electrons of pollutants and the improvement of Fenton reaction efficiency.