Effective degradation of phenol via Fenton reaction over CuNiFe layered double hydroxides

• Published in: Journal of hazardous materials 2018-07, Vol.353, p.53-61
• Main Authors: Wang, Hao, Jing, Mengmeng, Wu, Yan, Chen, Weiliang, Ran, Yao
• Format: Article
• Language: English
• Subjects: CuNiFe layered double hydroxides; Electron transfer; Fenton reaction; Phenol degradation; Synergetic effect
• ISSN: 0304-3894; 1873-3336
• DOI: 10.1016/j.jhazmat.2018.03.053

[Display omitted] •Electron transfer from Ni2+ to Cu2+ via MOM bridges produces highly active Cu+.•Cu+ increases with decreasing Cu/Ni ratio and dominates phenol degradation.•Cu0.5Ni2.5Fe can completely mineralize phenol at ambient pH and low H2O2 dosage.•Regeneration of Cu+ may be achieved by electron transfer from Ni2+ to Cu2+. A series of CuNiFe layered double hydroxides (LDHs) with various Cu/Ni molar ratios were synthesized as catalysts for Fenton degradation of phenol. It is found that Cu+, Cu2+, Ni2+, Ni3+ and Fe3+ are present on LDHs, owing to an electron transfer from Ni2+ to Cu2+ via metal-oxo-metal bridges. At lower Cu/Ni ratios, the highly dispersed MO6 octahedra and the electron donation effect of Ni facilitate such electron transfer and thus increase the percentage of Cu+. The catalytic activity increases with the decrease in Cu/Ni ratio. The most active Cu0.5Ni2.5Fe LDH can mineralize 98.9% phenol at ambient pH and less excessive H2O2 dosage (MH2O2/Mphenol = 37). Even at the H2O2 dosage close to the theoretical value, around 90% phenol can be mineralized. The structure-activity correlation indicates Cu+ which can readily react with H2O2 to produce hydroxyl radicals may dominate the reaction. The regeneration of Cu+ could be achieved by the electron transfer between Cu2+ and Ni2+ in LDHs. Moreover, Fe3+ can also act as Fenton-like active sites. The special structure of CuNiFe LDHs could offer surface-enriched and easily regenerated Cu+ species, leading to the complete mineralization of phenol and the efficient use of H2O2.