Unconventional electro-Fenton process operating at a wide pH range with Ni foam cathode and tripolyphosphate electrolyte

Fengxia Deng; Hugo Olvera-Vargas; Orlando Garcia-Rodriguez; Shan Qiu; Fang Ma; Zhonglin Chen; Olivier Lefebvre

doi:10.1016/j.jhazmat.2020.122641

Unconventional electro-Fenton process operating at a wide pH range with Ni foam cathode and tripolyphosphate electrolyte

J Hazard Mater. 2020 Sep 5:396:122641. doi: 10.1016/j.jhazmat.2020.122641. Epub 2020 Apr 11.

Authors

Fengxia Deng¹, Hugo Olvera-Vargas², Orlando Garcia-Rodriguez², Shan Qiu³, Fang Ma⁴, Zhonglin Chen⁴, Olivier Lefebvre⁵

Affiliations

¹ Centre for Water Research, Department of Civil and Environmental Engineering, National University of Singapore, 1 Engineering Dr. 2, Singapore, 117576, Singapore; State Key Laboratory of Urban Water Resources Centre, School of Environment, Harbin Institute of Technology, Harbin, 150090, PR China.
² Centre for Water Research, Department of Civil and Environmental Engineering, National University of Singapore, 1 Engineering Dr. 2, Singapore, 117576, Singapore.
³ State Key Laboratory of Urban Water Resources Centre, School of Environment, Harbin Institute of Technology, Harbin, 150090, PR China. Electronic address: qiushan@hit.edu.cn.
⁴ State Key Laboratory of Urban Water Resources Centre, School of Environment, Harbin Institute of Technology, Harbin, 150090, PR China.
⁵ Centre for Water Research, Department of Civil and Environmental Engineering, National University of Singapore, 1 Engineering Dr. 2, Singapore, 117576, Singapore. Electronic address: ceelop@nus.edu.sg.

PMID: 32339874
DOI: 10.1016/j.jhazmat.2020.122641

Abstract

We propose an unconventional electro-Fenton (EF) system with a nickel-foam (Ni-F) cathode and tripolyphosphate (3-PP) electrolyte at near-neutral pH (EF/Ni-F-3-PP) to overcome pH restrictions in EF while preventing Ni-F corrosion. Response surface modelling was used to optimize the main operating parameters with a model prediction analysis (R² = 0.99): pH = 5.8, Fe²⁺ = 3.0 mM and applied current = 349.6 mA. Among the three variables, the pH exerted the highest influence on the process. Under optimal conditions, 100 % of phenol removal was achieved in 25 min with a pseudo-first-order apparent rate constant (k_app) of 0.2 min^-1, 3.2-fold higher than the k_app of EF/Ni-F with SO₄^2- electrolyte at pH 3. A mineralization yield of 81.5 % was attained after 2 h; furthermore, it was found that 3-PP enhanced H₂O₂ accumulation by preventing bulk H₂O₂ decomposition. Finally, toxicity evaluation revealed the formation of toxic by-products at the early stages of treatment, which were totally depleted after 2 h, demonstrating the detoxifying capacity of the system. In conclusion, this study shows for the first time the potential of Ni-F as a cathode for EF under near-neutral conditions, rendered possible by the 3PP electrolyte. Under these conditions, the Ni-F corrosion issue could be alleviated.

Keywords: Electro-Fenton (EF); Near-neutral pH Fenton; Nickel-foam (ni-f); Response surface modelling (RSM); Tripolyphosphate (3-PP).

Publication types

Research Support, Non-U.S. Gov't