Enhanced recovery of phosphorus from hypophosphite-laden wastewater via field-induced electro-Fenton coupled with anodic oxidation

Juanjuan Zhang; Yunhan Liu; Jiaxi Li; Kaifeng Wang; Xu Zhao; Xueyu Liu

doi:10.1016/j.jhazmat.2023.132750

Enhanced recovery of phosphorus from hypophosphite-laden wastewater via field-induced electro-Fenton coupled with anodic oxidation

J Hazard Mater. 2024 Feb 15:464:132750. doi: 10.1016/j.jhazmat.2023.132750. Epub 2023 Oct 10.

Authors

Juanjuan Zhang¹, Yunhan Liu², Jiaxi Li³, Kaifeng Wang², Xu Zhao⁴, Xueyu Liu⁵

Affiliations

¹ State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012, PR China; Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, PR China; Institute of Water Environment Research, Chinese Research Academy of Environmental Sciences, Beijing 100012, PR China.
² Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, PR China.
³ State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012, PR China; Institute of Water Environment Research, Chinese Research Academy of Environmental Sciences, Beijing 100012, PR China.
⁴ Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, PR China. Electronic address: zhaoxu@rcees.ac.cn.
⁵ State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012, PR China; Institute of Water Environment Research, Chinese Research Academy of Environmental Sciences, Beijing 100012, PR China. Electronic address: liuxueyu@craes.org.cn.

PMID: 37956560
DOI: 10.1016/j.jhazmat.2023.132750

Abstract

Electrochemical recovered ferric phosphate (FePO₄) precipitates from hypophosphite-laden wastewater were shown to be an efficient method for phosphorus (P) recovery. However, the influence of chloride ions (Cl^-) coexisting commonly in wastewater is not known for this treatment. Herein, a field-induced electro-Fenton coupled with anodic oxidation electrochemical system consisting of a Ti-RuO₂ anode, an Fe inductive electrode and an activated carbon fiber (ACF) cathode, namely Ti-RuO₂/Fe/ACF(NaCl) system, was established to recover phosphorus (P) as FePO₄ from hypophosphite-laden wastewater in the presence of Cl^-. This system enabled a hypophosphite (H₂PO₂^-, 1.0 mM) removal ratio of ~100% and all P was recovered within 30 min at 5.0 V under the initial solution pH of 3.0. The Faradaic efficiency and energy consumption of P recovery achieved the maximum value (~94%) and the lowest value (~16 kW h kg^-1 P), respectively. Reactive oxygen species including ¹O₂, Fe^IVO²⁺, •O₂^- and •OH contribute to convert H₂PO₂^- to PO₄^3-, which immediately formed FePO₄ with the generated Fe³⁺ at the optimized conditions. Therein, the contribution of non-radical ¹O₂ was very considerable. This system exhibited good stability. The efficiency and cost for treatment of actual hypophosphite-laden wastewater were addressed to check its applicability for P recovery.

Keywords: Anodic oxidation; Ferric phosphate precipitates; Field-induced electro-Fenton; Hypophosphite; Phosphorus recovery.