Improved mineralization and total nitrogen reduction by combination of electro-reduction and electro-oxidation for nitrophenol removal. (October 2022)

• Record Type: Journal Article
• Authors: Jiang, Bicun; Li, Aimin; Shuang, Chendong; Tan, Yan; Pan, Yang; Liu, Fuqiang
• Is Part Of: Chemosphere. Volume 305(2022)
• Publication Date: 2022-10
• Subjects: Nitrophenol (NP) -- Electrochemical -- Mineralization -- TN removal -- Toxicity; Pollution -- Periodicals; Pollution -- Physiological effect -- Periodicals; Environmental sciences -- Periodicals; Atmospheric chemistry -- Periodicals; 551.511
• DOI: 10.1016/j.chemosphere.2022.135400
• Languages: English
• ISSNs: 0045-6535

Abstract

Abstract: In this work, p -Nitrophenol ( p -NP) was electro-chemically removed by using a prepared Co3 O4 /Ti cathode and a BDD anode to achieve the simultaneous reduction of total organic carbon (TOC), total nitrogen (TN) and toxicity. The prepared Co3 O4 /Ti cathode showed higher electro-activity than the Ti cathode towards p -NP reduction with the removal rate higher than 90.6% but without mineralization. The electro-oxidation removed 84.3% of TOC but none of TN. To develop an optimized process for mineralization and TN removal during p -NP electrolysis, the combination of electro-oxidation and electro-reduction were evaluated by using a dual-chamber cell and a single-chamber cell, respectively. As a result of the re-oxidation and re-reduction in the single-chamber cell, the typically used mode of the simultaneous redox, showed a lower removal of TOC and TN than the combination processes as well as an increased toxicity. The TN removal for both combined modes (21.0%–32.9%) was all higher than that of the mode of reduction because the produced inorganic nitrogen such as ammonia and nitrate could be partially oxidized or reduced to nitrogen gas. The results suggested that the combination process could significantly improve the mineralization and TN reduction for p -NP removal, accompanied with 60.3% decrease of acute toxicity for the reduction after oxidation mode. Graphical abstract: Image 1 Highlights: p -NP's electro-oxidation decreased TOC and increased nitrate greatly. p -NP's electro-reduction produce a large amount of p -AP and ammonia. The combination of oxidation and reduction was proposed. The typically single-chamber cell showed a relatively low removal on TOC and TN. Oxidation after reduction decreased 21.92% (TOC) energy over simultaneous redox.