Radiolytic degradation of formic acid and formate in aqueous solution: modeling the final stages of organic mineralization under advanced oxidation process conditions

WATER RESEARCH

卷:186

Article

Horne, Gregory P.¹  Zalupski, Peter R.¹  Daubaras, Dayna L.¹  Rae, Cathy¹  Mezyk, Stephen P.²  Mincher, Bruce J.¹ 

[1] Idaho Natl Lab, Ctr Radiat Chem Res, POB 1625, Idaho Falls, ID 83415 USA

[2] Calif State Univ Long Beach, Dept Chem & Biochem, 1250 Bellflower Blvd, Long Beach, CA 90840 USA

关键词: Formic acid;    Formate;    Radical-induced degradation;    Kinetic model;    Advanced oxidation processes;   

DOI  :  10.1016/j.watres.2020.116314

来源: Elsevier

【 摘 要 】

The successful use of advanced oxidation processes to treat aqueous solutions containing undesirable or-ganic species requires the degradation of these species to lower molecular weight, lower hazard compounds. Safe application of this technology requires a thorough understanding of the mechanisms of degradation. These oxidative transformations are mainly initiated by the reactions of reactive oxygen species, particularly hydroxyl radicals. These react with organic molecules to generate carbon-centered radicals. In the presence of dissolved oxygen, the carbon-centered radicals are next converted to peroxyl radicals, which then decay to lower molecular weight species by multiple mechanistic pathways. Formic acid and its conjugate base formate are the last stable chemical species produced immediately before the complete mineralization of any organic molecule undergoing oxidative degradation in aqueous solution. Once understood, the radical-induced chemistry of formic acid/formate under these conditions has wide applicability in all advanced oxidation technologies. To develop this quantitative knowledge, we have performed a series of Co-60 gamma irradiation studies on aqueous formic acid/formate over different pH and solution conditions. The measured species concentration changes, as a function of applied dose, are compared with the predictions of a kinetic computer model constructed from literature reactions and reported rate coefficients. The excellent agreement found between the results and modeling gives confidence in the mechanism presented here and provide the first complete computer model for the radiolytic degradation of formic acid in water. (c) 2020 Elsevier Ltd. All rights reserved.

【 授权许可】

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