Photodegradation of para-arsanilic acid mediated by photolysis of iron(III) oxalate complexes

• Published in: Chemosphere (Oxford) 2020-12, Vol.261, p.127770-127770, Article 127770
• Main Authors: Tyutereva, Yuliya E., Sherin, Petr S., Polyakova, Evgeniya V., Koscheeva, Olga S., Grivin, Vyacheslav P., Plyusnin, Victor F., Shuvaeva, Olga V., Pozdnyakov, Ivan P.
• Format: Article
• Language: English
• Subjects: AOPs; Ferrioxalate complex; Hydroxyl radical; Laser flash photolysis; p-ASA; Photodegradation
• ISSN: 0045-6535; 1879-1298
• DOI: 10.1016/j.chemosphere.2020.127770

Organic arsenicals are important environment pollutants due to wide use in livestock and toxicity of degradation products. In this work we report about the efficient photodegradation of the p-arsanilic acid (p-ASA) and its decomposition products in the Fe(III)-oxalate assisted approach under nature-relevant conditions. At neutral pH under near-visible UV irradiation the Fe(III) oxalate complexes generate the primary oxidizing intermediate, OH radical (the quantum yield of ϕOH ∼ 0.06), which rapidly reacts with p-ASA with high rate constant, (8.6 ± 0.5) × 109 M−1s−1. Subsequent radical reactions result in the complete photooxidation of both p-ASA and basic aromatic photoproducts with the predominant formation of inorganic arsenic species, mainly As(V), under optimal conditions. Comparing with the direct UV photolysis, the presented Fe(III)-oxalate mediated degradation of p-ASA has several advantages: higher efficiency at low p-ASA concentration and complete degradation of organic arsenic by-products without use of short-wavelength UV radiation. The obtained results illustrate that the Fe(III)-oxalate complexes are promising natural photosensitizers for the removal of arsenic pollutants from contaminated waters. •Optimal conditions for Fe-oxalates induced photodegradation of p-ASA were determined.•Fe-oxalate system keeps high initial efficiency at low concentration of the pollutant.•Quantum yield of OH radical generation was evaluated as 0.06•OH radical reacts with p-ASA with rate constant as high as (8.6 ± 0.5) × 109 M−1s−1.