Mineralization of pentachlorophenol by ferrioxalate-assisted solar photo-Fenton process at mild pH.

Zhihong Ye, Ignasi Sirés, Hui Zhang, Yao-Hui Huang

Journal: Chemosphere 2019;217():475-482

PMID: 30439659

Full Text on Elsevier Science View on PubMed

Abstract

This work reports the use of ferrioxalate complexes to assist solar photo-Fenton treatment of pentachlorophenol (PCP) in aqueous medium at mild pH, which inhibits the precipitation of iron hydroxides and allows working at a low iron dosage. The experimental parameters were optimized by assessing the effect of initial concentrations of HO (0-2.5 mM) and Fe(II) (2-10 mg/L), pH (3.0-9.0) and iron/oxalic acid molar ratios (1:0-1:13.5) on total organic carbon (TOC) removal. Ferrioxalate-assisted solar photo-Fenton achieved 97.5% mineralization in 120 min, clearly outperforming conventional Fenton and solar photo-Fenton. The presence of photosensitive ferrioxalate complexes accounted for the enhancement, as a result of Fe(II) regeneration that accelerated the hydroxyl radical (OH) production. The time course of HO and Fe(II) concentrations was evaluated under different iron/oxalic acid ratios. The five carboxylic acids determined by ion-exclusion HPLC and the eight aromatic by-products identified by GC-MS allowed the proposal of a degradation pathway that included hydroxylation, dechlorination and dimerization steps. Complete chloride ion release was achieved after 90 min of treatment.

Address: Department of Environmental Science and Engineering, Wuhan University, Wuhan 430079, China; Laboratori d'Electroquímica dels Materials i del Medi Ambient, Departament de Química Física, Facultat de Química, Universitat de Barcelona, Martí i Franquès 1-11, 08028 Barcelona, Spain.; Laboratori d'Electroquímica dels Materials i del Medi Ambient, Departament de Química Física, Facultat de Química, Universitat de Barcelona, Martí i Franquès 1-11, 08028 Barcelona, Spain.; Department of Environmental Science and Engineering, Wuhan University, Wuhan 430079, China. Electronic address: [email protected].; Department of Chemical Engineering, National Cheng Kung University, Tainan 701, Taiwan. Electronic address: [email protected].

DOI: 10.1016/j.chemosphere.2018.10.221

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MeSH Terms: Oxalates, Oxidation-Reduction, Pentachlorophenol, Solar Activity