title: Assessment of PCDD/Fs formation in the Fenton oxidation of 2-chlorophenol: Influence of the iron dose applied.
abstract: Toxic polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) may be formed during remediation of chlorinated phenols via Fenton oxidation. To highlight the need for monitoring the production of toxic byproducts in these reactions, this work assessed the influence of iron dose (0.09-0.36 mM) on the Fenton oxidation of 2-chlorophenol (2-CP, 15.56 mM), a potential precursor of PCDD/Fs, by quantifying 2-CP removal and mineralization rates as well as byproducts yields, including PCDD/Fs. Although the increase in the iron dose showed positive contribution to 2-CP oxidation, under the operating conditions of the current study (H2O2 at 20% of the stoichiometric dose and 20 °C), there was no effect on the mineralization rate, and TOC and chlorine balances were far to be closed, depicting the presence of chlorinated organic byproducts in the reaction medium. After 4 h of treatment, the total PCDD/Fs concentrations increased by 14.5-39 times related to the untreated sample when the iron doses tested decreased from 0.36 to 0.09 mM, with preferential formation of PCDFs over PCDDs and dominance of lower chlorinated congeners such as tetra and penta-PCDD/Fs. The treatment with the highest iron dose (0.36 mM) exhibited the lowest PCDD/Fs yields and was thus most successful at mitigating toxic byproducts of the Fenton oxidation, leading to lower sample toxic equivalence (TEQ) value.
authors.affiliation: Departamento de Ingenierías Química y Biomolecular, ETSIIyT, Universidad de Cantabria, Avda. de los Castros, 39005 Santander, Spain.
authors.forename: Marta
authors.initials: M
authors.lastname: Vallejo
authors.affiliation: Departamento de Ingenierías Química y Biomolecular, ETSIIyT, Universidad de Cantabria, Avda. de los Castros, 39005 Santander, Spain.
authors.forename: Pablo
authors.initials: P
authors.lastname: Fernández-Castro
authors.affiliation: Departamento de Ingenierías Química y Biomolecular, ETSIIyT, Universidad de Cantabria, Avda. de los Castros, 39005 Santander, Spain.
authors.forename: M Fresnedo
authors.initials: MF
authors.lastname: San Román
authors.affiliation: Departamento de Ingenierías Química y Biomolecular, ETSIIyT, Universidad de Cantabria, Avda. de los Castros, 39005 Santander, Spain. Electronic address: ortizi@unican.es.
authors.forename: Inmaculada
authors.initials: I
authors.lastname: Ortiz
mesh_terms: D001572:Benzofurans / Q000032:analysis* / Q000737:chemistry; D002733:Chlorophenols / Q000737:chemistry*; D000072338:Dibenzofurans, Polychlorinated; D006861:Hydrogen Peroxide / Q000737:chemistry*; D007501:Iron / Q000737:chemistry*; D010084:Oxidation-Reduction; D000072317:Polychlorinated Dibenzodioxins / Q000031:analogs & derivatives* / Q000032:analysis / Q000737:chemistry; D062065:Wastewater / Q000737:chemistry*; D014874:Water Pollutants, Chemical / Q000032:analysis* / Q000737:chemistry; D018508:Water Purification
chemical_list: D001572:Benzofurans; D002733:Chlorophenols; D000072338:Dibenzofurans, Polychlorinated; D006861:Hydrogen Peroxide; D007501:Iron; D000072317:Polychlorinated Dibenzodioxins; D062065:Wastewater; D014874:Water Pollutants, Chemical; C045076:Fenton's reagent; C030683:2-chlorophenol
keywords: 2-Chlorophenol; Fenton oxidation; Iron dose; PCDD/Fs formation; Toxic equivalence value