title: Development of a spectrophotometric method for on-site analysis of peroxygens during in-situ chemical oxidation applications.
abstract: Activated peroxygens are frequently used as active agents in in-situ chemical oxidation (ISCO) contaminated site remediation applications, and fast and simple quantitative analysis of these species on site is necessary. In this work, the use of a spectrophotometric method based on classic iodometric titration is studied for quantitative analysis of S2O8(2-) and H2O2. Instead of a back-titration step, the absorbance of the yellow iodide colour was measured at 352 nm in the presence of a bicarbonate buffer. A linear calibration curve was obtained from 0 to 0.1 mM for both S2O8(2-) and H2O2. By dilution, the method can be used for all concentrations typically applied in the field. Concerning pH dependence, neutral pH levels caused no significant error whereas pH levels above 8 caused a 9% and 6% deviation from the theoretical peroxygen concentrations. Furthermore, the method showed little dependence on other matrix components, and absorbance was stable (<2% change) for more than a week. Overall, the method proved to be fast and simple, which are important features for a field method.
authors.affiliation: Section of Chemical Engineering, Department of Biotechnology, Chemistry and Environmental Engineering, Aalborg University, Niels Bohrs Vej 8, DK-6700 Esbjerg, Denmark E-mail: jm@bio.aau.dk; Rambøll Denmark A/S, Lystholt Allé 10, DK-7100 Vejle, Denmark.
authors.forename: Lars Rønn
authors.initials: LR
authors.lastname: Bennedsen
authors.affiliation: Section of Chemical Engineering, Department of Biotechnology, Chemistry and Environmental Engineering, Aalborg University, Niels Bohrs Vej 8, DK-6700 Esbjerg, Denmark E-mail: jm@bio.aau.dk.
authors.forename: Erik Gydesen
authors.initials: EG
authors.lastname: Søgaard
authors.affiliation: Section of Chemical Engineering, Department of Biotechnology, Chemistry and Environmental Engineering, Aalborg University, Niels Bohrs Vej 8, DK-6700 Esbjerg, Denmark E-mail: jm@bio.aau.dk.
authors.forename: Jens
authors.initials: J
authors.lastname: Muff
mesh_terms: D004784:Environmental Monitoring / Q000379:methods*; D052918:Environmental Restoration and Remediation; D006861:Hydrogen Peroxide / Q000032:analysis / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D007454:Iodides / Q000032:analysis / Q000737:chemistry; D010084:Oxidation-Reduction; D010545:Peroxides / Q000032:analysis* / Q000737:chemistry; D013053:Spectrophotometry; D013461:Sulfur Oxides / Q000032:analysis / Q000737:chemistry
chemical_list: D007454:Iodides; D010545:Peroxides; D013461:Sulfur Oxides; D006861:Hydrogen Peroxide