title: Contaminant degradation by irradiated semiconducting silver chloride particles: kinetics and modelling.
abstract: The kinetics and mechanism of light-mediated formic acid (HCOO(-)) degradation in the presence of semiconducting silver chloride particles are investigated in this study. Our experimental results show that visible-light irradiation of AgCl(s) results in generation of holes and electrons with the photo-generated holes and its initial oxidation product carbonate radical, oxidizing HCOO(-) to form CO2. The HCOO(-) degradation rate increases with increase in silver concentration due to increase in rate of photo-generation of holes while the increase in chloride concentration decreases the degradation rate of HCOO(-) as a result of the scavenging of holes by Cl(-), thereby resulting in decreased holes and carbonate radical concentration. The results obtained indicate that a variety of other solution conditions including dioxygen concentration, bicarbonate concentration and pH influence the availability of holes and hence the HCOO(-) degradation rate in a manner consistent with our understanding of key processes. Based on our experimental results, we have developed a kinetic model capable of predicting AgCl(s)-mediated HCOO(-) photo-degradation over a wide range of conditions.
authors.affiliation: School of Civil and Environmental Engineering, The University of New South Wales, Sydney, NSW 2052, Australia.
authors.forename: Tian
authors.initials: T
authors.lastname: Ma
authors.affiliation: School of Civil and Environmental Engineering, The University of New South Wales, Sydney, NSW 2052, Australia.
authors.forename: Shikha
authors.initials: S
authors.lastname: Garg
authors.affiliation: School of Civil and Environmental Engineering, The University of New South Wales, Sydney, NSW 2052, Australia.
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Miller
authors.affiliation: School of Civil and Environmental Engineering, The University of New South Wales, Sydney, NSW 2052, Australia. Electronic address: d.waite@unsw.edu.au.
authors.forename: T David
authors.initials: TD
authors.lastname: Waite
mesh_terms: D002254:Carbonates / Q000737:chemistry; D002384:Catalysis; D003666:Decontamination / Q000379:methods*; D005561:Formates / Q000302:isolation & purification / Q000378:metabolism*; D007700:Kinetics; D008027:Light; D008956:Models, Chemical; D010084:Oxidation-Reduction; D010100:Oxygen / Q000737:chemistry; D010777:Photochemistry; D010782:Photolysis; D018030:Silver Compounds / Q000737:chemistry* / Q000528:radiation effects*; D014025:Titanium / Q000737:chemistry
chemical_list: D002254:Carbonates; D005561:Formates; D018030:Silver Compounds; C030544:formic acid; D014025:Titanium; C037548:silver chloride; D010100:Oxygen
keywords: Formic acid; Free chlorine; Photocatalyst; Plasmonics; Reactive oxygen species; Silver chloride