Sunlight-driven environmental photodegradation of 2-chlorobiphenyl (PCB-1) in surface waters: kinetic study and mathematical simulations

Autor(es)

Lastre-Acosta, Arlen Mabel ^[1] ; Rocha, Carolina Mendes ^[1] ; Mendes, Maria Anita ^[2] ; Silva Costa Teixeira, Antonio Carlos ^[1] ; Oller do Nascimento, Claudio Augusto ^[2]

Afiliação do(s) autor(es)

^[1] Univ Sao Paulo, Chem Syst Engn Ctr, Dept Chem Engn, Res Grp Adv Oxidat Proc AdOx, Av Prof Luciano Gualberto, Tr 3, 380, Sao Paulo, SP - Brazil

^[2] Univ Sao Paulo, Chem Syst Engn Ctr, Dept Chem Engn, Dempster MS Lab, Av Prof Luciano Gualberto, Tr 3, 380, Sao Paulo, SP - Brazil

• Tipo de documento: Artigo Científico
• Fonte: Environmental Science and Pollution Research; OCT 2021.
• Citações Web of Science: 0

Resumo

Polychlorinated biphenyls (PCBs) are a family of highly toxic, resistant, and persistent organic pollutants, among which 2-chlorobiphenyl (PCB-1) is one of the simplest. Most studies on PCBs' photochemistry are limited to their direct photolysis, while the important role of reactive photo-induced species (RPS) (hydroxyl radicals, HO?; singlet oxygen, O-1(2); and triplet excited states of chromophoric dissolved organic matter, (CDOM)-C-3{*}) in removing PCBs in natural waters through indirect photolysis has not yet been evaluated. In this work, the rate constants of the reactions between aqueous PCB-1 and RPS were obtained under simulated solar radiation (450-W Xenon lamp and an AM 1.5 global filter) by competition kinetics, and the effects of the initial pollutant concentration and the physicochemical characteristics of the water were investigated. The direct photolysis quantum yield of PCB-1 in the range 290-800 nm was found as 1.60 x 10(-2) mol Einstein(-1). The value of k(PCB-1,HO?) = (6.80 +/- 0.09) x 10(9) L mol(-1) s(-1) is in good agreement with the literature. For O-1(2), k(PCB-1,1O2) = (1.13 +/- 0.20) x 10(6) L mol(-1) s(-1), while for (CDOM)-C-3{*}, k(PCB-1,3CBBP{*}) = (2.44 +/- 0.04) x 10(9) L mol(-1) s(-1) and k(PCB-1,3AQ2S{*}) = (3.36 +/- 0.04) x 10(9) L mol(-1) s(-1) were obtained using 4-benzoylbenzoic acid (CBBP) and anthraquinone-2-sulfonate (AQ2S) as CDOM proxies, respectively. These results show that the main pathways involved in PCB-1 photodegradation are the reactions with HO? and (CDOM)-C-3{*} together with direct photolysis. In addition, the photodegradation of PCB-1 in sunlit waters was simulated using the kinetic model APEX (Aqueous Photochemistry of Environmentally Occurring Xenobiotics). According to simulations, a greater influence of the water depth and dissolved organic carbon concentration (DOC) on the persistence of PCB-1 is expected, being only slightly influenced by the concentrations of nitrite, nitrate, and bicarbonate. Finally, based on data reported for Brazilian surface waters, the average half-life (t(1/2)) of PCB-1 is expected to vary from 2 to 14 days. In particular, the t(1/2) in the Paranapanema River is estimated at 7 to 8 days. (AU)

• Processo FAPESP: 19/24158-9 - Destinação ambiental de poluentes emergentes em águas superficiais e alternativas sustentáveis de mitigação: abordagem híbrida experimental-computacional
• Beneficiário: Antonio Carlos Silva Costa Teixeira
• Modalidade de apoio: Auxílio à Pesquisa - Regular