Photochemical persistence of sulfa drugs in aqueous medium: kinetic study and mathematical simulations

Author(s)

Lastre-Acosta, Arlen Mabel ^{[1, 2]} ; Cristofoli, Bruno Segawa ^[1] ; Parizi, Marcela Prado Silva ^[3] ; do Nascimento, Claudio Augusto Oller ^[2] ; Teixeira, Antonio Carlos Silva Costa ^[1]

Affiliation

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

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

^[3] Sao Paulo State Univ UNESP, Energy Engn Dept, Ave Barrageiros 1881, Rosana, SP - Brazil

• Document type: Journal article
• Source: Environmental Science and Pollution Research; v. 28, n. 19, SI, p. 23887-23895, MAY 2021.
• Web of Science Citations: 1

Abstract

This study aimed at investigating the photochemical behavior of sulfa drugs containing five and six-membered heterocyclic substituents (sulfamethoxazole (SMX) and sulfadiazine (SDZ), respectively), in an aqueous medium. Despite their importance, studies devoted to the use of photochemical models to predict the environmental phototransformation of pollutants in surface waters, by combining laboratory results and natural aquatic systems parameters, are still scarce in the scientific literature. In this work, the second-order reaction rate constants of SDZ and SMX with hydroxyl radicals ((OH)-O-?), singlet oxygen (O-1(2)), and triplet excited states of chromophoric dissolved organic matter ((CDOM)-C-3{*}) were experimentally determined at pH 7, using the competition kinetics approach. The results show that (OH)-O-? and (CDOM)-C-3{*} are the key species involved in sulfonamide degradation, with anionic SMX, most prevalent at pH 6-9, being degraded much slower than the anionic form of SDZ. Moreover, SDZ and SMX photodegradation in natural water samples (spring-fed natural pond, public supply reservoir, and sea water) was significantly enhanced relative to depletion in pure water. Finally, from mathematical simulations of the sunlight-driven sulfonamide degradation, half-life times were predicted for these drugs varying from less than 2 to about 90 days, depending on the water depth, concentration of key species (DOC, HCO3-, NO2-, CO32-) in natural aqueous systems, as well as on the particular heterocyclic substituent. (AU)

• FAPESP's process: 16/03695-8 - Environmental photochemical fate and degradation of antibiotics by membrane BIOREACTOR-OZONE integrated systems
• Grantee: Arlen Mabel Lastre Acosta
• Support Opportunities: Scholarships in Brazil - Post-Doctoral