Radiolytic degradation of 4-hydroxybenzoate in aerated and deoxygenated aqueous solutions
| Autor: | Guadalupe Albarrán, Edith Mendoza |
|---|---|
| Jazyk: | angličtina |
| Rok vydání: | 2024 |
| Předmět: | |
| Zdroj: | Water Science and Technology, Vol 89, Iss 12, Pp 3178-3191 (2024) |
| Druh dokumentu: | article |
| ISSN: | 0273-1223 1996-9732 |
| DOI: | 10.2166/wst.2024.167 |
| Popis: | The radiolytic degradation of 4-hydroxybenzoate (4-HBA–) in aerated, oxygen-free and N2O-saturated aqueous solutions at concentrations of 0.10 and 0.25 mmol/dm3 were gamma irradiated at different doses in a source of Co-60. The results show that ·OH adds predominantly to the 3 position of the aromatic ring, and elimination of the acid group leads to the degradation of 4-HBA–. With an N2O-saturated 0.10 mmol/dm3 4-HBA– solution, total degradation occurred at 1.6 kGy, and with a 0.25 mmol/dm3 solution, total degradation occurred at 3.5 kGy. In the aerated and oxygen-free 0.25 mmol/dm3 4-HBA– solutions, the behavior was similar, degradation occurring at a dose of 13.1 kGy. At the concentration of 0.10 mmol/dm3, total degradation occurred at 7.0 kGy, with small amounts of radiolytic products and byproducts. We propose a mechanism for the degradation of 4-HBA– caused by water radicals produced in the three environments, leading to formation of the identified stable products. Oxidation was followed by chemical oxygen demand (COD), which decreased as the 4-HBA− concentration increased. The kinetics showed a pseudo-first-order behavior. The rate constant of degradation was similar for the solutions with and without oxygen. HIGHLIGHTS Study of radiolytic degradation of 4-hydroxybenzoate in aqueous solutions.; Distribution of radiolitic products from the degradation of 4-hydroxybenzoate in aqueous solutions.; Formation and degradation of primary and secondary products from irradiated 4-hydroxybenzoate.; Degradation kinetics, mechanisms, and chemical oxygen demand in the degradation of 4-HBA−.; Mechanistic scheme for gamma radiation degradation of 4-hydroxybenzoate.; |
| Databáze: | Directory of Open Access Journals |
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