Oxidation of sulfamethoxazole by UVA radiation and modified Fenton reagent: toxicity and biodegradability of by-products

Abstract

Improvement of sulfamethoxazole (4-amino-N-(5-methylisoxazol-3-yl)-benzenesulfonamide-SMX) biodegradability using a modified Fenton's reaction has been studied. The modification consists of replacing hydrogen peroxide with atmospheric air and adding copper sulphate as a reaction promoter. Two series of experiments were carried out. The first (Series 1) was conducted using only the catalysts with aeration. In the second series (Series 2), cycles of UVA radiation and aeration were used. During UVA radiation, the removal of sulfamethoxazole proceeds less rapidly than in only aerated solution. After 1.5 h of these two processes, the SMX degradation was 23% in Series 2 and 59% in Series 1. The opposite trend was observed for mineralization and the removal of DOC was about 5% higher in Series 2 than in Series 1. The FTIR spectra of the extracts of reaction products yielded by four organic solvents of varying polarity revealed a wide diversity of functional groups in the post-reaction mixture in comparison to the extracts from sulfamethoxazole solution. Based on FTIR analysis, several oxidation products of sulfamethoxazole are proposed. Apparently, hydroxyl radicals initially attack sulphonamide bonds, resulting in the formation of sulfanilic acid and 3-amino-5-methylisoxazole. Irrespective of the reference organism used in toxicity tests, the post-reaction mixture in the Series 2 was more toxic than the post-reaction mixture in Series 1. In contrast, the biodegradability calculated as BOD(5)/DOC ratio, was higher for post-reaction mixture 2 and amounted to 0.43.

UV/H2O2 and UV/PDS Treatment of Trimethoprim and Sulfamethoxazole in Synthetic Human Urine: Transformation Products and Toxicity

“…58,59 At least two or multiple bioassays are commonly needed to reveal the overall toxic potential. 60,61 Cytotoxicity, 62 genotoxicity, 63 and estrogenicity 64 have been applied to test the toxic effect of the pharmaceuticals and transformation products. 58 Luminescent bacteria, particularly Vibrio f ischeri, 65−67 are frequently employed to assess acute toxicity.…”

Catalytic ozonation of sulphamethoxazole in the presence of carbon materials: Catalytic performance and reaction pathways

“…The treatment technologies that have been commonly used are the chemical oxidation with ferrate [11,12], ozonation [13][14][15][16][17][18][19][20][21][22][23][24], catalytic ozonation [17,[25][26][27][28], photocatalytic ozonation [29], O 3 /H 2 O 2 [15,30], photo-Fenton process [31,32], solar photoFenton [33][34][35][36], TiO 2 photocatalysis [17,29,[37][38][39], UV photolysis [40][41][42] and UV/H 2 O 2 [6,43]. Catalytic ozonation has emerged as a powerful technology for the treatment of pharmaceuticals in water, even for refractory compounds.…”

Kinetics of UV-A/TiO2 photocatalytic degradation and mineralization of the antibiotic sulfamethoxazole in aqueous matrices

“…It is the most commonly employed antibiotic of this group and it is extensively used in both human and veterinary medicine. There have been a few recent studies dealing with SMX advanced oxidation by means of ozonation [8][9][10], anodic oxidation over boron-doped diamond electrodes [11,12], oxidation with free chlorine and monochloramine [13] and modified Fenton reaction [14]. Particular emphasis has recently been given on photochemical AOPs such as (i) homogeneous Fenton oxidation induced by solar [15][16][17][18] or artificial [17,19] light and coupled with biological post-treatment [20], and (ii) semiconductor photocatalysis [21][22][23][24][25].…”