Photodegradation of sulphadimethoxine in water by medium pressure UV lamp

Abstract

The photodegradation rate of sulphadimethoxine (SMT) in water was studied under polychromatic UV light, in a bench scale apparatus. SMT photolysis was carried out at pH levels of 2.5, 6.5 and 10 to study the impact of acid base properties on the degradation of SMT. The highest SMT photolysis fluence based rate was found at pH=2.5 (k=7.22x10(-4) cm2/mJ) and the lowest rate at pH=10 (k=4.72x10(-4) cm2/mJ), thus the reaction rate decreases with an increase in pH between pH values of 2.5-10. Results indicated that direct photolysis is not satisfactory for degradation of SMT by polychromatic UV lamp as a fluence of approximately 7,000 mJ/cm2 is needed to break down 99% of SMT at pH 6.5. The photodegradation products of SMT were studied at various pH values. Photodegradation of SMT results in dissimilar relative amounts of intermediates formed at different pH values which may exert a photon demand and impact on SMT photodegradation rate.

Photolysis and UV/H 2 O 2 of diclofenac, sulfamethoxazole, carbamazepine, and trimethoprim: Identification of their major degradation products by ESI–LC–MS and assessment of the toxicity of reaction mixtures

“…In direct photodegradation, a compound absorbing radiation can become unstable and consequently decay, whereas the indirect pathway involves naturally occurring compounds that produce strong reactive species (such as singlet oxygen, and/or hydroxyl radicals) that then react with organic compounds. The photolytic degradation products formed may have molecular weights lower than their parent compounds [30,37,38]. Conversely the detected photolytic degradation products could be observed with slightly higher molecular weights than their parent compounds, as a result of radical additions rather than direct photolysis [30,37].…”

“…The photolytic degradation products formed may have molecular weights lower than their parent compounds [30,37,38]. Conversely the detected photolytic degradation products could be observed with slightly higher molecular weights than their parent compounds, as a result of radical additions rather than direct photolysis [30,37].…”

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.…”

Development of an HPLC method to analyze four veterinary antibiotics in soils and aqueous media and validation through fate studies

“…[6][7][8] Analytical methods for the quantitative analysis of sulfonamides, macrolides and many other antibiotics are mostly based on high performance liquid chromatography (HPLC), which offers a reliable and repeatable analytical tool for separating these contaminants from environmental samples. HPLC has been used for the analysis of antibiotic residues with single wavelength UV detection [9][10][11][12][13][14][15] fluorescence detection, [9,[16][17][18] diode array detection, [16,17,19] and with more sensitive but more expensive mass spectrometric detectors (MS). [20][21][22] Extensive sample pre-treatment and analyte derivatization make GC-MS a rather time-consuming method, [23] and thus GC-MS has rarely been used for the analysis of these compounds.…”