Photo-removal of sulfamethoxazole (SMX) by photolytic and photocatalytic processes in a batch reactor under UV-C radiation (λmax=254nm)

Abstract

In this study, photolytic and photocatalytic removal of the antibiotic sulfamethoxazole (SMX) under UVC radiation (λ=254 nm) was investigated. The light intensity distribution inside the batch photoreactor was characterized by azoxybenzene actinometry. The intensity of incident radiation was found to be a strong function of position inside the reactor. 12 mg L(-1) of SMX was completely removed within 10 min of irradiation under UVC photolysis, compared to 30 min under TiO(2) photocatalysis. COD measurement was used as an indication of the mineralization efficiency of both processes and higher COD removal with photocatalysis was shown. After 6h of reaction with photolysis and photocatalysis, 24% and 87% removal of COD was observed, respectively. Two of the intermediate photo-products were identified as sulfanilic acid and 3-amino-5-methylisoxazole by direct comparison of the HPLC chromatograms of standards to those of treated solutions. Ecotoxicity of treated and untreated solutions of SMX towards Daphnia magna was also investigated. It was found that a 3:1 ratio of sample to standard freshwater and a high initial concentration of 60 mg L(-1) of SMX were used to obtain reliable and reproducible results. The photo-products formed during photocatalytic and photolytic processes were shown to be generally more toxic than the parent compound.

Inhibitory effect of salinity on the photocatalytic degradation of three sulfonamide antibiotics

“…The photocatalytic process includes the absorbance of light by a semiconductor material and the generation of e À /h þ pairs for eliciting further redox reactions on the catalyst surface (Bahnemann, 2004;Herrmann, 2005). For example, titanium dioxide (TiO 2 ) has been frequently used in the photocatalytic degradation of pharmaceutical and organic compound residues in water and wastewater, coupled with the irradiation of ultraviolet (UV) light (Herrmann, 2005;Nasuhoglu et al, 2011). However, the activities of photocatalysts in water have decreased frequently because of a few characteristics pertaining to the water quality (e.g., dissolved ions and suspended solids) (Elmorsi et al, 2010;Ghodbane and Hamdaoui, 2010;Yuan et al, 2012).…”

Photodegradation of sulfapyridine under simulated sunlight irradiation: Kinetics, mechanism and toxicity evolvement

“…Indirect photolysis under irradiation due to energy transfer or chemical reactions with transient reactive intermediates such as hydroxyl radicals Å OH and singlet oxygen 1 O 2 can also significantly enhance the photochemical decay for SAs (Boreen et al, 2004;Prados-Joya et al, 2011). Many studies on the photochemical degradation of SAs such as sulfamethazine, sulfamethoxazole, sulfadimethoxine have been conducted (Boreen et al, 2005;Lam and Mabury, 2005;Accinelli et al, 2006;Baran et al, 2006;Guerard et al, 2009;Nasuhoglu et al, 2011). Although they have similar structures, the photochemical behaviors of SAs are different from one another (Boreen et al, 2004(Boreen et al, , 2005.…”

Degradation and toxicity assessment of sulfamethoxazole and chlortetracycline using electron beam, ozone and UV

“…UV disinfection has been widely used in water treatment plants. Also, pharmaceutical parent compounds and intermediates such as SMX, 5-methyl-1,3,4-thiadiazole-2-methylthio and 5-methyl-1,3,4-thiadiazole-2-thiol were degraded by the UV or UV/H 2 O 2 process in aqueous solution [17,18]. The UV/H 2 O 2 process effectively degraded persistent pharmaceutical compounds such as carbamazepine, while the process using UV alone was ineffective [19].…”