Photodegradation of Sulfadiazine by Goethite−Oxalate Suspension under UV Light Irradiation

Abstract

Sulfadiazine, a potent antibacterial agent belonging to the group of antibiotics called sulfonamides, has been reported to be present in surface and groundwater. This study investigated the degradation of sulfadiazine in a goethite (α-FeOOH)−oxalate Fenton-like system under UV irradiation. The results showed that sulfadiazine could be effectively photodegraded by the goethite−oxalate Fenton-like system as a result of the formation of the highly oxidizing hydroxyl radicals, •OH. Among the iron oxides tested (α-FeOOH, γ-Fe2O3, γ-FeOOH, and α-Fe2O3), α-FeOOH was found to be the most effective. Degradation of sulfadiazine depended significantly on the pH and initial concentration of oxalic acid in the system, with optimal values of 3.5 and 4.0 mM, respectively, under UV irradiation. Five intermediate products of sulfadiazine degradation were identified using high-performance liquid chromatography−mass spectrometry (HPLC−MS), gas chromatography−mass spectrometry (GC−MS), and ion chromatography (IC), and a possible sulfadiazine degradation pathway in such a system was proposed. Organic sulfur and organic nitrogen mineralization were also observed, and the results indicated that cleavage of the sulfonylurea bridge was easier than the other potential cleavage bonds under the goethite−oxalate system. In addition, results from Biolog assays suggested that the ecological toxicity of the sulfadiazine solution was effectively reduced after degradation.

Degradation of sulfamethazine antibiotics using Fe3O4–Mn3O4 nanocomposite as a Fenton‐like catalyst

“…This phenomenon can be ascribed to the consumption of · OH with M n+ as reaction . Thus, the optimal catalyst dosage was 0.5 g L −1 , which is similar to many reported heterogeneous Fenton‐like catalysts for catalytic degradation of sulfonamides (SAs) …”

“…Thus, the optimal catalyst dosage was 0.5 g L −1 , which is similar to many reported heterogeneous Fenton-like catalysts for catalytic degradation of sulfonamides (SAs). 47,48,58 To have a clearer comparison of bimetallic catalysts in AOPs for the degradation of pollutants, we summarized the parameters influencing the efficiency of pollutants degradation with different iron-based catalysts in AOPs (Table 1).…”

How UV photolysis accelerates the biodegradation and mineralization of sulfadiazine (SD)

“…Following the pathway patterns observed previously for SD by Wang et al (2010) and the mass-balance strategy of Zhang et al (2013), we developed the SD-photolysis pathway shown in Figure 4. The C, N, and S balances that underlie the pathway are summarized in Table 2.…”

“…The ABS is further hydrolyzed to generate aniline and sulfate (step D) (Takeo et al, 1998). Aniline mineralization is initiated by means of a mono-oxygenation reaction (step E) (Takeo et al, 1998;Baran et al, 2009b;Sukul et al, 2008;Wang et al, 2010;Neafsey et al, 2009) that requires O 2 and 2H and that inserts an -OH group into the ring (Li et al, 2003) to form aminophenol (C 6 H 7 NO). This is followed by a hydrolytic substitution (step F) that replaces the amino group with hydroxyl group to form catechol (C 6 H 4 O 2 ) while generating ammonia (NH 3 ) simultaneously.…”

Degradation of aquatic sulfadiazine by Fe0/persulfate: kinetics, mechanisms, and degradation pathway

“…Of various chemical techniques, such as advance oxidation process (AOPs), 11 ozonation, 12 and permanganate, 13 AOPs have been frequently employed to remove many antibiotics in water and wastewater treatment processes since hydroxyl radical (cOH) produced by AOPs possesses stronger redox potential (E 0 ¼ 1.9-2.7 V), 14 higher performance, and superior mineralization rate than traditional chemical oxidants. 15 In recent years, new AOPs based on sulfate radical (cSO 4 À ) have been developed to destroy organic pollutants include antibiotics 16 and dyes 17 in surface water, 18,19 hospital effluents, 20 and waste water. 21 Sulfate radical has been known as a strong oxidant for its higher redox potential (E 0 ¼ 2.5-3.1 V) 14 than hydroxyl radical.…”