Electron Beam Irradiation-Induced Degradation of Sulfadiazine in Aqueous Solutions

The degradation of sulfadiazine (4-amino-N-pyrimidin-2yl-benzenesulfonamide, SDZ), a widely used sulfonamide antibiotic, in aqueous solution under electron beam irradiation was investigated to explore its potential as an Advanced Oxidation Process for environmental remediation. This study evaluated the effects of irradiation dose, initial sulfadiazine concentration, and initial pH on the degradation efficiency. It was found at 0.5 kGy that the degradation efficiency decreased with increasing initial SDZ concentration, from 83.0% at 5 mg/L to 35.0% at 30 mg/L. The kinetic results showed a pseudo-first order model. The degradation efficiencies of 30 mg/L SDZ reached 80.8%, 75.3%, 69.5% and 69.8%, respectively, at pH 3.0, 6.3, 9.0, and 11.0 at 3.0 kGy, indicating the pH dependence to SDZ degradation under electron beam. The maximum removal efficiency was around 90% after UV analysis and 99% after HPLC analysis for 10mg/L SDZ at absorbed doses of 2–3 kGy and pH 6.3. Increasing the degradation efficiency of 10 mg/L SDZ from 0.5 kGy to 3.0 kGy showed the dose dependence on SDZ removal. Reactive species generated during irradiation, including hydroxyl radicals, hydrogen radicals, and solvated electrons, were identified as primary contributors to the degradation process. The effect of reactive species on the degradation of 10 mg/L SDZ was evaluated at variable doses, revealing the following trend: •OH>•H>eaq−. Transformation products were characterized using high-performance liquid chromatography (HPLC) and mass spectrometry (MS), providing insights into the degradation pathway. The results demonstrate that electron beam irradiation is an effective and sustainable method for sulfadiazine removal in water treatment systems, offering an innovative approach to mitigating antibiotic pollution in aquatic environments.