Optimization of High Energy Radiation-Induced Degradation of Sulfamethoxazole Using Response Surface Methodology

Abstract

Ionizing irradiation is an emerging technology for the removal of toxic pollutants, such as antibiotics, in water and wastewater. In this study, gamma radiation-induced degradation of sulfamethoxazole (SMX) was optimized using response surface methodology (RSM) based on a Box-Behnken design. LC-MS analysis identified nine intermediate products (M1-M9), elucidating a dual oxidative-reductive degradation mechanism driven by hydroxyl radicals (•OH) and hydrated electrons (e_aq⁻). These intermediates, characterized by hydroxylation, sulfonamide bond cleavage, and aromatic ring fragmentation, aligned with pathways distinct from conventional chlorination systems, underscoring the absence of toxic halogenated byproducts. According to experimental data, The study revealed that absorbed dose (0.2-2.0 kGy) and initial SMX concentration (5-40 mg/L) critically governed SMX degradation efficiency, achieving >99% removal under optimized conditions (≥1.2 kGy for 5-10 mg/L SMX). The robust RSM model (R² = 0.9931) and experimental validation (±2% error) demonstrated the method’s reliability in reconciling nonlinear dose-concentration interactions as well as providing an effective approach to parameter optimization, offering practical insights for enhancing the treatment efficiency of antibiotic-containing wastewater.

Keywords

Ionizing irradiation / Sulfamethoxazole / Response surface methodology / Antibiotics degradation / Optimization

Author Contributions

Y.S.: Data curation, Formal analysis, Investigation, Writing—original draft; Y.W.: Data curation, Investigation; J.W.: Funding acquisition, Supervision, Writing—review & editing.

Ethics Statement

Not applicable.

Informed Consent Statement

Not applicable.

Data Availability Statement

Data will be available upon request.

Funding

The research was funded by the Key Program for Intergovernmental S&T Innovative Cooperation Project of China (2024YFE0101700).

Declaration of Competing Interest

No potential conflict of interest was reported by the authors.

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