Reaction of antibiotic sulfadiazine with manganese dioxide in aqueous phase: Kinetics, pathways and toxicity assessment

ABSTRACT

Sulfonamide antibiotics are often detected in terrestrial and aquatic environment, but little is known about abiotic degradation of these antibiotics. In the present study, the degradation of the sulfonamide antibiotic sulfadiazine by a synthesized δ-MnO₂ was investigated. The initial reaction rate of sulfadiazine oxidized by manganese dioxide increased as the solution pH decreased by weakening electrostatic attraction between sulfadiazine and MnO₂ and enhancing the reduction potential of MnO₂. The presence of metal ions (Mn²⁺, Na⁺ and Ca²⁺), especially Mn²⁺, decreased the initial reaction rate by competitively adsorbing and reacting with MnO₂. Two different products were identified during the reaction of sulfadiazine with MnO₂ and the transformation of parent compound started with the formation of sulfadiazine radicals. Furthermore, toxicity assay results showed that the toxicity of products produced by bacteria decreased with elapse of reaction time. Results from the present study indicate that manganese dioxides in environmental matrix could be helpful in dissipation of sulfadiazine released into the environment.

KEYWORDS:

• Kinetics
• MnO₂
• oxidation
• pathways
• sulfadiazine
• toxicity assessment

Funding

This work was financially supported by the Hunan Provincial Natural Science Foundation of China (13JJ3155), the China Postdoctoral Science Foundation (2014M562104), the Scientific Research Fund of Hunan Provincial Education Department (15A130), the Startup Foundation for Doctors of Hunan University of Arts and Science (BSQD1004) and the Construct Program of the Key Discipline in Hunan Province (Applied Chemistry).