The fate of aqueous betrixaban during adsorption, photolysis, and advanced oxidation: Removal, kinetics, and reaction mechanisms

Abstract

This study investigated the fate of aqueous betrixaban, an oral anticoagulant, during adsorption, photolysis, and advanced oxidation in the presence of radicals. Adsorption studies revealed 95% removal of betrixaban at 10 h contact time with coconut shell-based granular activated carbon (CSGAC). The adsorption kinetics and isotherms best-fitted pseudo-first-order and Freundlich models, respectively, suggesting chemisorption. UVC (254 nm) irradiation (3 J/cm2), in combination with H2O2 (0.5 mM), led to the highest degradation (>90%) of betrixaban at pH 7. An increase in the initial H2O2 dosage, light intensity, and contact time enhanced the degradation rates of betrixaban. Lower degradation rates were observed in secondary wastewater effluent than with deionized water, but reactions in both matrices obeyed pseudo-first-order kinetics. Experiments using different scavengers, including tert-butyl alcohol (TBA), potassium iodide (KI), and methanol, demonstrated hydroxyl radicals (•OH) as the major reactive species involved in degradation during the UV/H2O2 process. This is the first study on the fate of betrixaban under photolysis, advanced oxidation, and adsorption, which helps to understand betrixaban's removal efficiencies and mechanisms during these processes.