Accelerated degradation and toxicity reduction of ribavirin by organic free radicals in the ferrate-acetylacetonate system

Abstract

This study found that during the degradation of ribavirin (RBV) by ferrate (Fe(VI)) and acetylacetone (AA), organic free radicals significantly accelerated the degradation of ribavirin (RBV) and reduced the toxicity of degradation products. When [Fe(VI)]:[RBV] = 4:1, the pseudo 1st order rate constant of ribavirin removal increased 22.63 times compared with that without AA addition. Through quenching experiments, it was found that quenching of organic free radicals would reduce the degradation efficiency of RBV by 52.88%, while there was no significant effect on the degradation efficiency of RBV after ·OH and Fe(IV)/Fe(V) were quenched. Organic free radical addition products were found in the analysis of intermediate products of RBV degradation in Fe(VI)/AA system, which proved the existence of organic free radicals in Fe(VI)/AA system. Toxicity analysis by ECOSAR found that triazole was the most toxic intermediate product in the degradation process, and analysis of the electrophilic potential points by Dual descriptor found that the carbon-nitrogen double bond on triazole was the most susceptible position for electrophilic attack. The Laplacian bond order was analyzed and found that the addition of organic free radicals decreases the Laplacian bond order of the carbon-nitrogen double bond. The organic free radical (·CH3) generated in the Fe(VI)-AA system facilitated the degradation of RBV and accelerated the toxicity reduction by reducing the bond order of more toxic intermediates.