Effect of log Kow on the degradation of pharmaceutically active compounds in a heterogeneous catalytic persulfate activation system

Abstract

In heterogeneous catalytic advanced oxidation processes (HC-AOP), enhancing the reaction rate is the biggest challenge. To enhance the reaction rate, it is necessary to increase the mass transfer rate of reactants toward the catalyst surface and the number of active sites that will provide better contact with the reactants and higher mass transfer. The hydrophobicity of the reactant is an important parameter that affects the transport of molecules toward solid surfaces. In this study, the effect of log Kow, an indicator of hydrophobicity, on enhancing the catalytic activity in persulfate (PS) activation for pharmaceutic compounds (PCs) degradation was investigated. For this purpose, some PCs with different log Kow were selected and their adsorption and degradation behaviors were investigated depending on the PS concentration, catalyst dosage, contact time, pH, and temperature in HC-AOP. Adsorption percentages increased significantly with increasing log Kow value. PCs with higher log Kow were completely degraded at the end of the shorter contact times in the presence of lower catalyst and PS. PCs were significantly degraded by the triple catalytic effect of AC, Fe, and temperature. The pseudo-first-order kinetic model was the best fit for the degradation reaction for all PCs. The higher apparent rate constants and lower activation energy values of the PCs belonging to high log Kow confirmed that log Kow is an effective parameter in enhancing the catalytic activity.