Enhanced adsorption and catalytic oxidation of ciprofloxacin on hierarchical CuS hollow nanospheres@N-doped cellulose nanocrystals hybrid composites: Kinetic and radical generation mechanism studies

In this study, a new hybrid catalyst/adsorbent, CuS hollow nanospheres@N-doped CNCs hybrid composites, was synthesized and demonstrated to be highly efficient for enhanced adsorptive removal and catalytic oxidation of ciprofloxacin (CIP) in the presence of PMS (peroxymonosulfate) as an oxidant in aqueous solution. A comprehensive characterization was performed to identify as-prepared materials. The efficiency of the new nanocomposites was compared to untreated CNCs and N-doped CNCs at the same conditions that the fabricated nanocomposites removed CIP with higher efficiency. Kinetic studies showed that CIP degradation follows first order reaction kinetics and it was remarkably faster when using CuS hollow nanospheres@N-doped CNCs hybrid composites as a catalyst (> 68 times using only PMS). PMS activation mechanism and CIP oxidation was clarified by utilizing electron paramagnetic resonance (EPR) studies. The results showed that both of OH center dot and SO4-center dot radicals were generated and played crucial roles in CIP degradation. Regarding the adsorption process, the efficiency of the process was in agreement with specific surface area (SSA) order indicating domination of SSA on the adsorption process.