Pre-adsorption and Fenton-like oxidation of mitoxantrone using hybrid green synthesized rGO/Fe nanoparticles

Abstract

Emerging contaminants such as Mitoxantrone (MTX) are a major environmental concern because they have potential genotoxicity and mutagenesis to both aquatic organisms and humans. In this study, a pre-adsorption/Fenton-like oxidation system was developed which used a reduced graphene oxide/iron nanoparticles hybrid (rGO/Fe NPs) as both the adsorbent and the Fenton catalyst to remove MTX from solution. While the addition of H2O2 alone removed only 11.3% of MTX, the rGO/Fe NPs/H2O2 system was significantly more efficient removing 99.8% of MTX in the same period. This indicated that rGO/Fe NPs had excellent catalytic activity even at pH 7. This efficient removal was attributed to significant production of ·OH mainly by heterogeneous catalysis but supplemented by a homogeneous Fenton reaction, where ·OH had a higher affinity for MTX than SO4−·. The sequential Fenton-like oxidation process best fits a pseudo-second-order kinetic model (R2 ≥ 0.974). Characterizations of rGO/Fe NPs before and after the reaction, together with the identification of specific MTX degradation products, allowed possible degradation pathways to be proposed together with insights into the underlying mechanisms of MTX degradation when using rGO/Fe NPs in a pre-adsorption/Fenton-like oxidation system. Finally, the rGO/Fe NPs developed was successfully applied for the removal of MTX from spiked wastewater with 93.6% removal efficiency, which indicated that the proposed system had significant potential for wastewater treatment applications.