Recycled carbon (RC) materials made functional: An efficient heterogeneous Mn-RC catalyst

Abstract

A MnII-Schiff-base catalyst was synthesized and covalently immobilized onto Pyrolytic Carbon surface from waste tyres (PCox), resulting in the heterogeneous catalyst MnII-L@PCox which was evaluated for degradation of methyl orange (MO) using NaIO4 as oxidant. Importantly, no additive as co-catalyst was needed. For comparison, a reference heterogeneous catalyst MnII-L@ACox was also tested, using Activated Carbon (ACox) as carbon matrix. The catalytic and recyclability data of MnII-L@PCox catalyst demonstrate that it is superior, in terms of TONs and TOFs vs. MnII-L@ACox. To study the reaction path, electron paramagnetic resonance spectroscopy was used to monitor the redox evolution of the Mn-centers. Furthermore, a full mapping of the catalytic degradation of MO and product formation was carried out using LC-MS and HPLC. Combining catalytic and spectroscopic data we discuss the protective effect of the PCox matrix on Mn-centers; it allows their rapid redox evolution to higher oxidation states.