Enhanced catalytic activation of H2O2 by CNTs/SCH through rapid Fe(III)/Fe(II) redox couple circulation: Insights into the role of functionalized multiwalled CNTs

Abstract How to achieve the efficient generation of Fe(II) from Fe(III) in Fenton reaction is a significant issue. In this work, a novel composite of oxidized multiwalled carbon nanotubes - Schwertmannite (CNTs-SCH) were successfully synthesized through a coprecipitation and hydrothermal strategy. The results indicated that the prepared 15%CNTs-SCH would exhibit an excellent catalytic performance in activation of hydrogen peroxide for degradation of tetracycline. The Fe(III)/Fe(II) redox couple circulation would be greatly enhanced from dynamic and thermodynamic aspects. The sulfate radicals generating from SO42− on the surface of Schwertmannite would contribute to TC degradation, which was in line with the enhanced generation rate of Fe(II) and hydroxyl radical in the 15%CNTs-SCH system. In addition, C = C and C = O (in CNTs) were acting as key active sites in prompting formation of Fe(II) and hydroxyl radical. What’s more, the effects of pH, CNTs-SCH, hydrogen peroxide dosages, and common anions on TC removal were assessed. This investigation showed that the prepared 15%CNTs-SCH was an effective catalyst for hydrogen peroxide activation in the heterogeneous system with a wide pH range and good recyclability, confirming its stronger potential practical application.