Chemical Engineering Journal, Vol.356, 262-271, 2019
Degradation of UV filter BP-1 with nitrogen-doped industrial graphene as a metal-free catalyst of peroxymonosulfate activation
Instead of previously reported graphene oxide (GO), industrial graphene (reduced graphene oxide (IrGO)) was annealed with a nitrogen precursor. The obtained nitrogen-doped graphene (N-IrGO) was then employed as a novel catalyst for peroxymonosulfate (PMS) activation to degrade benzophenone-1 (BP-1) for the first time. The results show that N-IrGO exhibits excellent catalytic performance over conventional GO and its nitrogen-doped sample and was even better than the metal catalysts Co3O4 and Fe3O4. The enhanced catalytic performance might be attributed to graphitic-like nitrogen. Moreover, the effects of various factors were studied, including catalyst load, PMS concentration and reaction temperature. Possible degradation pathways of BP-1 in the N-IrGO/PMS system were proposed based on detected intermediates and the frontier electron density calculation. Radical quenching experiments and electron paramagnetic resonance (EPR) tests indicated that nonradical oxidation (singlet oxygen (O-1(2))) plays a dominant role in the BP-1 degradation, in contrast to the previously proposed radical process. Finally, mineralization and stability experiments confirmed that N-IrGO may be an alternative catalyst for environmental remediation. This study contributes to designing novel graphene materials with N doping and gives new insight into nonradical oxidation on benzophenone-type UV filters degradation.
Keywords:Industrial graphene (IrGO);Nitrogen doping;Peroxymonosulfate (PMS);Benzophenone-1;Nonradical oxidation