Peroxymonosulfate activation by a nitrogen-doped multilayer graphene catalyst derived from cotton for enhanced flurbiprofen degradation

Abstract

Recalcitrant pharmaceuticals and personal care products (PPCPs) like flurbiprofen often elude conventional wastewater treatments, posing significant environmental risks that necessitate innovative solutions. Advanced oxidation processes based on sulfate radicals (˙SO₄⁻) from activated peroxymonosulfate (PMS) can facilitate the thorough degradation of PPCPs in wastewater thanks to their superior oxidation potential. This study developed a nitrogen-doped multilayer graphene catalyst, INC_II, from cotton fibers via template-assisted pyrolysis. Sodium chloride was used as the hard template, facilitating easy template removal and avoiding usage of hazardous hydrofluoric acid. A nitrogen-containing ionic liquid [EMIm][N(CN)₂] was employed as the nitrogen source. With 0.5 g L⁻¹ of the INC_II catalyst and 6 mM of PMS, the flurbiprofen removal rate reached approximately 94.9% (initial concentration = 20 mg L⁻¹), surpassing all previously reported work. Pyridinic nitrogen proved the most potent active site for PMS activation. By incorporating waste cotton fibers into the pharmaceutical wastewater treatment solution, this study offers a practical approach to biomass recycling and an actionable reference for treating waste with waste.