Enhanced peroxymonosulfate activation for ciprofloxacin degradation enabled by a delignified wood-derived carbon

Developing high-performance and sustainable carbon catalysts for enhancing the degradation of organic antibiotics remains a great challenge. Herein, a delignified wood-derived carbon embedded with nitrogen (DLWC@N) was designed to enhance peroxymonosulfate (PMS) activation for the degradation of aqueous ciprofloxacin (CIP). The removal of lignin and hemicellulose in poplar wood was found to facilitate the formation of a more porous architecture and tailed the permeability of channels in the carbon. N species and N content were regulated on this hydrophilic cellulose skeleton through a simple pyrolysis strategy. The resulting DLWC@N-700 achieved 97.49 % CIP removal within 60 min and exhibited 79.64 % removal efficiency after four consecutive cycles. The unique three-dimensional network structure in the derived carbon promoted the diffusion of the solution and exposed much more active sites. Graphitic N and N-O bonds as main active sites during PMS activation were revealed. The quenching experiments combined with electron paramagnetic resonance and electrochemical analysis unveiled that the degradation process was dominated by a non-radical pathway of singlet oxygen and electron transfer. Liquid chromatography-mass spectrometer results demonstrated that the main degradation pathway of CIP included hydroxylation, cleavage of the piperazine ring, and cyclopropane shedding, resulting in the formation of seventeen reaction intermediates. This work proposes an advanced free-metal wood-derived carbon catalyst to enhance PMS activation for antibiotics degradation, facilitating the development of wastewater treatment technology.