Sustainable cellulose/kraft lignin carbon xerogel applied to H2O2 electrogeneration using gas diffusion electrodes: Exploring the degradation of sulfamerazine in H2O2-based processes

This study investigated the application of cellulose/kraft lignin-derived carbon xerogels for hydrogen peroxide (H₂O₂) electrogeneration using gas diffusion electrodes, intending to develop cost-effective and environmentally sustainable H₂O₂-based processes for antibiotic degradation. Electrochemical characterization revealed that increasing the proportion of kraft lignin in the xerogels enhanced selectivity towards H₂O₂ electrogeneration, whereas calcination at elevated temperatures caused a positive shift in the onset potential of the oxygen reduction reactions (ORR), indicating a reduction in the energy requirements for H₂O₂ production. These enhancements are likely related to morphological and structural modifications induced by kraft lignin incorporation into the carbon xerogel, including changes in particle morphology, an increase in specific surface area, and the development of a microporous structure. Additionally, the synthesis process introduced oxygen and nitrogen-containing functional groups into the carbon xerogel, which are likely linked to the high selectivity obtained for H₂O₂ electrogeneration. When implemented in the fabrication of gas diffusion electrodes, the optimized carbon xerogel achieved a maximum H₂O₂ concentration of 700 mg L⁻¹ within 1 h of electrolysis at a current density of 100 mA cm⁻². Among the techniques evaluated, the photoelectro-Fenton process demonstrated the highest efficiency for sulfamerazine removal, achieving complete degradation within 15 min and 75 % mineralization after 90 min.