Biomass-derived carbon aerogel for peroxymonosulfate activation to remove tetracycline: Carbonization temperature, oxygen-containing functional group content, and defect degree

A biomass-derived carbon aerogel (CA) was prepared and employed as an efficient metal-free and green carbon-based catalyst for peroxymonosulfate (PMS) activation to degrade tetracycline (TC). The surface functional groups, morphology, and other properties of the CA were characterized using various methods. Different carbonization temperatures were used to produce CA samples to control the oxygen-containing functional group content and defect degree, both of which play important roles in PMS activation. The carbonization temperature showed a clear negative correlation with the oxygen-containing functional group content on the CA surface, while exhibiting a positive correlation with the degree of defects in the CA. The optimal temperature for producing the CA was 300 degrees C owing to the high oxygen-containing functional group content and low loss rate. Neutral and weakly alkaline conditions were conducive to TC removal. Under optimal conditions, 93% removal of TC could be achieved within 90 min. The results of reactive oxygen species (ROS) quenching experiments and electron paramagnetic resonance (EPR) spectroscopy indicated that both non-radical species (O-1(2) and electrons) and radical species (center dot OH and SO4 center dot-) resulted in the removal of TC. O-1(2) was identified as the main activated ROS. This study deepens our understanding of the preparation of biomass-derived carbon aerogels and control of the oxygen-containing functional group content and defect degree for improving the pollutant removal efficiency.