Acid-modified anaerobic biogas residue biochar activates persulfate for phenol degradation: Enhancement of the efficiency and non-radical pathway

Abstract

The treatment of biogas residue with complex composition from anaerobic bog has gradually become a challenge for energy utilization of solid waste. However, biogas residue rich in cellulose hemicellulose and lignin can be employed to prepare biochar. In this study, biogas residue biochar (HBC800) activated persulfate(PS) was prepared by a two-step method of 800 ℃ calcination and acid modification, which has the characteristics of large specific surface area, rich functional groups. HBC800 had excellent activated PS degradation efficiency of phenol (91.6 %). The effect of common ions was weak and showed good environmental adaptability in groundwater on phenol degradation. Electron Paramagnetic Resonance (EPR) and quenching tests were employed to find that electron transfer and singlet oxygen (1O2) were the main mechanisms for phenol degradation in the HBC800/PS system. This result is mainly attributed to the important role played by surface oxygen-containing functional groups, defects and graphite nitrogen as active sites. HBC800 has good recycling efficiency and practical ability to treat coking wastewater. This study provides an alternative to biogas residue biochar utilization and better support for the closed-loop utilization of agroforestry waste resource.