The potential of green biochar generated from biogas residue as a heterogeneous persulfate activator and its non-radical degradation pathways: Adsorption and degradation of tetracycline

Advanced oxidation aided by sulfate radicals (SO4 center dot- ) is an effective option for the treatment of refractory pollutants from aqueous solutions. In this work, a metal-free biochar catalyst was prepared using pyrolyzed biogas residue as the raw material. The biogas residue carbon (BRC) obtained at 800 degrees C showed excellent catalytic activity and adsorption capacity for the removal of tetracycline (TC) with 97.9% of removal efficiency. Such performance is accounted for by the rich pores and accelerated electron transformability conferred by its defect structure with the crucial role of pyrolysis temperature in regulating catalyst properties. The BRC-800/ peroxymonosulfate (PMS) system worked predominantly through non-radical pathways with high stability/ recyclability without being interfered by organic/inorganic compounds in an actual water environment. The exceelent removal performance is also supported by the kinetic reaction rate of the BRC-800/PMS system as estimated to be 0.03017 min-1. This work provides a simple and effective path for modifying biogas residue waste for versatile applications.

Automated summary

Metal-free biochar catalyst prepared from pyrolyzed biogas residue showed excellent catalytic activity and adsorption capacity for tetracycline removal in aqueous solutions. The catalyst works predominantly through non-radical pathways with high stability/recyclability and a kinetic reaction rate of 0.03017 min-1. The work provides a simple and effective method for modifying biogas residue waste for versatile applications.