In situ nitrogen functionalization of biochar via one-pot synthesis for catalytic peroxymonosulfate activation: Characteristics and performance studies

Abstract

A facile and scalable one-pot synthesis method was designed to fabricate N-doped biochar from wood residue for peroxymonosulfate (PMS) activation. The urea:wood residue w/w ratio was varied from 0:1 to 100:1, and the intrinsic (surface chemistry) and extrinsic (morphology, specific surface area, etc.) properties of the N-doped biochar were systematically investigated. Notably, the urea:wood residue w/w ratio played a significant role in tuning the N species composition in the N-doped biochar. A higher urea:wood residue w/w ratio resulted in greater at.% of graphitic N and higher specific surface area. The results show that the catalyst prepared with urea:wood residue w/w ratio of 100:1 (NC800-20) manifested the greatest catalytic activity as PMS activator for organics removal due to its highly favorable combination of intrinsic (highest at.% graphitic N) and extrinsic (excellent specific surface area) properties. The catalyst loading, PMS dosage and pH were found to be operationally crucial for PMS activation. Under the best condition, the NC800-20 can be used to degrade various organic pollutants. The recyclability of NC800-20 was studied and while the catalytic activity gradually deteriorated over successive cycles, it can be completely restored by simple calcination at 500 °C. The used catalyst was extensively characterized, revealing insights into the mechanism of PMS activation. The prevailing mechanism for PMS activation was the nonradical pathway. Overall, this research provides insights into preparing N-doped biochar with favorable extrinsic and intrinsic properties from biowaste for sustainable pollutant removal via PMS activation.