Peroxymonosulfate activation by nitrogen-doped biochar from sawdust for the efficient degradation of organic pollutants

The fabrication of low-cost, high-performance and environmentally friendly carbon-based catalysts capable of activating peroxymonosulfate (PMS) for wastewater treatment applications is still a challenge. In this work, a novel nitrogen-doped biochar (N-biochar) was prepared through a facile one-step calcination method using sawdust and different organic nitrogen-containing compounds as starting materials. It was found that the catalytic activity of the N-biochar relies heavily on the type of nitrogen precursor, the relative amount of sawdust to nitrogen precursor, and the calcination temperature. Different types and amounts of the nitrogen precursor mainly affect the content of total nitrogen and pyridinic nitrogen, and the calcination temperature mainly affects the content of graphitic nitrogen in the N-biochar. Based on a systematic comparison, an optimized N-biochar (N-C-d-4-800) with a higher content of graphitic and pyridinic N, rich defects, larger SSA and porous structure was obtained, and exhibited a superior catalytic activity for activating PMS to oxidize various organic pollutants, such as bisphenol A (BPA), phenol, acetaminophen (AAP) and sulfamethoxazole (SMX). Moreover, the N-C-d-4-800/PMS system can work effectively at a wide pH range and high salinity conditions, despite the background of the real water matrix. The present study highlights the enormous potential of the novel N-biochar prepared from sawdust for wastewater remediation applications.