Degradation of organic pollutants by Fe/N co-doped biochar via peroxymonosulfate activation: Synthesis, performance, mechanism and its potential for practical application

• Published in: Chemical engineering journal (Lausanne, Switzerland : 1996) Switzerland : 1996), 2020-11, Vol.400 (C), p.125870, Article 125870
• Main Authors: Xu, Lu, Fu, Borui, Sun, Yan, Jin, Pengkang, Bai, Xue, Jin, Xin, Shi, Xuan, Wang, Yong, Nie, Suting
• Format: Article
• Language: English
• Subjects: Fe/N co-doped biochar; Organic decomposition; Peroxymonosulfate activation; Sulfate radical
• ISSN: 1385-8947; 1873-3212
• DOI: 10.1016/j.cej.2020.125870

[Display omitted] •Fe-N-C was prepared and utilized to activate PMS to degrade organic pollutants.•Fe-N-C showed 37.07 and 6.04-fold higher activity to biochar and N-biochar.•Synergistic effects between Fe and N species facilitated the production of ROS.•SO4•−, •OH and 1O2 were identified under the Fe-N-C/PMS treatment.•Fe-N-C showed great separation performance and reusability. This study shows that the simple pyrolysis of mixed sawdust, FeCl3 and dicyandiamide can produce Fe/N co-doped biochar (Fe-N-C) with great catalytic and separation performances. Fe-N-C had a larger specific surface area (215.25 m2/g), higher defective degree (ID/IG = 0.98) and more active species for PMS activation because of the synergy between Fe and N doping. Furthermore, graphitic N, pyridinic N, Fe-Nx, Fe2O3 and Fe0 were identified as the dominant reactive species contributing to the activation of PMS. As a result, the production of reactive oxidizing species (ROS), including both sulfate radical (SO4•−), hydroxyl radical (•OH) and singlet oxygen (1O2), in the Fe-N-C/PMS system was significantly promoted. As a result, Fe-N-C exhibited 37.07 and 6.04-fold higher reaction rates for activating peroxymonosulfate (PMS) to degrade bisphenol A (BPA) relative to the rates achieved by pristine biochar and nitrogen doped biochar, respectively. Moreover, the mineralization rate of BPA by the Fe-N-C/PMS system was 68.9%, which was much higher than that achieved by the pristine biochar/PMS and N-biochar/PMS systems. Chemical-quenching tests further suggested that SO4•− and •OH played dominant roles in the degradation of BPA under acidic and neutral conditions, while 1O2 played a dominant role under alkaline conditions. Furthermore, the potential of Fe-N-C to be used in practical applications was systematically evaluated in terms of its stability, separability and selectivity to organics; the effect of operating parameters was also studied. Generally, our study highlighted the great potential of Fe/N co-doped biochar and provided valuable insight into the synthesis of highly efficient carbon-based catalysts for environmental applications.