Efficient peroxymonosulfate activation for practical wastewater treatment by Biochar-Iron oxide composite-based hydrogel beads

• Published in: Chemical engineering journal (Lausanne, Switzerland : 1996) Switzerland : 1996), 2024-11, Vol.500, p.157226, Article 157226
• Main Authors: Ruan, Zefeng, Wu, Ronghao, Fu, Cheng, Fu, Hailu, Xiang, Hai, Li, Yongfu, Qiu, Zhen, Yu, Bing
• Format: Article
• Language: English
• Subjects: Advanced oxidation; Hydrogel beads; Peroxymonosulfate; Sulfadiazine
• ISSN: 1385-8947
• DOI: 10.1016/j.cej.2024.157226

[Display omitted] •Biochar-iron oxide composite-based hydrogel beads for PMS activation were prepared.•The Fe2O3/BC-PMS system is superior in PMS activation over individual systems.•The formation of surface-PMS complex is more favorable for PMS activation.•SDZ removal efficiency still reaches 68.44% after 384 bed volumes in column tests. Developing a highly stable catalyst for advanced oxidation to eliminate organic pollutants from wastewater is of considerable practical importance. In this study, we presented a biochar-iron oxide composite-based hydrogel bead system, designated as Fe2O3/BC/CS, designed for the efficient activation of peroxymonosulfate (PMS). Utilizing the degradation of sulfadiazine (SDZ) as a probe, our results revealed that the Fe2O3/BC/CS catalyst demonstrated exceptional performance in column tests. It maintained over 80 % SDZ removal efficiency for the first 150 bed volumes and achieved a removal efficiency of 68.4 % even after processing 384 bed volumes of wastewater. Additionally, the Fe2O3/BC catalyst achieved over 90 % degradation of three other common organic pollutants (bisphenol A, atrazine, and tetracycline) within 360 min. The degradation efficiency for SDZ reached 98.4 %, with a degradation rate constant (kobs) of 0.0115 min–1. After five cycles of 180 min, the SDZ degradation efficiency remained at 68.8 %, further demonstrating its potential for practical applications. Electron paramagnetic resonance analysis and quenching tests indicated that the catalyst-PMS system undergoes a catalytic oxidation process involving both radical and nonradical pathways. Combining the results of electrochemical tests and density functional theory calculations, we discovered that the main pathway for Fe2O3/BC to activate PMS involves electron transfer. The positively charged biochar layer was essential to induce PMS to donate electrons to the catalyst, leading to the formation of SO5•–, which was subsequently decomposed into 1O2. Overall, this study highlights the Fe2O3/BC/CS system as a highly effective and versatile catalyst for PMS-based advanced oxidation processes.