Enhanced activation of peroxydisulfate by regulating pyrolysis temperature of biochar supported nZVI for the degradation of oxytetracycline

• Published in: Journal of the Taiwan Institute of Chemical Engineers 2023-04, Vol.145, p.104775, Article 104775
• Main Authors: Yang, Yuxiao, Zhu, Junfeng, Zeng, Qingzhu, Zeng, Xiangchu, Zhang, Guanghua, Niu, Yuhua
• Format: Article
• Language: English
• Subjects: Biochar loaded with zero-valent iron; Degradation; Oxytetracycline; Pyrolysis temperature; Soybean straw biochar
• ISSN: 1876-1070; 1876-1089
• DOI: 10.1016/j.jtice.2023.104775

•Pyrolysis temperature has a strong influence on the catalyst.•nZVI-BC1000 was successfully prepared by increasing the pyrolysis temperature to 1000 °C.•100% Fe2O3 is reduced to nZVI and C-Fe.••SO4−, •OH and 1O2 promote the degradation efficiency of OTC.•The removal rate of total organic carbon (TOC) in OTC solution needs to be improved. Biochar-loaded zero-valent iron composites have been widely studied due to their potential applications in the degradation of organic pollutants. However, increasing the content of zero-valent iron in composites faces challenges. A series of biochar-supported nano-zero-valent iron catalysts (nZVI-BC) were prepared by co-pyrolysis of soybean straw and Fe2O3 at different pyrolysis temperatures. The results of N2 adsorption/desorption, XRD, XPS, and FT-IR show that different pyrolysis temperatures have great influence on the maximum N2 adsorption capacity and the content of nano-zero-valent iron (nZVI) in nZVI-BC. The total organic carbon (TOC) content results indicate that the nZVI-BC/PDS system resulted in a successful conversion of organic carbon to CO2. The •SO4−, •OH, and 1O2 are the main active species in nZVI-BC1000/PDS system. At the pyrolysis temperature of 1000 °C, nZVI-BC1000 exhibited high-efficiency activation performance for peroxydisulfate (PDS) and high-efficiency degradation performance for oxytetracycline (OTC). The strong catalytic activity of the nZVI-BC1000 for PDS is due to the high content of the nZVI in nZVI-BC1000. Finally, the pyrolysis temperature has great influence on the preparation and catalytic performance of nZVI-BC. This study provides a scientific guidance for the development of biochar energy and the optimization of catalysts in advanced oxidation technology. The summary of pyrolysis temperature on active sites of catalyst, and mechanism diagram of nZVI-BC activating PDS to degrade OTC are described in graphical abstract. The influence of pyrolysis temperature on the catalyst mainly occurs in the reduction process of Fe2O3. First, a large amount of BC was produced at high temperature. The high temperature can provide enough energy for the reduction reaction, so that the Fe-O bond of Fe2O3 breaks. With the increase of pyrolysis temperature, the Fe-O bond content of Fe2O3 decreases. Meanwhile, the Fe° content of nZVI-BC is increasing. This indicates that the active sites of nZVI-BC are also increasing. Increasing the pyrolysis temperature of the catalyst can improve the nZVI content of the ca