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

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.