Efficient activation of persulfate by biochar-supported zero-valent iron for enhanced tetracycline removal

Straw biochar loaded with zero-valent iron, which could remove the tetracycline in the wastewater by liquid phase reduction and activated peroxydisulfate, was prepared at different pyrolysis temperatures (500 °C, 700 °C, and 900 °C). The zero-valent iron supported on modified activated carbon was characterized by scanning electron microscope, X-ray diffraction, and Brunauer−Emmett−Teller. Batch experiments were carried out to investigate the effect of different factors, such as the different peroxydisulfate concentrations, straw biochar loaded with zero-valent iron dosages, reaction temperature, initial pH, and various inorganic anions, on the degradation efficiency of straw biochar loaded with zero-valent iron. The straw biochar loaded with zero-valent iron prepared at a pyrolysis temperature of 900 °C/peroxydisulfate system exhibited excellent degradation effects on tetracycline, which was degraded and removed through the adsorption and sulfate radical oxidation of the novel catalyst. According to the experimental results, 0.05-g biochar-supported zero-valent iron prepared at a pyrolysis temperature of 900 °C catalyst could remove 93% of tetracycline within 30 min at a temperature of 323K and peroxydisulfate concentration of 0.5 g·L -1 . And it was less affected by reaction temperature, initial pH, and various inorganic anions. In terms of stability and reusability, biochar-supported zero-valent iron prepared at a pyrolysis temperature of 900 °C remained stable and reusable after three adsorption-desorption cycles. Excellent catalytic activity and stability made it highly valuable for practical applications. This study provided a promising strategy for water treatment for antibiotic-containing wastewater.