Efficient removal of sulfadiazine by water hyacinth (Eichhornia crassipes) biochar combined with periodate in water.

Water hyacinth biochar (EBC), derived from the invasive plant water hyacinth, exhibited remarkable capabilities in activating periodate (PI) and facilitating the degradation of sulfadiazine (SD). Notably, EBC outperformed Alligator weed BC and Canadian goldenrod BC in this regard. Among various pyrolysis temperatures, EBC prepared at 500℃(EBC500) demonstrated superior PI activation, effectively removing SD within a mere 20 minutes using a lower PI dose (0.15mmol/L). As the dosage of EBC500 and PI increased, the removal rate of SD also increased accordingly. Comprehensive analyses, including bursting experiments and electron paramagnetic resonance analysis, revealed that iodine radicals (·IO3, ·IO4), superoxide radicals (O2•−), and singlet oxygen (1O2) served as the primary reactive species responsible for the degradation of SD in the EBC500/PI system. Meanwhile, under the conditions of EBC500 and PI dosages of 0.15g/L and 0.15mmol/L, respectively, SD can be completely removed across a wide range of initial pH values (5~9). Coexisting substances such as common anions (including Cl−, SO42−, and NO3−) had minimal impact on the degradation of SD in the EBC500/PI system. However, HCO3− and HA exhibited inhibitory effects on the removal of SD. Moreover, the EBC500/PI system demonstrates robust applicability for the degradation of SD in natural water matrixes, and good application potential for degradation of other typical sulfonamide antibiotics as well. Additionally, EBC500 demonstrated favorable reusability. Based on the identification of six intermediates, potential degradation pathways of SD were proposed. Ecotoxicity analysis and plant seed germination tests confirmed that the treatment with the EBC500/PI system significantly reduced the biological toxicity of SD, underscoring its promising application prospects. © 2024 Chinese Society for Environmental Sciences. All rights reserved.