(755b) Iron-Activated Waste Hay-Derived Biocarbon for Removal of Antibiotic Sulfamethoxazole in Water

Sulfamethoxazole (SMX), one of major antibiotics for human and animal infection, has been extensively found from aquatic environment in concentration levels of ng/L to mg/L, resulting in developing antibiotic resistance and threating human health and environments. Adsorption has been identified as a cost-effective, easily operated, and scalable method for elimination of SMX from water. Among these adsorbents, biochars (BCs), made by pyrolysis of biomass and solid wastes under oxygen-limited environment, have been recognized as low-cost and sustainable adsorbents for various wastewater and water treatment. However, the adsorption of SMX onto raw BCs were often limited by their limited surface area and poor porous structure. Therefore, various activating agents including NaOH, KOH, FeCl₃, ZnCl₂, and H₃PO₄ have been applied for improving the porous structures and surface areas of BCs. Compared with other activating agents, FeCl₃ as an activating agent is more inexpensive and environmental-friendly. Moreover, iron oxides can be attached onto BCs after FeCl₃ activation, which enable the BCs to be easily separated by the magnet after adsorption.

This study focused on the effects of various iron impregnation ratios on the properties of iron (FeCl₃)-activated bermudagrass-derived BCs (IA-BCs), and adsorption of sulfamethoxazole (SMX) onto IA-BCs. The FeCl₃ activation resulted in great enhancement in surface areas (1014-1035 m²/g). The maximum adsorption capacity of IA-BC at iron impregnation ratio of 2 reached 265 mg/g which was higher than chemically and thermally activated BCs and commercial activated carbons. The adsorption results indicated various interactions between SMX and IA-BCs via π-π EDA, hydrophobic and hydrogen bond interactions. Moreover, the intraparticle diffusion mainly controlled the adsorption rate of SMX onto the IA-BC_2.0. The thermodynamic study revealed the adsorption process was spontaneous and exothermic. Future works will include cost-effective regeneration of IA-BC, process optimization and scale-up study for practical development of this adsorption process treatment of real wastewater.