(277a) Heterogeneous Fenton-like Oxidation Using a Novel Iron-Activated Bermudagrass-Derived Biochar for Removal of Aqueous Antibiotic Sulfamethoxazole

Fenton oxidation has been considered as one of the most effective techniques for wastewater and water treatment owing to easy operation and high oxidation of broad ranges of contaminants at ambient temperature and pressure. However, Fenton oxidation often requires acidic conditions for high reactivity while it generates significant amount of iron sludge which is not reused. Therefore, recent studies have shifted to heterogeneous Fenton oxidation by immobilization of iron catalysts onto solid supports to overcome current limitations of homogeneous Fenton oxidation. While expensive and engineered carbon materials (i.e., activated carbon, carbon nanotube, graphene) are used as the carbon supports, biochar (BC) can be a cost-effective support for heterogeneous Fenton oxidation due to its cheap feedstocks including agricultural, municipal and industrial wastes. Nevertheless, most biochar-based heterogeneous Fenton catalysts are prepared via two-step processes including the production of raw biochar via pyrolysis and attachment of iron oxides onto the BC via chemical precipitation or calcination, which requires much time and energy input. Thus, this study focused on preparation and application of FeCl₃-activated Bermudagrass-derived biochar as a novel heterogeneous Fenton catalyst for degradation of aqueous sulfamethoxazole (SMX). The FeCl₃-activated bermudagrass-derived biochar (Fe-BC) was prepared via one step pyrolysis of Bermudagrass mixed with FeCl₃ at 800 ^oC for 2 h for simultaneous carbonization, activation and generation of iron oxides. The Fe-BC was fully characterized and applied for simultaneous adsorption and Fenton-like oxidation of SMX in water. The Fe-BC exhibited the great surface area (835 m²/g) and high adsorption ability (204 mg SMX/g BC), which is higher than various BCs, and comparable to commercial activated carbons. Moreover, after one-step pyrolysis, Fe₂O₃, Fe⁰, and Fe₃O₄ as active Fenton catalysts were successfully attached onto the Fe-BC. The removal efficiencies of SMX and COD by the Fe-BC reached 99.94% (with the reaction rate of 0.46 h^-1 )and 65.19%, respectively under the optimal conditions (pH 3, 0.1 g Fe-BC/L, 200 mg/L of H₂O₂ for 0.1 L of 100 mg/L SMX at 22^oC). With the elevation of reaction temperature from 22 °C to 50 °C, the SMX removal rates also increase from 0.46 h^-1 and 1.04 h^-1 which indicates higher temperature could enhance reaction rate and diffusion during the heterogeneous Fenton. The hydroxyl radical was proved to be the dominant radical in SMX degradation via the scavenging test. Furthermore, the reusability of Fe-BC showed that 90-99% of SMX removal efficiencies were kept during three repeated reaction cycles under the optimal conditions. Therefore, the novel heterogeneous Fenton oxidation using the Fe-BC shows the great potential for elimination of SMX and possibly other organic contaminants in wastewater and water through simultaneous adsorption and Fenton-like degradation. Future works include mathematical modeling for detailed understanding of reaction-diffusion-mass transport mechanisms, optimization and scale-up.