Potential Application of Ferrate-Modified Commercial Biochar to Control Ammonia and Hydrogen Sulfide

Biochar produced from natural organic waste has attracted considerable attention as a promising resource for odor control due to its porous structure. In this study, the potential application of commercially available biochar as an adsorbent for ammonia (NH3) and hydrogen sulfide (H2S) removal was investigated. Among the tested samples, HT800 biochar pyrolyzed at 800 °C exhibited the highest adsorption capacity, showing superior performance compared to conventional activated carbon. Surface modification produced contrasting effects on the adsorption efficiencies of activated carbon and biochar, with ferrate-modified biochar demonstrating the highest adsorption performance. Fourier transform infrared spectroscopy (FT-IR) analysis confirmed that ferrate modification significantly enhanced Fe–O functional groups on the biochar surface. These findings suggest that the improved ammonia removal performance may be attributed not only to acid–base interactions associated with surface functional groups, but also to the direct oxidation of odor-causing compounds by iron oxide species.