An enhanced approach for biochar preparation using fluidized bed and its application for H₂S removal

Fluidized bed efficiently intensifies the carbonization step for biochar preparation by significantly reducing carbonization duration down to 6 min at 450 °C. The BET specific surface area of the char carbonized at 6 min can reach 60 m²/g. The produced porous biochar possesses both micropores and mesopores. The produced biochars are found to be alkaline. The degree of heterogeneity on the surface of biochar is far more than that of commercial activated carbon. The maximum monolayer adsorption capacity from Langmuir model can reach 25 mg/g at room temperature and ambient pressure by using equilibrium isotherm approximation. The maximum sulfur removal can reach 70 mg/g using column dynamic adsorption. The moisture shows a beneficial effect on the adsorption of H₂S on biochar. The maximum removal rate and saturation constants were obtained using Mechael's-Menten type equation. The mass transfer diffusivities data indicate the surface diffusion being significant to the effective diffusivity at experimental conditions. The dynamic experimental results indicate a good performance of resultant biochar in H₂S removal at room temperature.