Innovative biofiltration materials for H2S removal from biogas

Background: Following an extensive examination of various biofiltration packing materials within a typical bioreactor (a biofilter) is aiming to remove hydrogen sulfide (H2S) in the raw biogas. Methods: Both biochar (pre- and post-pyrolysis at 400, 500, and 600 °C) and cellular concrete (CLC) waste, representing organic and inorganic packing materials, respectively, displayed remarkable removal efficiency (RE) performance under dynamic conditions. Nevertheless, the physical and chemical properties of these packing materials play a crucial role in absorbing and trapping H2S for further filtration from the raw biogas. Key evaluations encompass chemical compositions, porosity, and specific surface area, aligning with contemporary research methodologies (e.g., XRF, Walkley-black, Kjeldahl, BET, T-plot), as analyzed in this study. Results: Subsequently, the modification of these physicochemical properties aimed to demonstrate continued interactions of iron (III) oxide (Fe2O3) with H2S for chemical modification of CLC waste, and enhance the specific surface area of biochar from 12, 22, and 24 m2/g to 235, 433, 475 m2/g, and for porosity from 0.01, 0.42, and 0.025 cm3/g to 0.096, 4, 0.24 cm3/g, respectively, for physical modification of biochar samples after pyrolysis at 400, 500, and 600 °C. Conclusion: In the end, improving the possibility of getting better RE from a laboratory-scale biofilter is possible by modification of the most effective physical (adding KOH to biochar and increasing porosity by 9 times, specific surface area by 19 times) and chemical (adding Fe2O3 to CLC waste) properties of the environment-friendly packing materials.