Innovative biofiltration materials for H۲S 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 (H۲S) in the raw biogas. Methods: Both biochar (pre- and post-pyrolysis at ۴۰۰, ۵۰۰, and ۶۰۰ °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 H۲S 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 (Fe۲O۳) with H۲S for chemical modification of CLC waste, and enhance the specific surface area of biochar from ۱۲, ۲۲, and ۲۴ m۲/g to ۲۳۵, ۴۳۳, ۴۷۵ m۲/g, and for porosity from ۰.۰۱, ۰.۴۲, and ۰.۰۲۵ cm۳/g to ۰.۰۹۶, ۴, ۰.۲۴ cm۳/g, respectively, for physical modification of biochar samples after pyrolysis at ۴۰۰, ۵۰۰, and ۶۰۰ °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 ۹ times, specific surface area by ۱۹ times) and chemical (adding Fe۲O۳ to CLC waste) properties of the environment-friendly packing materials.

Keywords:

Bioreactors , Hydrogen sulfide , Biofuel , Biochar , Pyrolysis