Biogas sweetening using new sorbent derived from soda ash from Lake Natron, Tanzania

• Published in: Cleaner Engineering and Technology 2023-06, Vol.14, p.100646, Article 100646
• Main Authors: Mrosso, Register, Mecha, Achisa C., Kiplagat, Joseph
• Format: Article
• Language: English
• Subjects: Biogas; Flow rate; Hydrogen sulfide; Mass of adsorbent; Regeneration; Soda ash
• ISSN: 2666-7908; 2666-7908
• DOI: 10.1016/j.clet.2023.100646

Biogas is among the renewable and sustainable energy sources that could overcome the problems associated with conventional energy sources. The presence of impurities such as hydrogen sulfide, which harm biogas user's purification, is a major concern. Soda ash from Lake Natron was used for the desulfurization of raw biogas; it was ground and sieved to obtain particle sizes of 280 and 400 μm. The adsorbent mass was varied (25 g, 50 g, and 75 g), and gas flow rates were (0.03 m3/h and 0.04 m3/h). The Nitrogen adsorption-desorption isotherms, pore size distribution, and multipoint BET surface area were determined. The Zeiss Ultra Plus Field Emission Scanning Electron Microscopy (FE-SEM) characterized surface morphology. The sample sieved at 280 μm packed with a mass of 75 g, and a flow rate of 0.03 m3/h showed a removal efficiency of 94% with a sorption capacity of 0.02g/100g. The spent sample was successfully regenerated for 1, 5, and 7 days, where 7 days of exposure showed the highest removal efficiency of 90%. The sorption capacity was 0.01g/100g at the breakthrough time with five cycles. This is the first study to demonstrate the application of soda ash for biogas purification. The high removal efficiency, sorption capacity obtained, and regenerative ability make the soda ash sorbent a promising material for biogas purification. [Display omitted] •Biogas is an alternative to conventional energy resources.•The presence of H2S in biogas has health and environmental effects.•Soda ash (280 μm, 75g, 0.03 m3/h) achieved 94% H2S removal with SC 0.02g/100g.•Adsorbent was regenerated and reused five times with a removal efficiency of 90%.