Utilizing zeolitic imidazolate framework-8 for enhanced carbon dioxide/methane separation and improved carbon dioxide...

Area of Science:

• Materials Science
• Environmental Science
• Biotechnology

Background:

• Zeolitic imidazolate framework-8 (ZIF-8) is known for gas separation and storage.
• Its role in biological biogas upgrading by enhancing CO2 to CH4 conversion is unexplored.
• Biogas typically contains significant amounts of CO2, limiting its direct use.

Purpose of the Study:

• To investigate the efficacy of ZIF-8 in a biological biogas upgrading system.
• To determine the optimal ZIF-8 dosage for maximizing CO2 to CH4 conversion.
• To assess the impact of ZIF-8 on microbial communities and metabolic pathways in methanogenesis.

Main Methods:

• Synthesis of ZIF-8 material.
• Application of ZIF-8 in a biological biogas upgrading reactor.
• Analysis of gas composition (CO2, CH4) over time.
• Microbial community and metabolic pathway analysis.

Main Results:

• The addition of 0.75 g/L ZIF-8 maximized the CO2 to CH4 conversion rate.
• CH4 proportion increased from 60% to 97% in a single 5-day reaction cycle.
• Continuous operation over three cycles consistently yielded >95% CH4, meeting biomethane standards.
• ZIF-8 increased hydrogenotrophic methanogen abundance and shifted metabolism from acetotrophic to hydrogenotrophic pathways.

Conclusions:

• ZIF-8 is effective in enhancing biological biogas upgrading.
• ZIF-8 facilitates the conversion of CO2 to CH4, producing high-purity biomethane.
• The material promotes a shift towards hydrogenotrophic methanogenesis for improved biogas quality.