Sequestration of Sulphide from Biogas by thermal-treated iron nanoparticles synthesized using tea polyphenols

ABSTRACTDark tea-iron nanoparticles (DT-Fe NPs) were prepared using extracts of dark tea leaves as a reducing agent, and further underwent thermal treatment in air. The H2S removal performances of thermal-treated DT-Fe NPs for biogas were further evaluated using a custom-designed fixed-bed reactor (reaction temperature of 250°C, H2S content of 1%). Significant morphology and chemical composition differences were observed when DT-Fe NPs were treated at different temperatures (300–800oC). X-ray diffractometer analysis revealed that a phase transition from γ-Fe2O3 to α-Fe2O3 occurred under heat treatment. When the thermal treatment temperature was 300°C, only α-Fe2O3 was detected. Both α-Fe2O3 and γ-Fe2O3 were present in the sample treated at 400°C. When the thermal treatment temperature was 500–800°C, γ-Fe2O3 in the sample was completely converted to α-Fe2O3. The H2S removal capacity is 14.72 mg H2S/g for DT-Fe NPs without treatment. However, the value increased significantly to 408.30 mg H2S/g after 400°C ...