Optimizing hydrogen-rich syngas production from sanitary waste via CO₂ gasification and pyrolysis

This study evaluates the feasibility of converting sanitary waste (diapers) into syngas through CO₂ gasification and pyrolysis in a lab-scale semi-batch reactor and through thermogravimetric analysis (TGA). The research focuses on the impact of reactor temperature and absorbed water content on the efficiency and effectiveness of the processes. TGA indicated significant mass loss between 420 and 520 °C, influenced by the catalytic effects of inorganic species in the char. The experiments revealed that increasing the temperature enhances syngas yields, with CO₂ gasification achieving promising results. At 1173 K, CO₂ gasification of the 20% waste diaper material with 80% water content (G-D20W80) sample produced the highest syngas yield, while pyrolysis at the same temperature reached a H₂ yield of 22%. CO₂ gasification promoted the Boudouard reaction, increasing CO yield and reducing char residue, while also demonstrating net CO₂ consumption, contributing to a reduced carbon footprint. The study found that water content significantly affects syngas production, with minimal yields at 20% water content for gasification and 40% for pyrolysis. Energy recovery values for gasification at 1173 K were over 9 kJ/kg, indicating the potential for substantial, scalable energy recovery. Additionally, methane production was higher in pyrolysis samples due to the decomposition of hydrocarbon oligomers. The research highlights the potential of diaper waste gasification and pyrolysis as viable and sustainable methods for energy recovery and waste reduction. The processes demonstrated significant syngas yields, enhanced energy recovery, and effective CO₂ utilization, providing a pathway for clean energy production and reduced environmental impact.