CONVERSION OF WASTE MATERIALS TO ACTIVATED CARBON ADSORBENTS FOR BIOGAS PURIFICATION

The potential of plastic waste-derived activated carbon was investigated for the removal of carbon dioxide and hydrogen sulfide from biogas. Activated carbon materials were prepared by carbonizing plastic waste followed by activation via microwave heating after mixing with potassium hydroxide. Samples were tested using thermogravimetric analysis to determine the equilibrium uptake of carbon dioxide. Samples were modified with tetraethylenepentamine and diethanolamine however, sample texture produced was deemed unusable for further testing due to operational concerns. Adsorbent screening was conducted in conditions mimicking that of biogas at a temperature of 40 °C and 30% carbon dioxide in nitrogen. Performant samples were identified as those achieving uptakes greater than 3 wt.%. The best performing sample achieved an uptake of 3.57 wt.% and maintained 99% of its uptake during cycling. Column breakthrough experiments demonstrated that the final candidate achieved complete removal of both carbon dioxide and hydrogen sulfide, suggesting viability for larger scale biogas purification.