Carbonization of hydrothermally modified spent coffee grounds and tea leaves and the ethene adsorption properties of the resulting carbons

Hydrothermal treatment and carbonization of various residues from the extraction of beverages, namely coffee grounds and tea leaves, were performed to investigate the morphological properties and the potential for ethene adsorption of the resulting carbons. Hydrothermal treatment promoted the pore development of the carbons. Removal of crystalline fatty acid produced by hydrothermal treatment with ethanol washing before carbonization significantly increased the BET specific surface area, especially in coffee grounds. The carbonization process contributed to the development of ultra-micropores due to the pyrolysis of the cellulose components in as-received residues. Such narrower pores in the carbons functioned effectively for ethene adsorption.