Activated Carbons Prepared from a Broad Range of Residual Agricultural Biomasses Tested for Xylene Abatement in the Gas Phase

The environmental problems in Peru are rooted in the waste management of the residual agricultural biomass. Via our cooperative international research, nine different agricultural wastes from Peru were used as renewable sources to produce activated carbons that were tested in gas-phase xylene adsorption. The special properties of agro-waste activated carbons are the very large mesopore surface area, the narrow pore size distribution within the microporous-mesoporous region, and the slightly acidic character in the presence of oxygen-containing surface groups. The textural, structural, and surface properties of nine agro-waste activated carbons were correlated with their adsorption capacities in xylene adsorption and compared with those of a commercial activated carbon made of black coal. Adsorption capacities of agro-waste activated carbons were in the range of 371-115 mg_xylene/g_AC, whereas the adsorption capacity was 214 mg_xylene/g_AC for black coal-activated carbon. Higher adsorption capacities of ACs can be assigned to the synergism of their textural properties (larger mesopore surface area and larger micropore volume related to total pore volume) and their surface properties (lower content of surface oxygen functional groups related to their less acidic character and higher π- π∗ transitions in aromatic rings resulting in fewer defects within the graphitic structure).