Preparation of high adsorption capacity bio-chars from waste biomass

Bio-chars with high adsorption capacity derived from rice-husks and corncobs were prepared at different retention times (RTs) in a pyrolysis reactor. At a fixed pyrolysis temperature, the pyrolysis RT is a key factor influencing the surface areas and functional group contents of the bio-chars, and further influencing their adsorption capacities. The results indicate that the bio-char prepared at RT of 1.6 s exhibits a higher phenol adsorption capacity (589 mg g−1) than other bio-chars and many activated carbons reported in the literature. An adsorption mechanism based on acid–base interaction and hydrogen binding between phenol and the functional groups was proposed to elucidate the adsorption process. An economic evaluation of the use of bio-chars as adsorbents was made.