Preparation of Sodium Humate-Modified Biochar Absorbents for Water Treatment

Some chemical substances could improve the sorption capacity of biochars. In this paper, sodium humate was introduced to the pyrolysis of two biomass samples at 600 °C, and sodium humate-biochars have been successfully synthesized. The surface area and surface morphologies of all of the biochars were characterized, and the results indicated that sodium humate-biochars have higher surface areas, and sodium humate particles were grown on the surfaces of the biochars. Adsorption isotherm and kinetics of methylene blue (MB) onto the biochars were carried out by batch adsorption experiments. The results suggested that incorporation of sodium humate could increase the adsorption capacity of MB onto the biochars (from 10.79 to 16.21, 8.62 to 11.03 mg/g for peanut shells and white clover residues, respectively). The adsorption experimental results also suggest that the adsorption process of MB onto sodium humate-biochars is controlled by both intraparticle diffusion and film diffusion. As a whole, this work probes the possibility of sodium humate to modify the surface of biochar and improve its adsorption ability with contaminants.