Multiple heavy metal removal simultaneously by a biomass-based porous carbon

Activated carbon from sawdust was produced with an environmentally friendly process involving single-stage carbonization and activation with steam at 800°C. Production process is scalable because lignocellulosic biomass is ubiquitous worldwide as a waste or as a virgin material. Single-stage production without any cooling steps between carbonization and activation is easier in larger scale production. Monometal adsorption and multimetal adsorption of cobalt, nickel, and zinc were investigated by using the produced carbon, with a commercial one as control. Effect of pH, initial metal concentration, adsorbent dosage, and adsorption time was evaluated in batch experiments. Multimetal experiments showed the order of the maximum adsorption capacities: zinc > nickel > cobalt. Experimental adsorption capacities were 17.2, 6.6, and 4.5 mg/g for zinc, nickel, and cobalt, respectively, in multisolute adsorption. In case of monometal adsorption, adsorption capacity was notably lower. Experimental data fitted into the single-solute and multisolute Freundlich models. The best fit kinetic model varied among the metals. The Weber and Morris intraparticle diffusion model was used. Regeneration was performed with 0.1 M HNO₃ , 0.1 M HCl, or 0.1 M H₂ SO₄ . The adsorption capacity remained at the same within three adsorption-desorption cycles. PRACTITIONER POINTS: Activated carbon was produced from sawdust with environmentally friendly process Monometal adsorption and multimetal adsorption with heavy metals were studied Best-fitting models to the experimental data were single-solute and multisolute Freundlich models Regeneration could be performed with diluted acids Worldwide available raw material successfully used as adsorbent for heavy metals.