Self-foaming calcium modified carbon foam derived from a liquefied product resin of tobacco stalks for the removal of Pb2+ in water

This study demonstrated a self-foaming plus in-situ modification strategy that led to an efficient and environmentally friendly carbon foam adsorbent for removal of Pb2+ from aqueous solution. Specifically, the resin derived from liquefied tobacco stalk (TSLPR resin) was used as the precursor of carbon foams. Various characterization techniques were employed to investigate the morphology, structure, surface area, pore size, and adsorption capacity of the materials. Upon carbonization of the resin foam at 800 ℃, considerable CaO and CaCO3 converted from Ca (NO3)2 were distributed on the surface of the cell wall, indicating the success of the in-situ modification. By using a carbon foam loaded with 7% calcium (Ca@CF-7) as an adsorbent for removal of Pb2+ at a pH of 4 and 25 ℃, the dynamic adsorption equilibrium was achieved within 480 minutes. The theoretical maximum adsorption capacity (qm) obtained by Sips model reached 348.8 mg·g−1, which is more than 4.5 times higher than the pristine carbon foam. The findings of this study indicated that the chemical co-precipitation of Pb3(CO3)2(OH)2 played a significant role for removal of Pb2+, which could be attributed to the surface alkaline environment provide by CaO and CaCO3. This study offers a novel approach for in-situ modification of carbon foam and also demonstrated the potential of the straw biomass with low lignin content in production of high-performance carbon adsorbents.