Sorghum-Waste-Derived High-Surface Area KOH-Activated Porous Carbon for Highly Efficient Methylene Blue and Pb(II) Removal

[Image: see text] With the development of the environment and human society, the removal of metal ions and dyes in wastewater treatment remains an urgent problem to solve. In this work, two biomass carbon adsorbents were synthesized by a KOH activation and carbonization route using sorghum stem and root as carbon precursors. In comparison with the samples without KOH activation, the pore structure of the KOH-activated carbon has been dramatically improved. The findings show that the specific surface areas of the adsorbents by sorghum stem (S(1)) and sorghum root (R(1)) were 948.6 and 168.1 m(2) g(–1), respectively. Meanwhile, the abundant OH(–) and COO(–) groups on the surface of these adsorbents endow them with negative polarity, thereby exhibiting excellent adsorption performance for removing methylene blue (MB) and Pb(II) from wastewater. The adsorption amount and removal rate of S(1) were 98.1 mg g(–1) and 98.08%, respectively, for MB, whereas those of R(1) were 197.6 mg g(–1) and 98.82% for the Pb(II) ion, respectively. Our findings offer an invaluable insight into designing and synthesizing a highly efficient sustainable adsorbent to remove MB and Pb(II) based on biomass agricultural waste.