Construction of a Carbon/Lignosulfonate Adsorbent to Remove Pb²⁺ and Cu²⁺

Abstract

Removing heavy metal ions from water is an important issue to improve water quality. However, using cost-effective and more environmentally friendly adsorbents to achieve efficient adsorption capacity remains a challenge. Carbon spheres were prepared by the hydrothermal method and then combined with sodium lignosulfonate to form a lignosulfonate carbon (C/SL) adsorbent. C/SL achieved the adsorption of Pb 2+ and Cu 2+ after 60 min (the adsorption capacity was 281 mg g –1 for Pb 2+ and 276mg g –1 for Cu 2+ ) and had good selectivity and reusability (5 cycles). The simulated experimental data show that the pseudo-second-order kinetics and Langmuir isotherm are closer to the actual adsorption. Thermodynamic studies show that the adsorption of Pb 2+ and Cu 2+ is enhanced by the spontaneous process at higher temperature. This study also shows that functional groups such as hydroxyl and amino groups play an important role in the adsorption process.