A carbon-rich CDBC for the removal of toxic Ni ²⁺ , Pb ²⁺ , and Cd ²⁺ ions

Heavy metal-related water contamination is now considered to be a major threat to the environment. Adsorption-based removal of heavy metals has been a promising, economic, and environmentally friendly technique for wastewater treatment. The biochar derived from plant biomass has been used as a successful adsorbent for water treatment. Biochar, as a renewable, eco-friendly, and high-adsorption-capacity material, has immense potential for wastewater treatments. In this study, Cynodon dactylon-based biochar (CDBC) was used for the removal of Ni2+, Pb2+, and Cd2+ ions from wastewater. The prepared CDBC was characterized using XRD, FTIR, FESEM, and EDX techniques. The maximum removal efficiencies of Ni2+, Pb2+, and Cd2+ ions were found to be 97.9%, 98.9%, and 88.8%, respectively. Additionally, the reusability of the adsorbent was also assessed based on three repeated adsorption–desorption cycles. CDBC achieved removal efficiencies of 53.6%, 68.5%, and 49.6% toward Ni2+, Pb2+, and Cd2+ ions after the third cycle. An investigation of the adsorption behavior and mechanisms was carried out using the adsorption isotherm and kinetic models. Based on the results, the use of CDBC was confirmed as an efficient, sustainable adsorbent for the remediation of heavy metal ions in wastewater treatment.