<i>Eucalyptus camaldulensis</i> leaves-derived biochar for effective removal of Cd(II) and Pb(II) ions from aqueous solutions

Remediation of heavy metal pollution is essential for safeguarding ecological integrity and public health. The present work aimed to prepare a novel biochar from <i>Eucalyptus Camaldulensis</i> leaves (EC-biochar) for the effective removal of Cd²⁺ and Pb²⁺ cations, as representative heavy metals, from aqueous solutions. The adsorption performance of Cd²⁺ and Pb²⁺ cations by EC-biochar was assessed by varying different operating parameters (<i>e.g.</i> pH, temperature, EC-biochar dose, adsorption time, and adsorbate concentration). The maximum removal efficiencies of Pb²⁺ (83.8%) and Cd²⁺ (89.6%) ions were achieved at pH 4.5. The pseudo-second order and Langmuir isotherm models satisfactorily predict the adsorption of Pb²⁺ and Cd²⁺ cations onto EC-biochar. The negative values of Δ<i>G</i>° and Δ<i>H</i>° demonstrated that the adsorption process is spontaneously feasible and exothermic. It is also worth pointing out that the regeneration/reuse study revealed that the as-prepared EC-biochar maintained an excellent adsorption performance after five reuse cycles, demonstrating its suitable reusability. These findings demonstrate that the EC-biochar can serve as an inexpensive, effective and recyclable adsorbent for treating heavy metal-laden effluents.