Removal of lead ions from aqueous solutions using functionalized pine cone powder

In this work, a new carboxylate-modified pine cone is synthesized via esterification of pine cone with isopropylidene malonate. The chemical modification procedure is optimized, and then, the adsorbent prepared is characterized by different techniques such as field emission scanning electron microscopy, energy-dispersive X-ray diffraction, and FT-IR spectroscopy in order to approve the presence of carboxylic groups on the surface of pine cone. The performance of the bio-sorbent is investigated for the removal of lead ions from the aqueous solution. The factors affecting the performance of the prepared adsorbent are analyzed and optimized in an experimental setup. Under the optimum conditions, studying the experimental data illustrates that the Langmuir isotherm can suitably describe the equilibrium data, and at a temperature of 298 K, pH 4.8, and 0.40 g L−1 of the adsorbent, the maximum adsorption capacity of 400.0 mg g−1 is obtained; this value is much higher than some of the newly reported ones. The high lead ion adsorption can be attributed to the abundant functional groups present in the adsorbent. Carboxylate-modified pine cone can be successfully regenerated for 3 times using EDTA-2Na as the solvent elution.