Insights into Preparation of Polycaprolactone–Chitosan–Montmorillonite Composite for Pb(II) and Cd(II) Removal

Abstract

Industries frequently discharge elevated levels of lead and cadmium into the environment, posing significant threats to ecological balance and public health. This study developed a novel polycaprolactone–chitosan–montmorillonite (PCL/CS/MMT) composite to adsorb Pb(II) and Cd(II) from aqueous solutions. The composite was synthesized via twin-screw melt extrusion and subsequently characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), Fourier transform infrared spectroscopy (FTIR), and thermogravimetric analysis (TGA), revealing a crystalline structure, cracked surface morphology, functionalized surface groups, and thermal stability. Under optimal batch conditions, the adsorbent achieved maximum adsorption capacities of 12.35 mg/g for Pb(II) and 16.92 mg/g for Cd(II). Adsorption behavior followed the Langmuir isotherm model, and kinetic data aligned with the pseudo second-order model, indicating a chemisorption-driven mechanism. The composite demonstrated effective regeneration, retaining over 55% adsorption efficiency after seven desorption cycles with 0.1 M $$ (pH 8). These findings position the PCL/CS/MMT composite as a promising, sustainable adsorbent for wastewater treatment, offering a viable solution to heavy metal pollution and advancing the development of eco-friendly materials for environmental remediation.