Integrating experimental and molecular dynamics insights into fluorescein dye adsorption on natural bentonite

This study explores the adsorption of fluorescein dye (FD) onto bentonite (BT) to enhance its potential in environmental remediation and water treatment. X-ray diffraction (XRD) analysis confirmed montmorillonite as the dominant phase in BT, with significant SiO₂ and quartz peaks. SEM and EDX characterization revealed a regular bulk morphology and the presence of silicon, aluminium, magnesium, iron, and trace elements. Adsorption experiments were conducted to evaluate the effects of adsorbent dosage, solution pH, and temperature. Increasing BT dosage from 20 mg to 400 mg enhanced dye removal efficiency from 21% to 78.6%, attributed to the availability of more adsorption sites. However, higher dosages led to reduced efficiency, likely due to limited surface contact between dye molecules and active sites. Optimal adsorption was observed at pH 6 and 30 °C. Adsorption mechanisms were analysed using kinetic and isotherm models, while molecular dynamics simulations confirmed stable fluorescein–bentonite interactions. This study provides new insights into the adsorption behaviour of fluorescein on BT, demonstrating its efficiency as an eco-friendly adsorbent for organic dye removal.