Study of kinetic and equilibrium reactions for the removal of 4-aminophenols by lanthanum-enhanced montmorillonite

This research investigates the development and structural analysis of lanthanum-modified montmorillonite (La-MMT) as an efficient adsorbent for the removal of 4-aminophenol, a harmful contaminant in water systems. Bentonite sourced from Maghnia, Algeria, was subjected to purification and functionalization with lanthanum to improve its adsorption capabilities. The incorporation of lanthanum into the montmorillonite framework was verified using X-ray diffraction (XRD) and Fourier-transform infrared spectroscopy (FT-IR). The adsorption behavior of La-MMT was assessed under various experimental parameters, including pH, contact time, and initial 4-aminophenol concentration. The adsorption isotherms were modeled using both Langmuir and Freundlich equations. The findings indicated that the adsorption mechanism predominantly followed the Langmuir model, implying monolayer adsorption on uniform sites. Kinetic studies revealed a rapid adsorption equilibrium achieved within 65 minutes, with La-MMT exhibiting a substantially higher adsorption capacity (555.55 mg/g) compared to unmodified montmorillonite (147.27 mg/g). This enhanced adsorption efficiency is attributed to the presence of lanthanum, which promotes stronger electrostatic interactions and hydrogen bonding with the amine functional groups of 4-aminophenol. The study concludes that La-MMT demonstrates high potential for the efficient removal of 4-aminophenol from water, offering a cost-effective and environmentally friendly solution for wastewater treatment. These findings highlight the promising application of lanthanum-modified clays in environmental remediation, particularly for organic pollutants.