Preparation and Evaluation of Phenol Formaldehyde-Montmorillonite and Its Utilization in the Adsorption of Lead Ions from Aqueous Solution.

In this study, phenol formaldehyde-montmorillonite (PF-MMT) was prepared and used for lead ion (Pb2+) adsorption. Batch adsorption experiments were conducted to determine the optimal conditions. The calculated adsorption equilibrium (q) revealed that pseudo-second-order (PSO) and Langmuir isotherm models best fit the experimental data, suggesting chemisorption as the main mechanism. An adsorption capacity (qmax) of 243.9 mg/g was achieved. Fourier transform infrared (FTIR) analysis showed new peaks in PF-MMT-Pb, indicating metal complexation. Scanning electron microscopy (SEM) imaging displayed distinct Pb2+ clusters on the adsorbent surface. Adsorption was rapid, attaining equilibrium within 90 min. Effects of time, dose, concentration, and pH were systematically investigated to optimize the process. Lead ion removal efficiency reached 98.33% under optimum conditions after 90 min. The adsorption process was chemisorption based on the Dubinin-Kaganer-Radushkevich model with a free energy of 14,850 J/mol. The substantial adsorption capacity, rapid kinetics, and high removal efficiency highlight PF-MMT's potential for effective Pb2+ removal from aqueous solution.