Enhancing Pb²⁺ removal using a novel cerium-based metal organic framework: Post-synthetic modification and response...

Contamination of water by heavy metals poses a serious threat to human health, prompting global research into effective remediation strategies. This research presents an innovative method utilizing a Cerium (Ce)- based metal-organic framework, i.e., Ce-MOF-808, modified with 3-aminopropyltriethoxysilane (APTES) for the first time, for the remediation of Pb²⁺ from aqueous solutions. Ce-MOF-808 was synthesized at ambient temperature, followed by APTES grafting via a hydrothermal method. The successful synthesis of Ce-MOF-808-APTES was confirmed through comprehensive characterization techniques. Batch adsorption experiments were conducted to evaluate the effects of pH, adsorbent dose, adsorbate concentration, temperature, and contact time on Pb²⁺ removal. The material achieved a removal efficiency of 99.87% for an initial Pb²⁺ concentration of 10 ppm at room temperature, thereby lowering the residual Pb²⁺ level to 0.01 ppm, which meets the WHO drinking water standards and effluent discharge limits. Kinetic studies indicated a pseudo-second-order model, although equilibrium facts associated with the Langmuir isotherm suggested a maximum adsorption capacity of 184.32 ± 18.32 mg g^-1, indicative of monolayer chemisorption. Thermodynamic analysis confirmed the process as spontaneous and exothermic. Optimization using Response Surface Methodology (RSM) with a Central Composite Design (CCD) across 30 trials identified optimal conditions, with a quadratic model yielding an R² of 0.99, ensuring robust predictability. These results highlight Ce-MOF-808-APTES as a highly effective adsorbent for Pb²⁺ removal and underscore the need for further exploration into its application for diverse heavy metal contaminants in wastewater treatment.