Natural zeolite-iron nanocomposite for advanced water treatment: Adsorption of metformin and multiple contaminants with antibacterial performance

Metformin (MET) is one of the most prescribed antidiabetic drugs worldwide, and its recurrent detection in aquatic environments raises concerns regarding ecological and human health risks. In this work, a multifunctional composite based on natural zeolite functionalized with iron nanoparticles (NZ-FeNPs) was synthesized via a green route using Guazuma ulmifolia extract. The material was thoroughly characterized, confirming successful functionalization, structural stability, and preservation of the zeolitic framework. Comprehensive characterization techniques, including SEM, TEM, EDX, FTIR, XRD, XRF, leaching tests, and zeta potential measurements, confirmed the successful formation, homogeneous dispersion, and chemical stability of Fe nanoparticles within the zeolitic framework. Adsorption studies revealed a maximum capacity of 9.66 mg/g for MET at 45 °C, with the Sips and pseudo-second-order models accurately describing the equilibrium and kinetic data. Thermodynamic analysis indicated an endothermic and spontaneous process, governed by hydrogen bonding, electrostatic interactions, and metal–ligand complexation. The composite also demonstrated robust performance in multicomponent systems, achieving complete removal of chloroquine and neutral red while maintaining high MET adsorption efficiency. Desorption tests with NaOH confirmed the catalyst's reusability over multiple cycles. Furthermore, NZ-FeNPs exhibited antibacterial activity against Escherichia coli , with MIC and MBC values of 62.5 and 125 mg/mL, respectively. These results demonstrate the potential of NZ-FeNPs as a sustainable, versatile material that can couple adsorption and antibacterial functionalities for advanced water purification. • Green synthesis of Fe-based nanoparticles using Guazuma ulmifolia extract. • Natural zeolite acted as an efficient support for nanoparticle formation and stabilization. • NZ–FeNPs preserved zeolitic structure and mesoporosity after green functionalization. • NZ–FeNPs showed effective removal of metformin, chloroquine, and neutral red in multicomponent systems. • NZ-FeNPs exhibited antibacterial activity against Escherichia coli.