An Assessment of Biopolymer-Based Metal Oxide Nanoparticles for the Removal of Heavy Metals from Water

Water contamination by toxic heavy metals continues to be a major environmental and public health issue, requiring affordable and sustainable remediation solutions. This study developed a nanocomposite from banana peel, incorporating Fe3O4 and TiO2 nanoparticles through a combined co-precipitation and hydrothermal method, and evaluated its effectiveness in adsorbing Cr(VI), Cd(II), and Pb(II) from water. Characterization techniques such as FTIR, SEM–EDS, and XPS confirmed successful integration of Fe3O4 and TiO2 into the banana peel matrix, improving surface properties and magnetic separability. The adsorption data fit the Langmuir and Redlich–Peterson models best, indicating monolayer adsorption with maximum capacities of 14.4 mg.g-1 for Cr(VI), 10.9 mg.g-1 for Cd(II), and 100 mg.g-1 for Pb(II). Kinetic analysis showed the adsorption follows a pseudo-second-order model (R2 = 0.97–0.93). The nanocomposite exhibited excellent adsorption efficiency and competitive capacity compared to other metal oxide adsorbents, demonstrating its potential as a lowcost, sustainable material for removing multiple heavy metals and valorizing agricultural waste.