An assessment of biopolymer-based metal oxide nanoparticles for the removal of heavy metals from water

Abstract

Water contamination by toxic heavy metals remains a persistent environmental and public health challenge, demanding cost-effective and sustainable remediation approaches. In this study, a banana peel–based metal oxide nanocomposite (Fe₃O₄/TiO₂/BP) was synthesized via a combined co-precipitation and hydrothermal-assisted method and evaluated for the removal of Cr(VI), Cd(II), and Pb(II) from water.  Characterization using FTIR, SEM–EDS, and XPS confirmed the successful incorporation of Fe₃O₄ and TiO₂ nanoparticles into the banana peel matrix, resulting in enhanced surface functionality and magnetic separability. The equilibrium data were best described by the Langmuir and Redlich–Peterson isotherm models, indicating monolayer adsorption with maximum capacities of 14.4 mg/g for Cr(VI), 10.9 mg/g for Cd(II), and 100 mg/g for Pb(II). Kinetic modeling revealed that adsorption followed the pseudo-second-order model (R² = 0.97–0.93), suggesting a chemisorption-controlled mechanism involving electron exchange and surface complexation. The Fe3O4/TiO/BP nanocomposite exhibited excellent performance and competitive adsorption capacity compared to other reported metal oxide-based adsorbents, confirming its potential as a sustainable, low-cost material for multicomponent heavy metal removal and agricultural waste valorization.

Keywords: Adsorption; Langmuir isotherm; Kinetic study, chemisorption