Bioengineered Iron Nanoparticles From Canavalia cathartica Seeds: A Promising Nanobiosorbent for Cr (VI) Remediation

This study reports the green synthesis of iron nanoparticles (FeNP-CC) using aqueous seed extract of Canavalia cathartica, a less explored mangrove associate, and evaluates their efficacy in the remediation of hexavalent chromium (Cr(VI)) from aqueous systems. Phytochemical and spectroscopic analyses using LC-MS/MS, UV-visible spectroscopy, FTIR, HR-TEM, and XRD confirmed that bioactive constituents such as polyphenols and L-canavanine acted as both reducing and stabilizing agents during the synthesis of FeNP-CC, resulting in nanoparticles with a nanocrystalline core-shell morphology. Adsorption experiments revealed that Cr(VI) removal followed pseudo-second-order kinetics, suggesting a chemisorption-dominated mechanism. Equilibrium studies fitted best to the Freundlich isotherm model (R² = 0.99), indicating multilayer adsorption on a heterogeneous surface. Optimal removal (100%) was achieved for 10 mg/L Cr(VI) within 50 min under acidic conditions. Furthermore, FeNP-CC successfully remediated complex, real-world laboratory wastewater containing 30 mg/L Cr(VI) despite competitive matrix interferences. Overall, this biogenic nanobiosorbent represents a highly sustainable, low-cost, and efficient candidate for practical wastewater purification.