GREEN SYNTHESIS OF NANO-ZERO-VALENT IRON USING CLEISTOCALYX OPERCULATUS EXTRACT FOR EFFICIENT RHODAMINE B DEGRADATION

Abstract

In this study, nano-zero-valent iron (nZVI) was successfully synthesized via a green method using Cleistocalyx operculatus leaf extract as a natural reducing agent. The synthesized nZVI was characterized by XRD, SEM-EDS, FT-IR, and BET analyses. The XRD pattern confirmed the formation of crystalline α-Fe⁰while SEM images revealed spherical aggregates in the 50-100 nm size range. FT-IR analysis identified organic functional groups from the plant extract on the nanoparticle surface, indicating bio-capping. BET analysis showed a specific surface area of 67.484 m2/g with a mixed micro-mesoporous structure. Batch degradation experiments were conducted at an initial Rhodamine B (RhB) concentration of 10 mg/L, using an nZVI dose of 0.3 g/L, H2O2 dose of 0.01 M, and initial pH of 7.0. Results demonstrated that nZVI alone mainly adsorbed RhB, whereas H2O2 alone exhibited limited oxidation. In contrast, the combined nZVI/H2O2 system achieved nearly complete decolorization within 50 min, following a pseudo-first-order kinetic model with an apparent rate constant of 0.083 min-1. The enhanced efficiency was attributed to a heterogeneous Fenton-like process generating highly reactive ·OH radicals. These findings highlight that C. operculatus-mediated nZVI provides a sustainable and efficient strategy for the removal of organic dyes from wastewater, underscoring its promise for advanced water treatment applications.