Green synthesis of high dispersion and narrow size distribution of zero-valent iron nanoparticles using guava leaf (Psidium guajava L) extract

Pichsinee Somchaidee and Karaked Tedsree

Abstract

Zero-valent iron nanoparticles (Fe⁰ nanoparticles) with particle sizes in range 2–5 nm were synthesized using guava leaf extract from the reduction of Fe⁺³ soluble precursor. The most effective solvent for the extraction of polyphenolic compounds from guava leaf was identified to contain 70% hydroethanolic solution. It was also found that this extract gives high reduction potential and a strong chelating ability for the preparation of Fe⁰ nanoparticles from soluble Fe⁺³ in basic aqueous solution at room temperature. At pH 8, the deprotonation of the polyphenolic groups with terminal –OH provides the strong binding sites to form a stable complex with Fe⁺³ and can take part in the redox reduction. The formation and growth of Fe⁰ nanoparticles were monitored by UV-visible absorption spectroscopy and transmission electron microscopy. The achieved high dispersion and narrow size distribution of Fe⁰ nanoparticles are attributed to the ability of tannins which are the major components of the polyphenolic groups to form strong complex with Fe⁺³ and stabilize Fe⁰ nanoparticles from aggregation. Methylene blue degradation in an aqueous solution was used as a model for study catalytic reduction performance of the synthesized tannin-stabilized Fe⁰ nanoparticles in colloidal form