Synthesis and Characterization of Gum Arabic–Stabilized Gold Nanoparticles for Heavy Metal Remediation

This research presents the green synthesis of gold nanoparticles (AuNPs) utilizing natural Gum Arabic (GA) resin as an environmentally reducing and stabilizing agent. The study addresses pressing water pollution concerns in Oman by developing a sustainable nanotechnology-based approach for the remediation of trace heavy metal ions (Cu²⁺, Pb²⁺, and Zn²⁺) from aqueous environments. GA was employed at concentrations of 5% and 10% (w/v) in reactions with chloroauric acid (HAuCl₄) under systematically varied conditions, including temperature (23.0–80.0 °C), pH (6.00–9.00), and reaction time (0.33–48.00 h). The synthesised AuNPs were characterised using ultraviolet–visible (UV–Vis) spectroscopy, Fourier transform infrared spectroscopy (FTIR), and transmission electron microscopy (TEM) to assess their optical properties, morphology, and surface chemistry. Optimal synthesis conditions—10% GA, 5 mM HAuCl₄, 55.0 °C, pH 9.00, and 0.67 h—resulted in a stable ruby-red colloidal dispersion exhibiting a distinct surface plasmon resonance (SPR) peak at 518 nm, indicative of monodisperse spherical AuNPs. FTIR analysis confirmed the involvement of hydroxyl, carbonyl, and amine functional groups in nanoparticle formation and stabilization. The biosynthesis AuNPs demonstrated efficient removal of heavy metal ions from aqueous solutions in the order of Pb²⁺ > Cu²⁺ > Zn²⁺.These findings highlight the potential of Gum Arabic as a green, cost-effective, and biocompatible material for fabricating functional AuNPs suitable for environmental sensing and water purification applications.