Green Synthesis of Gold Nanoparticles Using Aqueous Leaf Extract of Alchornea cordifolia and Catalytic Reduction of Methylene Blue

International Journal of Chemistry | Vol. 8, No. 12, December 2017 | pp. 89–96

DOI: 10.46882/2017/IJC/000111

Article Type: Original Research Paper

Title: Green Synthesis of Gold Nanoparticles Using Aqueous Leaf Extract of Alchornea cordifolia and Catalytic Reduction of Methylene Blue

Names of Authors: S. I. Musa¹, C. R. de Souza²*

Authors’ Affiliations:
¹Department of Chemistry, University of Jos, Jos, Nigeria.
²Department of Chemical Engineering, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil.

Abstract: The biological synthesis of noble metal nanomaterials using tropical flora presents an eco-friendly and economically sustainable alternative to hazardous chemical reduction pathways. This study describes the green synthesis of stable gold nanoparticles (AuNPs) utilizing the aqueous leaf extract of Alchornea cordifolia as a powerful reducing and capping agent. The bioreduction process was monitored via UV-Vis spectrophotometry, which revealed a distinct surface plasmon resonance peak at 532 nm, confirming the nucleation of metallic gold. Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) analyses showed highly spherical nanoparticles with an average particle diameter of 15 nm. X-ray diffraction (XRD) patterns confirmed the face-centered cubic crystalline structure of the biosynthesized gold. Fourier-transform infrared (FT-IR) spectroscopy indicated that water-soluble polyphenols and flavonoids within the leaf matrix were responsible for capping and protecting the AuNPs against structural agglomeration. The catalytic efficiency of the synthesized AuNPs was evaluated by tracking the chemical reduction of methylene blue dye by sodium borohydride (NaBH₄) in an aqueous system. In the presence of the green catalyst, the reaction achieved 96.8% decolorization within 8 minutes. The dye degradation kinetics conformed tightly to the pseudo-first-order kinetic model with a rate constant of 0.295 min⁻¹, indicating excellent catalytic potential for textile wastewater treatment arrays.

Keywords: Gold nanoparticles; Green synthesis; Alchornea cordifolia; Biosynthesis; Heterogeneous catalysis; Methylene blue degradation

Manuscript Timeline: Received: October 12, 2016; Revised: November 24, 2016; Accepted: December 18, 2016; Published: December 04, 2017.

Citation: Musa, S. I., & de Souza, C. R. (2017). Green Synthesis of Gold Nanoparticles Using Aqueous Leaf Extract of Alchornea cordifolia and Catalytic Reduction of Methylene Blue. International Journal of Chemistry, 8(12), 89–96.

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