Adsorption Efficacy of Silver Nanoparticles Synthesized Using Wintergreen Plant Extract: A Green Approach to Dye Removal

Abstract

This study uses wintergreen (Gaultheria procumbens) plant extract as a reducing agent in a green synthesis technique to create silver nanoparticles (AgNPs). Numerous analytical methods, including scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), UV-visible spectroscopy, and zeta potential analysis, were used to characterize the synthesized AgNPs. The results revealed the successful synthesis of AgNPs with an average size of approximately 25 nm and a face-centered cubic (FCC) crystalline structure. Furthermore, the synthesized AgNPs effectively removed direct yellow 4 (DY4) dye from aqueous solutions, displaying a maximum adsorption capacity of 92 mg/g. The adsorption kinetics of DY4 on AgNPs followed the pseudo-second-order model, indicating that chemisorption mechanisms predominantly govern the adsorption process. Additionally, the adsorption isotherms of DY4 on the surface of AgNPs adhered closely to the Langmuir isotherm model, suggesting monolayer adsorption on the uniform surface of AgNPs through strong adsorbate-adsorbent interactions. Moreover, the AgNPs demonstrated promising potential for reusability, as evidenced by the retention of approximately 97% adsorption efficiency even after undergoing four consecutive adsorption-desorption cycles. This highlights the robustness and durability of the AgNPs as effective adsorbents for wastewater treatment applications.