Elettaria cardamomum seed extract synthesized silver nanoparticles for efficient catalytic reduction of toxic dyes

Abstract

The emissions of lethal organic pollutants, e.g., toxic dyes, from various industries result in the contamination of water, and hence, it is highly desirable to eradicate these pollutants. Herein, the catalytic reduction of hazardous methylene blue (MB) and rhodamine B (RhB) dyes has been evaluated (using sodium borohydride (NaBH4) as a reductant) by silver nanoparticles prepared from an extract of Elettaria cardamomum seeds (EC-Ag NPs). The UV–visible spectroscopy confirmed the successful formation of EC-Ag NPs. The results from the transmission electron microscopic (TEM) study indicated the spherical shape with an average particle size of 5.4 nm, along with the crystalline nature of EC-Ag NPs revealed from the XRD study. What is more, the FTIR result verified the existence of phytoconstituents that act as both stabilizing and reducing agents. The as-synthesized ES-Ag NPs showed excellent activity in the catalytic reduction of both lethal dyes (MB and RhB) in the presence of NaBH4. The reduction results revealed that it takes 7 and 10 min, respectively, to completely eradicate the MB and RhB, with rate constants of 0.328 and 0.244 min−1, which are significantly better than those previously reported. In addition, the as-synthesized ES-Ag NPs exhibit outstanding stability up to several rounds during the reduction of both dyes, proving their practical applicability at industrial and domestic levels.