Photodegradation of methylene blue using phyto-mediated synthesis of silver nanoparticles: effect of calcination treatment

Abstract

In this study, discrete Ag0 nanoparticles (10–40 nm) were synthesized by a simple electrochemical method in Cymbopogon nardus leaves extract as a medium. The leaves extract remarkably reduce the Ag ion to produce Ag0 nanoparticles without any agglomeration. Its crystallinity, morphology, and functional characteristics were analyzed by using X-ray diffractometer, transmission electron microscope, and Fourier-transform infrared spectrometer, respectively. The characterization results verified that Cymbopogon nardus leaves extract containing flavonoids plays an important role in reducing the Ag0 nanoparticles in the electrochemical cell. The activity of the synthesized Ag0 nanoparticles was tested on a photodegradation of methylene blue (MB). The calcined Ag0 nanoparticles give higher degradation percentage of MB (92%) as compared to the uncalcined Ag0, operating in pH 5, with a reaction time of 180 min, at 30°C, using 0.02 g L−1 of catalyst dosage and 10 mg L−1 of MB initial concentration. A reusability study showed that the catalyst was still stable after five subsequent reactions. The results provide strong evidence to support the potential use plant-based extracts to synthesize nano-sized photocatalyst that can be used to treat organic pollutants such as MB