Citrullus Colocynthis Fruit Extract Mediated Green Synthesis of Silver Nanoparticles: The Impact of pH, Temperature, and Silver Nitrate Concentration

Abstract

Silver nanoparticles (Ag NPs) can be produced from various approaches including physical, chemical, and biological approaches. However, green synthesis methods are simple, efficient, and eco-friendly methods and provide relatively more stable nanoparticles. In the current investigation, Ag NPs have been synthesized utilizing Citrullus colocynthis fruit extract as a reducing, capping, and stabilizing agent. Then, Ag NPs were characterized through various classification methods to investigate their size, purity, stability, degree of crystallinity, structure, and optical properties. The impact of different parameters including concentration of AgNO₃, pH, and reaction temperature on the biosynthesized Ag NPs and corresponding surface plasmon resonance (SPR) behavior were investigated intensively. This study showed that increasing pH values cause tightening the SPR peaks, and therefore, obtaining monodisperse NPs. On the other hand, increasing the reaction temperature increased the band gap of NPs and, thus, reduced the size of NPs. However, the agglomeration state and later the stability of the biosynthesized Ag NPs are increasing with increasing the AgNO₃ concentration. This investigation, exceptional and unique, confirms that reaction pH, the reaction temperature, and the precursor concentration play important roles in the formation process of NPs. Through selective combination of these trio, one can produce Ag NPs with desired structural, morphological, and optical properties which can be suitable for different applications.