Green Synthesis of Silver Nanoparticles Using Azadirachta Indica Aqueous Leaf Extract

Silver nanoparticles (AgNPs) are used very often because they have special antimicrobial and optical properties and have high electrical conductivity. The sonochemical synthesis route using kappa carrageenan is a simple, convenient and environmentally friendly method for the production of silver nanoparticles.

The κ-carrageenan serves as a natural, green stabilizer, while high-performance ultrasound acts as an environmentally friendly reducing agent. Green, ultrasound-assisted synthesis of silver nanoparticles Elsupikhe et al. (2015) have developed a green, ultrasound-assisted synthesis route for the production of silver nanoparticles (AgNPs). It is known that the entry of high-performance ultrasound into chemical systems (so-called sonochemistry) has a positive effect on many wet-chemical reactions.

For example, it is possible to use ultrasound to synthesize AgNPs with κ-carrageenan as a natural stabilizer. The reaction takes place at room temperature and produces silver nanoparticles with an fcc crystal structure without impurities. The grain size distribution of the AgNPs can be influenced by the concentration of κ-carrageenan.

In order to be able to evaluate the result of the synthesis, the samples were analyzed by means of UV spectroscopy, X-ray diffraction, FT-IR (Fourier Transform Infrared), TEM and SEM images. The number of Ag-NPs increases with increasing κ-carrageenan concentrations. The formation of Ag / κ-carrageenan was determined by UV-visible spectroscopy, where the surface plasmon absorption maximum at 402 to 420 was observed.

The X-ray diffraction (XRD) analysis revealed that the Ag NPs have a face-centered cubic structure. Fourier transform (FT-IR) infrared spectrum indicated the presence of Ag-NPs in κ-carrageenan. Transmission electron microscopy (TEM) image for the highest concentration of κ-carrageenan showed the distribution of Ag NPs with an average particle size close to 4.21nm.

Scanning electron microscopy (SEM) images illustrates the spherical shape of the Ag-NP. The SEM analysis shows that with increasing concentration of κ-carrageenan, changes occurred in the surface of Ag / κ-carrageenan, so that smaller

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