Guava seeds synthesized silver nanowires
Contents
Guava synthesis of the Ag-NW
This experiment synthesis Ag-NWs with Psidium Guajava seed, Guava seeds contain some compounds, such as polyphenols and alkaloids, which might reduce silver nitrate to silver and synthesis the particle to wire-alike or "flakes" shapes under certain conditions. These compounds acted as reducing agents and stabilizers during the preparation process, thus enabling a green synthesis method without external stabilizers. However although we did repeated the experiment introduced in the paper and have obtained the orange solution, the dried solution didn't show the conductivity, and the SEM result doesn't show the existence of nanowires. This maybe due to the absence of PVP the caping agent and insufficient UV exposure during the synthesis process.
Experiments
The experiment process is introduced below in the gallery. The process aims to repeat the result introduced in the paper "UV-Light Mediated Biosynthesis of Silver Nanowires; Characterization, Dye Degradation Potential and Kinetic Studies". The first attempt was made in BioClub Tokyo. Additionally, 3 groups of mixtures with different concentration of guava seed extraction was prepared: 1. silver nitrate solution mixed with distilled water, 2. silver nitrate solution mixed with guava seed extraction heat stirred for 50 mins, 3. silver nitrate solution mixed with guava seed extraction heat stirred for 4 hours. All beakers are put under UV exposure for 4 hours, the color of the second and 3rd mixture were changed from milky white to orange. The orange solution and the aggregations were collected separately, but only the solution was examined by the UV-vis spectrum in Tokyo.
- step by step process
The seeds was extracted from guava purchased in Taiwan.
The seeds was firstly dried in oven at 50ºC for 48 hours and then powdered by grinder pestle without filtering.
Mix 0.1g of the guava seed powder with 100ml distilled water, and it's stirred with heat stirrer at 40ºC for 50 minutes.
Prepare 1mM silver nitrate solution by dissolving 1.7 grams of silver nitrate crystals in 100 ml of distilled water. Stir it in room temperature until the solution turns clear.
Mix the silver nitrate solution and guava extraction by the ratio of 2:1.
The mixed solution was put into an UV chamber and was exposure for 4 hours in room temperature. All beakers are sealed with cling film.
The change of the color of the final solutions after UV exposure.
The final solution was filtered with filter paper and the color is in orange.
The UV-vis spectrum comparism
The result of UV-Vis spectrum data can be downloaded here.
- UV-vis spectrum result
UV-vis analytic chart was made and supported by Shohei Asami, member BioClub Tokyo.
UV-vis graphs of the orange final solution and clear final solution.
UV-Vis graphs of P. Guajava extraction and Ag-NWs from the paper.
SEM photography
Two samples were prepared, the first one is the final solution drop dried on glass, the second is the aggregations collected from the centrifuged final solution. There's no sign shows the existence of the wire-alike shape, indicating the failure of the nano wire synthesis with guava seeds extraction. Only "flake-alike" shape was found in the sample.
- SEM result
Centrifuged final solution.
The final solution and the prepared sample for SEM. The right one on glass is the drop of solution, the left one is the aggregation from the centrifuge.
The SEM photograph of the aggregated sample under 50 µm..
The SEM photograph of the aggregated sample under 10 µm..
Preferences
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