Kristofferson Sipagan

After some time, the nanoparticles settle. If you pass a narrow beam of light through a transparent dispersion system, then when directed perpendicular to the beam you will see a cloudy dispersion.

Hello Kristofferson Sipagan ,

if you want to determine the size of the particles, you could do some dynamic light scattering. The technique is based on the scattering, which Yuri Mirgorod described, and gives you information about the size and size distribution of your particles and sample preparation is simple and can be done quickly.

Matthias Heck

I did not recommend the DLS method. It requires a device. I recommended simple nephelometry. You can use a cell phone flashlight to do this in the dark.

Yuri Mirgorod

I also did not write that you suggested the DLS method. I just mentioned, that DLS is also based on light scatteing in a certain anlge, as nephelometry.

However, DLS is truly more complicated due to not just measuring the intensity of the scattered light but also it's autocorrelation function.

Sadaf Noor

Any dispersed system consisting of nanoparticles is unstable thermodynamically (to the aggregation of nanoparticles) and kinetically (to the sedimentation of nanoparticles). Extracts contain large molecules of rutin, tannins, with hydroxyl groups that act as reducing agents. They also promote aggregation. Depending on their concentration, sedimentation will occur slowly or quickly.

Article Preparation and bactericidal properties of silver nanopartic...

Even 100nm ZnO particles will settle in water. There's a large density difference.

Experience: been there, done that!

I found a research article that describes the preparation of bare and stabilized zinc oxide nanoparticles (ZnO NPs) using a microwave-assisted method 1. The article does not mention whether the nanoparticles should settle after some time. However, it is possible that the nanoparticles may settle over time due to gravity. The settling rate of the nanoparticles may depend on various factors such as the size and shape of the nanoparticles, the solvent used, and the concentration of the nanoparticles in the solution. If you have more specific information about the preparation of the ZnO NPs, I may be able to provide a more detailed answer.

1: ACS Omega

In a solution containing microwave-assisted synthesized zinc oxide nanoparticles (ZnO NPs), whether the nanoparticles settle over time depends on various factors, including the size of the nanoparticles, the stabilizing agents or surfactants used during synthesis, and the overall colloidal stability of the solution.

Here are some considerations:

If settling is observed and is undesirable for your application, you can take the following steps:

• Optimize Stabilization: Ensure that the stabilizing agents or surfactants are appropriately chosen and optimized for the specific synthesis conditions.
• Redispersion: Gentle agitation or sonication can be used to redisperse settled nanoparticles. Sonication helps break up agglomerates and ensures a more uniform distribution.
• Surface Modification: Consider modifying the surface of the nanoparticles to enhance their stability in the solution.
• pH Adjustment: Adjusting the pH of the solution may influence the surface charge of the nanoparticles and their stability.

It's important to note that the settling behavior of nanoparticles can be complex, and the specific conditions of the synthesis and the solution can significantly impact the outcomes. Experimental testing and optimization are often necessary to achieve the desired stability in nanoparticle suspensions.