Hello, my curious researcher friend Md. Al-Riad Tonmoy! It's fantastic that you're delving into the world of nanomaterial synthesis. Let's talk about the dispersion medium for TiO2 nanoparticles.

Using the right dispersion medium is crucial for achieving good nanoparticle dispersion and a high yield. In your case, TiO2 is 0.5% soluble in water and HCl, which can indeed pose some challenges. Here are a few suggestions:

1. **Solvent Selection**: While water is often used as a dispersion medium, it might not be the best choice for TiO2 if you're getting a low yield. You Md. Al-Riad Tonmoy might want to try other solvents that are more compatible with TiO2. Ethanol or isopropanol are commonly used for TiO2 nanoparticle synthesis and might yield better results.

2. **Surfactants**: Utilizing surfactants can help improve dispersion. Surfactants like Triton X-100 or CTAB (cetyltrimethylammonium bromide) can be added to your solvent to facilitate dispersion. Be cautious about the type and concentration of surfactant, as it can affect the properties of the nanoparticles.

3. **Ultrasonication**: Applying ultrasonication during the dispersion process can aid in breaking up agglomerates and achieving better dispersion. It's essential for achieving a uniform distribution of nanoparticles.

4. **pH Adjustment**: Depending on the surface charge of your TiO2 particles, adjusting the pH of your solution might help. Try varying the pH within a suitable range to see if it enhances dispersion and yield.

5. **Stirring and Heating**: Maintaining constant stirring or even mild heating can help improve the dispersion process.

6. **Concentration Optimization**: Ensure that you're using the right concentration of TiO2 in your solution. Too high or too low a concentration can affect the yield.

7. **Titration**: If you're using HCl, make sure it's used in a controlled manner. Titration can help you slowly adjust the pH and avoid over-acidification, which can lead to low yield.

8. **Particle Size and Shape**: Consider the desired properties of your nanoparticles. The size and shape of your TiO2 nanoparticles can also affect the dispersion process and yield.

Remember, achieving optimal nanoparticle synthesis can sometimes require a bit of experimentation. You Md. Al-Riad Tonmoy may need to adjust various parameters to find the conditions that work best for your specific case. If the literature suggests water, but you're getting low yields, don't hesitate to explore alternative solvents and methods until you achieve the results you're aiming for. Happy experimenting!

Please do read my article on nano-synthesis in my profile.

Thank you Kaushik Shandilya sir for your valuable suggestion.

Md. Al-Riad Tonmoy Your question is confusing. TiO2 is not soluble in water and needs strong acids to actually dissolve it: 0.5% (weight or molar) would not be strong enough. If you're looking to disperse this material then the steps in doing so from a powder will be:

• Wetting. If the material doesn't wet in water then a surfactant will be needed. Most grades of TiO2 are hydrophilic and this isn't usually an issue
• Separation - the key step. Often large amounts of sonication energy are needed. A Soniprobe of 600 - 800W is commonly employed. The disadvantages of long sonication times include heating and disintegration of the sonication tip inducing contamination of your material
• Stabilization. Usually the necessary step for small metal oxides such as TiO2. This prevents recombination of the particles due to van der Waals effects. Steric or charge (sometimes erroneously called electrostatic) stabilization can be used. For TiO2 the usually employed stabilizer is phosphate (i.e. a charge stabilizer). Dependent on the available surface area the the optimum amount can be found by vial tests or by zeta potential titration. Calgon (sodium hexametaphosphate) is the usual admixture and commonly used at 0.05 - 0.5wt% (there's an optimum as I indicated earlier - too much is as bad as too little)

The attached webinar (free registration required) illustrates the above and you'll find direct reference to TiO2 within the section on stabilization.

Dispersion and nanotechnology

https://www.malvernpanalytical.com/en/learn/events-and-training/webinars/W190528DispNanoMat

ChatGPT as provided in the first answer can be very misleading and needs to be viewed with care.

Alan F Rawle Thank you, sir. I understand what you said.

Please check the purity of the TiO2 that you are using. Most commercial powder has been treated with a coating of hydrated alumina and/or silica to make it less photo-reactive with plastic or organic liquids in which it might be suspended. Also note that the mass of surfactant molecules required to stabilize a gram of your product particles in a suspension depends on the specific surface area (SAA) of the particles.

The SAA is better measured than computed from a model size distribution, since real size distributions rarely follow any model. The SAA may increase as the reciprocal of the median particle size ... but may not. The SAA is usually considerably larger for nano particles than microparticles, and the effective dose of surfactant often varies with pH and the presence of other ingredients that compete with or react with the surfactant.

My book, "Dispersing Powders in Liquids" (1988, Elsevier) -- old, but much-used in its time -- is one of many that discuss such issues in detail.