Dear Noor Ul Ain

I hope this message finds you Noor Ul Ain well! Upscaling the production of nanoparticles can indeed be quite an adventure, and it’s fantastic to see you Noor Ul Ain considering the various factors that might influence your results. One crucial element to keep in mind is the size of the magnetic stirring bar, which can significantly impact the synthesis process by affecting mixing efficiency and reaction kinetics.

When scaling up, the size of the stirring bar should be proportional to the volume of your reaction mixture. A stirring bar that is too small may not generate the necessary turbulence for effective mixing, potentially leading to larger or poorly distributed nanoparticles. Additionally, increasing the stirring speed can enhance mixing and influence nucleation rates, which may result in smaller nanoparticles overall.

It’s also essential to pay attention to the concentration and volume of your reaction. Maintaining the correct concentration ratios is vital, as variations can affect supersaturation levels and subsequently impact nucleation and growth rates. Larger reaction volumes may necessitate adjustments in temperature control and stirring mechanics to replicate the conditions of smaller batches accurately.

Lastly, keep in mind that consistent temperature control becomes more challenging with larger batches. Uneven heating can lead to variations in nanoparticle size, and you Noor Ul Ain may need to monitor reaction times closely to ensure that the kinetics remain consistent when scaling up.

Each of these factors can significantly alter your experimental conditions, so I recommend documenting any changes you Noor Ul Ain make to better understand their impacts. Good luck with your experiments, and feel free to reach out if you Noor Ul Ain have any questions or need further insights!

The size of the magnetic stirring bar can indeed influence the size of nanoparticles during synthesis, especially when scaling up the process. When transitioning from small-scale synthesis (e.g., 100 mg of precursor salt) to larger-scale production (e.g., 10 g of precursor salt), several factors must be considered to maintain the quality and size distribution of the nanoparticles. These factors include the stirring bar size, mixing efficiency, hydrodynamics, precursor concentration, and reactor geometry.

1. Stirring Bar Size and Mixing Efficiency: The size of the magnetic stirring bar is crucial for efficient mixing. At smaller scales, the stirring bar is typically optimized for the volume of the reaction mixture. However, as you scale up, the volume of the solution increases, and the stirring bar may need to be adjusted to ensure sufficient mixing. Inadequate mixing can lead to non-uniform distribution of reactants, which can result in nanoparticles with varying sizes.

2. Hydrodynamics and Fluid Mixing: In larger-scale reactions, efficient fluid mixing becomes more challenging. The Reynolds number (Re) and Péclet number (Pe) should be optimized to ensure proper fluid dynamics. Inadequate mixing can lead to poor nucleation, causing a wider size distribution of nanoparticles.

3. Thermal Management: Larger-scale synthesis can result in more heat generation, which, if not properly managed, could lead to uneven temperature distribution. Localized temperature variations may affect particle growth, causing agglomeration or the formation of larger particles. It is important to use temperature-controlled reactors or jacketed systems during scale-up.

4. Precursor Concentration and Reaction Time: As the scale increases, the precursor concentration should be carefully adjusted to maintain supersaturation levels that promote consistent nucleation. Additionally, the reaction time may need to be extended to accommodate the larger volume and ensure that the nanoparticles grow within the desired size range.

5. Reactor Geometry: The design of the reactor, including factors such as the height-to-diameter ratio and the presence of baffles, can significantly influence the mixing efficiency and the uniformity of the reaction. Poor reactor design can result in regions with insufficient mixing or shear forces, leading to inconsistencies in nanoparticle size.

For further insights on nanoparticle synthesis at different scales and the influence of synthesis parameters on particle size, you may find relevant studies like :

· Khan, M., Shaikh, A. J., & Memon, Z. H. (2019). Effect of stirring time and speed on particle size and morphology of ZnO nanoparticles synthesized by co-precipitation method. Materials Today: Proceedings, 17, 806–811. https://doi.org/10.1016/j.matpr.2019.06.205

· Zheng, H., Wang, Y., & Bai, S. (2021). Strategies for scaling up nanoparticle synthesis: A review. Industrial & Engineering Chemistry Research, 60(30), 11093–11113. https://doi.org/10.1021/acs.iecr.1c01333

· Lee, K. X., Shameli, K., Yew, Y. P., & Teow, S. Y. (2018). Scale-up synthesis of nanomaterials: A review. Chemical Engineering Research and Design, 132, 518–533. https://doi.org/10.1016/j.cherd.2018.02.018

· Li, Z., & Wang, C. (2016).Scale-up considerations for nanoparticle production in continuous reactors. Chemical Engineering Science, 151, 1–17. https://doi.org/10.1016/j.ces.2016.05.027

· Ghadiri, M., & Zhang, Z. (2015).Scaling up nanoparticle synthesis processes. Advanced Powder Technology, 26(5), 1162–1170. https://doi.org/10.1016/j.apt.2015.05.005

· Kumar, A., & Gangawane, K. M. (2022). Synthesis and effect on the surface morphology & magnetic properties of ferrimagnetic nanoparticles by different wet chemical synthesis methods. Powder Technology, 410, 117867. https://doi.org/10.1016/j.powtec.2022.117867

Yes, magnetic stirrer size affects nanoparticle size by influencing mixing intensity-larger bars improve mixing and produce smaller, more uniform particles. When scaling up, maintain similar mixing conditions, temperature control, and reactant addition rates to preserve nanoparticle size and properties.

Kaushik Shandilya Thank you for providing the detailed suggestions. Suppose my first small scale reaction is in 100 mL beaker with a small stirring bar and volume of reaction is total 50 mL. Now I want to upscale it to 2 L. Then what dimension of stirring bar should I select?

Yeah, the size of the magnetic stirring bar can influence the size of nanoparticles during synthesis. A larger stirring bar generally improves mixing efficiency, which can lead to smaller and more uniformly distributed nanoparticles. Maintaining similar mixing conditions, temperature control, and reactant addition rates is crucial to preserving nanoparticle size and properties when scaling up production.

Several imp factors:

A stirring bar that is too small may not generate enough turbulence, leading to larger or inconsistently sized nanoparticles.

Stirring speed and bar size affect nucleation rates, which can impact nanoparticle growth.

Larger reaction volumes require careful temperature control to prevent uneven heating, which can alter nanoparticle size.

Maintaining the correct concentration ratios ensures consistent nucleation and growth rates.

I think yes