Dear Naser,

It would be possible if you use single-step method. By two-step method, it seems impossible or at least very difficult to have a long-time stable suspension with minimum sedimentation and agglomeration.

Good luck

Dear Naser,

It would be possible if you use single-step method. By two-step method, it seems impossible or at least very difficult to have a long-time stable suspension with minimum sedimentation and agglomeration.

Good luck

Amin Asadi Thank you very much Amin for sharing this information

I think it would not be possible to maintain its stability by simply adjusting the pH. This may be possible if surfactant is used.

Graphene oxide may maintain long-term stability without the use of surfactants, but I think this is not the case for graphene and CNT.

Thank you for your reply and for sharing the information Nese Keklikcioglu Cakmak

You need to define what stability means. It's a termed that is misused and misunderstood.

You are relying on electrostatics. You cannot have a stable colloid that way. It will always aggregate. All you can do is slow the aggregation down. Electrostatically "stabilized" dispersions of lyophobic particles (e.g., CNT) are, in fact, thermodynamically unstable.

Dear Dr. John Francis Miller ,

Perhaps what the OP is referring to is a "kinetically" stable dispersion, in the sense that the rate of clustering is so "slow" that it becomes of no practical relevance.

Dear Dr. Naser Ali ,

I think that a more important issue when we talk about pH control to "stabilize" a nanofluid is that, over time, dissolution of nanoparticles and reactions with the container and tubing can take place as a result of the non-neutral pH value. Therefore, it is recommended to keep the pH neutral in real applications. Unfortunately, this point is very rarely considered in the nanofluid literature (most likely because nanofluids are very rarely used in real applications).

Hi John Francis Miller

Thanks for sharing this very useful information.

Hi Omar Z. Sharaf

Thank you for your participation. I totally agree with you in regard to researchers occasionally ignoring the effect of the pH value of their nanofluids, where I think better attention needs to be given to the aforementioned parameter.

Hi Naser pH adjustment is a way to manipulate the Zeta potential of nanofluids. You need to change the pH and then measure the Zeta potential of your used nanofluid. When the Zeta potential index is upper than 30 mV or lower than -30 mV, you can claim your nanofluid is stable. Hope this can help. Good Luck with your research.