I have made metal nanoparticles ~50nm (probably also has some surface oxide) when it is dispersed in acetone, it settles down quite fast, but when it is dispersed in ethanol, some particles settle down, but some particles are well dispersed. It is known that acetone is less polar than ethanol. What can we say about the properties of the metal nanoparticles from the observation?
Pranay Gandharapu,
Thanks for your question. This all depends on the surface of the nanoparticles, specifically what atoms terminate the surface, and their associated charge. This can be measured by a pH meter.
For example, if you have MnO2 nanosheets in suspension has a negative charge (OH- ions) and therefore a high pH (12-13). The suspension can be destabilized by adding H+ ions in the form of HCl, driving the pH to 1 or 2. Try measuring the pH with the suspension and go from there.
Good luck!
Thanks for your question.
Of course, this observation is related to the presence of the OH-group. It can also be said that only finer particles were dispersed, which are significantly less than 50 nm.
Good luck!
Almost certainly the particles carry a net charge which, through charge-charge repulsion, is central to their solubility. The repulsive potential energy is inversely proportional to the dielectric constant. Ethanol's dielectric constant is ~24, and acetone's is ~20. The electrostatic field around the particles will depend on the charge, but also can depend the particle size.
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