I think if the synthesis procedures are the same you can rely on the data from the literature to have a good estimation of Zp. However, as Jadhav said, you can find the pI value by your own.

Prepare solutions at different pHs and name them pHi. Then add the nano-particles to each solution. measure the final pH of the solutions and call them pHf.

Plot (pHf-pHf) vs. pHi. The curve might cross the horizontal axis at some point. The point is the Point of Zero Charge. Zp gives almost the same result! 

For more information see the attached file.

Dear Parisa Zare,

I suggest adding ZnO within the title.

For unmodified ZnO you may use the estimation of the charge (below 9.4+-0.4 positive, above negative). Note that the zeta potential is not the surface charge. But you have to analyse the surface by IR (as performed within the publication). You find also pH-dependent zeta potential measurement of bare ZnO within the work (normed by 17.33).  

Article Synthesis and testing of ZnO nanoparticles for photo-initiat...

Zp values are case sensitive and can vary with the concentration of suspension, type of instrument and with pH. Zp is not exactly the total charge on surface. You have to construct the graph of Zp values of a material (with a fix conc. of suspension) with pH from 1 to 12. So you will get an idea of overall charge of your material and importantly its iso-electronic point.

I think if the synthesis procedures are the same you can rely on the data from the literature to have a good estimation of Zp. However, as Jadhav said, you can find the pI value by your own.

Prepare solutions at different pHs and name them pHi. Then add the nano-particles to each solution. measure the final pH of the solutions and call them pHf.

Plot (pHf-pHf) vs. pHi. The curve might cross the horizontal axis at some point. The point is the Point of Zero Charge. Zp gives almost the same result! 

For more information see the attached file.

For the IEP you may also measure the turbidity or transmission as function of pH.

Before doing anything you need to know what is on the surface of your nanoparticles. Are they pure ZnO? Are they stabilized perhaps by short ligands? or by a polymer shell?

This will have a huge influence on the things that everyone suggested. If you are in fact sure the particles are "naked" ZnO, then varying the pH to find the IEP is possible, otherwise forget about it.

If particles have an IEP you can find it by pH variation, also if they have ligands. But of course not every particles have an IEP.

His question specifically relates to a ZnO IEP graph he found in literature and to whether he can use it to estimate the ZP of his ZnO particles. If he indeed has naked ZnO, it could be very similar. However, if he has surface modified ZnO the IEP from the graph he found and his particles might be completely different.

Dear Parisa,

Please take a look at the paper entitle"Investigation on Ultrasonicaton Energy Density Effect on Size Distribution of Zinc Oxide (ZnO) Nanoparticles by Using Zeta-Sizer" , in my profile which included limited data. I hope it helps.

Regards,

Mohsen

Thank you everybody for your complete answers. I only want to use the data in literature and measure the pH of my own solution in order to estimate my solution's zeta potential and not measure its Zp.

Dear Parisa,

I have uploaded the datasets.

Best regards

Data Zeta data-original to synthesis and testing of ZnO ...

Data Zeta data-mean value to synthesis and testing of ZnO ...

Dear Michael,

I appreciate your help.

Best wishes