Effect of the pH on the synthesized nanoparticles [closed]








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I have synthesized gold nanoparticles in water through the seed-mediated thermal method by cationic additive $\ce{Ag+}$ as an assisted growth procedure [[article](http://pubs.acs.org/doi/abs/10.1021/nl201796s)]. The pH of the nanoparticles solution is about 2. I would like to reach the pH of the solution to 5.I found that when I use NaCl solution or buffer (such as sodium acetate) for adjasting pH, it cause the aggregation of nanoparticles.  

How to increase the pH without any aggregation in the nanoparticles solution?




It should have, because with pH you change the electostatic forces between particles. 
I guess you would increase pH adding more electrolytes and this might decrease double-layer thickness of the NPs, so repulsive forces would decrease and the NPs might agglomerate. It strongly depends on electrolyte conc.


Therefore I think you should rather try to synthesize them in pH5 then increase pH from 2 to 5.


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