I have synthesized Au-Ag bimetallic NPs using millipore water (100 ml) as solvent and ATP as a capping agent. The precursors used for metals ar HAuCl4 and AgNO3. Since the ions of these two metals can form AgCl and hence precipitate out, I have used very small concentration (~ 10^(-6)). Hence, the NPs synthesized are dilute. I want to centrifuge it but for this, precipitation of NPs is required. I have seen in literature that for organic solvents (oleylamine) we can use ethanol 2-propanol. Can I use the same solvent for water or is their any other sovent necessary for precipitation of NPs.
At the concentrations you have used, the amount of AgCl formed in the reaction would be very less. AgCl will only precipitate if ionic product exceeds the solubility product. Moreover the solubility product is temperature dependent. Increasing the temperature of the reaction vessel will increase the solubility of AgCl, leading to decrease in the amount of AgCl precipitated.
When you sediment the bimetallic nanoparticles by centrifugation, the amount of AgCl precipitating out will be very less which can be removed by multiple washings I.e., by repeated sedimentation and resuspension in Millipore water.
Thank you for the answer. I have taken care of the AgCl precipitation. Now, I want to sediment NPs. But, the problem is that the quantity of Au and Ag present are very less (~ 1 mg). I have tried centrifugation for 1 hour at 15000 rpm. But, there was no separation between the supernatant and the precipate. Hence, I want to extract all this amount of salt by adding a solvent (ethanol, 2-propanol) followed by centrifugation.
Can you suggest a method for the same?
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