I have synthesized silver nanoparticles form green route. While washing the glassware, the nanoparticle are released which must be entering into the environment. I want to know that is there any possibility that can it be change from Ag0 to Ag+ again?
what are the consequences of Ag0 and Ag+ when these released into the environment?
From where do you get Ag3+? The silver on the surface (top 5 - 10 atomic layers) of your 'silver' in actually in the oxidized form (Ag+). As such it is slightly soluble in water and it's this ion (Ag+ not Ag0) that's the bactericide. Ag0 is insoluble in water. More information in:
Silver colloids and invisible ink
https://www.brainshark.com/malvern/vu?pi=560497681&b=1&tx=120486&c1=22
Yeah AgNPs can revert to Ag+ however the rate of this transformation depends on the stability of the NPs and the specific environment where they are released.
From where do you get Ag3+? The silver on the surface (top 5 - 10 atomic layers) of your 'silver' in actually in the oxidized form (Ag+). As such it is slightly soluble in water and it's this ion (Ag+ not Ag0) that's the bactericide. Ag0 is insoluble in water. More information in:
Silver colloids and invisible ink
https://www.brainshark.com/malvern/vu?pi=560497681&b=1&tx=120486&c1=22
There is no doubt you release Ag or Ag(+) (higher oxidation states are practically impossible) into the environment with your process. Both redox states can easily change, depending on the reductive/oxidative nature. This is especially true for proteins and hence for living organisms. The release will be bactericidal, as already stated, and moderately toxic for humans, but it will be very dangerous for aquatic organisms and in agriculture. We talk about trace amounts here! So altogether this sounds like a very bad idea to follow through. However greenyour synthesis, the overall result will be very "un-green".
Respected Alan F Rawle Sir,
Thank you so much for your response and providing me valuable link
I am sorry, it is Ag+ not Ag3+ (I used silver nitrate)
Dear Alexander M Bittner,
Thank you for your response. What if the nano-particles are synthesized by green route using leaves extract? Can it still release Ag+ ions?
Dear Rahman,
Thank you for your response
Can you please explain in which condition it will get revert?
'What if the nano-particles are synthesized by green route using leaves extract? Can it still release Ag+ ions?' Sorry, I am not sure, I can only provide a guess: The extract might contain typical oxygen-containing groups (OH, COOH) that bind to the Ag surface. However, other groups such as thiols or disulfides from proteins bind stronger, and they could oxidize Ag to Ag(+). So I would expect that it sill releases Ag(+).
Any 'silver' in air will form an (surface) oxide (or sulfide if SO2 is present). Thus Ag+ will leach out with moisture. This fact is easily shown with XPS. The only way to prevent this is to make the Ag material (nanoparticles or anything else) in a reducing atmosphere and completely exclude oxygen or air for any subsequent use.
Vijay,
I've attached few articles that you'll find useful. I recently studied the SPR behavior of AgNPs in an environment where they were exposed to NaCl solutions at sea water concentration.
Dear Rahman,
Thank you so much for your response and providing me the important link
Depending of the reducing agent, especially for biologic synthesis methods.
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