Electrodeposition using constant potential methods, precipitated solution: as for example nickel in borate buffer pH = 9.2
thanks for your reply :). also there is another idea, but may be wrong:
due to the equilibrium between ions and precipitate, is there a problem if i filter the solution and make the electrodeposition from the filtrate?!
In principle, it is Yes but the outcome may not be as good as you expected. Do you know any advantages for electrodeposition from a precipate-containing solution? In other words, do you really need such an experimental condition? Otherwise, for example for the Ni electrodeposition Ni(Ac)2 is normally a good salt.
Even when a little amount of material is present in the solution it is possible to do electrodeposition by increasing the deposition time but in this case it will be difficult to get reproducible results all the time when ever you make new solution for electrodeposition.
I will go with Prof Qijin Chi. Instead of working with a precipitated solution it is easy to change the precursor and have a stable electrolyte for the electrodeposition.
during the preparation of nickel borate (soluble complex) from nickel nitrate in borate buffer pH=9.2, nickel hydroxide was precipitated. now, i want to deposit nickel borate complex, not changing the electrolyte, can i make this or no ?
thanks in advance.
I suggest you to calculate the thermodynamic equilibrium of the species and reaction products you mention. There you will see the regions of predominancy of the soluble species as well as the regions of stability of solids. If you do see a region of stability for nickel borate, it means that this would be at least thermodynamically feasible--however it may be that it is not, kinetically. Typically, in aqueous media it is not usual nor easy to form solid boron species.
Lets assume that indeed nickel borate can be stable as solid in the presence of water, then all you need is to have very good mixing so that the precipiated particles effectively collide with the electrode in which you want to do the deposit; also a sufficient contact time may be needed to achieve electron transfer successfully, if the process is potential dependent. You can think of a confinuration where the electrode in which you will do the plating faces up, and then the precipitate falls by gravity on top of the electrode.... Anyway, without knowing if the solid can be actually thermodynamically stable, addressing cell design is early.
Theoretically possible, kinetically slow and the eventual addition of an electrolyte decreases the solubility further. However, the presence of an insoluble salt may be an interesting way to maintain a relatively constant low concentration of the metal ion through Ksp. The suspension must be kept in motion so it won't block the electrode surface.
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