Consider monoliths with homogeneous composition of Carbon(C), Silica(SiO2) and zinc Oxide(ZnO). Calcining them and obtain monoliths of (SiO2 +ZnO). Now, how to separate ZnO from silica? ( if HF is usedto etch silica out, it dissolves them both.)
Also is it possible to recover the ZnO particles in the same (crystallographic) structure as they are formed inside the monoliths without altering their structure via dissolution, etching etc. ?
Try solving it in 0.1M aqueous HCl. Hydrochloric acid shoul dissolve zinc oxide and won't react with SiO2. If that doesn't help try using piranha etch but it is far more agressive.
Dear Igor, actually I want to retain the zinc oxide particles and remove the silica from the solid (template). Can you tell me any solvent that would do so.
Because if I use HCl/piranha soln. , then when I extract the ZnO particles from it via heating(or crystallization) , the structure of ZnO particles that I obtain might be different than formed in the (ZnO+Silica) template.
I'm afraid that using HF will for sure dissolve ZnO. Sillica is much "tougher" than ZnO... I'll think about it and try to give you some tips later, ok?
Try this out. Prepare an 30-40 percent aqueous solution of KOH. Crush your material and make fine powder of particle size around few microns. You can use mortar pestle for this purpose. Add the powder in the specified solution at 85-90oC. Etch rate of Si substrate in KOH solution at 90 deg is very high. But for SiO2 it is around half a micron per hour. So for etching micron size particle you need around 1-2 hours. Generally ZnO remain intact in basic solution.
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