Hi everyone!
I am synthesizing cerium oxide nanoparticles using cerium nitrate hexahydrate salt. Initially when I was preparing batches yield was between 40-50%. Suppose I am taking 50 mg salt the nanoparticles produced are 29 mg. After 2 years I am using same salt from same bottle but I am getting lesser yield of nanoparticles, there's no change in color and UV vis spectral scan of nanoparticles but yield is compromised. Since it is hydrated salt it is more liquid in bottle. Kindly give me suggestion about it.
Cerium nitrate hexahydrate, Ce(NO3)3.6H2O is the most common nitrate of cerium(III) with Molar mass: 434.23 g/mol. Anhydrous Cerium nitrate, Ce(NO3)3 have Molar mass: 326.12 g/mol. If you go for stoichiometric calculation, the maximum yield of cerium oxide, CeO2, Molar mass:172.115 g/mol, you can get from anhydrous form is about 52.77 %. From hexahydrate form, you can get max. yield about 39.66%. This is when the oxide conversion is 100%. If you are using any wet chemical method for conversion, the yield will be even less as conversion will never be 100%.
What is your method of conversion? For wet chemical methods, greater dilution and reaction time may work...
If it is hygroscopic, then the content of water will increase with the time. So, if you use the same amount of reagent (with different water content due to absorption), you will get less product.
My recommendations: 1) purchase a new flask and use a vacuum chamber or vacuum plastic bag to store it. 2) Dry your reagent, but it must be at a low temp (44-60 C) because you could decompose nitrate ions.
Akhilesh Kumar Singh thank you so much for your guidance. When I was initially using the salt after opening it fresh and prepared nanoparticles the yield was 40-45% from cerium nitrate hexahydrate. But after 2 years I am using same salt bottle but it became liquid not all but most. I am using hydrolysis method.
Gregorio Guadalupe Carbajal Arizaga a vacuum heating oven available in my lab. Can I use it for drying the salt?
Noor Ul Ain By yield, you mean to say solid CeO2. So at what temp. you are drying? And what is your hydrolyzing agent? Is It ammonia? How you are washing/separating the unreacted precursors from your final product? Any of given factors/procedure may change your final yield.
Noor Ul Ain , yes, you can use that vacuum oven.
May be the effects of reducing agent, temperature and pH.