rocketman - 13-2-2021 at 23:41
I have made what I believe is Selenium Sulphoxide, SeSO3
I would like to be left with SeO3.
what is the easiest way to remove the sulfur?
Thanks for any help. 
vano - 14-2-2021 at 00:12
Do you want selenium trioxide? There are eazy ways to make it.
[Edited on 14-2-2021 by vano]
Bedlasky - 14-2-2021 at 01:54
SeSO3 acutally doesn't exist (and it is not Se(VI) compound). As was discovered, this compound is actually two compounds - Se4S4O13 and Se4(HS2O7)2.
First is prepared by dissolving selenium in pure, freshly distilled sulfur trioxide at 0°C, second is prepared by dissolving selenium in 65% oleum.
Look at this document.
So one questions: Are you really sure that you make "SeSO3"?
And answer to your question: If you really make one of these compounds, you cannot easily convert them in to SeO3. As said Vano, there are easiest
ways how to make it. But if you want to prepare SeO3, you must be well experienced and well equipped chemist.
vano - 14-2-2021 at 02:05
I agree with Bedlasky.
This is a preparation method. Look at properties.
[Edited on 14-2-2021 by vano]
woelen - 14-2-2021 at 02:21
SeO3 is extreme stuff, even more so than SO3. Not something you easily make at home. SeO2 on the other hand, is fairly benign (it is toxic though, but
not corrosive, nor energetic).
Dilute H2SeO4 can be made from selenium fairly easily. You can dissolve Se in a mix of HNO3 and H2O2. Se in HNO3 alone produces quite a lot of H2SeO3,
but with added concentrated H2O2 you get H2SeO4. By boiling this down, you can drive off excess HNO3 and H2O2. What remains is dilute H2SeO4. I would
not heat too much, because you certainly don't want to inhale fumes of selenate or selenic acid. This stuff is toxic!