We are trying to purify BaSO4 by dissolving it in an Na5DTPA solution and then re-precipitating it out, but we can't seem to get past the first step of dissolving the BaSO4! We are using a 0.05M DTPA solution made up with 1M NaOH which we got from a journal article. We've tried grounding the BaSO4 into fine powder, heating, ultrasonicating but nothing works. Any ideas?
2007-07-03 19:58:02 · 3 answers · asked by carlaeh 1 in Science & Mathematics ➔ Chemistry
I wonder about your use of 0.05 M Sodium diethylenetriaminepentaacetic acid (DTPA). For every gram of Barium Sulfate you should have at least 1.68 grams of Na5DTPA per liter of solution.
DTPA is an excellent chelating agent, but even with high temperatures and adequate mixing, some specimens require several days to completely dissolve.
2007-07-08 07:52:09 · answer #1 · answered by Richard 7 · 6⤊ 0⤋
I'd just boil the finely ground up barium sulfate in the solution of DTPA for a few hours to leech out any heavy metal impurities. Just plain boiling in water should take care of any alkali metals, and a little chelating agent should handle the rest. It's not all going to dissolve, unless you use a very small amount. If you're overly concerned with purity, you may want to go that route, and then crash it out slowly while it's still hot.
2007-07-07 16:53:20 · answer #2 · answered by Art V 3 · 0⤊ 0⤋
BaSO4 is a very sparingly soluble salt. A better method is centrifuging.
2007-07-04 12:25:56 · answer #3 · answered by ag_iitkgp 7 · 0⤊ 1⤋