calcium carbonate solubility

waterguy · Probably a bot. Joined: 06 Mar 2008 Posts: 1

I plan to use nanofltration to remove calcium cabonate from a salt brine solution. The brine (NaCl) is about 30% concentration, and the calcium carbonate is assumed to be saturated.
My question is:
Calcium carbonate will normally start to precipitate as it is concentrated by nanofiltration. Will the high ionic strength of the sodium chloride inhibit this precipitation?
If the precipitation is not inhibited, is there anything (short of adding an antiscalant) that will minimize the precipitation of the calcium carbonate?
Thank you for your help.
Peter

Hix3r · Regular Joined: 24 Apr 2007 Posts: 43 Location: Hungary

I don't think NaCl will say anything about CaCO3. It will just precipitate. I don't think you should worry about that.

If you are looking for some agent to inhibit the precipitation of CaCO3, then you have to form it into a soluble material like CaCl2 and to do it you just have to add some HCl to the solution, then CO2 will form. But surely you know this. I can't think of a substance that is inhibiting the precipitation without changing the molecule, except heat.

If you have to increase solubility, therefore increase heat. It is the only other way I can think of to ensure that CaCO3 is untouched but is still soluble. If you want to forcefully precipitate the cool the liquid, but then again you will see that NaCl could precipitate too, if the liquid is cooled.