[ahmeddodo]

Dear any one can help :)

How to make a treatment for the sodium chloride brine solution to eleminate the calcium from the solution and then adjust the PH for the solution without having any reversed reaction, knowing that I tried to do so using the soda ash (sodium carbonate) and the PH of the solution come to 8.2 and then I added Hcl to adjust the PH but the reaction reversed to form calcium chloride but the carbonate in the solution becomes Nil and the bicarbonate increased when I used to evaporate that brine solution it come to form carbonate again and the PH increased again and the calcium content increased also.
So how can I solve this problem?

Thanks

[Perito]

I think you have the right idea. After you raise the pH high enough to precipitate Calcium Hydroxide, you must either allow the calcium hydroxide to settle out -- or better, centrifuge it -- (and remove the supernatant liquid by decantation) or you need to filter the precipitate (Ca(OH)2) out. If you leave the calcium in the solution, it will redissolve when you raise the pH.

There may be no particular benefit in using sodium carbonate. You could just as well use sodium hydroxide. With sodium hydroxide (caustic soda), you would be able to raise the pH higher.

[ahmeddodo]

Dear perito,
First of all thank you for your quick reply.
What I need is to precepitate the calcium ions in the soluion in the form of calcium carbonate by using the soda ash but if I used the caustic soda I will precepitate the magnesium ions.
After I added the soda ash and precipitate the calcium ions I filter it using sand filters after that I adjust the PH with using HCl but the problem occur when I start to evaporate that brine solution as I told you.
Can the bicarbonate be broken to carbonate by heating?

Thanks

[Perito]

Bicarbonate will decompose when heated as follows:



It's the reaction that's responsible for the action of "baking soda".

If the sand filters didn't take out the calcium hydroxide, the pH must not be quite high enough. However, it's going to be difficult to get it right without precipitating the magnesium (you didn't say you needed that). The chemistries of calcium and magnesium are very similar, as you already know.