phasor - 30-12-2016 at 13:29
Hello,
To help solidify some understanding of A/B, neutralization, etc I have given myself the problem of recovering the acid salts from a liquid solution of
sulfuric and oxalic acids. The two salts should be recovered separately. I have decided to go about this by precipitating the sulfate and oxalate as
salts of either calcium or sodium. I am asking for some help choosing the neutralization reagent.
I first thought that precipitating as the calcium salt would be preferable, as calcium sulfate and calcium oxalate have extremely low solubility in
water. However both calcium hydroxide and calcium carbonate have very low solubility as well, so I am concerned that the acid salts will be
contaminated by the neutralization salt. This route would theoretically lead to the highest recovery, but could have lower purity.
Another route would be to go with a sodium 'base' route (OH, carbonate, bicaronate). These reagents have high solubility, but the corresponding
neutralization salts (sodium sulfate, sodium oxalate) have low solubility. My thoughts on this route is it could lead to higher purity acid salts, but
some acid would be lost.
A third route, for better recovery of the oxalate, would be to neutralize the solution with appropriate amount of NaOH (or other Na 'base'), and then
add appropriate amount of CaCl. This would result in the roughly the same yield and purity as the other two methods?
Is my thinking here more or less correct? Are there advantages/disadvantages to using the strong OH base versus the weaker carbonate base?
After I get this figured out, then I am going to move on to performing the neutralization of unknown concentration of the same two acids in solution.
For this a pH meter would be used to titrate the solution, in an attempt to firstly separate the sulfate, and then the oxalate. Would carbonate or OH
be easier to control the titration?
thanks for your thoughts...
Sulaiman - 30-12-2016 at 14:04
maybe zinc or a similar metal could be used as zinc sulfate is soluble and zinc oxalate is not.