Hi All,
I'm reacting various types of limestone with 38% HCL to make Calcium Chloride Brine. Some older, hard grey limestones produce a very colorless CaCl2 solution. I'm currently using a very pourous, soft, oceanic limestone but I get a yellow CaCl2 product. How can I remove the yellow color?
My method for making the CaCl2 is to react the acid with the limestone in a bucket to completion. I then raise the pH to 8.3 and filter with a buchner filter apparatus. Fe is 1 ppm, Mg is 75 ppm and Mn is 0.1 ppm. EMF is +375 at pH 8.3. However, the solution is yellow. I suspect its a residual organic from the limestone but how would I remove it. I tried a 0.2 g/liter addition of Ca(OCl)2 Calcium Hypochlorite then added some Ditomaceous Earth, followed by still another filtration. EMF is +600 at this point as I'm creating a oxidizing enviornment. I thought this would oxidize the organic (if its an organic) but the yellow color still remains. I tried adding 30% H2O2 also, it didn't work.
Anybody have any ideas on how to remove the yellow color?
