we are synthesis sodium polyacrylate and using it to hold calcium ions from water to decrease the hardness so now we are in need to measure number of milligrams of calcium ions that taken by the polymer , the imported company gives us procedure that it follows to accept our polymer
this procedure
measure 1-2mg polymer in100ml dist.water then neutralize PH by HCl to PH 7 then add 10ml of soda ash 10%the titrate it versus calcium acetate (0.25M)
mg calcium binded to polymer =Vep*0.25*158.166/wt of polymer
but when we applied this procedure the result be 150_180
buy the resut observed in the imported company is 250-300 what is the problem that cause this defect?
Hello,
one possible explanation could be that your system is not in an equilibrium yet. I didn't read about a time period after which the amount of bound calcium is measured.
If it takes some time for the calcium to bind to the polymer and you test before the end of this time period, the amount should be too low.
The time needed to bind to the polymer might be influenced by the polymer itself. If the polyacrylic acid (PAA) is not crosslinked, it's soluble in water and well acessible for the calcium ions. If the PAA is crosslinked, the calcium has to diffuse into the polymer first.
Other factors, such as mixing or the temperature, might additionally influence the availability of the caclium ions to the polymer and thus the time to reach an equilibrium.
I would suggest to use AAS for determination of Ca concentration, you get more accurate data.
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