I have done my soil washing using EDTA and got result at pH 8 gives more removal of Cr.What is the reason for base pH?usually removes for acid pH but for Cr gave more efficiency at pH 8..
EDTA is a chelating agent that can remove heavy metals, but is not necessarily a safe compound for environmental use. I am not chemist, but many heavy metals and other compounds are in more soluble forms at low pH and less soluble at higher pH. For that reason, limng contaminated soil to raise pH has some temporary to short term benefit until acid rain or other factors converts the pH back. There is a difference in binding a heavy metal, breaking it down to diffuse it, altering its chemistry, and removing it altogether. I cannot tell you which is EDTA.
I am somewhat more aware of MeHg and Pb issues, and I would recommend liming of spills or areas of concentration to contain if eventual removal or bioremediation is to be used. We also recommend kitty litter as a chemical absorbant of spills or activated carbon. Once the Cr is chelated or precipitated by pH increase, does it breakdown, how is it actually removed, or is it just put in temporary state of inactivity, to reappear at some later date? If you chelate it with EDTA, or precipitate it with pH change, what are acceptable disposal mechanisms or is it safe to leave in place? If we remove physically and dispose, is it hazardous or toxic, can it be remrdiated? These are questions that I am not trained sufficiently to answer, but deserve looking into to be sure one hazard is not replaced with another.
Hi:
I agree with Dr. S. Kalidhasan, and thanks to share this information.
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