Dear Ankita

You can use soluble compound of calcium such as Calcium Chlorid ( or Calcium nitarate 0.01 M) in order to remove Lead, Cadmium and Nickel, Chrome 6 and 3 and Cobalt.

For soil 0.01 M CaCl2 is typically used to exchange heavy metals such as Cd, Pb, Zn etc.

You may try it on plant material as well.

EDTA and DTPA work more efficiently, however, the effect is not by cation exchange (as with CaCl2) but by complexation.

Dear Ankita Paul,

different heavy metals has different adsorption capacity for ion exchange so please see the heavy metal ion ex changer order based on their   capacity. but for you i recommend to read the book entitle" process chemistry for water and waste water treatment" 

Depending what you want to displace there is a range of options, but one usually needs to test them even if they appear to have been tested definitively under apparently identical conditions. In general, more highly charges cations displace lower charged cations.  There is an extensive literature, much of which involves radioisotopic techniques

Please clear if that metals are "adsorbed" or "absorbed".

Again: adsorbed or absorbed?

It is a very difficugt task. The metals are generally inside proteins structure..

Perhaps inmmersion into an Edta  ( or similar quelant) solution for a long time

may help,

20 mM Na2EDTA

Dear Ankita

You can use soluble compound of calcium such as Calcium Chlorid ( or Calcium nitarate 0.01 M) in order to remove Lead, Cadmium and Nickel, Chrome 6 and 3 and Cobalt.