Abstract:The elution of lead from vermiculite was investigated by using a novel biodegrad able chelating reagent, L-asparagic-N,N-diacetic acid (ASDA) and water solubled epolymerized pecticacid and comparing with a conventional chelating reagent, EDT A, as well as acetic acid. The influences of the reagent concentration, equilibrium pH and the suspension contact time on Pb extraction were examined. It is concluded that the acetic acid is not effective for Pb removal in any case due to its weak complexing ability with Pb. Although Pb is easier to be released by EDTA with stoichiometric amount, it is by no means the preferable alternative for the purpose because of its low biodegradability. On the other hand, ASDA and depolymerized pecticacid have the potential application because they are not only effective for Pb elution but also environmentally friendly.

Key words: elution; lead; vermiculite; chelating reagents; pecticacid