Lead(II) Adsorption by Soils at pH from 4 to 6

摘要

It is shown that the adsorption of Pb(II) by chernozem, gray forest soil, and soddy-podzolic soil at pH 4, 5, and 6 is accompanied by the displacement of both Ca2+ and H+ ions into solution and represents a three-cation exchange process rather than a two-cation one. This exchange is a reversible process. At pH 6 and above, another mechanism of Pb(II) adsorption, namely, the precipitation of lead carbonate, comes into effect and becomes predominant. The treatment with a mixture of N(a)2EDTA and Ca(NO3)(2) almost completely extracts the Pb(II) adsorbed. The Freundlich equation fits all Pb2+ adsorption isotherms well, although it is only an empirical approximation.