Nonstoichiometric binding of lead(II) ions with sodium alginate

The ability of sodium alginate to bind Pb2+ at a ratio of 500 ions per uronide link was established. The residual concentration of Pb2+ in the solution was 4 x 10(-4)-3 x 10(-3) mol 1(-1) and did not depend on the concentration of the reagents (the concentration of sodium alginate was 2 x 10(-4) x 10(-3) g-equiv per 1, the concentration of the ph salt was 0.001-0.5 mol 1(-1)). The binding was found to be reversible, which can be at least partly explained by sorption excess Pb2+ by the gel of Pb alginate formed at the initial step of the process.