Fig. 2. (a) Cadmium and Pb sorption as a function of pH (I = 0.01 M NaNO₃). (b) Sorption envelopes of Cd and Pb using a linear model (R² > 0.91). Points where the % sorbed was 8% when pH was approximately 1 were omitted (I = 0.01 M NaNO₃; %S = percent sorbed).