Figure 1. The effect of pH on the biosorptive copper uptake capacity of U. reticulata (M = 2 g/L). Initial solution pH:(◊), pH 3.0;(□), pH 3.5; (Δ), pH 4.0; (×), pH 4.5; (*), pH 5.0; (○), pH 5.5; (+), pH 6.0.