Figure 3. Linearized Freundlich isotherm for copper sorption by U. reticulata (M = 2 g/L). Initial solution pH: (◊) pH 3.0; (□) pH 3.5; (Δ) pH 4.0; (×) pH 4.5; (*) pH 5; (○) pH 5.5; (+) pH 6.0.