Fig. 3. Effect of initial pH on the kinetics of copper sorption by dried sun-
flower leaves (C0 = 100 mg/L, dose = 2 g/L, w = 400 rpm, dp = 0.5–3.15 mm;
T = 25 ◦C); (a) qt = f(time); (b) pH = f(time).
pH value of solutions for all studied initial copper concentrations
(figure not shown here), without or just reaching the pH value
of copper precipitation.s