To study the effect of pH on sorption, the
pH of the metal ion solution was adjusted to values in the
range of (2–10) by the addition of CuSO4Æ5H2O, (NiNO3)2Æ6-
H2O, FeSO2Æ7H2O prior to the experiment. The Langmuir isotherms
were obtained by equilibrating metal ion solutions of
different adsorbent doses (5–30) mg/l with different times
(20–150 min) at equilibrium pH and rpm with an initial metal
concentration of 10 mg/l at room temperature.