Effect of pH, ionic strength, foreign ions and temperature on the adsorption of Cu(II) from aqueous solution to GMZ bentonite

摘要

The adsorption of Cu(II) from aqueous solution to GMZ bentonite was studied using batch techniqueunder ambient conditions. Removal percentage (%) and distribution coefficient (Ku) were determined asa function of contact time, pH, ionic strength and temperature. The adsorption of Cu( II) on GMZ bentoniteincreased with increasing pH gradually at pH <6.5, and maintained high level at pH > 6.5. At pH < 6.5, theremoval percentage of Cu(II) was the highest at ionic strength of 0.001 M NaNO3 and was the lowestat ionic strength of 0.1 M NaNO_3. The presence of complementary cations depressed the adsorption ofCu(II) on bentonite in the order of Li~+> Na~+> K~+at pH < 6.5. The adsorption isotherms were simulatedby the Langmuir, Freundlich, and Dubinin-Radushkevich (D-R) models very well. The thermodynamicparameters (i.e., ΔH~0, ΔS~0 and ΔG~0) for the adsorption of Cu(II) were determined from the tempera-ture dependent isotherms at 293.15, 313.15 and 333.15 K, respectively, and the results indicated thatthe adsorption reaction was favored at higher temperature. The results suggest that GMZ bentonite isa suitable material as an adsorbent for preconcentration and immobilization of Cu(II) from aqueoussolution.