ADSORPTION OF MALATHION FROM AQUEOUS-SOLUTION ON HOMOIONIC BENTONITE SAMPLES

Adsorption of malathion on potassium, sodium, magnesium and calcium-homoionic bentonite samples from aqueous solution at 10-degrees-C, 25-degrees-C and 40-degrees-C has been studied. The adsorption isotherms may be classified as L type of the Giles classification which suggests an average affinity of the malathion molecules for the bentonite surface and that there is no strong competition from the solvent for the adsorption sites. The experimental data points have been fitted to the Freundlich equation in order to calculate the adsorption capacities of the solids. The adsorption capacity values (Kf) range from 0.10 for the magnesium-bentonite sample at 40-degrees-C to 0.47 for the potassium-bentonide sample at 10-degrees-C, these values increasing as temperature decreases. On the other hand, the highest adsorption capacity values correspond to the potassium-bentonite sample and the lowest to the magnesium-bentonite sample.