The research of adsorption of Cu2+ metal ion on dithizone-immobilized natural bentonite (DNB) had been carried out. The experiment was begun by the activation of natural bentonite with HCl 4 M and dithizone-immobilized on activated bentonite surface. This study included synthesis and characterization of dithizone-immobilized bentonite and its application in adsorption of Cu2+ metal ions. The type of interaction occurred in the adsorption was tested by sequential desorption. The result showed that dithizone successfully immobilized on activated natural bentonite (ANB). The optimum conditions for Cu2+ metal ions adsorption using dithizone-immobilized natural bentonite are at pH 5; 0.1 g mass of adsorbent, with interaction time 60 min, and the initial concentration of ion at 80 ppm. Kinetics and adsorption isotherm studies suggest that the capacity, of the dithizone-immobilized natural bentonite in adsorbing Cu2+ metal ion is significantly improved compared to activated natural bentonite. The adsorption of Cu2+ metal ions by activated natural bentonite was through several interactions dominated by electrostatic interaction (82%). Otherwise, the interaction of dithizone-immobilized natural bentonite with Cu2+ metal ions in the sequence were dominated by the mechanism of complex formation of (75%). The result shows that the immobilization of dithizone changes the type of electrostatic interaction into complex formation.
