KARAKTERISTIKA INTERAKSI ION KROMIUM (III) DAN KROMIUM (VI) PADA BENTONIT

Experiment was carried out to define characteristic of the interaction between chromium (III) and chromium (VI) on bentonites clay Chromoium solution was interacted to bentonites with batch procedure. The concentration of solution after treatment was measured by spectrophotometer. The result showed that both of interaction follow the Langmuir isotherm adsorption with different optimum condition. For each ion Cr (III) and Cr (VI) the optimum stirring time was 60 and 40 minutes. The optimum pH solution was Cr (III) and 2 for Cr (VI). The capacity of exchangeable ion for Cr (III) was 270.154 mek/100 grams bentonites, and 11.429 mek/100 grams bentonites for Cr (VI). The process of ion exchange on bentoniter’s interlamellar room, coused a change of d value of X-ray diffraction from d = 15.4109 A for Ca bentonites to d = 15.8533 A for Cr (III)-bentonites. The diffractogram of Cr (VI)-bentonites showed several new peaks with d value 3.77; 2.87; 2,77 A. Thus peaks was identifield as the characteristic peak of mineral Ca4 CrO4Cl. Ca5 (CrO4)3 Cl and Ca2CrO4Cl. These data could be concluded as the resalt chromate binding to the surface of bentonites clay with calcium ions as connecting bridges.