ZrO2THIN FILM GRAFTED ON SILICA GEL SURFACE: PREPARATION AND Cr(VI) ADSORPTION PROPERTY. The present experiment describes in easy procedure for obtaining SiO2/ZrO2 by reacting ZrOCl2 with SiO2 with the following characteristics: S-BEC = 500 m(2) g(-1) and an average pore diameter of 6 nm. The material obtained presented 1.3 wt% ZrO2 content corresponding to 140 mumol g(-1). The average density of ZrO2 onto SiO2/ZrO2 matrix is 2.8x10(-11) mol cm(-2). The adsorption isotherm for Cr(VI) showed a maximum of adsorption value (200 mumol g(-1)) at pH 2. The adsorption can be described by the reaction: =Zr(OH)(2) + 2HCrO(4) . + 2H(+) reversible arrow [(=Zr(OH2+)(2)) (HCrO4.)(2)]. Above the zero point of charge, i.e. pH > 5.5 due to the surface charge inversion, desorption of Cr(VI) occurs according to the reaction: [(=Zr(OH2+)(2)) (HCrO4.)(2)] + 60H reversible arrow (=ZrO2)(2.) + 6H(2)O + 2CrO(4)(2-).253499501