Above pH 5 trivalent chromium forms probably chromium hydroxide Cr(OH)3 which is insoluble in water. To ascertain, try to look at Pourbaix diagram for chromium.

Dear Usama

Cr(III) undergoes hydrolysis in water and the pH of the solution is reduced. Cr(OH)3 can be formed as the final product of the hydrolysis. Cr(IH)3 is a gelatinous green solid and you can easily confirm if it is really the hydroxide. If you take a small amount of the solid , put it in a test tube and add some NaOH solution to it, the solid will dissolve in strong basic solution because it is an amphoteric hydroxide. If you don't want Cr(OH)3 to precipitate perform your adsorbtion study at lower pH.

Good luck.