Dyes are known to be harmful organic compounds for the environment since only a small amount of dyes can be hazardous. So, the treatment of industrial dye effluent using a commercial and effective catalyst is the study's main objective. The adsorptive and photocatalytic activity of the Egyptian bentonite was improved by acid treatment, followed by incorporation of cerium dioxide on bentonite surface via simple precipitation method and then thermal treatment by calcination. The natural bentonite and the modified bentonite (B-CeO2) samples were characterized by XRD and TEM-EDX techniques. The removal% of dye was studied by changing the initiator, catalyst dosage, temperature, and solution pH in dark and visible light. The maximum dye removal (91%) was obtained in acidic solution (6.34, the normal pH of dye effluent) using 2 g/L catalyst dosage, 5 mM/L ammonium persulfate, 200 W lamb at 40 oC with constant stirring. The results indicated that the modified bentonite has high photocatalytic activity in dye treatment due to a synergism between the effect of light, ammonium persulfate, CeO2, and exfoliated/delaminated bentonite.