The synthesis procedure mainly consists of purification of bentonite clay followed by in situ intercalation of clay with nanosized ZnO. The bentonite sample was ground and sieved to 200-mesh size then washed with demineralized water for 3–4 times. The slurry of bentonite prepared water was stirred for 1 h, kept overnight, filtered under vacuum and the resultant solid cake was exposed to slow evaporation till the completely dry material was obtained. The purified clay was used for the synthesis of nanocomposites described as follows: 10 g of purified bentonite was added to a solution containing 2 g zinc acetate dihydrate dissolved in 250 ml of DMF and the mixture was sonicated for about 3 h in order to obtain homogeneous suspension. To this solution, 100 ml of 0.1 M NaOH/H2O solution was added with constant stirring for 1 h. The nanocomposites powder was obtained after successive centrifugation and dispersions in alcohol and the solid mass was dried at 75 ◦C under vacuum for 4 h and calcinated at 200 ◦C for 2–3 h. The dried ZnO–bentonite nanocomposite was then used for photocatalytic experimentation.