XRD diffraction patterns of natural bentonite, ZnO–bentonite nanocomposite are recorded on powder X-ray diffractometer (Philips PW 1800) with Cu K˛ radiation (LFF tube 35 kV, 50 mA). Scanning electron microscopy (SEM) image was taken on JSM- 6400 (JEOL). Transmission electron microscopy (TEM) image was taken on a Philips Tecnai 20 model, which has resolution of 2 ˚A unit and AC voltage 200 kV. FTIR spectra are of ZnO–bentonite nanocomposite before and after phenol treatment are recorded on FTIR Spectrophotometer (Perkin-Elmer, model BX2) in the range 4000–400 cm−1.