In this work, modification of calcium bentonite was carried out by three chemical methods converted calcium bentonite to sodium bentonite then acid activation by sulfuric acid (3M) and finally combined activated bentonite to Fe₃O₄ nano composite was prepared by chemical co-precipitation method. The prepared samples were characterized by Energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), Fourier Transformation Infrared (FTIR) spectroscopy, (BET) surface area, scanning electron microscope (SEM) and High resolution transmission electron microscope (TEM). The characterization study demonstrated a substantial improvement in several adsorptive parameters of modified bentonite, like surface area, surface morphology, and active sites where increase in surface area of the modified bentonite was recorded as 25.259 m²/g, 31.86 m²/g, 62.194 m²/g and 107.998 m²/g by Ca- bentonite, Na-bentonite, acid activated bentonite and nano composite bentonite, respectively. Effects of pH, initial concentration, mass of the adsorbent and the contact time on the adsorption capacity were studied. The results showed that the best pH for adsorption was at pH=6, optimum dose of modified bentonite at 0.5 g and contact time at 15 min. The maximum removal for heavy metals were obtained by bentonite nano composite as (98.4 %) for chromium, (98.8 %) for arsenic, (91.3 %) for selenium, (90.8 %) for molybdenum, (79.1 %) for antimony, (75.3 %) for barium .