Studied in this research is the preparation of activated carbon (AC) from the carbonized carbon (CB) of Combretum quadrangulare Kurz. Pyrolysis was used to activate the CB under (400 and 500) degrees C for (1-5) h. Chemical activation by 45%w/w phosphoric acid (H3PO4) was also used as an activating agent with a ratio of acid to carbon of 2.3 by weight under the same temperature and time as that of pyrolysis process. It was found that the AC prepared at 500 degrees C for 1 h (501) showed the best adsorption capacity. Batch absorption experiments were performed as a function of absorbent dose and pH for removal of 100 mg L-1 of Fe2+ followed by 4 mgL(-1) of Cr2O72. The 501 and commercial activated carbon (ACC) could remove (21.33 and 5.42) mg L-1 of Fe2+, respectively, (0.45 and 1.32) mg L-1 of Cr2O72, respectively. The ACC was also found to be favoured for adsorption of non-polar I-2 molecules. Physicochemical properties of prepared adsorbents such as surface area, total functional groups and pH(pzc) were also studied. Moreover, adsorption isotherm was found to be well fitted with Langmuir model. The adsorption kinetic followed the pseudo-second-order kinetic model. Thermodynamic study indicated that the adsorption of Fe2+ and Cr2O72-onto absorbent surface was endothermic. Desorption characteristic of Fee"' and Cr203-on activated carbon was applied by HNO3. This research was proven that the activated carbon could remove Fe2+ followed by Cr2O72-effectively in water. (C) 2016 Elsevier Ltd.