A bio-adsorbent was derived from the coconut shells and surface modification of the adsorbent was done by physical activation by using carbon dioxide (CO2), ozone (O3) and steam (H2O). The consequence of physical activation on the physicochemical properties was analyzed by N2 adsorption, thermogravimetric analysis (TGA) and temperature programmed decomposition (TPD). Typical results indicated that the physical activation of carbon is an efficient approach for the removal of heavy metal Cr(VI) from the aqueous solution and the best adsorption was achieved at pH 2.0. The equilibrium studies indicated that Cr(VI) adsorption follows Langmuir adsorption isotherm and pseudo-2nd-order kinetics. © 2018 Elsevier Ltd.