In this work activated carbon was prepared from green coconut shells by chemical activation method. It was then characterized by XRD, SEM, FT-IR and TGA. Different physical properties such as bulk density, moisture content, volatile matter content, ash content, and surface area and porosity were also determined. The activated carbon was used as adsorbent for the removal of carbon dioxide from flue gas as well as various inorganic contaminants from waste water. Removal efficiency of Methylene blue was studied by changing various parameters such as adsorbent dosage and contact time. This study showed that for the removal of various pollutants from flue gas and waste water treatment activated carbon can be used as a good adsorbent.