To evaluate the surface area, mean pore diameter and pore volume, adsorption-desorption of nitrogen (N2) at 77K was carried out by a Quantachrome Instrument (Autosorb-1 Model No. ASIMP.VP4, USA). Before taking adsorption data, degassing at 120°C and a residual pressure of 300μm Hg for 24h was performed using the degas port. The surface area was calculated using the Brunauer-Emmett-Teller (BET) equation and the mean pore diameter and pore volume was obtained by applying the Barret-Joyner- Halenda (BJH) method on the desorption branch [13].