Determination of the surface area and pore size of adsorbents
N2 adsorption–desorption experiments were conducted at 77 K using a Micrometrics Surface and Pore Size Analyzer, model ASAP 2020. Prior to the experiment the sample was degassed at 573 K for 18 h. The surface area was obtained using the BET model. The pore size distribution was evaluated from the desorption branches of the isotherms using the Barrett–Joyner–Halenda (BJH) method.