3.3. Scanning electron micrography (SEM) before and after 2-nitroaniline adsorption
The SEM photographs of cotton stalk activated carbon before and after 2-nitroaniline adsorption are shown in Fig. 3. It was foundthat the surface of cotton stalk activated carbon after 2-nitroaniline adsorption had many holes and looked rougher. Tansel and Nagarajan also found that the percentage of rough area on the external surface of granular activated carbon increased more than 70%. Tang et al. explained this phenomenon as heterogeneous energy distribution of the activated adsorption sites on activated carbon surface.