Investigation the adsorption mechanisms, chemical resistance and mechanical strength of the synthesized chitosan/activated carbon composite in methylene blue removal.

This study is based on a new approach to the development of the adsorption process from two perspectives, including the possibility of using the adsorbent in a wide range of pH (increasing chemical resistance) and also its easy separation from solution (mechanical strength), or in other words the possibility of preparing a simple fixed bed for the adsorbent during adsorption process. According to this view, chitosan/activated carbon composite was synthesized and used to remove of methylene blue as a cationic pollutant from water. The structural properties of the synthesized adsorbent were analyzed using FE-SEM, FTIR, BET and zeta potential analyses, which showed significant improvement in chemical and physical stability. The influence of main parameters such as adsorbent dose, contact time, initial concentration and pH value of the solution in the adsorption process was investigated. The results showed that if chitosan is used more than half amount of carbon, the performance of the adsorbent decreases, which may be related to the filling of carbon pores by chitosan. According to the zeta potential analysis, the pH of point zero charge of the adsorbent was found to be 4.4. Also, the adsorption mechanism followed the Langmuir model and pseudo-second-order kinetics, and the maximum adsorption capacity of a single layer for methylene blue dye was measured 22.52 mg/g.