Honeycomb-like structure-tunable chitosan-based porous carbon microspheres for methylene blue efficient removal

Chitosan (CS) can be used for the preparation of carbon materials with different morphologies due to its excellent properties, but there are no reports on its spherical morphology. In this study, a feasible step-by-step strategy was proposed to fabricate nitrogen-containing chitosan-based porous carbon microspheres (CPCM) in HCl and KOH. The unique spherical morphology and honeycomb-like porous structure of CPCM were accurately regulated. A great quantity of micro/mesopores endowed CPCM an ultra-high specific surface area up to 2463.9 m² g^-1. Moreover, CPCM exhibited an ultra-high maximum adsorption capacity up to 1599.03 mg g^-1 for methylene blue (MB), meanwhile the adsorption process was in well agreement with the Langmuir isotherm and pseudo-second-order kinetic models. It was simultaneously a favorable reusable adsorbent with high regenerative capacity. The high dye adsorption properties suggest that chitosan can be a promising candidate for sewage treatment in the form of carbon microspheres.