Superior Adsorption Performance of Mesoporous Carbon Nitride for Methylene Blue and the Effect of Investigation of Different Modifications on Adsorption Capacity

Abstract

A series of mesoporous carbon nitride (MCN) with tunable specific surface area, pore volume, and nitrogen content has been prepared by using SBA-15 as template and ethylenediamine (EDA) and carbon tetrachloride (CTC) as precursors, respectively. The composition and structural properties of the obtained materials were characterized by FT-IR, XRD, SEM, TEM, N2 adsorption-desorption, zeta potential, and elemental analysis. Results revealed that the largest special surface area could reach up to 667 m2 cm−3 and specific pore volume to 0.496 cm3 g−1, and the nitrogen content of MCN could be controlled by adjusting the EDA to CTC weight ratio. It was demonstrated for the first time that the synthesized MCN exhibited excellent adsorptive capability toward methylene blue (MB) and the adsorption capacity was attributed to the large specific surface area and surface functional groups. The effects of parameters, including pH, initial concentration, contact time, and temperature, were investigated in batch static adsorption experiments. Besides, the adsorption process of MB onto MCN is fitted to the Langmuir isotherm and pseudo-second-order kinetic models, and the maximum adsorption amounts of MB on MCN were 360.8 mg g−1. Moreover, the thermodynamic analysis showed that the adsorption was endothermic and spontaneous. MCN remained to have high adsorption capacity after five times of recycling test. All these results demonstrated that MCN is a promising material for adsorbing cationic dye in aqueous solution.