Study on a novel N-doped mesoporous carbon for the efficient removal of methylene blue from aqueous solution

Abstract

A novel N-doped mesoporous carbon (AC-N) was prepared by impregnation method on the basis of cypress-derived activated carbon for methylene blue (MB) removal. The introduction of nitrogen atoms with appropriate proportion could improve MB adsorption capacity of the prepared mesoporous carbon (AC-N). AC-N obtained at optimized modification (1 mol/L urea) had an excellent MB adsorption of 910.95 mg/g and the removal efficiency was ca. 91% at 25℃. Elemental analysis showed that the nitrogen content of AC-N was high up to 2.6%. A large specific surface area (S<sub>BET</sub>) 1,215 cm<sup>3</sup>/g and an obvious mesoporous structure with a high mesopore to total pore volume ratio (V<sub>mes</sub>/V<sub>tot</sub>) 91% was observed on AC-N. X-ray photoelectron spectroscopy (XPS) results indicated a successful doping of nitrogen element into the mesoporous carbon and pyridinic-N, pyrrolic-N and amino-N were existed in AC-N. Scanning electron microscope (SEM) and Fourier transform infrared spectrometry (FTIR) were also used to characterize this prepared adsorbent. MB adsorption kinetics parameters and isotherm results on the produced carbon were well fitted by the pseudo-second-order kinetic model and Langmuir model. According to the thermodynamic analysis, the adsorption of MB on AC-N was found to be an endothermic, spontaneous process in nature.