Rapid and selective adsorption of organic dyes with ultrahigh adsorption capacity using Na and Fe co-doped g-C3N4

Abstract

Fe and Na co-doped g-C3N4 were facilely synthesized by one-step calcination. The effect of Na doping on the adsorption of MB and the mixture of MB and RhB was studied, in which 10-CN showed excellent adsorption properties for cationic MB. Langmuir’s model was more suitable for describing the adsorption process. The maximum adsorption capacity reached 1955 mg/g for only 3 min, which was significantly higher than that reported. 10-CN showed selective adsorption for MB from the mixture containing MB and MO. The experimental results indicated that the electrostatic interaction between MB and 10-CN played a key role in the adsorption, and the π-π conjugation and the hydrogen bonding between MB and 10-CN were found. Methanol was used as a desorbing agent for MB desorption from 10-CN. 10-CN showed excellent stability for MB adsorption, and the removal efficiency of MB remained above 95% after five cycles.