A novel functionalized ordered mesoporous carbon as an efficient adsorbent for dye removal from water

This research developed a novel ordered mesoporous carbon with nitrogen functionalities by tailoring the surface chemistry of ordered mesoporous carbon CMK-3 with ammonia gas at high temperature. This novel adsorbent is designed with the expectation of better adsorbing anionic dyes from solutions.;It was found that ammonia-tailoring at high temperature is an effective way to modify the surface chemistry of CMK-3 without destroying its hexagonally ordered mesoporous structure. Four types of nitrogen-containing functional groups (pyridine, aromatic amines, quaternary nitrogen and protonated amide) were successfully created on the carbon surface with pyridine-like nitrogen and aromatic amines being the dominant functional groups. These surface functional groups made the carbon "more basic" and its surface more heterogeneous.;Adsorption kinetics and equilibrium studies in single component systems showed that this novel adsorbent had much higher uptake rate than that of a commercial activated carbon and unmodified CMK-3, particularly for the adsorption of large molecule Acid Black 1 (AB1) with long chain, and could enhance the adsorption capacity of anionic dyes (Orange II, Reactived Red 2 (RR2) and AB1) by 90%--200% and 40%--60% as compared to the activated carbon and unmodified CMK-3, respectively. The significant improvement in the dye uptake rate and adsorption capacity was attributed to the ordered mesoporous structure of the novel carbon and the electron-donating effect induced by the nitrogen-containing functional groups on its surface. Binary adsorption studies revealed that competitions between the RR2 and AB1 molecules existed in all of the three RR2+AB1 binary adsorption systems and the ammonia-tailored CMK-3 had higher adsorption affinity towards AB1. The film-mass-transfer-control kinetics model gave reasonable good correlation with the experimental uptake data for orange II with smaller molecular size and simpler chemical structure but overestimated the uptake rate for RR2 and AB1 which have larger molecular size and more complicated chemical structure.;This novel functionalized ordered mesoporous carbon is a promising material with many potential applications in adsorption and catalysis due to its attractive physical and chemical properties.