Hydrophobic N-doped porous biocarbon from dopamine for high selective adsorption of p-Xylene under humid conditions

Abstract

N-doped hydrophobic microporous carbons (N-PCs) derived from dopamine were synthesized by using different methods. The effects of their graphitic C/N, basic N groups as well as oxygen content on the competitive and selective adsorption towards p-xylene were systematically studied in this work. The synthesized N-PCs possessed higher amount of sp2 C/N than some known activated carbons, enhancing their adsorption interaction towards weakly-polar p-xylene. Meanwhile, the pyrrolic/graphitic N groups and oxygen deficiency could also improve the water resistance of the N-PCs. Temperature programmed desorption (TPD) and inverse gas chromatography (IGC) results showed that the hydrogen-treated HN-PC surface had much higher special interaction towards weakly polar VOCs but lower interaction with H2O than other selected carbon materials with lower sp2 C, free-N and richer O content. Breakthrough experiment of p-xylene/water mixture depicted that the HN-PC samples maintained a very high working capacity of p-xylene (>5.1mmol/g) at 80% relative humidity. This value was approximately 1–3 times greater than that of some activated carbon and MOF materials. Besides, its diffusion rate constant (kb) of p-xylene was also undisturbed by water molecules. Thus, it can be seen the novel porous N-PCs with high water-resistance can become a good candidate for VOCs pollution control under humid air.