Adsorption of Cr(VI) from aqueous solution on mesoporous carbon nitride

Mesoporous carbon nitride (MCN) was synthesized using mesoporous silica SBA-15 as the template and employed for the adsorption of Cr(VI) from aqueous solutions. Cr(VI) adsorption over MCN followed pseudo-second-order kinetic model and the Langmuir adsorption model. The maximum sorption capacity of MCN for Cr(VI) was 48.31 mg/g at pH 5.7, higher than activated carbon (AC) and ordered mesoporous carbon (CMK-3). An electrostatic interaction mechanism between Cr(VI) and surface pyridine groups on MCN was proposed by Fourier transform infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS) analysis. The coexisting anions, especially the carbonate, influenced the adsorption amount due to the competitive adsorption of Cr(VI) on the surface of MCN. The adsorbed Cr(VI) could be effectively desorbed by 0.5 mol/L NaOH solution, suggesting that MCN could be a promising adsorbent for Cr(VI) removal from waste effluents.