Hydrophilic hollow carbon nanocapsules for high-capacity adsorptive removal of cationic dyes in aqueous systems

Abstract

Hollow carbon nanocapsules (HCNs) are prepared via the decomposition and leaching of nickel carbide (Ni₃C) nanoparticles. The leaching process renders the HCNs hydrophilic and improves their aqueous dispersibility through the formation of oxygen-containing functional groups on the surface. These functional groups, in conjunction with the graphitized shell of the HCNs, result in a high affinity for cationic dye species such as rhodamine B (RB) and crystal violet (CV) in aqueous solution. Adsorption experiments are performed to investigate the absorptive performance of the HCNs as a function of the initial dye concentration, contact time and temperature. The results confirm that the HCNs have both a high adsorption rate and a high maximum adsorption capacity for the considered organic dyes. Specifically, 85% of the maximum adsorption capacity is obtained within the first 5 minutes of adsorption and the maximum adsorption capacity at 333 K is 628.93 and 675.68 mg g⁻¹ for RB and CV dyes, respectively.