Application of hollow mesoporous carbon nanospheres as an high effective adsorbent for the fast removal of acid dyes from aqueous solutions

In this study, hollow mesoporous carbon nanospheres (HMCN) prepared from core-shell structured mesoporous silica sphere using chemical vapor deposition were used as a novel adsorbent for the investigation of the adsorption of two acid dyes: Acid Orange 8 (AO8) and Acid Red 88 (AR88) from aqueous solutions. The adsorbent was characterized by X-ray diffraction XRD, high-resolution transmission electron microscopy HRTEM, Raman spectroscopy, Fourier infrared spectroscopy FTIR, N-2 adsorption/desorption isotherms and zeta potential measurements. The effects of initial dye concentration, pH and temperature on adsorption capacity were studied. The experimental data were analyzed by the Langmuir and Freundlich models of adsorption. Equilibrium data fitted well with the Langmuir model. The maximum adsorption capacities of AO8 and AR88 onto HMCN from the Langmuir isotherm model were 454.6 and 555.6 mg g(-1), respectively. The contact time required to obtain the equilibrium of AO8 and AR88 was 90 and 110 min, respectively. Kinetic adsorption data were analyzed using the pseudo-first-order kinetic model, the pseudo-second-order kinetic model and the intraparticle diffusion model. The adsorption kinetics well fitted using a pseudo-second-order kinetic model. Thermodynamics parameters, Delta G(0), Delta H-0 and Delta S-0, were calculated, indicating that the adsorptions of AO8 and AR88 was spontaneous and exothermic in nature. (C) 2013 Elsevier B.V. All rights reserved.