Ordered mesoporous carbons modified with cerium as effective adsorbents for azo dyes removal

Ordered mesoporous carbons modified with cerium were applied for removal of tartrazine and sunset yellow FCF from aqueous solutions. These novel materials were characterised by different techniques such as X-ray diffraction, low-temperature nitrogen sorption, scanning electron microscopy and laser diffraction. Unique physicochemical properties of the mesoporous adsorbents (well developed surface area, large pore volume, regular structure) in addition to the presence of various functional groups make them promising materials for efficient removal of azo dyes. Adsorption experiments were carried out as batch studies for different contact times and initial dye concentrations. The dye adsorption equilibrium was rapidly attained after 50 min for tartrazine and 70 min for sunset yellow FCF. Percentage of dyes removal was greater at lower initial concentrations (100% for the concentrations below 12.5 mg/L for tartrazine and below 25 mg/L for sunset yellow FCF) and smaller at higher initial concentrations (35-66% for 100 mg/L of tartrazine solution and 76-97% for 100 mg/L of sunset yellow FCF solution). The equilibrium data were analysed by the Langmuir and Freundlich models, which revealed that the former model was more suitable to describe the tartrazine and sunset yellow FCF adsorption than the latter one. The maximum adsorption capacities of the mesoporous carbons modified with cerium towards tartrazine were in the range 128.04-171.20 mg/g, while towards sunset yellow FCF they were from the range 223.91-323.91 mg/g. Pseudo-first-order and pseudo-second-order kinetic models and intraparticle diffusion model were used to evaluate the adsorption kinetic data. The kinetic data of two azo dyes were better described by the pseudo-second-order model. (C) 2015 Elsevier B.V. All rights reserved.