Equilibrium and kinetic studies of chromotrope 2R adsorption onto ordered mesoporous carbons modified with lanthanum

• Mesoporous carbons CSBA-15 and CKIT-6 were modified with lanthanum(III) chloride.
• Batch tests were conducted to investigate the chromotrope 2R adsorption.
• The sorption capacity of the samples, increases with increasing wt.% of LaCl3.
• Azo dye adsorbs onto the mesoporous carbons following the Langmuir type isotherm.
• The adsorption kinetics was represented by pseudo-second-order model.

Ordered mesoporous carbons CSBA-15 and CKIT-6 of hexagonal and regular structure, respectively, modified with lanthanum(III) chloride have been synthesised and used as adsorbents of chromotrope 2R, an azo dye. The materials obtained were characterised by X-ray diffraction, low-temperature nitrogen sorption, transmission and scanning electron microscopy. The results showed that impregnation of mesoporous carbons with lanthanum salt caused a decrease in ordering of their structure. The modified samples were found to have smaller surface area and pore volume than those of pure CSBA-15 and CKIT-6. The decrease in both parameters was proportional to the amount of LaCl3 nanoparticles introduced on the support surface.Batch tests were conducted to investigate the adsorption performance. The sorption capacities towards chromotrope 2R of carbons of regular structure were greater than those of materials of hexagonal structure. Kinetics of the adsorption processes was studied using pseudo-first and second-order models and the intra-particle diffusion model. The regression results showed that the adsorption kinetics was more accurately represented by pseudo-second-order model. Chromotrope 2R is adsorbed onto the carbon materials studied following the Langmuir type isotherm.

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