Mesoporous carbons modified with lanthanum(III) chloride for methyl orange adsorption

• Ordered mesoporous carbons were modified with lanthanum(III) chloride.
• LaCl3 strongly determine structural, textural as well as acid–base properties.
• Removal of methyl orange in acidic solutions was better than in basic solutions.
• The dye adsorption equilibrium was rapidly attained after 120 min of contact time.
• The adsorption of dye increased with increasing initial dye concentration.

Ordered mesoporous carbons of regular structure have been for the first time modified with lanthanum(III) chloride. The physicochemical properties of materials were characterised by X-ray diffraction, electron transmission microscopy and low-temperature nitrogen sorption. The results show that lanthanum(III) chloride strongly determine structural, textural as well as acid–base properties of the mesoporous carbons. All materials obtained were used for the removal of methyl orange from aqueous solution. Adsorption experiments were carried out as batch studies at different contact time, pH and initial dye concentration. Removal of methyl orange in acidic solutions was more efficient than in basic solutions. The adsorption of dye increased with increasing initial dye concentration. The adsorption capacities of different mesoporous adsorbents decrease in the following order: 5 La/CKIT-6 (455 mg/g) > 3 La/CKIT-6 (409 mg/g) > 1 La/CKIT-6 (375 mg/g) > 0.5 La/CKIT-6 (332 mg/g) > CKIT-6 (259 mg/g). Thermodynamic study showed that the adsorption was a spontaneous and exothermic process.