Study of liquid phase adsorption of congo red on micro and mesoporous adsorbents containing lanthanum

In the present work, microporous and mesoporous adsorbents containing lanthanum of LaNaY and LaMCM-41 type were synthesized for the use in the removal of textile dyes and characterized by different techniques such as x-ray diffractometry and adsorption/desorption of N-2 at 77 K. The adsorption kinetics was evaluated using the pseudo-first-order model. The systems with lower concentrations of the dye (10 mg l(-1) and 20 mg l(-1)) reached equilibrium between 40 and 90 min, whereas for the system with higher concentration of dye (30 mg l(-1)) the equilibrium is reached in the initial phase. The adsorption capacity data were determined using the Langmuir and Freundlich models applied to the experimental data. The Langmuir model was the best fit for the system with mesoporous adsorbents, however the system with microporous adsorbents presented better correlation with the Freundlich model. The adsorbent LaMCM-41 showed a significantly higher adsorption efficiency than that of the LaNaY adsorbent, which is correlated with its larger total area, volume and pore diameter.