STUDY ON KINETICS, ISOTHERMS AND THERMODYNAMICS OF ADSORPTION OF RHODAMINE B DYE ON CuZIF-11 MATERIAL

The adsorption behavior of rhodamine B (RhB) on a material ZIF-11 modified with Cu²⁺ ions (CuZIF-11) was studied. The results showed that CuZIF-11 exhibited excellent adsorption capacity toward RhB. The adsorption data fit well to the Langmuir isotherm model, with a maximum adsorption capacity of 138.89 mg/g at 313 K. The adsorption kinetics followed the pseudo-second-order model and were also consistent with the intraparticle diffusion model. Thermodynamic parameters indicated that the adsorption process was endothermic. The activation energy of adsorption (Ea) was determined to be 10.46 kcal/mol. This relatively high Ea suggested that the adsorption of RhB onto CuZIF-11 was likely a chemical adsorption process. The adsorption mechanism was attributed to electrostatic attraction and π–π stacking interactions between RhB and the CuZIF-11 adsorbent.