تحضير هيدروجيل الكيتوسان-الزيوليت/موردينايت/ ودراسة امتزازها على الأصباغ الأنيونية والكاتيونية.

Synthesis of Chitosan – Zeolite /H-mordinate/ hydrogel and Study their Adsorption on Anionic and Cationic Dyes.

This study investigated the adsorption of Congo red dye on the surface of the polymer chitosan – zeolite mordenite (ZCS). This polymer was diagnosed using infrared technique (IR) and X-ray diffraction (XRD). The external appearance of the surface was diagnosed using scanning electron microscopy (SEM). The factors affecting the adsorption of Congo red were studied through a series of experiments, including: adsorbent surface weight, pH, initial dye concentration and the effect of temperature at 298,308, and 318 K.
Where the results showed that equilibrium was obtained for the surface (ZCS) at a time of (70 min) and a weight of (0.05 g) from the adsorbent surface and a high pH function), and the best concentration of the dye is (40 ppm), and best pH = 13. It was also observed a gradual decrease in the percentage of removal accompanied by significant increases in the adsorption capacity values with increasing dye concentration. The lowest removal percentage (69.94%) and the highest adsorption efficiency (50.03 mg/g) were recorded at (120 ppm) concentration.
As that adsorption isotherms (Langmuir, Freundlich, TemKin) were studied, as the highest correlation coefficient (R2) was recorded for the Langmuir isotherm. This indicates that adsorption obeys the Langmuir isotherm. Calculating the separation constant (RL), it shows the susceptibility of the adsorption process and whether it is preferred or not, and its value was equal to (0.0206), which indicates the adsorption of Congo red dye on the ZCS surface occurs as a favored process by Langmuir isotherm. The adsorption kinetics was also studied and the results indicated that the adsorption follows the pseudo-second order. When studying the thermodynamic functions (∆H = 35.174 KJ/mol, ∆S = 139.16 J/K.mol), So the adsorption process is spontaneous, with increase of entropy and endothermic according to the values of the thermodynamic functions.