THERMODYNAMIC STUDY OF THE ADSORPTION OF ALIZARIN RED ON ATABALGUID
This study is aimed to test the removal efficiency of the Alizarin Red Dye (ARD) from its acidic medium (pH=5.6) aqueous solution by using a local clay named Atabalguid (ATC). The optimum condition for the adsorption process were investigated, such effect of dose, effect of initial, effect of contact time, and effect of temperature. The study showed that the best amount of ATC used is (0.5gm) in a range of initial concentration that ranged between (24-216mg/l) and at a temperature range ranging between (288-328k°). The study showed that the time required to reach equilibrium was (90) minutes, and for this reason, the time (90) minutes was chosen to test the subsequent studies. Thermodynamic study was also included. Thermodynamic functions (∆So , ∆H , ∆G°) were calculated at one concentration (24 mg/L) and at several temperatures (288, 298, 308, 318,and 328). The experiment was repeated at several concentrations. ( 72, 120, 168, and 216 mg/L) The results showed, the equilibrium constant (K) decreases with increasing temperature. This is consistent with the physical nature of the adsorption process. The values of the thermodynamic functions proved that the adsorption system under study is spontaneous, and the forces controlling the bond between the alizarin red dye (ARD) molecules and the available sites on the Atabalguid clay (ATC) surface are physical in nature. The adsorption process leads to more ordered system at a concentration of 24 mg/L, while at higher concentrations the adsorption leads to more random dyes system. This can be attributed to the fact that increasing the concentration increases the number of remaining molecules in the dye solutions, thus increasing the randomness of the system, especially after equilibration
Keywords: Alizarin Red, Atabalguid, Adsorption, Thermodynamic Study