The removal of dye (RS) anionic (Benzene sulfonic acid, 4-hydroxy-3-((2-hydroxy-1-naphthalenyl)) azo monosodium salt) on flint clay in aqueous solution was investigated by using a system of the batch for different concentrations from the dye. The temperature, pH, contact time, adsorbent dose, was studied beneath the batch adsorption method. Data adsorption equilibrium appropriate with isotherm Langmuir and Freiundlich, when the correlation coefficient utilized to clarify the better model for the fitting isotherm. The thermodynamic constants like ∆Hº, ∆Sº, and ∆Gº. Thermodynamic analyses specified for the sorption of the dyes on to Alhusaenat clay (Baghdad Governorate in Iraq) was spontaneous as well as endothermic. Density Functional Theory (DFT) was studied the dye structure used Gaussian 09 and predicted the active site in a molecule by total electron density (TED) and electrostatic surface potential (ESP).
Key words: Adsorption, Dye RS, DFT, Langmuir model, Thermodynamic