Adsorption Study Of Malachite Green Dye On To Cadmium Oxide Surface (Thermodynamic and Kinetic)

Abstract

The subject of the research  is the study of adsorption of pigment dye malachite on to Metal oxide. One of these is metal oxides, cadmium oxide, was chosen as the adsorbents of this dye In the thermal range from 298K to 328K. The study included the test of applying the isotherm models of Langmuir, Freundlich, Elovich and Temkin to the practical adsorption data of the dye under study using the UV spectroscopy. The test results gave linear relations and good correlation coefficients, specifically Temkin and Freundlich .isotherm.

  The kinetic data were modeled  by using pseudo-first-order, pseudo-second-order, Elovich and intra-particle diffusion kinetics equations, The pseudo-second-order and intra-particle diffusion kinetic  model was found to  correlate  with the  experimental data well for the dye.

    Adsorption adsorbents were also used to obtain the values of the thermodynamic functions (Free energy ∆G, enthalpy ∆H and ∆S entropy) within the experimental thermal range (328-298K) based on the calculation of the values of the equilibrium constant (Keq). The results indicated that adsorption is endothermic and physical and that entropy increases with increasing temperature  and that the reaction is spontaneous in experimental conditions.