Adsorption of Methylene Blue and Safranine Using Activated Carbon of Cinnamon Plant Surface.

Abstract

Cinnamon plant Activated Carbon (C/AC) was prepared by chemical and thermal activation. The adsorption behaviour of (C/AC) in aqueous Methylene blue (MB) and Safranine (S) dyes was investigated and characterized by XRD, TEM and FESEM. The possible mechanism of the adsorption of (MB) and (S) dyes on the (C/AC) surface was studied.  The influence of various adsorption control parameters like the initial dye concentration, pH, contact time, and temperature was studied.  The data confirmed a high removal of (MB) and (S) at pH=11.  The experimental data were fitted to Langmuir and Freundlich isotherms to examine the adsorption mechanism.  The adsorption data reveal (MB) with the maximum capacity of (294.11) mg/g and (S) with the capacity of (285.714) mg/g.  The kinetic data for different initial dye concentration were computed using pseudo-first order, pseudo-second order, and intraparticle diffusion model. Thermodynamic parameters includes enthalpy (∆H), entropy (∆S), free energy (∆G), and activation energy (E_a) of the adsorption process were calculated and used to interpret the results, and revealed that the adsorption systems were a spontaneous and endothermic process for adsorption of MB and S dyes onto the adsorbent surface. Also, low activation energy values (E_a<40 kJ/mol) were characteristics of the physisorption mechanism and diffusion-controlled process.