Kinetic and Thermodynamic Study of Malachite Green and Phenol Red Dyes removal from Wastewater using Nanocomposites

Abstract

This study investigate the ability of a PVC–CuO nanocomposite to adsorb Malachite Green (MG) and Phenol Red (PR) dyes from aqueous solutions.  We initiated our batch investigation with 10 mg of the nanocomposite and 25 ppm of dye.  We employed Pseud first order and Pseudo second equations to construct a model of the kinetics. The inadequate correlation values (R²) indicate that the Pseud first order model inadequately represented the adsorption of body dye The Pseudo second equations model exhibited better fit, particularly for PR, which outperformed MG. Evaluating the thermodynamic properties at several temperatures, ranging from 20 to 40 degrees Celsius. The negative Gibbs free energy values (ΔG) indicated that adsorption occurs spontaneously, and MG exhibited greater capacity at higher temperatures.  The positive elevation in entropy (ΔS = 93.21 J/K·mol for PR and 69.66 J/K·mol for MG) indicate that the interface between the solid and liquid is becoming less organized.  PR has the most impact. The positive enthalpy values (ΔH) further indicated that the adsorption processes for both dyes were endothermic. The result demonstrated that the PVC–CuO nanocomposite act as an effective adsorbent for the removal of MG and PR dyes, utilizing spontaneous and endothermic thermodynamic process. Adsorption follows the Pseudo second equations kinetic model.