Isotherm and Kinetic Studies on the Adsorptive Removal of Metanil Yellow and Neutral Red Dyes Using Copper Oxide Nanoparticles

Abstract

This study investigated the adsorption property of copper oxide nanoparticles (CuO-NPs) for the removal of Metanil Yellow (MY) and Neutral Red (NR). The influence of variables such as contact time, initial concentration and pH for the adsorption process were investigated. The percentage removal and optimum contact time for the removal of MY and NR were obtained as 70.7% during 25 min and 56.9% over 30 min respectively. The experimental isotherms data were analyzed using Langmuir, Temkin, Freundlich and Dubinin-Radushkevich (D-R) isotherms and it was observed that MY fits closely to Temkin isotherm with an R2 value of 0.860 and NR fits more to D-R isotherm with R2 0.953. The kinetics of both MY and NR dyes fits better to pseudo-second order with the experimental values of qe 2.844 and 3.536 for NR and MY respectively been closer to the calculated values of the qe 2.739 and 3.222 for NR and MY respectively. Effect of pH of both dyes shows that they adsorb better at the initial pH of 3.37 and 5.09 for NR and MY respectively. Lower values of mean square energies of 0.354 for NR and 0.791 kJ/mol for MY indicates that the adsorption process is physical. The results indicated that copper oxide nanoparticle can be used as a low-cost adsorbent for the removal of MY and NR from aqueous solutions.