Adsorption Kinetics for the Removal of Hazardous Dye Congo Red by Biowaste Materials as Adsorbents

Abstract

The present work aims to investigate the removal of dye congo red from aqueous solutions by two low-cost biowaste adsorbents such as ground nut shells charcoal (GNC) and eichhornia charcoal (EC) under various experimental conditions. The effect of contact time, ionic strength, temperature, pH, dye concentration, and adsorbent dose on the removal of dye was studied. The kinetic experimental data were fitted to pseudo-first order, pseudo-second order, intraparticle diffusion, Elovich model, and Bangham’s model. Results imply that adsorption of congo red on these adsorbents nicely followed the second order kinetic model and maximum adsorption capacity was found to be 117.6 and 56.8 mg g−1for GNC and EC at 318 K, however it increases with increase in temperature for both adsorbents. Equilibrium isotherms were analyzed by Langmuir, Freundlich, Temkin, Dubinin and Radushkevich, and Generalized Isotherms. Freundlich isotherm described the isotherm data with high-correlation coefficients. The results of the present study substantiate that biowaste material GNC and EC are promising adsorbents for the removal of the dye congo red.