Investigating Biomass Valorization for Synthetic Dye Red Congo Elimination: Kinetics, Isothermals, and Thermodynamics Study

Abstract

This study delves into the utilization of unprocessed raw walnut shells as an eco-friendly biosorbent for the removal of Congo Red (CR) dye from water. The research investigates the adsorption capabilities of walnut shells in their natural state and incorporates a comprehensive thermodynamic analysis.

Characterization utilizing Scanning Electron Microscopy (SEM) and X-ray Diffraction (XRD) unveiled the predominantly cellulose-rich structure of raw walnut shells. Kinetic analysis revealed that the adsorption process adheres to second-order kinetics, highlighting a robust interaction between CR dye and walnut shells. The application of the Freundlich adsorption model effectively described the adsorption process, confirming monolayer formation on the walnut shell surface.

Furthermore, our thermodynamic study demonstrated that the adsorption process is exothermic and spontaneous, adding an essential dimension to the understanding of this environmentally benign dye removal method. Impressively, the biosorbent achieved a dye removal rate exceeding 92%. These findings underscore the economic and environmentally friendly potential of unprocessed raw walnut shells for the treatment of dye-contaminated water. This research not only contributes to sustainable materials but also addresses the pressing issue of dye pollution through a practical and eco-conscious approach.