Green clay materials applied in packed bed columns for adsorption of hexavalent chromium from aqueous solutions

Abstract

The removal of hazardous metal ions from polluted water is a crucial process aimed at enhancing water quality. In this study, we conducted a dynamic adsorption investigation utilizing natural green clay for the removal of hexavalent chromium from aqueous solutions. The material underwent characterization through various techniques, including fluorescence spectrometry (XRF), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and nitrogen-physisorption (BET). Column tests of green clay material and sand mixtures were performed to evaluate sorption in dynamic systems. Adsorption conditions were examined by varying the initial Cr6+ concentration, flow rate and column height. The maximum purification was achieved at a concentration of 50 mg/L, a flow rate of 3mL/min and a bed height of 12 cm. The mathematical models of Bohart-Adams, Thomas, and Yoon-Nelson were employed to analyze experimental data and predict breakthrough curves in continuous adsorption. Through comparison of R2 values, it was determined that the Yoon-Nelson and Thomas diffusion models effectively capture and accurately describe the experimental data. The results obtained indicate a potential expansion of fixed-bed adsorption for the heavy metals treatment in industrial-scale wastewater. Additionally, the natural green clay material exhibited remarkable reusability and showed promising characteristics for various environmental and industrial applications.