Selective and competitive removal of three basic dyes from single, binary and ternary systems in aqueous solutions: A combined experimental and theoretical study

Abstract

The present study evaluates the selective and competitive adsorption of three basic dyes, namely, Basic blue 9 (BB9), Basic blue 41 (BB41) and Basic yellow 28 (BY28) from single, binary and ternary solutions onto natural safiot clay (NSC). For this, the effect of various parameters such as initial pH, initial dye concentration, adsorbent dose and temperature of the solution was studied and examined in a batch mode. The tested adsorbent was characterized by X-ray fluorescence (XRF), Scanning Electron Microscopy (SEM), Dispersive X-ray spectroscopy (EDX), Fourier Transform Infrared (FT-IR) and X-Ray Diffraction (XRD). XRF results indicate high percentages of SiO2 (47.44%) and Al2O3 (31.24%). X-ray diffraction diffractogram identified kaolinite as the main mineral phase in the presence of quartz, illite, calcite, and dolomite. The adsorption data were examined by Langmuir, Freundlich and Dubinin-Radushkevich isotherms. It was found that for single, binary and ternary systems the results indicated that Langmuir model provided the better correlation of experimental data. The experimental results obtained demonstrate high adsorption efficiency of dyes in the mono and multi systems by NSC. DFT calculations show that BB9 (ω = 6.18) is more electrophilic than BB41 (ω = 4.10) and BY28 (ω = 2.60) which indicates that BB9 is adsorbed first and favored compared to BB41 and BY28. Moreover, Molecular dynamics (MD) and Monte Carlo (MC) simulations are used as a powerful tool to provide a better theoretical scenario for understanding the mode of adsorption on the natural safiot clay (NSC).