Molecular modeling of cationic dyes adsorption on agricultural Algerian olive cake waste

Abstract

In this research, the adsorption isotherms of Methylene Blue (MB) and Basic Yellow 28 (BY28) on agricultural Algerian olive cake waste (AAOCW) were modeled at molecular level using statistical physics and COSMO–RS theories. This molecular modeling aimed to demonstrate an alternative way to describe the interactions between dyes and adsorbents. The adsorption equilibrium isotherms of MB and BY28 on AAOCW were constructed at different temperatures. The statistical physics model was used to quantify the number of adsorbed dye molecules per site, the anchorage number, the receptor sites density, the adsorbed quantity at saturation, the concentration at half saturation and the molar adsorption energy. The COSMO–RS theory was used to quantify the interaction energies: Electrostatic, hydrogen bonding and Van der Waals. σ–Profile and σ–potential were calculated to show the ability of each of the two dyes to interact with every adsorbent site. It was demonstrated that statistical physics and COSMO–RS theories are confident ways to elucidate the interactions between dye molecules and adsorbent surface at a molecular level.