Analysis of the kinetics and isotherm of the adsorption of the dyes on the Montmorillonite clay, as well as a modeling research using techniques from density-functional theory (DFT)
摘要
This research discusses the efficacy of Montmorillonite Clay (MC) in removing single and binary (combination of dyes) systems of Safranin and Methyl Orange (MO) from aqueous solutions. The effects of contact periods (10–120 min), initial dye concentrations (10–300 mg.L−1), and dye solution pH (2–10) on the adsorption of two dyes were investigated. A substantial correlation was found between the adsorption of safranin and MO and the initial dye concentration and the pH of the dye solution. Kinetic analysis was performed using the pseudo-first-order kinetics model, the pseudo-second-order kinetics model, and the intraparticle diffusion model. Dye adsorption onto MC was found to be best described by a pseudo-second-order model. The correlation coefficients are extremely close to (R2 = 0.999 of MO dye and R2 = 0.993 of SF dye), indicating that the adsorption closely followed the Freundlich model. The Langmuir isotherm, along with other adsorption isotherms, was also investigated. The current study suggests that MC is a suitable choice for eliminating colors from water as a result of its high adsorption capability and low environmental impact. To optimize the species under investigation, the method of DFT, or density-functional theory was carried out utilizing the level of theory B3LYP/6–31 + g (d, p) in aqueous solution. The molecular reactivity descriptors and a potential mechanism for the adsorption process was suggested by the calculation of local reactivity indices.
Graphical abstract