Removal of basic dye by modified Unye bentonite, Turkey.

Area of Science:

• Environmental Chemistry
• Materials Science
• Adsorption Science

Background:

• Crystal violet (CV(+)) is a common basic dye that pollutes water bodies.
• Bentonite is a clay mineral with potential for adsorbing pollutants.
• Modification of bentonite with manganese oxide can enhance its adsorption properties.

Purpose of the Study:

• To investigate the adsorption behavior of crystal violet (CV(+)) onto raw bentonite (RB) and manganese oxide-modified bentonite (MMB).
• To evaluate the adsorption capacity, kinetics, and thermodynamics of CV(+) adsorption.
• To determine the suitability of MMB as an adsorbent for basic dye removal.

Main Methods:

• Adsorption experiments were conducted by varying initial CV(+) concentration, contact time, and temperature.
• Equilibrium adsorption isotherms were analyzed using Langmuir, Freundlich, and Dubinin-Radushkevich (D-R) models.
• Kinetic data were fitted to pseudo-first-order, pseudo-second-order, and intraparticle diffusion models.
• Thermodynamic parameters (ΔH, ΔS, ΔG) were calculated.

Main Results:

• MMB exhibited a significantly higher Langmuir monolayer adsorption capacity (1.12 mmol/g) compared to RB (0.32 mmol/g).
• Adsorption onto MMB was identified as chemical adsorption based on D-R isotherm analysis.
• MMB demonstrated a much faster adsorption rate, removing over half the CV(+) in 5 minutes, compared to 55 minutes for RB.
• Thermodynamic analysis indicated spontaneous and endothermic adsorption processes for both adsorbents.

Conclusions:

• Manganese oxide modification substantially enhances the adsorption performance of bentonite for crystal violet.
• MMB possesses a high adsorption capacity and rapid adsorption rate, making it an effective material for removing basic dyes from aqueous solutions.
• The findings highlight the potential of MMB as a cost-effective and efficient adsorbent in wastewater treatment.