Methylene blue adsorption on thermo plasma expanded graphite in a multilayer column system

Area of Science:

• Environmental Science
• Materials Science
• Chemical Engineering

Background:

• Dye removal from wastewater is crucial for environmental protection.
• Methylene blue (MB) is a common industrial pollutant.
• Adsorption is an effective method for dye removal.

Purpose of the Study:

• To evaluate thermo plasma expanded graphite (TPEG) as an adsorbent for methylene blue (MB) removal.
• To investigate the adsorption mechanism and capacity of TPEG.
• To assess the reusability of TPEG in a multilayer column system.

Main Methods:

• Batch adsorption experiments were conducted varying pH, MB concentration, and temperature.
• Adsorption kinetics and isotherms were analyzed using pseudo-second order, Langmuir, and Freundlich models.
• Thermodynamic parameters, including Gibbs free energy change (ΔG°), were calculated.
• TPEG reusability was tested after regeneration with HCl.

Main Results:

• Optimal MB adsorption occurred at pH 11, indicating electrostatic interactions.
• Adsorption capacity increased with MB concentration and temperature (20–40 °C).
• Maximum adsorption capacities reached 95 mg/g at 20 °C and 265 mg/g at 40 °C.
• The process is spontaneous (ΔG° = -7.80 kJ/mol) and TPEG was reusable up to 5 times.

Conclusions:

• TPEG is a highly effective and reusable adsorbent for MB removal from wastewater.
• Electrostatic interactions play a key role in the adsorption mechanism.
• TPEG shows significant potential for industrial wastewater treatment applications.