Removal of methylene blue from aqueous solution using wine-processing waste sludge.

Area of Science:

• Environmental Chemistry
• Materials Science
• Waste Management

Background:

• Dye wastewaters pose significant environmental challenges due to toxins and high chroma, often resisting conventional biological treatment.
• Adsorption is a crucial process for removing recalcitrant dyes from industrial effluents.
• Wine-processing waste sludge (WPWS) presents a potential biosorbent due to its high cation-exchange capacity and organic matter content.

Purpose of the Study:

• To investigate the adsorption mechanism of methylene blue (MB) using wine-processing waste sludge (WPWS).
• To evaluate the influence of various parameters on MB adsorption efficiency.
• To determine the thermodynamic and kinetic characteristics of the adsorption process.

Main Methods:

• Adsorption experiments were conducted by varying pH, initial MB concentration, temperature, WPWS particle size, and dosage.
• Adsorption isotherms were analyzed using the Langmuir model.
• Thermodynamic parameters (activation energy, Gibb free energy, enthalpy) were calculated using Arrhenius and Van 't Hoff equations.

Main Results:

• The Langmuir adsorption isotherm model accurately described MB adsorption by WPWS.
• The maximum adsorption capacity (Q(m)) for MB was determined to be 285.7 mg g⁻¹ at 25 °C.
• Thermodynamic analysis indicated a spontaneous, exothermic physisorption process with an activation energy of 29.995 kJ mol⁻¹.

Conclusions:

• WPWS is a highly effective and sustainable adsorbent for methylene blue removal from wastewater.
• The adsorption process is favored at lower temperatures, suggesting an exothermic physisorption mechanism.
• The findings support the use of WPWS as a viable material for dye wastewater treatment.