Deep eutectic solvent-treated palm oil mill sludge adsorbents for methylene blue adsorption

Area of Science:

• Environmental Chemistry
• Materials Science
• Adsorption Science

Background:

• Palm oil mill sludge is a significant waste product.
• Wastewater contamination by dyes poses environmental risks.
• Developing cost-effective adsorbents is crucial for dye removal.

Purpose of the Study:

• To evaluate deep eutectic solvent (DES)-treated palm oil mill sludge as an adsorbent for methylene blue removal.
• To characterize the prepared adsorbents and understand their adsorption mechanisms.
• To assess the efficiency of DES treatment on sludge properties for enhanced adsorption.

Main Methods:

• Palm oil mill sludge was treated with DES at different temperatures (80°C and 25°C) and without DES (dry sludge).
• Adsorbent characterization included surface functional groups, textural properties (specific surface area), and morphology.
• Batch adsorption experiments were conducted varying methylene blue concentration, adsorbent dosage, pH, contact time, and temperature.

Main Results:

• DES-treated adsorbents exhibited significantly higher specific surface areas (up to 534 m²/g) compared to dry sludge (184 m²/g).
• The maximum adsorption capacities were 72.07 mg/g (P1:D2@80°C), 56.18 mg/g (P1:D2@25°C), and 48.33 mg/g (DS).
• Adsorption followed Sips isotherm and pseudo-second-order kinetics, indicating physical adsorption via pore filling and electrostatic attraction.

Conclusions:

• DES treatment enhances the adsorptive properties of palm oil mill sludge for methylene blue.
• The P1:D2@80°C adsorbent demonstrated the highest efficiency and adsorption rate.
• DES-treated palm oil mill sludge is a promising, sustainable adsorbent for industrial dye removal from wastewater.