Synergistic combination of natural deep eutectic solvents and green extraction techniques for the valorization of date palm leaves: Optimization of the solvent-biomass interaction

Did you know that over 120 million date palm trees produce 20–35 kg of leaves each year, creating an environmental burden that could become a treasure trove of natural antioxidants?

Date palm leaves are often discarded, but they hide a wealth of polyphenolic compounds with potential health benefits. This study sought to unlock their value using green chemistry, specifically Natural Deep Eutectic Solvents (NADES) paired with cutting-edge extraction techniques. Among the solvents tested, glycerol-based NADES outperformed saccharide and organic acid-based ones, yielding higher phenolic content. The researchers then optimized microwave-assisted (MAE) and ultrasonication-assisted (UAE) extraction using a factorial design. Surprisingly, UAE-NADES proved ineffective, while MAE-NADES significantly boosted recovery. Moreover, MAE-NADES extracts showed superior bioactive properties. To fine-tune the process, a Box-Behnken design of Response Surface Methodology was applied. The optimal conditions were a 49% NADES concentration, 800 W power, and just 0.84 minutes of microwave exposure. This approach not only enhances efficiency but also aligns with eco-friendly principles, turning a waste product into a valuable resource for desert economies.

Key Points

• Glycerol-based NADES yielded highest phenolics from date leaves.
• Microwave-NADES outperformed ultrasonication-NADES in recovery.
• Optimized extraction: 49% NADES, 800 W, 0.84 min.