Efficient Extraction of Methylene Blue from Aqueous Solution Using Phosphine-Based Deep Eutectic Solvents with Carboxylic Acid

Methylene blue (MB), an organic thiazine dye, has numerous industrial and medical applications. However, MB is a wastewater contaminant that harmful to humans aquatic life. Hence, its removal from water bodies essential. In this work, five novel deep eutectic solvents (DESs) were synthesized using different precursors, screened, studied for the extraction of methylene (MB) aqueous solution liquid–liquid extraction. The first, TOP-SA, was trioctylphosphine (TOP) as hydrogen bond acceptor (HBA) 2-hydroxy benzoic acid donor (HBD). Among these, TOP-SA had highest efficiency. effects pH, contact time, initial concentration, volumetric ratio, temperature, ionic strength optimized. A 99.3% achieved in 5 min 200 mg dm−3 mixed 1:10 ratio with at 25.0 °C. structural properties interactions investigated FTIR. TOP-SA’s toxicity human cells vitro. found be comparatively less toxic more efficient remover than other literature reported liquids (ILs).