Forward Osmosis Dye Concentration Using MgCl ₂ ·6H ₂ O–ChCl Deep Eutectic Solvent

In a growing world where high‐pressure‐based membrane technologies have occupied the market for water treatment, forward osmosis, a method based on osmotic difference, is well appreciated and a viable option for the future. In this study, magnesium chloride hexahydrate: Choline chloride (1:1) deep eutectic solvent was utilized as a forward osmosis draw solution with an HFNF 600 nanofiltration membrane. The water flux with 1%, 5%, and 10% (v/v) solutions of DES illustrated average flux values of 6.0073 L m −2 h −1 , 7.6949 L m −2 h −1 , and 12.8338 L m −2 h −1 , respectively, over the time period of 4 h. Similarly, for Congo Red against 10% DES solution, the flux value shows a high flux of 7.8954 L m −2 h −1 . Moreover, focusing on the cost‐effectiveness of the water‐dye separation step, a more convenient freezing technique is used to regenerate the DS. Here, the MAGCC DES, which is used as a DS, has been separated from water by freezing at −5°C. The Reverse solute flux has been found to be 27.14 ppm with 10% DES. A commercial nanofiltration membrane, HFN600, has been used for this study. The Water achieved is useful for different purposes.