Abstract:
In this study, a novel thin-film composite Reverse Osmosis (TFC-RO) membrane was synthesized with the help of a green solvent: Hydrophobic Deep Eutectic Solvents (DES) as an organic reagent phase for the very first time. This pilot-scale approach was based on the exchange of the hazardous organic solvent (n-hexane) with its more environmentally friendly substitutes, (DL-Menthol: Palmitic Acid), (DL-Menthol: Lauric Acid) and [TETA]Cl-Thymol based DES, respectively. Out of the three DESs, Lauric acid-based DES was selected for further analysis due to its low density and viscosity values. The first step was based on a qualitative analysis, where different monomer concentrations were used for piperazine (0.1%, 0.2%, 0.5%, and 1%) in water and Trimesoyl Chloride (TMC) (0.10%, 0.25%, 0.5%, and 1%) in DES, respectively. The best concentration (1% piperazine and 0.25% TMC) with a spontaneous, viscous polyamide layer formation was undergone another batch of experimentations. In the next step, this before-mentioned best concentration was first tested with Rose Bengal (RB) dye as a test solute and the results were then compared with pure hexane. The DES membrane showed similar water permeation and RB retention values, as compared to the commercially viable n-hexane. Also, as compared to the additive-free DES membrane, more porous membranes were formed with an increased water permeation (383.1506849 LMHbar-1, 461.8493151 LMH bar-1 and, 441.3013699 LMH bar-1) and decreased RB dye retention values (52%, 36%, and 46%) when tested with 0.1% Sodium-n-dodecyl sulfate (SDS), 2% Triethylamine (TEA) and (0.1% SDS + 2% TEA), respectively. Moreover, the hydrophobic lauric acid-based DES showed Sodium Chloride (NaCl) retention values of almost 32% when tested for their RO potential, showing that this membrane could provide promising results in the desalination industry while being environmentally benign, easy to prepare, and free for the need of any additives or surfactants addition.