Ionic Liquids and Activated Carbon: Effective Materials for the Sustainable Production of Fresh Water from Salt Effluents (BRINE)

Abstract

Water stress in Morocco is a major concern and considerably affects the economic and social sectors. Seawater desalination processes are part of the solutions adopted, and direct contact membrane distillation (DCMD) processes have been proposed to treat salty discharge from reverse osmosis units. Recently, composite polymer membranes based on ionic liquids (ILs) have been adopted for extraction and separation processes. In this context, a composite membrane was prepared based on polymer supports poly(vinylidene fluoride) (PVDF) and polysulfone (PSU) and ionic liquid trioctylmethylammonium oleate (TOMAO) and doped with activated carbon (AC). The PVDF/ PSU -IL-AC membrane has been adopted in DCMD processes for the diffusion and extraction of water vapor (WV). This composite membrane has good hydrophobicity (126.04°) and high porosity (91.07%). Significant flux 18.29 kg m −2 h −1 and salt rejection 99.93% were observed at 60 °C, with good reproducibility of the results (9 weeks). The activation parameters E a , ΔH # , and ΔS # were quantified, the diffusion mechanism of water molecules through the membrane has been identified, and the roles of IL and AC have been elucidated. All results indicate that the developed membrane is an effective tool for producing pure water from saline waters (BRINE). Finally, seawater desalination tests were carried out under optimal conditions.

Reliable and efficient membrane processes for clean and sustainable production of fresh water from saline waste

“…13 The MD process, centered on distilled water recovery, encompasses four primary configurations: vacuum membrane distillation (VMD), 14 air gap membrane distillation (AGMD), 15 sweep gas membrane distillation (SGMD) 16 and direct contact membrane distillation (DCMD). 17,18 The DCMD technology stands out as the most studied and costeffective. 19 Operating below the boiling point of water, DCMD processes provide a straightforward approach to desalinate and treat brine solutions.…”

“…30 The incorporation of hydrophobic ILs enhances the stability of the membranes, improves their properties, and increases their effectiveness in desalinating saltwater and removing salts. 18,31,32 The method of membrane preparation is crucial in optimizing membrane properties and morphology for DCMD process. 33 Traditionally, phase inversion techniques ensure the creation of membranes with well-controlled pore size and porosity, meeting the requirements of the DCMD process.…”