Preparation and assessment of carboxylate polyelectrolyte as draw solute for forward osmosis

Abstract

Reverse draw solute diffusion not only reduces the water flux in forward osmosis (FO), but also contaminates the feed solution and eventually increases the regeneration cost of draw solution. In the present study, a new polyelectrolyte was synthesized as FO draw solute to address this problem. Acrylic acid and sodium p-styrenesulfonate monomers with hydrophilic group were used to fabricate carboxylate polyelectrolyte through free radical polymerization reaction. Results demonstrated that the osmotic pressure of carboxylate polyelectrolyte solution had a good linear relationship with concentration, and the viscosity of 0.18 g/mL solution was less than 5.4 cP. Active layer facing draw solution produced the initial water flux of 11.77 LMH and active layer facing feed solution yielded the initial water flux of 6.68 LMH when the concentration of draw solution was 0.18 g/mL. The reverse solute flux was around 1 gMH, and specific reverse solute flux of 0.18 g/mL carboxylate polyelectrolyte draw solution was 0.11 g/L which was much lower than that of traditional inorganic salts. Finally, diluted draw solution was regenerated via ultrafiltration, and the recovery efficiency of 94.78% was achieved. So, carboxylate polyelectrolyte can be suitable draw solute for FO.

Effect of lithium chloride additive on forward osmosis membranes performance

“…In the AL-FS orientation, ICP is severe as the draw solute passes through the porous side of the membrane, resulting in a low water flux [27,29]. Cui et al [30] and Mi and Elimelech [31] showed that when DI water is used as the feed solution, the AL-DS orientation shows much higher water flux than the AL-FS orientation because the former shows concentrative ICP, while the latter shows dilutive ICP.…”

Application of Poly(diallyl dimethylammonium chloride) as a Forward Osmosis Draw Agent: The Quantified Effect of Osmotic Pressure and Viscosity

“…For the same solution, the diffusion coefficient is negatively correlated with the solution viscosity . Since osmotic pressure and viscosity of polyelectrolyte solution could be easily characterized by relevant instruments, they were usually used to qualitatively explain the FO water flux in many studies. ,− The polyelectrolyte solutions with high osmotic pressure and low viscosity have been considered as ideal draw solution. However, the influence of osmotic pressure and viscosity on the relevant water flux was yet ambiguous.…”