Characterization and membrane stability study for the switchable polarity solvent N,N-dimethylcyclohexylamine as a draw solute in forward osmosis

Abstract

Commercially available reverse osmosis and forward osmosis thin-film composite membranes were assessed for long-term chemical stability when immersed in 10 molal N,N-dimethylcyclohexylammonium hydrogen carbonate draw solution, a model switchable polarity solvent draw solute for forward osmosis. Membrane performance was monitored with reverse osmosis testing, including rejection of 2000 ppm sodium chloride (NaCl), for three commercial reverse osmosis membranes-Dow BW30, SW30HR, and SW30HR with polyester backing layer removed-and a commercial forward osmosis membrane (HTI TFC). The RO membranes were observed to be mostly unaffected by exposures up to 90 days while the HTI TFC suffered a sharp increase in both water permeance and sodium chloride permeability, manifesting itself as a reduction in intrinsic rejection of NaCl from 95% to 82%. The as-received HTI TFC membrane was characterized for osmotic water flux, where it was found the water flux was very insensitive to draw solute concentration in both the pressureretarded osmosis and forward osmosis operating modes. Reverse permeation of the draw solute was highly variable, despite lower variability in the forward water flux. Forward osmosis desalination of a 0.5 molal sodium chloride feed with the HTI TFC membrane and 10 molal draw solution indicated higher rejection (ca. 98.7) than under reverse osmosis testing, albeit with lower flux and the presence of reverse permeation of the draw solute. The overall results imply that a forward

Forward Osmosis Membrane Technology in Wastewater Treatment

“…heating [22] 1--Cyclohexylpiperidine (CHP) heating [23] Organic compounds Micellar solution UF [24] oxalic acid complexes with Fe/Cr/Na nanofiltration (NF) [25] trimethylamine-carbon dioxide heating [26] CO2-responsive polymers (PDMAEMA) UF [27] poly(sodium styrene-4-sulfonate-co-Nisopropylacrylamide) (PSSS-PNIPAM) MD [28] Switchable polarity solvent (SPS) RO [29] polyelectrolyte incorporated with triton-x114 MD [30] dimethyl ether heating with solar energy [31] poly(4-styrenesulfonic acid-co-maleic acid) NF [32] Super hydrophilic nanoparticles UF [33] hydrophilic superparamagnetic nanoparticles magnetic separation [34] Functional nanoparticles magnetic core-hydrophilic shell nanosphere magnetic separation [35] thermoresponsive Magnetic Nanoparticle magnetic separation [36] dextran-coated MNPs magnetic separation magnetic separation [37] hyperbranched polyglycerol coated MNPs magnetic separation [38] In addition to fouling of membrane, concentration polarization has an impact on the water flux, particularly at the support layer, which leads to the severity in internal concentration polarization (ICP). A low ICP requires a low S-value (structural parameter) [43,77].…”

Recent Advance on Draw Solutes Development in Forward Osmosis

“…NaCl reverse osmosis (RO) [33] inorganic fertilizer direct use [45] potassium sulfate (K 2 SO 4 ) RO [33] sodium nitrate (NaNO 3 ) direct use [46] aluminum sulfate (Al 2 (SO 4 ) 3 ) precipitation [47] magnesium sulfate (MgSO 4 ), copper sulfate (CuSO 4 ) precipitation [48,49] Organic compounds Switchable polarity solvent (SPS) RO [50] sodium polyacrylate (PAA-Na) ultrafiltration (UF), membrane distillation (MD) [51,52] CO 2 -responsive polymers (PDMAEMA) UF [53] poly(sodium styrene-4-sulfonate-co-N-isopropylacrylamide) (PSSS-PNIPAM) MD [54] poly (aspartic acid sodium salt) MD [55] N,N-dimethylcyclohexylamine (N(Me) 2 Cy) heating [56] 1-Cyclohexylpiperidine (CHP) heating [57] Micellar solution UF [58] oxalic acid complexes with Fe/Cr/Na nanofiltration (NF) [59] 2-Methylimidazole compounds MD [60] trimethylamine-carbon dioxide heating [61] glucose, fructose RO [62][63][64] polyelectrolyte incorporated with triton-x114 MD [65] dimethyl ether heating with solar energy [66] poly(4-styrenesulfonic acid-co-maleic acid) NF [67] Functional nanoparticles…”

“…Besides, the removal of the trace amounts of ammonia in product water is still a big challenge. Later, to overcome the mentioned defects above, a series of ammonium carbonate salts with similar function of NH 3 -CO 2 , such as N,N-dimethylcyclohexylamine (N(Me) 2 Cy) [56], 1-Cyclohexylpiperidine (CHP) [57], trimethylamine (N(CH 3 ) 2 ) [61] and switching polarity solution (SPS) [50] have been reported.…”

Diamines as switchable-hydrophilicity solvents with improved phase behaviour

“…In addition to extracting lipids from soybeans, SHSs have been used to isolate lipids from algae, [5][6][7][8] bitumen from oil sands, 9,10 and phenols from lignin pyrolysis oil. 11 Interest has also been shown in applying SHSs to other applications such as water purication, [12][13][14][15][16][17][18] microextraction for detecting and quantifying environmental contaminants, [19][20][21][22][23][24][25] separations of reaction products from organocatalysts, 26 emulsion formation, 27 and processing recyclable materials. 3,28 Previous studies showed that monoamine SHSs can be largely separated from dissolved products by the action of carbonated water, but some solvents might not be sufficiently removed from the product because the partitioning of the SHS into the aqueous phase was inadequate.…”