Lactic acid enantioseparation by means of porous ceramic disc and hollow fiber organic membrane

Chiral separation using a novel combination of cooling crystallization and a membrane barrier: Resolution of DL-glutamic acid

“…The product purity from all experiments was analyzed by HPLC and ranged from 94% to 98%, which corresponds to a separation factor of 16-60. This separation factor was higher than chiral separations reported in the membrane systems (Gumi et al, 2005a,b;Hadik et al, 2005), which had separation factors of 2.3 at most.…”

“…Membrane separation has potential for enantioseparation due to its energy efficiency, simple set-up and possible continuous operation even though the initial investment is high (Gumi et al, 2005a). Membrane separation in chiral resolution is not well established, but in principle, a chiral selector membrane binds one of the enantiomers while allowing the other enantiomer to pass though the membrane (Hadik et al, 2005). The membrane matrix itself can be enantioselective; otherwise the enantioselective carrier is bounded chemically or physically into the nonselective membrane.…”

“…Dense membranes and ultrafiltration membranes have been studied by several researchers (Higuchi et al, 2002;Overdevest et al, 2002;Higuchi et al, 2003;Gumi et al, 2005a,b;Hadik et al, 2005). From recent studies of solid membranes, the isothermal process started with an undersaturated racemate liquor solution on one side and a pure solvent on the other side (Gumi et al, 2005a,b;Hadik et al, 2005). Hypothetically, each enantiomer will be in a separated vessel in a solution form and the solid products need to be crystallized afterward.…”

Microreaction and membrane technologies for continuous single-enantiomer production: A review

“…An ee value of a mixture of enantiomers equals 0%, while the ee value of a single pure enantiomer equals 100%. The enantiomeric excess can be assessed using molar fractions of the enantiomers in a mixture as expressed in the following equation: 1.0 g/L concentrated feed solutions of racemic lysine and asparagine at 100psi (=689.5 kPa) enantiomeric excess of D-lysine of 92%, enantiomeric excess of D-asparagine of 68% [110] p-hydroxy phenylglycine solid membrane of sodium alginate and hydroxypropylβ-cyclodextrin aqueous solution of 10 mL of racemate used as the feed solution enantiomeric excess of up to 89.1%; the membrane may be used for nanofiltration or dialysis (i.e., applied pressure up to 0.5 MPa may be applied) [117] D/L-tryptophan supported liquid membrane prepared from a 0.5-µm pore membrane (Millex; Millipore, Billerica, MA) and encapsulated surfactant-enzyme complex works as a chiral selector feed phase consisted of 40 vol % ethanol, 10 mM racemic amino acid and 60 vol % McIlvaine buffer (pH 6.3) at 37°C enantiomeric excess reached after 24 h operation was 81% of L-isomer [113] D/L-tryptophan crosslinked sodium alginate and chitosan aqueous racemic solutions of tryptophan (0.49 mmol/l) enantiomeric excess of over 98% [139] D/L-lysine supported liquid membrane prepared from a 0.5-µm pore membrane (Millex; Millipore, Billerica, MA) and encapsulated surfactant-enzyme complex works as a chiral selector feed phase consisted of 40 vol % ethanol, 10 mM racemic amino acid and 60 vol % McIlvaine buffer (pH = 6.3) at 37°C enantiomeric excess reached after 24 h operation of 74% L-isomer [113] (Continued) enantiomeric excess of 100% after 16 hours and 86.3% after 233 hours [145] where X D and X L are the molar fractions or molar amounts of D-and Lenantiomers in a stream, typically in the permeate. The optimal membrane shows both high permeability and selectivity.…”

Control of oxygen concentration in water using a hollow fiber membrane contactor

“…The membrane may be either porous or nonporous depending on the application. The membrane contactor has been applied for diverse separation purposes: adsorptive removal of copper ions [5], recovery of Sb(V) [6], purification of gelsolin from plasma [7], separation of the enantiomer with a porous membrane [8] and a hybrid absorber-heat exchanger [9], removal of dissolved O 2 with a nonporous membrane [10]. When a porous membrane is used as an interface, there are two operating modes: the non-wetted mode and the wetted mode.…”