US 10,888,820 B2
Osmotic membrane
Prakash Narayan Govindan, Melrose, MA (US); and Looh Tchuin Choong, Somerville, MA (US)
Assigned to Gradiant Corporation, Woburn, MA (US)
Filed by Gradiant Corporation, Woburn, MA (US)
Filed on Oct. 18, 2017, as Appl. No. 15/786,973.
Claims priority of provisional application 62/410,170, filed on Oct. 19, 2016.
Prior Publication US 2018/0104649 A1, Apr. 19, 2018
Int. Cl. B01D 61/02 (2006.01); B01D 61/14 (2006.01); B01D 71/56 (2006.01); B01D 71/64 (2006.01); C02F 1/44 (2006.01); B01D 69/02 (2006.01); B01D 69/12 (2006.01); B01D 69/10 (2006.01); B01D 71/68 (2006.01)
CPC B01D 61/025 (2013.01) [B01D 61/022 (2013.01); B01D 61/14 (2013.01); B01D 69/02 (2013.01); B01D 69/10 (2013.01); B01D 69/12 (2013.01); B01D 71/56 (2013.01); B01D 71/64 (2013.01); B01D 71/68 (2013.01); C02F 1/441 (2013.01); C02F 1/444 (2013.01); B01D 2311/25 (2013.01); B01D 2323/24 (2013.01); B01D 2323/39 (2013.01); B01D 2325/04 (2013.01)] 25 Claims
OG exemplary drawing
 
20. A method for performing reverse osmosis, comprising:
utilizing a reverse osmosis membrane, comprising:
a) an active layer that selectively allows passage of water molecules but rejects at least some dissolved ion;
b) a composite support layer including a bonded side that is bonded to the active layer and a draw side opposite from the bonded side, wherein the composite support layer comprises:
i) an electrospun-fiber sub-layer; and
ii) a phase-inversion sub-layer, wherein the phase-inversion sub-layer is bonded to the active layer, and wherein the electrospun-fiber sub-layer has a substantially lower structural parameter, S, than a structural parameter, S, of the phase-inversion sub-layer, and wherein the structural parameter, S, is defined as follows:

OG Complex Work Unit Drawing
wherein t represents layer thickness, τ represents layer tortuosity, and ε represents layer porosity;
flowing a feed liquid comprising water and dissolved ions at a first pressure across a feed side of the active layer opposite from the side of the active layer that is bonded to the composite support layer;
flowing a draw liquid at a second pressure that is lower than the first pressure along a draw side of the composite support layer opposite from the bonded side of the composite support layer; and
using the active layer to retain at least some of the dissolved ions from the feed liquid, as retentate while passing purified water as permeate through the active layer and through the composite support layer into the draw liquid.