Abstract: A membrane stack comprising the following components: (a) a first ion diluting compartment (D1); (b) a second ion diluting compartment (D2); (c) a first ion concentrating compartment (C1); (d) a second ion concentrating compartment (C2); and (e) a membrane wall (CEM1, mAEM, mCEM, AEM, CEM2) between each compartment and on the outside of the first and last compartment of the stack; wherein: (i) each membrane wall comprises a cation exchange membrane (CEM1, mCEM, CEM2) or an anion exchange membrane (mAEM, AEM) and the order of the cation and anion exchange membranes alternates from each wall to the next; (ii) the membrane walls (mAEM, mCEM) on each side of compartment (a) both have a higher monovalent ion selectivity than the corresponding membrane walls (AEM, CEM2) on each side of compartment (b); and (iii) the stack further comprises a means for communicating fluid between compartments (a) and (b).

Abstract: A redox flow battery system (10) comprises an electrochemical cell (11) divided into first and second compartments (11a, 11b) by a porous membrane (13). Each of the first and second compartment (11a, 11b) houses an electrode. An electrolyte storage tank (14) has a first volume (14a) and a second volume (14b) separated from the first volume by a movable separator (15). The first volume (14a) of the storage tank (14) is in fluid communication with the first compartment (11a) and the second volume (14b) of the storage tank (14) is in fluid communication with the second compartment (11b). The system (10) also includes a flow control system configured to move fluid between the first volume (14a) of the storage tank and the second volume (14b) of the storage tank through the first and second compartments (11a, 11b) of the electrochemical cell (11). An associated method is also described.

Abstract: A composite ion exchange membrane obtainable by a process comprising reacting an ionically-charged membrane with a composition comprising: (a) a monofunctional ethylenically unsaturated monomer having an ionic charge opposite to the charge of the ionically-charged membrane; and (b) a crosslinking agent comprising two or more ethylenically unsaturated groups; wherein the molar ratio of (b):(a) is lower than 0.04 or is zero.

Abstract: A composite ion exchange membrane comprising a cationically-charged membrane and an oppositely charged compound covalently bound thereto, the composite ion exchange membrane having: (i) a zeta-potential lower than ?8 mV; and (ii) an effective charge lower than 20 ?mol/m2.

Abstract: A membrane obtainable from curing a composition comprising: (i) a curable compound comprising at least two (meth)acrylic groups and a sulphonic acid group and having a molecular weight which satisfies the equation: MW<(300+300n) wherein: MW is the molecular weight of the said curable compound; and n has a value of 1, 2, 3 or 4 and is the number of sulphonic acid groups present in the said curable compound; and optionally (ii) a curable compound having one ethylenically unsaturated group; wherein the molar fraction of curable compounds comprising at least two (meth)acrylic groups, relative to the total number of moles of curable compounds present in the composition, is at least 0.25.

Abstract: A membrane stack comprising the following components: (a) a first ion diluting compartment (D1); (b) a second ion diluting compartment (D2); (c) a first ion concentrating compartment (C1); (d) a second ion concentrating compartment (C2); and (e) a membrane wall (CEM1, mAEM, mCEM, AEM, CEM2) between each compartment and on the outside of the first and last compartment of the stack; wherein: (i) each membrane wall comprises a cation exchange membrane (CEM1, mCEM, CEM2) or an anion exchange membrane (mAEM, AEM) and the order of the cation and anion exchange membranes alternates from each wall to the next; (ii) the membrane walls (mAEM, mCEM) on each side of compartment (a) both have a higher monovalent ion selectivity than the corresponding membrane walls (AEM, CEM2) on each side of compartment (b); and (iii) the stack further comprises a means for communicating fluid between compartments (a) and (b).

Abstract: A composite ion exchange membrane obtainable by a process comprising reacting an ionically-charged membrane with a composition comprising: (a) a monofunctional ethylenically unsaturated monomer having an ionic charge opposite to the charge of the ionically-charged membrane; and (b) a crosslinking agent comprising two or more ethylenically unsaturated groups; wherein the molar ratio of (b):(a) is lower than 0.04 or is zero.

Abstract: A composite ion exchange membrane comprising a cationically-charged membrane and an oppositely charged compound covalently bound thereto, the composite ion exchange membrane having: (i) a zeta-potential lower than ?8 mV; and (ii) an effective charge lower than 20 ?mol/m2.

Abstract: A membrane obtainable from curing a composition comprising: (i) a curable compound comprising at least two (meth)acrylic groups and a sulphonic acid group and having a molecular weight which satisfies the equation: MW<(300+300n) wherein: MW is the molecular weight of the said curable compound; and n has a value of 1, 2, 3 or 4 and is the number of sulphonic acid groups present in the said curable compound; and optionally (ii) a curable compound having one ethylenically unsaturated group; wherein the molar fraction of curable compounds comprising at least two (meth)acrylic groups, relative to the total number of moles of curable compounds present in the composition, is at least 0.25.

Abstract: A membrane obtainable from curing a composition comprising: (i) a curable compound comprising at least two (meth)acrylic groups and a sulphonic acid group and having a molecular weight which satisfies the equation: MW<(300+300n) wherein: MW is the molecular weight of the said curable compound; and n has a value of 1, 2, 3 or 4 and is the number of sulphonic acid groups present in the said curable compound; and optionally (ii) a curable compound having one ethylenically unsaturated group; wherein the molar fraction of curable compounds comprising at least two (meth)acrylic groups, relative to the total number of moles of curable compounds present in the composition, is at least 0.25.

Abstract: A device selected from the group consisting of an electrodialysis or reverse electrodialysis unit, an electrodeionization module and a flow through capacitor, the device comprising a membrane obtained from a process comprising the following steps: applying a curable composition to a support; and curing the composition to form a membrane; wherein the curable composition comprises: (i) 2.5 to 50 wt % crosslinker comprising at least two acrylamide groups; (ii) 12 to 65 wt % curable ionic compound comprising an ethylenically unsaturated group and a cationic group; (iii) 10 to 70 wt % solvent; (iv) 0 to 10 wt % of free radical initiator; and (v) non-curable salt comprising a cation and an anion, wherein the anion is not sulfate; wherein the molar ratio of (i):ii) is greater than 0.10 and less than 5.

Abstract: A process for preparing a membrane comprising applying a curable composition to a porous support and curing the composition, wherein the composition comprises: a) a curable ionic compound; b) a first crosslinking agent; c) a second crosslinking agent; d) an inert solvent; and e) optionally a free radical initiator; wherein the second crosslinking agent has a melting point below 80° C. Also claimed are the compositions and membranes obtainable by using the process.

Abstract: A curable composition comprising: (i) 2.5 to 50 wt % crosslinker comprising at least two acrylamide groups; (ii) 20 to 65 wt % curable ionic compound comprising an ethylenically unsaturated group and an anionic group; (iii) 15 to 45 wt % solvent; and (iv) 0 to 10 wt % of free radical initiator; wherein the molar ratio of (i):(ii) is 0.1 to 1.5. The compositions are useful for preparing ion exchange membranes.

Abstract: A curable composition comprising: (i) 2.5 to 50 wt % crosslinker comprising at least two acrylamide groups; (ii) 12 to 65 wt % curable ionic compound comprising an ethylenically unsaturated group and a cationic group; (iii) 10 to 70 wt % solvent; and (iv) 0 to 10 wt % of free radical initiator; and (v) non-curable salt; wherein the molar ratio of (i):(ii) is >0.10. The compositions are useful for preparing ion exchange membranes.

Abstract: A curable composition comprising: (i) 2.5 to 50 wt % crosslinker comprising at least two acrylamide groups; (ii) 20 to 65 wt % curable ionic compound comprising an ethylenically unsaturated group and an anionic group; (iii) 15 to 45 wt % solvent; and (iv) 0 to 10 wt % of free radical initiator; wherein the molar ratio of (i):(ii) is 0.1 to 1.5. The compositions are useful for preparing ion exchange membranes.

Abstract: A membrane obtainable from curing a composition comprising (i) a curable compound comprising at least two acrylic groups and a quaternary ammonium group; (ii) solvent; and optionally (iii) a curable compound having one ethylenically unsaturated group.

Abstract: A curable composition comprising: (i) 2.5 to 50 wt % crosslinker comprising at least two acrylamide groups; (ii) 12 to 65 wt % curable ionic compound comprising an ethylenically unsaturated group and a cationic group; (iii) 10 to 70 wt % solvent; and (iv) 0 to 10 wt % of free radical initiator; and (v) non-curable salt; wherein the molar ratio of (i):(ii) is >0.10. The compositions are useful for preparing ion exchange membranes.

Abstract: A curable composition comprising: (i) 2.5 to 50 wt % crosslinker comprising at least two acrylamide groups; (ii) 20 to 65 wt % curable ionic compound comprising an ethylenically unsaturated group and an anionic group; (iii) 15 to 45 wt % solvent; and (iv) 0 to 10 wt % of free radical initiator; wherein the molar ratio of (i):(ii) is 0.1 to 1.5. The compositions are useful for preparing ion exchange membranes.

Abstract: A membrane obtainable from curing a composition comprising: (i) a curable compound comprising at least two (meth)acrylic groups and a sulphonic acid group and having a molecular weight which satisfies the equation: MW<(300+300n) wherein: MW is the molecular weight of the said curable compound; and n has a value of 1, 2, 3 or 4 and is the number of sulphonic acid groups present in the said curable compound; and optionally (ii) a curable compound having one ethylenically unsaturated group; wherein the molar fraction of curable compounds comprising at least two (meth)acrylic groups, relative to the total number of moles of curable compounds present in the composition, is at least 0.25.

Abstract: A curable composition comprising: (i) 2.5 to 50 wt % crosslinker comprising at least two acrylamide groups; (ii) 20 to 65 wt % curable ionic compound comprising an ethylenically unsaturated group and an anionic group; (iii) 15 to 45 wt % solvent; and (iv) 0 to 10 wt % of free radical initiator; wherein the molar ratio of (i):(ii) is 0.1 to 1.5. The compositions are useful for preparing ion exchange membranes.