Purification of ultra-high saline and contaminated water by multi-stage ion concentration polarization (ICP) desalination
A water stream is passed between two juxtaposed similar ion exchange membranes (AEMs or CEMs), forming an ion depletion and ion enrichment zones when an electric field is applied. As cations are selectively transferred through the CEMs, for example, anions are relocated in order to achieve electro-neutrality, resulting in the concentration drop (increase) in ion depletion (enrichment) zone. Trifurcation of the output channel allows collection of concentrated, dilute and intermediate streams, with the intermediate stream serving as input to the next stage of a serialized implementation.
1. A method of purifying and/or concentrating a first water stream containing ionic impurities comprising the steps:
a. directing the water stream in a channel comprising an inlet and an outlet and defined, at least in part by at least a first ion exchange membrane and at least a second ion exchange membrane, wherein the ion exchange membranes are juxtaposed and characterized by a functional group having the same polarity;
b. applying an electric field across the channel causing formation of an ion depletion zone comprising a purified water stream, formation of an ion enrichment zone comprising a concentrated ion aqueous stream and formation of a neutral concentration zone comprising an intermediate stream, wherein the electric field is created by an electrode and a ground each located external and parallel to the channel and the electrode forms a second channel with the at least a first ion exchange membrane and the ground forms a third channel with the at least a second ion exchange membrane;
c. trifurcating the channel in relation to the ion depletion zone, the ion enrichment zone and the neutral concentration zone of step b to cause separation of the purified water stream, the intermediate stream and the concentrated ion aqueous stream;
d. collecting any portion of the purified water stream and/or the intermediate stream and/or the concentrated ion aqueous stream; and
wherein the concentration of ionic impurities in the collected intermediate stream is greater than that found in the collected purified water stream and less than that found in the collected concentrated ion aqueous stream, and the concentration of ionic impurities in the collected intermediate stream is substantially the same as the first water stream.
2. The method of claim 1 , wherein the at least a first and at least a second juxtaposed ion exchange membrane are cationic exchange membranes.
3. The method of claim 1 , wherein the at least a first and at least a second juxtaposed ion exchange membrane are anionic exchange membranes.
4. The method of claim 1 , wherein the second and third channel are filled with an electrolyte solution.
5. The method of claim 4 , wherein the electrolyte solution is the first water stream.
6. The method of claim 1 , wherein the first water stream comprises salt.
7. The method of claim 1 , wherein the first water stream comprises biomolecules.
8. The method of claim 1 , wherein steps a through d are repeated and wherein the intermediate stream collected in step d acts as the first water stream in subsequent repetitions of the method.
9. The method of claim 7 , wherein the electrical field of step b is common to at least one repetition of the method.
10. The method of claim 1 , wherein steps a through d are repeated and wherein the intermediate stream collected in step d acts as the first water stream in a subsequent repetition of the method in a serially arranged, stacked channel.
11. The method of claim 10 , wherein the electrical field of step b is common to each serially arranged channel and wherein the electric field is created by an electrode and a ground each located external and parallel to each stacked channel.