Separation device and ion separation method

Abstract

The invention discloses an electrochemical separation device and a method for removing ions in liquid to be treated. The electrochemical separation device comprises at least two electrochemical separation units which are connected in series, and each electrochemical separation unit comprises one or at least two electrochemical separation groups which are connected in parallel. In the desalting process, in the liquid flow direction, the total number of desalting flow channels of one electrochemical separation unit is larger than the total number of desalting flow channels of one electrochemical separation unit located behind the electrochemical separation unit. The electrochemical separation group consists of a plurality of cation exchange membranes and anion exchange membranes which are alternately arranged. The electrochemical separation group can also be composed of at least one bipolar membrane. The electrochemical separation units with different flow channel numbers are arranged in the electrochemical separation device, so that the flow velocity of liquid in the flow channels is increased, the limiting current density of the electrochemical separation units is maintained or increased, the salt removal rate is improved, and the cost is reduced.

Description

technical field [0001] The invention relates to an electrochemical separation device and a method for removing ions in liquid to be treated by using the electrochemical separation device. Background technique [0002] Electrochemical processes such as electrodialysis (ED), frequent electrode reversal (EDR), packed electrodialysis (EDI), packed inverted electrodialysis (EDIR) and capacitive desalter (SCD) have been widely used in the desalination of solutions. Desalination and desalination treatment and other separation processes. [0003] In the electrochemical separation process, taking electrodialysis as an example, when the material, also called the liquid to be treated (such as aqueous solution, raw water or influent water) flows in the concentrated chamber and the dilute chamber, under the action of a DC electric field, the solute in the solution Oriented migration of ions occurs. There is a stagnant layer between the ion exchange membrane and the solution. When the w...

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Problems solved by technology

However, due to the limited working current, it is difficult for a single electrodialysis unit to obtain a high desalination rate. Therefore, the current electrodialysis process often uses a multi-stage membrane stack in series for desalination and desalination treatment. For example, in order to achieve a desalination rate of about 85% , it is often necessary to use three or more electrodialysis devices and systems in series with more than three membrane stacks

The use of multi-stage membrane stacks increases the cost of the electrochemical separation device, making the electrochemical separation method not cost-effective compared with the reverse osmosis membrane method

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