The Principle of Electrodialysis

The principle of electrodialysis is illustrated in Figure 1. A typical electrodialysis cell arrangement consists of a series of anion and cation exchange membranes arranged in an alternating pattern between an anode and a cathode to form individual cells. If an electrolyte solution is passed through these cells and an electrical potential is established between the electrodes, the positively charged cations migrate towards the cathode and the negatively charged anions towards the anode. The positively charged cations can easily permeate the negatively charged cation exchange membrane but are retained by the positively charged anion exchange membrane. Likewise, negatively charged anions permeate the anion exchange membrane but are retained by the cation exchange membrane. The overall result is an increase in the ion concentration in alternate compartments, while the other compartments simultaneously become depleted. The depleted solution is referred to as diluate and the concentrated solution as brine or concentrate. The driving force for the ion transport in the electrodialysis process is the applied electrical potential. The total space occupied by the diluate and the concentrated solutions and the contiguous anion and cation exchange membranes make up a cell pair. The cell pair is the repeating unit in an electrodialysis stack.

Solar Panel Basics

Solar Panel Basics

Global warming is a huge problem which will significantly affect every country in the world. Many people all over the world are trying to do whatever they can to help combat the effects of global warming. One of the ways that people can fight global warming is to reduce their dependence on non-renewable energy sources like oil and petroleum based products.

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