Design and Implementation of an Electrical Characterization System for Membrane Capacitive Deionization Units for the Water Treatment

The desalination of seawater is one of the most established techniques in the world. In the middle of the 20th century this was achieved using water evaporation systems, later with reverse osmosis membranes and nowadays with the possibility of capacitive deionization membranes. Capacitive deionization and membrane capacitive deionization are an emerging technology that make it possible to obtain drinking water with an efficiency of 95%. This technology is in the development stage and consists of porous activated carbon electrodes, which have great potential for saving energy in the water desalination process and can be used for desalination using an innovative technology called capacitive deionization (CDI), or membrane capacitive deionization (MCDI) if an anion and cation membrane exchange is used. In this paper is proposed and designed a characterization system prototype for CDI and MCDI that can operate with constant current charging and discharging (galvanostatic method). Adequate precision has been achieved, as can be seen in the results obtained. These results were obtained from the performance of typical characterization tests with electrochemical double layer capacitors (EDLC), since they are electrochemical devices that behave similarly to MCDI, from the point of view of the electrical variables of the processes that take place in MCDI. A philosophy of using free software with open-source code has been followed, with software such as the Arduino and Processing programming editors (IDE), as well as the Arduino Nano board (ATmega328), the analogical-digital converter (ADC1115) and the digital-analogical converter (MCP4725). Moreover, a low-cost system has been developed. A robust and versatile system has been designed for water treatment, and a flexible system has been obtained for the specifications established, as it is shown in the results section.