Capacitive/pseudocapacitive water cleaning

Sammanfattning

Water scarcity is a growing problem worldwide. In order to ensure global access to freshwater, desalination technologies need to be made more energy efficient. Capacitive deionization (CDI) is a developing technology offering lower energy consumption than many traditional methods. By applying a voltage over a set of porous electrodes typically made of carbon, ions are removed from the feed water. To improve performance, new electrode materials are investigated. In this report, we examine the effect of coating activated carbon cloth (ACC) electrodes with a pseudocapacitive material known as high entropy Prussian blue analogue (HEPBA). The electrodes are operated using constant voltage control at 1 V, and the water is treated in single-pass mode. Different metrics such as salt adsorption capacity, charge efficiency and energy consumption were evaluated using water with different concentrations of NaCl. The HEPBA coating improved charge- and energy efficiency at concentrations of 500 ppm and 1000 ppm, but was found to lower performance at 200 ppm. The coating was also tested on industrial wastewater and was found to significantly reduce the effect of co-ion expulsion, which is an effect limiting the performance of carbon-based electrodes.