화학공학소재연구정보센터
Desalination, Vol.467, 257-262, 2019
Desalination via chemical energy: An electrodialysis cell driven by spontaneous electrode reactions
The form of the energy input for widely investigated desalination technologies include thermal energy (distillation), mechanical work (reverse osmosis) or electrical energy (electrodialysis and capacitive deionization). We here propose and characterize an electrodialysis-type desalination cell which is driven instead by spontaneous redox reactions occurring at electrodes. Thus, this system utilizes solely a chemical energy input to perform desalination, and requires no electricity input, instead producing electricity while desalinating. With our custom-built prototype system based on high performance zinc-bromine chemistry, we demonstrate the desalination of feedwater with an initial salinity of similar to 30 g/L while simultaneously generating up to 23.5 kWh of electricity per m(3) of desalted water. Further, we show our prototype cell can recover up to 85% of the input chemical energy as electricity during operation without needing a recovery device. The net energy usage, defined as chemical energy input minus electricity output, was measured to be 3.9 kWh/m(3) when desalting to near-zero concentration at 2 mA/cm(2) with our first-generation cell. Our proposed concept decouples reactant production from its usage in the cell, and we show that this decoupling can potentially lead to net negative operating costs when low-cost reactants are employed.