Photovoltaic solar electrodialysis with bipolar membranes

Abstract

Electrochemical process like Electrodialysis (ED) and Electrodialysis with Bipolar Membranes (EDBM) can contribute to the production of freshwater and to the valorization of waste streams. In particular, EDBM can valorise the waste from desalination technologies using electric power, producing acids (HCl) and basis (NaOH) from seawater rejected brines. The use of a variable current intensity coming from a low-carbon source such as photovoltaic (PV) solar energy means a decrease of the associated carbon footprint of the obtained products. In this work, the reduction of the specific energy consumption (SEC) of the acid from an EDBM process thanks to a feedback control loop under variable current intensity is presented. The EDBM process works in continuous or semi-continuous mode under constant or variable current intensity by means of a PV solar array simulator for 30 h. A concentration around 1 mol·L−1 HCl has been obtained in all experiments even under variable current intensity. A noticeable drop in the SEC from a reference value of 7.3 kWh·kg−1 HCl (constant current intensity) to 4.4 kWh·kg−1 HCl (variable current intensity and feedback control loop) was reported.