Extracting minerals from desalination brine using innovative capacitive photo electrocatalytic desalination cells (cPEDC)

Abstract

Limited freshwater supplies and increasing water demand prompt us to seek new advanced wastewater treatment and desalination technologies. Brine production and demanding energy limit the use of current desalination methods. However, this brine contains minerals that are valuable for extraction.In this study, a novel system, the capacitive photo electrocatalytic desalination cell (cPEDC), consists of a capacitive deionization (CDI) and a five-chamber photo electrocatalytic desalination cell, was designed and utilized for the first time. The cPEDC’ performance was evaluated based on TDS removal rate, magnesium, calcium, alkaline recovery from brine, membrane scaling reduction, and phenol removal from industrial saline wastewater.The results show a removal rate of 54.81 and 41.16% for magnesium and calcium from the brine. Recovering 76.8% of the removed magnesium as Mg(OH)2 precipitation was accomplished inside the chemical production chamber (CPC). In addition, 64.82% of the removed Ca was extracted via the desorption step of the CDI module. Meanwhile, the cPEDC can produce 31.45 mV power alongside achieving TDS and phenol removal efficiency and desalination rate (DR) of 50.77%, 58.78%, and 927.5 mg/h after 20 h, respectively.The cPEDC can be considered a “green” technology to desalinate brine, treat wastewater, produce power and extract minerals.

Keywords

• Photo electrocatalytic desalination cell (PEDC)
• Capacitive deionization (CDI)
• Mineral extraction
• Brine treatment