Lithium capture in seawater reverse osmosis (SWRO) brine using membrane-based capacitive deionization (MCDI) system

Abstract

Lithium-battery based industries including vehicles, electronics, fusion and thermonuclear, consume lithium rapidly, which raises the need for developing a lithium recovery system. Lithium global market consumption in 2016 was reported to be 35% in batteries manufacturing. The total content of lithium in seawater and oceans is estimated at 2.5 × 1014 kg, with an average concentration of 0.17 mg/L. Salt lakes contain 1,000–3,000 mg/L of lithium, while geothermal water up to 15 mg/L. In 2020, the US Geological Survey (USGS) reported that the total Li resource is about 80 million ton. In nature, lithium does not exist as pure metal owing to its high reactivity with water, air, and nitrogen. Commonly lithium is mined from metallic minerals from earth or brine salt marsh and used in various fields in the form of lithium carbonate (60%), lithium hydroxide (23%), lithium metal (5%), lithium chloride (3%), and butyl lithium (4%). The extraction of 1 kg of lithium needs around 5.3 kg of lithium carbonate. The amount required to produce lithium-ion batteries (LIB) for cell phones or electric cars is estimated to be 0.8 kg/s of lithium metal, which is equivalent to 25,000 tons per year. As we use this much of LIB, this will end up having significant amounts of lithium battery waste, thus recovering LIBS and using it as cathode electrode in MCDI is an excellent way with benefit. This work proposes to efficiently utilize seawater reverse osmosis (SWRO) brine as a medium to recover lithium from seawater followed by its selective capture of lithium element using SLIB as MCDI cathode electrode material. Thus, these attempts could be closer to an improved and more effective loop of lithium targeted capture-reuse system.