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Salt splitting amplifies the energy transition towards an increasingly green world.
Lithium-ion battery manufacturing
A wide variety of salts can be treated and electrochemically split into their corresponding acids and bases. A series of cations can be recollected as their hydroxide such as sodium, lithium, potassium, tetramethylammonium and ammonium. Regarding the anions, halogens, sulfate, carbonate, nitrate, acetate, and phosphate can be fed through the electrochemical system and transformed into their corresponding acids.
One important application of electrochemical salt splitting is the splitting of lithium sulfate (Li2SO4) which involves the separation of lithium (Li+) and sulfate (SO42-) ions from the salt. This process can be valuable in industries like lithium-ion battery re-processing, where the lithium-ion is a crucial component for battery production and salt splitting can offer a way of recovering the lithium ions without needing to extract and isolate new ones from geological sediments.
Pulp and paper industry
Similarly, sodium sulfate produced in the Kraft pulping process can be recovered in the pulp and paper industry. This chemical is a byproduct of separation of cellulose fibers from wood by dissolving lignin and other impurities.
Sodium sulfate can be recovered from wastewater by applying the salt splitting technique, eliminating the need to dispose of large quantities of brine and allowing the recovery of caustic soda and sulphuric acid that can be re-used in the process.
Sodium hydroxide
Another interesting application of electrochemical salt splitting is the recovery of caustic soda or sodium hydroxide (NaOH).
The traditional way of producing caustic soda is by the electrolysis of brine. The side product of this chemical process is chlorine gas produced at the anode in stoichiometric quantities with respect to the sodium hydroxide. There is a growing awareness of the need for new processes to manufacture of high-purity sodium hydroxide that does not lead to the co-production of toxic chlorine gas. Therefore, the recovery of sodium ions from waste streams is economically and environmentally beneficial as it allows for reusing and recovering this valuable chemical.