Dimethyl Removal From Wastewater

Dimethyl carbonate (DMC) in batteries is often used as it has some differences when compared with other solvents:

• Due to its good solvation and low viscosity, it can operate in a wider temperature range: -20 to 55 ºC. This is especially useful for battery electric vehicles (BEVs) as many are considerably less efficient in cold weather.
• It is not as toxic as other solvents and is biodegradable. However, in a spent lithium-ion batteries (LIBs) it can react with air and water, potentially causing pollution and health risks. Thus, any battery containing DMC should be recycled promptly.

Other dimethyl carbonate uses include the manufacturing of polycarbonates, lubricants, polyurethanes, cleaning and degreasing solvents, paints, adhesives, fuel additives, and in biodiesel.

DMC is partially soluble in water up to 13%, and it is hydrolysed in water-based systems over time to methanol and CO2 unless properly buffered.

The implication is that although DMC is classed as biodegradable and a ‘green reagent’, it is still a solvent and will contribute to water pollution.

When LIBs are recycled, plastic, copper and aluminium are first mechanically separated. What is eventually left is a powder – black mass – an amalgam of the chemicals in the electrolyte.

The valuable cobalt, nickel and lithium is reclaimed by hydrometallurgy. But the solvents remain in the water used in that process. This water is then too polluted to be discharged and must be treated or incinerated.

Electrolyte solvents for lithium-ion batteries can be successfully removed from wastewater – literally down to trace levels – with the Nyex Ellenox™ system.

Ellenox reactors can be scaled up or down to react to demand and are almost instantly available, so suitable for small batch processes. There is no toxic sludge produced and our reactors have no moving parts, thus reducing maintenance and staff training.

Pollutants are reduced to water and gas, making our systems the most environmentally conscious systems around.

If you would like to read more about Nyex Ellenox water treatment technology:

Dimethyl carbonate (DMC) is one of the electrolyte solvents used in modern lithium-ion batteries. These are found in everything from cell phones to electric vehicles.

Lithium battery recycling is important as valuable cobalt, nickel and lithium are recovered. Wastewater from the process contains a combination of electrolyte solvents including DMC.

Where plants are sited in areas of water scarcity, many recycling facilities will be aiming for zero liquid discharge.

Thus before re-use or discharge, it’s essential to remove down to trace levels all solvents from waste and wash-water.

For more information or to schedule a no-obligation chat with one of our water specialists, contact us today.

Several types of solvent are normally mixed together with the main metal salts to form an electrolyte for lithium-ion batteries.

Carbonates, including DMC, have several advantages when used in LIBs. They form a solid electrolyte interphase on the anode which is ionically conducting. This allows passage of Li ions whilst preventing electrons in the anode from further decomposing the electrolyte – leading to a longer life.

The proportions of each solvent are proprietary to each manufacturer and depend on the anode and cathode designs and the application, as well as the properties required for the individual battery. These could be re-charge speed/amperage, operating temperature window, longevity and power delivery.