The use of ionic liquids based on choline chloride for metal deposition: A green alternative?

• Published in: Journal of environmental management Vol. 90; no. 11; pp. 3245 - 3252
• Main Authors: Haerens, Kurt, Matthijs, Edward, Chmielarz, Andrzej, Van der Bruggen, Bart
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 01-08-2009; Elsevier; Academic Press Ltd
• Subjects: Animal, plant and microbial ecology; Antifreeze solutions; Applied ecology; Biological and medical sciences; Byproducts; Chlorides; Choline; Choline - chemistry; Choline chloride; Conservation, protection and management of environment and wildlife; Deep eutectic solvent; Deposition; Drag-out; Electrochemistry - methods; Electrode reactions; Environmental impact; Environmental management; Fundamental and applied biological sciences. Psychology; General aspects; Green solvents; Ion exchange; Ionic liquids; Ionic Liquids - chemistry; Ions; Liquids; Metal deposition; Metals - chemistry; Solvents; Toxicity; Choline chloride; Metal deposition; Deep eutectic solvent; Electrode reactions; Green solvents; Ionic liquids; Drag-out; Ion exchange; Metal; Environmental management; Depth; Chlorides; Solvent
• ISSN: 0301-4797; 1095-8630
• DOI: 10.1016/j.jenvman.2009.04.013

Ionic liquids are studied intensively for different applications. They tend to be denoted as “green solvents”, largely because of their low vapour pressure. In recent years toxicity and biotoxicity of ionic liquids have also been investigated, which proved that not all of these are “green”. In this paper the use of ionic liquids based on choline chloride and ethylene glycol in electrochemistry is discussed in the context of their use as green solvents. Due to their low toxicity and ready biodegradability, these deep eutectic solvents are promising for the electrodeposition of metals. The influence of the use of these liquids as metal deposition baths on the waste water is investigated. Drag-out was found to be the most influencing parameter on the environmental impact of the process, as it is three times higher compared to classical solutions due to the higher viscosity of the ionic liquid. There are no major changes needed in the rinsing configuration of classic electroplating plants, and ion exchange to remove the metal out of the waste water was not hindered by the presence of the ionic liquid. The formation of by-products during the deposition of metals has to be further investigated and evaluated in consideration of the environmental impact.