Catalytic dissolution of metals from printed circuit boards using a calcium chloride–based deep eutectic solvent

Abstract

Due to their high metal content, printed circuit board (PCBs) are an attractive resource for metal recovery. Until now, the dissolution and subsequent recovery of metals from PCBs considers either...

Tailoring lixiviant properties to optimise selectivity in E-waste recycling

“…Etch rates of up to 27 μm h −1 and 73 μm h −1 were measured for copper etching at 25 and 50 °C respectively using 1 mol kg −1 Cu II in a calcium chloride ethylene glycol eutectic. 4 Similar etch rates were also determined for gold using iodine in the EG : ChCl system. 10 In the present study the effect of water in the EG : ChCl system was studied and found to have a significant impact on the etching rates of copper, nickel, silver and gold.…”

“…Each individual gold rectangle is 2.5 × 1 mm, and is composed of 47 μm copper, 7 μm nickel, and 0.75 μm gold. 4…”

“…One of these methods is via the electrochemical oxidation of metals using a redox catalyst that can be regenerated in situ , such as Cl − /Cl 2 , O 2 /H 2 O 2 , Cu 2+ , Fe 3+ , or iodine complexes. 4–6 Iodine is a powerful, yet moderately benign, oxidising agent that has been used for metal and mineral oxidation, in both aqueous 7–9 and IL/DES environments, 10–13 often with a focus on the precious metal (high value) components of the system. A key property of ILs and DESs is that oxide/hydroxide chemistry can be avoided, as the anionic components of the solvent will dominate the chemistry.…”

Anion effect on the redox properties of copper ions in ionic liquids and deep eutectic solvents

“…32 Recently, systems formed from calcium chloride hexahydrate and ethylene glycol have been investigated, and remarkably, were found to have similar physicochemical properties to a DES formed from choline chloride and ethylene glycol. 33,34 In each of the solvent compositions investigated, copper, cobalt, and iron chloride complexes were present, despite the significant proportion of water in these systems – ranging from 17.5 to 24 kg mol −1 . This behaviour was proposed to be due to the water and ethylene glycol molecules being tightly solvated to the calcium cation.…”

Extraterrestrial mining – A novel method for extracting minerals and metals from asteroids

“…The most commonly investigated systems have been quaternary ammonium salts with hydrogen bond donors (HBD) such as urea, ethylene glycol and glycerol 40 . The utilisation of inorganic chloride salts-based DESs have also been investigated [41][42][43][44] , which opens the opportunity to synthesise novel DESs by utilising in space materials. The presence of calcium, aluminium, iron, and zinc, for instance, have already been reported in regolith 4,25,45 , whereas the presence of halogen gas (chlorine, bromide) have been reported in the atmosphere of some planets like Mars and Venus 46 .…”