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Leaching of metals from printed circuit boards using ionic liquids


The rise in the electronics industry has impacted the environment through the large volumes of waste that are improperly disposed of and the growing demand for precious and rare metals from natural sources. Leaching of copper, cobalt, gold, and silver from printed circuit boards of waste cellular phone has been carried out using imidazolium cation-based ionic liquids (ILs). For the studied metals, the obtaining of selective leaching obtained is reported for the first time, where acidic ionic liquids ([Bmim]HSO4 and [Hmim]HSO4) leached copper and cobalt, while basic ionic liquids ([Bmim]Cl and [Bmim]Br) extracted gold and silver. The effect of temperature has been studied by testing at 60 and 80 °C, where the highest extraction was obtained at the lowest temperature. The concentration of the ionic liquid was also studied through a test without ionic liquid and then varying from 20 to 60%, where at higher concentration the extraction is more efficient ratifying the use of ionic liquids as leaching solutions for metals. Ionic liquids have demonstrated the ability to leach metal ions as the primary reagent in the leaching solution. The following extraction percentages were obtained for each metal: 86.2% copper, 99.5% cobalt, 40.8% gold, and 44.6% silver.

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The authors would like to thank the company Antofagasta SCM for the donation of the printed circuit boards, the Atacama Desert pilot plant center for carrying out the reduction of the solid material, the mining engineering department of the University of Antofagasta, especially Professor Julia Vega, to Liey-Si Wong for the assistance provided for the realization of petrographic microscopy and the organic chemistry laboratory of the University of Antofagasta, particularly Dr. Jorge Borquez. Y. Barrueto thanks the Pontifical Catholic University of Valparaiso for the collaborative work and stay, professors Carlos Carlesi, Pedro Robles, and Álvaro Aracena for their advice. This work was funded by the National Agency for Research and Development (ANID)/National doctorate scholarship and Comisión Nacional de Investigación Científica y Tecnológica (DOCTORADO BECAS CHILE/2018-21180020) and Doctorado en Ingeniería en procesos de minerales de la Universidad de Antofagasta.

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Correspondence to Yahaira Barrueto or Yecid Jiménez.

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Barrueto, Y., Hernández, P., Jiménez, Y. et al. Leaching of metals from printed circuit boards using ionic liquids. J Mater Cycles Waste Manag 23, 2028–2036 (2021).

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  • e-waste
  • Ionic liquids
  • Printed circuit boards
  • Leaching