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Light emitting diode waste: Potential of metals concentration and acid reuse via the integration of leaching and membrane processes

2019; Elsevier BV; Volume: 246; Linguagem: Inglês

10.1016/j.jclepro.2019.119057

1879-1786

Raquel Annoni, Liséte Celina Lange, Míriam Cristina Santos Amaral, André Matsumura Silva, Mariana Coimbra Assunção, Mílton Batista Franco, Wagner de Souza,

Advancements in Battery Materials

Light emitting diode (LED) applications have been expanding throughout the world and during the next few years, the generation of LED-related waste is expected to grow considerably. Due to the increasing demand for strategic metals, it is evident that there is a need to find secondary sources of metals, particularly those used in more modern technological developments such as electronics. The aim of this study was to characterize this type of waste and to evaluate the recycling potential of the metals and of the acid using a conjugation of hydrometallurgical techniques and membrane separation processes. The concentrations of Ga, As, Au, and Cu present in red LED diodes were evaluated and 1.35 g/kg of Ga, 1.35 g/kg of As, 0.36 g/kg of Au and 290 g/kg of Cu were found. After leaching with nitric acid the leaching efficiencies reached 96.79% of Ga, 51.85% of As, 1.30% of Au, 93.33% of Cu and after a second leaching step with aqua regia solution the total leaching efficiencies reached 99.75% of Ga, 74.67% of As, 15.74% of Au and 98.85% of Cu. Concentration assays using nanofiltration applied to synthetic solutions indicated Ga rejections of 93.45% (pH −0.18) and of 98.39% (for all pH values tested from 2.0 to 4.0). During the experiment with LED leachate, the rejection values observed during the nanofiltration step were 85.00% of Ga, 74.14% of Cu, and 52.67% of As. HNO3 was successfully recycled from UF/NF permeate by using RO. These results indicate the potential for scarce metal retrieval from secondary resources.