Abstract
The recovery of valuable metals from waste printed circuit boards (WPCBs) is crucial in order to harness their economic resources, and prevents potential environmental contamination. However, selective extraction of Cu and Zn, and the co-extraction of other metals as impurities at ambient temperature using selected lixiviants such as HCl, H2SO4, HNO3, trifluoromethanesulfonic acid (TFMS), NaOH, and mixtures of NaCl and CuCl2 was studied. It is shown that the extraction efficiencies of all the metals increased with increases in lixiviant concentrations. High selectivity of Cu and Zn toward Fe were achieved in dilute H2SO4, HNO3, TFMS, and 0.5 M NaCl + 0.1 M CuCl2, and low dissolution of Pb (<5%) was observed in all H2SO4 lixiviants. Almost 100% Zn extraction using NaOH lixiviants without trace of other metals was achieved. Therefore, 0.5 M NaCl + 0.5 M CuCl2, 1.0 M HNO3, 0.5 M H2SO4, and 1.0 M TFMS showed high extraction selectivity toward Cu and Zn with low chemical consumption, and produced pregnant leach solution rich in Cu and Zn, as well as residue containing Fe, Ni, and other metals.
Highlights
One type of waste with great environmental concern and economic value is electronic waste [1]
Elemental analyses revealed that the sample mainly contained Cu (41.64%), Zn (1.79%), Ni (1.8%), Fe (11.12%), Pb (2.09%), Al (5.05%), and Sn (1.63%). These results reveal that Cu and Fe were the major metals in the waste printed circuit boards (WPCBs)
It is important to note that the extraction of powdered printed circuit boards (PCBs) sample by Hydrochloric Acid (HCl) lixiviant is not suitable for generating pregnant leach solution (PLS) that is rich in Cu and Zn since higher dissolution ofxother metals as impurities were observed
Summary
One type of waste with great environmental concern and economic value is electronic waste [1]. Various hydrometallurgical methods for the recovery of metals from printed circuit boards (PCBs) have been developed using leaching reagents such as acids, bases, and salts. The leaching of metals from the PCBs by acids produces pregnant leach solutions containing several metals, including iron, which have been identified as the major problem in the electro-winning or electrochemical deposition of metals. This study was carried out to investigate the selective extraction of Cu and Zn from waste printed circuit boards (WPCBs) using some selected lixiviants at ambient temperatures to produce pregnant leach solutions rich in Cu and Zn and residues rich in Fe and Ni, with other metals for further recovery.
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