scholarly journals Bioleaching of E-Waste: Influence of Printed Circuit Boards on the Activity of Acidophilic Iron-Oxidizing Bacteria

2021 ◽  
Vol 12 ◽  
Author(s):  
Juan Anaya-Garzon ◽  
Agathe Hubau ◽  
Catherine Joulian ◽  
Anne-Gwénaëlle Guezennec
Keyword(s):  
Microbial Activity ◽  
Printed Circuit Boards ◽  
Iron Oxidation ◽  
Circuit Boards ◽  
Printed Circuit ◽  
Inhibiting Effect ◽  
Promising Strategy ◽  
Iron Oxidizing Bacteria ◽  
Valuable Metals ◽  
Enriched Environments

Bioleaching is a promising strategy to recover valuable metals from spent printed circuit boards (PCBs). The performance of the process is catalyzed by microorganisms, which the toxic effect of PCBs can inhibit. This study aimed to investigate the capacity of an acidophilic iron-oxidizing culture, mainly composed of Leptospirillum ferriphilum, to oxidize iron in PCB-enriched environments. The culture pre-adapted to 1% (w/v) PCB content successfully thrived in leachates with the equivalent of 6% of PCBs, containing 8.5 g L–1 Cu, 8 g L–1 Fe, 1 g L–1 Zn, 92 mg L–1 Ni, 12.6 mg L–1 Pb, and 4.4 mg L–1 Co, among other metals. However, the inhibiting effect of PCBs limited the microbial activity by delaying the onset of the exponential iron oxidation. Successive subcultures boosted the activity of the culture by reducing this delay by up to 2.6 times under batch conditions. Subcultures also favored the rapid establishment of high microbial activity in continuous mode.

scholarly journals Characteristics of Metals Leached from Waste Printed Circuit Boards Using Acidithiobacillus ferrooxidans

Minerals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 224
Author(s):  
Jinsung An
Keyword(s):  
Acidithiobacillus Ferrooxidans ◽  
Printed Circuit Boards ◽  
Cost Effective ◽  
Low Grade ◽  
Circuit Boards ◽  
Printed Circuit ◽  
Waste Printed Circuit Boards ◽  
Iron Oxidizing Bacteria ◽  
Valuable Metals ◽  
Leaching Characteristics

The aim of this study was to compare leaching characteristics of metals from printed circuit boards (PCBs), taken from waste electrical and electronic equipment in the presence and in the absence of the iron-oxidizing bacteria, Acidithiobacillus ferrooxidans. A. ferrooxidans not only increases the leached concentration of Cu from the PCBs, but also inhibits the components of the 0K medium and leached Cu from forming precipitates such as libethenite (Cu2(PO4)(OH)), thereby assisting Cu recovery from the PCBs. In addition, the leached concentration of Pb from PCBs decreased in the presence of A. ferrooxidans, due to Pb forming amorphous precipitates. It is expected that Pb is not highly toxic to A. ferrooxidans. Consequently, A. ferrooxidans can be used as a cost-effective and environmentally friendly way to leach out valuable metals from PCBs as low-grade urban ore.

Supercritical CO2-induced alteration of a polymer–metal matrix and selective extraction of valuable metals from waste printed circuit boards

2020 ◽  
Vol 22 (20) ◽  
pp. 7080-7092
Author(s):  
Peng Peng ◽  
Ah-Hyung Alissa Park
Keyword(s):  
Metal Matrix ◽  
Supercritical Co2 ◽  
Printed Circuit Boards ◽  
Selective Extraction ◽  
Circuit Boards ◽  
Printed Circuit ◽  
Waste Printed Circuit Boards ◽  
Valuable Metals ◽  
Polymer Metal

Supercritical CO2-induced treatment of heterogeneous waste printed circuit boards resulted in selective recoveries of Au, Ni and Cu.

scholarly journals Extraction of Copper and Zinc from Waste Printed Circuit Boards

Recycling ◽  
2019 ◽  
Vol 4 (3) ◽  
pp. 36 ◽  
Author(s):  
Ayorinde Emmanuel Ajiboye ◽  
Folorunsho Emmanuel Olasehinde ◽  
Ojo Albert Adebayo ◽  
Olubode John Ajayi ◽  
Malay Kumar Ghosh ◽  
...  
Keyword(s):  
Printed Circuit Boards ◽  
Selective Extraction ◽  
Leach Solution ◽  
Economic Resources ◽  
Circuit Boards ◽  
Printed Circuit ◽  
Waste Printed Circuit Boards ◽  
Valuable Metals ◽  
Extraction Selectivity ◽  
Cu And Zn

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.

scholarly journals Hydrometallurgical Treatment of Waste Printed Circuit Boards: Bromine Leaching

Metals ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 462 ◽  
Author(s):  
Hao Cui ◽  
Corby Anderson
Keyword(s):  
Printed Circuit Boards ◽  
Sodium Concentration ◽  
Circuit Boards ◽  
Printed Circuit ◽  
Waste Printed Circuit Boards ◽  
Inorganic Acids ◽  
Valuable Metals ◽  
Bromine Concentration ◽  
Hydrometallurgical Treatment ◽  
Solid Liquid

This paper demonstrates the recovery of valuable metals from shredded Waste Printed Circuit Boards (WPCBs) by bromine leaching. Effects of sodium bromide concentration, bromine concentration, leaching time and inorganic acids were investigated. The most critical factors are sodium concentration and bromine concentration. It was found that more than 95% of copper, silver, lead, gold and nickel could be dissolved simultaneously under the optimal conditions: 50 g/L solid/liquid ratio, 1.17 M NaBr, 0.77 M Br2, 2 M HCl, 400 RPM agitation speed and 23.5 °C for 10 hours. The study shows that the dissolution of gold from waste printed circuit boards in a Br2-NaBr system is controlled by film diffusion and chemical reaction.

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