Journal
JOURNAL OF ENVIRONMENTAL MANAGEMENT
Volume 226, Issue -, Pages 76-82Publisher
ACADEMIC PRESS LTD- ELSEVIER SCIENCE LTD
DOI: 10.1016/j.jenvman.2018.08.049
Keywords
Aqueous two-phase systems; Printed circuit boards; Green chemistry; Ion separation; Electronic hazardous waste
Categories
Funding
- Fundacao de Amparo a Pesquisa do Estado de Minas Gerais (FAPEMIG) [APQ-02790-14]
- Conselho Nacional de Desenvolvimento Cientifico e Tecnologico (CNPq) [475062/2013-2]
- Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior (CAPES)
- CNPq
- FAPEMIG [CEX - RED-0010-14]
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Printed circuit boards (PCBs) make up a large part of e-waste and include high concentrations of high-value metals. Therefore, the recovery of these metals is interesting from both the environmental and economic points of view. Here, the extraction/separation of copper, nickel and silver from PCB leachate was studied using an aqueous two-phase system (ATPS) formed by triblock copolymers with an electrolyte and water, which is in compliance with the principles of green chemistry. The best conditions for the selective extraction consisted of 1-(2-pyridylazo)-2-naphthol (3.5 mmol kg(-1)) at pH = 6.0 in 6 sequential steps for the Cu(II), dimethylglyoxime (5.00 mmol kg(-1)) at pH = 9.0 for the Ni(II) and thiocyanate (5.20 mmol kg(-1)) at pH = 9.0 for the Ag(I). These conditions were applied sequentially for extraction of Cu, Ni and Ag from the PCB leachate, obtaining high separation factor (S) values between the analyte and the metallic concomitants (S-C(u,Ni) = 1,460, S-Cu,S-Fe = 15,500, S-Cu,S-Ag = 15,900, S-Ni,S-Fe = 32,700, S-Ni,S-Ag = 34,700 and S-Ag,S-Fe = 4800). The maximum extraction percentages (% E) for Cu, Ni and Ag were 99.9%, 99.9% and 99.8%, respectively. After the extraction, a single step stripping process was performed, resulting in more than 82% of the ion available in a clean lower phase. For the first time, an ATPS has been used for sequential extraction of several metal analytes from a real sample.
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