Oxidative Leaching of metals from electronic waste with solutions based on quaternary ammonium salts

Detalhes bibliográficos
Autor(a) principal: Pinheiro, Diana
Data de Publicação: 2009
Tipo de documento: Dissertação
Idioma: eng
Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
Texto Completo: http://hdl.handle.net/10400.22/2731
Resumo: The treatment of electric and electronic waste (WEEE) is a problem which receives ever more attention. An inadequate treatment results in harmful products ending up in the environment. This project intends to investigate the possibilities of an alternative route for recycling of metals from printed circuit boards (PCBs) obtained from rejected computers. The process is based on aqueous solutions composed of an etchant, either 0.2 M CuCl2.2H2O or 0.2 M FeCl3.6H2O, and a quaternary ammonium salt (quat) such as choline chloride or chlormequat. These solutions are reminiscent of deep eutectic solvents (DES) based on quats. DES are quite similar to ionic liquids (ILs) and are used as well as alternative solvents with a great diversity of physical properties, making them attractive for replacement of hazardous, volatile solvents (e.g. VOCs). A remarkable difference between genuine DES and ILs with the solutions used in this project is the addition of rather large quantities of water. It is shown the presence of water has a lot of advantages on the leaching of metals, while the properties typical for DES still remain. The oxidizing capacities of Cu(II) stem from the existence of a stable Cu(I) component in quat based DES and thus the leaching stems from the activity of the Cu(II)/Cu(I) redox couple. The advantage of Fe(III) in combination with DES is the fact that the Fe(III)/Fe(II) redox couple becomes reversible, which is not true in pure water. This opens perspectives for regeneration of the etching solution. In this project the leaching of copper was studied as a function of gradual increasing water content from 0 - 100w% with the same concentration of copper chloride or iron(III) chloride at room temperature and 80ºC. The solutions were also tested on real PCBs. At room temperature a maximum leaching effect for copper was obtained with 30w% choline chloride with 0.2 M CuCl2.2H2O. The leaching effect is still stronger at 80°C, b ut of course these solutions are more energy consuming. For aluminium, tin, zinc and lead, the leaching was faster at 80ºC. Iron and nickel dissolved easily at room temperature. The solutions were not able to dissolve gold, silver, rhodium and platinum.
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spelling Oxidative Leaching of metals from electronic waste with solutions based on quaternary ammonium saltsPrinted circuit boardPCBMetal recyclingIonic liquidsDeep eutectic solventsLeachingPlaca de circuito impressoPCIReciclagem de metaisLíquidos iónicosSolventes eutéticosLixiviaçãoThe treatment of electric and electronic waste (WEEE) is a problem which receives ever more attention. An inadequate treatment results in harmful products ending up in the environment. This project intends to investigate the possibilities of an alternative route for recycling of metals from printed circuit boards (PCBs) obtained from rejected computers. The process is based on aqueous solutions composed of an etchant, either 0.2 M CuCl2.2H2O or 0.2 M FeCl3.6H2O, and a quaternary ammonium salt (quat) such as choline chloride or chlormequat. These solutions are reminiscent of deep eutectic solvents (DES) based on quats. DES are quite similar to ionic liquids (ILs) and are used as well as alternative solvents with a great diversity of physical properties, making them attractive for replacement of hazardous, volatile solvents (e.g. VOCs). A remarkable difference between genuine DES and ILs with the solutions used in this project is the addition of rather large quantities of water. It is shown the presence of water has a lot of advantages on the leaching of metals, while the properties typical for DES still remain. The oxidizing capacities of Cu(II) stem from the existence of a stable Cu(I) component in quat based DES and thus the leaching stems from the activity of the Cu(II)/Cu(I) redox couple. The advantage of Fe(III) in combination with DES is the fact that the Fe(III)/Fe(II) redox couple becomes reversible, which is not true in pure water. This opens perspectives for regeneration of the etching solution. In this project the leaching of copper was studied as a function of gradual increasing water content from 0 - 100w% with the same concentration of copper chloride or iron(III) chloride at room temperature and 80ºC. The solutions were also tested on real PCBs. At room temperature a maximum leaching effect for copper was obtained with 30w% choline chloride with 0.2 M CuCl2.2H2O. The leaching effect is still stronger at 80°C, b ut of course these solutions are more energy consuming. For aluminium, tin, zinc and lead, the leaching was faster at 80ºC. Iron and nickel dissolved easily at room temperature. The solutions were not able to dissolve gold, silver, rhodium and platinum.O tratamento de resíduos electrónicos é um tema que requer cada vez mais, a nossa atenção, pois um tratamento não adequado leva a consequências prejudiciais para o meio ambiente. Este projecto tem como objectivo a investigação de novas alternativas de reciclagem de metais que constituem as placas de circuito impresso (PCIs) obtidas de computadores já não utilizáveis. O processo é baseado em soluções aquosas compostas por 0.2M CuCl2.2H2O ou 0.2M FeCl3.6H2O e um sal de amónio quaternário como o cloreto de colina. Estas soluções são designadas de solventes eutéticos e são baseados em sais quaternários. Os sais eutéticos são similares aos líquidos iónicos (LI´s) e são usados como solventes alternativos. A sua elevada diversidade de propriedades físicas torna-os atractivos para a substituição de solventes voláteis (ex. COV´s). Uma notável diferença entre solventes eutéticos e líquidos iónicos puros é a adição de determinadas quantidades de água. A presença de água tem inúmeras vantagens na dissolução de metais, mantendo-se ao mesmo tempo as propriedades dos solventes eutéticos. As capacidades oxidativas do Cu(II) provêm da existência de Cu(I) estável, presente em quaternários baseados em solventes eutéticos. Assim, a dissolução tem origem na actividade do par redox Cu(II)/Cu(I). A vantagem do Fe(II) combinado com solventes eutéticos é o facto de o par redox Fe(III)/Fe(II), tornar reversível mas não na presença de água. Isto abre perspectivas para a regeneração da solução lixiviante. Neste projecto foi estudada a dissolução do cobre em função do crescimento gradual do teor de água, desde 0-100w%, mantendo a mesma concentração de cloreto de cobre(II) e cloreto de ferro(III), à temperatura ambiente e 80ºC. As soluções foram também testadas em PCI´s. À temperatura ambiente a máxima lixiviação para o cobre foi obtida com 30w% de cloreto de colina e 0.2M CuCl2.2H2O. A dissolução do cobre foi mais eficaz a 80ºC, no entanto nestas condições há um maior gasto energético. Para o alumínio, estanho, zinco e chumbo verificou-se uma rápida dissolução a 80ºC. Ao contrário do ferro e níquel, a dissolução foi mais rápida à temperatura ambiente As soluções usadas não foram capazes de dissolver ouro, prata, ródio e platinaInstituto Politécnico do Porto. Instituto Superior de Engenharia do PortoMatthijs, EdwardFreitas, Olga M.Repositório Científico do Instituto Politécnico do PortoPinheiro, Diana2013-11-12T11:55:24Z20092009-01-01T00:00:00Zinfo:eu-repo/semantics/publishedVersioninfo:eu-repo/semantics/masterThesisapplication/pdfhttp://hdl.handle.net/10400.22/2731enginfo:eu-repo/semantics/openAccessreponame:Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)instname:Agência para a Sociedade do Conhecimento (UMIC) - FCT - Sociedade da Informaçãoinstacron:RCAAP2023-03-13T12:42:18Zoai:recipp.ipp.pt:10400.22/2731Portal AgregadorONGhttps://www.rcaap.pt/oai/openaireopendoar:71602024-03-19T17:23:44.488752Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos) - Agência para a Sociedade do Conhecimento (UMIC) - FCT - Sociedade da Informaçãofalse
dc.title.none.fl_str_mv Oxidative Leaching of metals from electronic waste with solutions based on quaternary ammonium salts
title Oxidative Leaching of metals from electronic waste with solutions based on quaternary ammonium salts
spellingShingle Oxidative Leaching of metals from electronic waste with solutions based on quaternary ammonium salts
Pinheiro, Diana
Printed circuit board
PCB
Metal recycling
Ionic liquids
Deep eutectic solvents
Leaching
Placa de circuito impresso
PCI
Reciclagem de metais
Líquidos iónicos
Solventes eutéticos
Lixiviação
title_short Oxidative Leaching of metals from electronic waste with solutions based on quaternary ammonium salts
title_full Oxidative Leaching of metals from electronic waste with solutions based on quaternary ammonium salts
title_fullStr Oxidative Leaching of metals from electronic waste with solutions based on quaternary ammonium salts
title_full_unstemmed Oxidative Leaching of metals from electronic waste with solutions based on quaternary ammonium salts
title_sort Oxidative Leaching of metals from electronic waste with solutions based on quaternary ammonium salts
author Pinheiro, Diana
author_facet Pinheiro, Diana
author_role author
dc.contributor.none.fl_str_mv Matthijs, Edward
Freitas, Olga M.
Repositório Científico do Instituto Politécnico do Porto
dc.contributor.author.fl_str_mv Pinheiro, Diana
dc.subject.por.fl_str_mv Printed circuit board
PCB
Metal recycling
Ionic liquids
Deep eutectic solvents
Leaching
Placa de circuito impresso
PCI
Reciclagem de metais
Líquidos iónicos
Solventes eutéticos
Lixiviação
topic Printed circuit board
PCB
Metal recycling
Ionic liquids
Deep eutectic solvents
Leaching
Placa de circuito impresso
PCI
Reciclagem de metais
Líquidos iónicos
Solventes eutéticos
Lixiviação
description The treatment of electric and electronic waste (WEEE) is a problem which receives ever more attention. An inadequate treatment results in harmful products ending up in the environment. This project intends to investigate the possibilities of an alternative route for recycling of metals from printed circuit boards (PCBs) obtained from rejected computers. The process is based on aqueous solutions composed of an etchant, either 0.2 M CuCl2.2H2O or 0.2 M FeCl3.6H2O, and a quaternary ammonium salt (quat) such as choline chloride or chlormequat. These solutions are reminiscent of deep eutectic solvents (DES) based on quats. DES are quite similar to ionic liquids (ILs) and are used as well as alternative solvents with a great diversity of physical properties, making them attractive for replacement of hazardous, volatile solvents (e.g. VOCs). A remarkable difference between genuine DES and ILs with the solutions used in this project is the addition of rather large quantities of water. It is shown the presence of water has a lot of advantages on the leaching of metals, while the properties typical for DES still remain. The oxidizing capacities of Cu(II) stem from the existence of a stable Cu(I) component in quat based DES and thus the leaching stems from the activity of the Cu(II)/Cu(I) redox couple. The advantage of Fe(III) in combination with DES is the fact that the Fe(III)/Fe(II) redox couple becomes reversible, which is not true in pure water. This opens perspectives for regeneration of the etching solution. In this project the leaching of copper was studied as a function of gradual increasing water content from 0 - 100w% with the same concentration of copper chloride or iron(III) chloride at room temperature and 80ºC. The solutions were also tested on real PCBs. At room temperature a maximum leaching effect for copper was obtained with 30w% choline chloride with 0.2 M CuCl2.2H2O. The leaching effect is still stronger at 80°C, b ut of course these solutions are more energy consuming. For aluminium, tin, zinc and lead, the leaching was faster at 80ºC. Iron and nickel dissolved easily at room temperature. The solutions were not able to dissolve gold, silver, rhodium and platinum.
publishDate 2009
dc.date.none.fl_str_mv 2009
2009-01-01T00:00:00Z
2013-11-12T11:55:24Z
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dc.publisher.none.fl_str_mv Instituto Politécnico do Porto. Instituto Superior de Engenharia do Porto
publisher.none.fl_str_mv Instituto Politécnico do Porto. Instituto Superior de Engenharia do Porto
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