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Liu J, Jiang Q, Wang H, Li J, Zhang W. Catalytic effect and mechanism of in-situ metals on pyrolysis of FR4 printed circuit boards: Insights from kinetics and products. CHEMOSPHERE 2021; 280:130804. [PMID: 33965868 DOI: 10.1016/j.chemosphere.2021.130804] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/01/2021] [Revised: 04/02/2021] [Accepted: 04/30/2021] [Indexed: 06/12/2023]
Abstract
Pyrolysis is a promising method for the recovery of waste printed circuit boards (WPCBs), but few researches have noticed the influence of in-situ metals. This study conducted a series of comparisons between metal-free leftover pieces (LP) and intact boards (IB), including pyrolysis characteristics, volatile emission, kinetics, and thermodynamic parameters. The thermo-gravimetry (TG) analyses indicated that both the samples presented predominant mass loss in narrow temperature intervals, and characteristic pyrolysis temperatures of IB were approximately 15 °C lower than those of LP. Dominant constituents in evolved gases were detected by Fourier-transform infrared spectrometry as CO2, phenol, bromophenol, ethers, ketones, and aldehydes, and metals accelerated the generation of light hydrocarbons and aromatic compounds. The activation energy and thermodynamic parameters were calculated and compared, and the results verified the presence of in-situ metals led to a lower energy barrier and higher reaction extent. Moreover, conversion behaviors of Cu, Fe, Sn, and Pb manifested the formation of metal bromides and implied the reduction of brominated volatiles. The obtained results confirmed the catalytic effect of in-situ metals on PCBs pyrolysis and their bromine fixation abilities. This study contributes to fundamental knowledge that can be used to guide the pyrolysis of WPCBs.
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Affiliation(s)
- Jingxin Liu
- School of Environmental Engineering, Wuhan Textile University, Wuhan, 430073, China; Engineering Research Centre for Clean Production of Textile Dyeing and Printing, Ministry of Education, Wuhan Textile University, Wuhan, 430073, China
| | - Qihao Jiang
- School of Environmental Engineering, Wuhan Textile University, Wuhan, 430073, China
| | - Hanlin Wang
- School of Environmental Engineering, Wuhan Textile University, Wuhan, 430073, China
| | - Jinping Li
- School of Environmental Engineering, Wuhan Textile University, Wuhan, 430073, China; Engineering Research Centre for Clean Production of Textile Dyeing and Printing, Ministry of Education, Wuhan Textile University, Wuhan, 430073, China
| | - Wenjuan Zhang
- School of Metallurgical and Ecological Engineering, University of Science and Technology Beijing, Beijing, 100083, China.
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Oleszek S, Kumagai S, Grabda M, Shiota K, Yoshioka T, Takaoka M. Mitigation of bromine-containing products during pyrolysis of polycarbonate-based tetrabromobisphenol A in the presence of copper(I) oxide. JOURNAL OF HAZARDOUS MATERIALS 2021; 409:124972. [PMID: 33388450 DOI: 10.1016/j.jhazmat.2020.124972] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/20/2020] [Revised: 11/19/2020] [Accepted: 12/23/2020] [Indexed: 06/12/2023]
Abstract
Polycarbonate (PC) is an engineering thermoplastic that is widely used in electrical and electronic equipment. This plastic often contains tetrabromobisphenol A (TBBA), the most common brominated flame retardant. Thermal degradation of the PC-TBBA leads to generation of numerous bromo-organic products in the pyrolytic oil, hindering its appropriate utilization, as well as corrosive hydrogen bromide gas. The purpose of this study was to experimentally investigate and compare the pyrolysis products of PC-TBBA and PC-TBBA + Cu2O at various temperatures, with an emphasis on the yield and distribution of brominated compounds. In pyrolysis of PC-TBBA + Cu2O, at the maximum degradation temperature (600 °C), as much as 86% of total Br was trapped in the residue, while 3% and 11% were distributed in the condensate and gas fractions, respectively. In contrast, the distribution of Br from non-catalytic pyrolysis of PC-TBBA (600 °C) was 0.5% residue, 40% condensate, and 60% gas. The results of this study revealed that in the presence of Cu2O, organo-bromine products were most likely involved in Ullman-type coupling reactions, leading to early cross-linking of the polymer network that efficiently hinders their vaporization. HBr in the gas fraction was suppressed due to effective fixation of bromine in residue in the form of CuBr.
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Affiliation(s)
- Sylwia Oleszek
- Department of Environmental Engineering, Graduate School of Engineering, Kyoto University, Nishikyo-ku, Katsura C-1-3, 615-8540 Kyoto, Japan; Institute of Environmental Engineering of the Polish Academy of Sciences, M. Sklodowska-Curie 34, 41-819 Zabrze, Poland.
| | - Shogo Kumagai
- Graduate School of Environmental Studies, Tohoku University, 6-6-07 Aoba, Aramaki-Aza, Aoba-ku, Sendai 980-8579, Japan.
| | - Mariusz Grabda
- Institute of Environmental Engineering of the Polish Academy of Sciences, M. Sklodowska-Curie 34, 41-819 Zabrze, Poland.
| | - Kenji Shiota
- Department of Environmental Engineering, Graduate School of Engineering, Kyoto University, Nishikyo-ku, Katsura C-1-3, 615-8540 Kyoto, Japan.
| | - Toshiaki Yoshioka
- Graduate School of Environmental Studies, Tohoku University, 6-6-07 Aoba, Aramaki-Aza, Aoba-ku, Sendai 980-8579, Japan.
| | - Masaki Takaoka
- Department of Environmental Engineering, Graduate School of Engineering, Kyoto University, Nishikyo-ku, Katsura C-1-3, 615-8540 Kyoto, Japan.
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3
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The behavior of cuprous species at electrodes polarized in hydrochloric acid solutions. J APPL ELECTROCHEM 2020. [DOI: 10.1007/s10800-020-01420-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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Souza JP, Freitas PE, Almeida LD, Rosmaninho MG. Development of new materials from waste electrical and electronic equipment: Characterization and catalytic application. WASTE MANAGEMENT (NEW YORK, N.Y.) 2017; 65:104-112. [PMID: 28392121 DOI: 10.1016/j.wasman.2017.03.051] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/28/2016] [Revised: 03/13/2017] [Accepted: 03/31/2017] [Indexed: 06/07/2023]
Abstract
Wastes of electrical and electronic equipment (WEEE) represent an important environmental problem, since its composition includes heavy metals and organic compounds used as flame-retardants. Thermal treatments have been considered efficient processes on removal of these compounds, producing carbonaceous structures, which, together with the ceramic components of the WEEE (i.e. silica and alumina), works as support material for the metals. This mixture, associated with the metals present in WEEE, represents promising systems with potential for catalytic application. In this work, WEEE was thermally modified to generate materials that were extensively characterized. Raman spectrum for WEEE after thermal treatment showed two carbon associated bands. SEM images showed a metal nanoparticles distribution over a polymeric and ceramic support. After characterization, WEEE materials were applied in ethanol steam reforming reaction. The system obtained at higher temperature (800°C) exhibited the best activity, since it leads to high conversions (85%), hydrogen yield (30%) and H2/CO ratio (3,6) at 750°C.
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Affiliation(s)
- J P Souza
- Ecolife Soluções Ambientais, Manhuaçu, MG, Brazil
| | - P E Freitas
- Departamento de Química, Instituto Federal de Minas Gerais - Campus Itabirito, Itabirito, MG, Brazil
| | - L D Almeida
- Departamento de Química, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil
| | - M G Rosmaninho
- Departamento de Química, Universidade Federal de Ouro Preto, Ouro Preto, MG, Brazil.
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Kaya M. Recovery of metals and nonmetals from electronic waste by physical and chemical recycling processes. WASTE MANAGEMENT (NEW YORK, N.Y.) 2016; 57:64-90. [PMID: 27543174 DOI: 10.1016/j.wasman.2016.08.004] [Citation(s) in RCA: 215] [Impact Index Per Article: 26.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/02/2016] [Revised: 08/02/2016] [Accepted: 08/04/2016] [Indexed: 05/11/2023]
Abstract
This paper reviews the existing and state of art knowledge for electronic waste (e-waste) recycling. Electrical and/or electronic devices which are unwanted, broken or discarded by their original users are known as e-waste. The main purpose of this article is to provide a comprehensive review of e-waste problem, strategies of e-waste management and various physical, chemical and metallurgical e-waste recycling processes, their advantages and disadvantages towards achieving a cleaner process of waste utilization, with special attention towards extraction of both metallic values and nonmetallic substances. The hazards arise from the presence of heavy metals Hg, Cd, Pb, etc., brominated flame retardants (BFRs) and other potentially harmful substances in e-waste. Due to the presence of these substances, e-waste is generally considered as hazardous waste and, if improperly managed, may pose significant human and environmental health risks. This review describes the potential hazards and economic opportunities of e-waste. Firstly, an overview of e-waste/printed circuit board (PCB) components is given. Current status and future perspectives of e-waste/PCB recycling are described. E-waste characterization, dismantling methods, liberation and classification processes are also covered. Manual selective dismantling after desoldering and metal-nonmetal liberation at -150μm with two step crushing are seen to be the best techniques. After size reduction, mainly physical separation processes employing gravity, electrostatic, magnetic separators, froth floatation, etc. have been critically reviewed here for separation of metals and nonmetals, along with useful utilizations of the nonmetallic materials. The recovery of metals from e-waste material after physical separation through pyrometallurgical, hydrometallurgical or biohydrometallurgical routes is also discussed along with purification and refining. Suitable PCB recycling flowsheets for industrial applications are also given. It seems that hydrometallurgical route will be a key player in the base and precious metals recoveries from e-waste. E-waste recycling will be a very important sector in the near future from economic and environmental perspectives. Recycling technology aims to take today's waste and turn it into conflict-free, sustainable polymetallic secondary resources (i.e. Urban Mining) for tomorrow. Recycling technology must ensure that e-waste is processed in an environmentally friendly manner, with high efficiency and lowered carbon footprint, at a fraction of the costs involved with setting multibillion dollar smelting facilities. Taking into consideration our depleting natural resources, this Urban Mining approach offers quite a few benefits. This results in increased energy efficiency and lowers demand for mining of new raw materials.
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Affiliation(s)
- Muammer Kaya
- Mining Engineering Department, Eskişehir Osmangazi University, Eskişehir, Turkey.
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Syed S. Silver recovery aqueous techniques from diverse sources: Hydrometallurgy in recycling. WASTE MANAGEMENT (NEW YORK, N.Y.) 2016; 50:234-256. [PMID: 26926782 DOI: 10.1016/j.wasman.2016.02.006] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/08/2015] [Revised: 02/04/2016] [Accepted: 02/04/2016] [Indexed: 06/05/2023]
Abstract
The demand of silver is ever increasing with the advance of the industrialized world, whereas worldwide reserves of high grade silver ores are retreating. However, there exist large stashes of low and lean grade silver ores that are yet to be exploited. The main impression of this work was to draw attention to the most advance technologies in silver recovery and recycling from various sources. The state of the art in recovery of silver from different sources by hydrometallurgical and bio-metallurgical processing and varieties of leaching, cementing, reducing agents, peeling, electro-coagulants, adsorbents, electro-dialysis, solvent extraction, ion exchange resins and bio sorbents are highlighted in this article. It is shown that the major economic driver for recycling of depleted sources is for the recovery of silver. In order to develop an nature-friendly technique for the recovery of silver from diverse sources, a critical comparison of existing technologies is analyzed for both economic viability and environmental impact was made in this amendment and silver ion toxicity is highlighted.
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Affiliation(s)
- S Syed
- Chemical Engineering Department, King Saud University, P.O. Box 800, Riyadh 11421, Saudi Arabia.
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Dong Y, Feng C, Zhang J, Jiang P, Wang G, Wu X, Miao H. A New p-Metal-n Structure AgBr-Ag-BiOBr with Superior Visible-Light-Responsive Catalytic Performance. Chem Asian J 2014; 10:687-93. [DOI: 10.1002/asia.201403217] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2014] [Indexed: 11/05/2022]
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