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Kumar P, Singh S, Gacem A, Yadav KK, Bhutto JK, Alreshidi MA, Kumar M, Kumar A, Yadav VK, Soni S, Kumar R, Qasim MT, Tariq M, Alam MW. A review on e-waste contamination, toxicity, and sustainable clean-up approaches for its management. Toxicology 2024; 508:153904. [PMID: 39106909 DOI: 10.1016/j.tox.2024.153904] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2024] [Revised: 07/23/2024] [Accepted: 08/02/2024] [Indexed: 08/09/2024]
Abstract
Ecosystems and human health are being negatively impacted by the growing problem of electrical waste, especially in developing countries. E-waste poses a significant risk to ecological systems because it can release a variety of hazardous substances into the environment, containing polybrominated diphenyl ethers and heavy metals, brominated flame retardants, polychlorinated dibenzofurans and polycyclic aromatic hydrocarbons, and dioxins. This review article provides a critical assessment of the toxicological consequences of e-waste on ecosystems and human health and data analyses from scientific journals and grey literature on metals, BFRs, PBDEs, PCDFs, and PAHs in several environmental compartments of commercial significance in informal electronic trash recycling. The currently available techniques and tools employed for treating e-waste are sustainable techniques such as bioremediation, chemical leaching, biological leaching, and pyrometallurgy have been also discussed along with the necessity of implementing strong legislation to address the issue of unregulated exports of electronic trash in recycling practices. Despite the ongoing hurdles, implementing environmentally sustainable recycling methods have the potential to address the detrimental impacts of e-waste and foster positive economic development.
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Affiliation(s)
- Pankaj Kumar
- Department of Environmental Science, Parul Institute of Applied Sciences, Parul University, Vadodara, Gujarat 391760, India.
| | - Snigdha Singh
- Department of Environmental Science, Parul Institute of Applied Sciences, Parul University, Vadodara, Gujarat 391760, India
| | - Amel Gacem
- Department of Physics, Faculty of Sciences, University 20 Août 1955, Skikda, Algeria
| | - Krishna Kumar Yadav
- Faculty of Science and Technology, Madhyanchal Professional University, Ratibad, Bhopal, Madhya Pradesh 462044, India; Environmental and Atmospheric Sciences Research Group, Scientific Research Center, Al-Ayen University, Thi-Qar, Nasiriyah 64001, Iraq
| | - Javed Khan Bhutto
- Department of Electrical Engineering, College of Engineering, King Khalid University, Abha, Saudi Arabia
| | | | - Manoj Kumar
- Department of Hydrology, Indian Institute of Technology, Roorkee, Roorkee, Uttarakhand 247667, India
| | - Anand Kumar
- School of Management Studies, Nalanda University, Rajgir, Bihar 803116, India
| | - Virendra Kumar Yadav
- Marwadi University Research Center, Department of Microbiology, Marwadi University, Rajkot, Gujarat, 360003, India
| | - Sunil Soni
- School of Medico-Legal Studies, National Forensic Science University, Gandhinagar, Gujarat 382007, India
| | - Ramesh Kumar
- Department of Environmental Science, Parul Institute of Applied Sciences, Parul University, Vadodara, Gujarat 391760, India
| | - Maytham T Qasim
- College of health and Medical Technology, Al-Ayen University, Thi-Qar 64001, Iraq
| | - Mohd Tariq
- Department of Life Sciences, Parul Institute of Applied Sciences, Parul University, Vadodara, Gujarat 391760, India
| | - Mir Waqas Alam
- Department of Physics, College of Science, King Faisal University, Al Ahsa 31982, Saudi Arabia.
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2
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Vance SM, Mojsak M, Kinsman LMM, Rae R, Kirk C, Love JB, Morrison CA. Selective Gold Precipitation by a Tertiary Diamide Driven by Thermodynamic Control. Inorg Chem 2024; 63:9332-9345. [PMID: 38722710 PMCID: PMC11110006 DOI: 10.1021/acs.inorgchem.4c01279] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2024] [Revised: 04/26/2024] [Accepted: 04/30/2024] [Indexed: 05/21/2024]
Abstract
The simple diamide ligand L was previously shown to selectively precipitate gold from acidic solutions typical of e-waste leach streams, with precipitation of gallium, iron, tin, and platinum possible under more forcing conditions. Herein, we report direct competition experiments to afford the order of selectivity. Thermal analysis indicates that the gold-, gallium-, and iron-containing precipitates present as the most thermodynamically stable structures at room temperature, while the tin-containing structure does not. Computational modeling established that the precipitation process is thermodynamically driven, with ion exchange calculations matching the observed experimental selectivity ordering. Calculations also show that the stretched ligand conformation seen in the X-ray crystal structure of the gold-containing precipitate is more strained than in the structures of the other metal precipitates, indicating that intermolecular interactions likely dictate the selectivity ordering. This was confirmed through a combination of Hirshfeld, noncovalent interaction (NCI), and quantum theory of atoms in molecules (QTAIM) analyses, which highlight favorable halogen···halogen contacts between metalates and pseudo-anagostic C-H···metal interactions in the crystal structure of the gold-containing precipitate.
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Affiliation(s)
- Susanna
S. M. Vance
- EaStCHEM School of Chemistry, University of Edinburgh, Edinburgh EH9 3FJ, United Kingdom
| | - Mateusz Mojsak
- EaStCHEM School of Chemistry, University of Edinburgh, Edinburgh EH9 3FJ, United Kingdom
| | - Luke M. M. Kinsman
- EaStCHEM School of Chemistry, University of Edinburgh, Edinburgh EH9 3FJ, United Kingdom
| | - Rebecca Rae
- EaStCHEM School of Chemistry, University of Edinburgh, Edinburgh EH9 3FJ, United Kingdom
| | - Caroline Kirk
- EaStCHEM School of Chemistry, University of Edinburgh, Edinburgh EH9 3FJ, United Kingdom
| | - Jason B. Love
- EaStCHEM School of Chemistry, University of Edinburgh, Edinburgh EH9 3FJ, United Kingdom
| | - Carole A. Morrison
- EaStCHEM School of Chemistry, University of Edinburgh, Edinburgh EH9 3FJ, United Kingdom
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Ma C, Kumagai S, Saito Y, Yoshioka T, Huang X, Shao Y, Ran J, Sun L. Recent Advancements in Pyrolysis of Halogen-Containing Plastics for Resource Recovery and Halogen Upcycling: A State-of-the-Art Review. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2024; 58:1423-1440. [PMID: 38197317 DOI: 10.1021/acs.est.3c09451] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/11/2024]
Abstract
Plastic waste has emerged as a serious issue due to its impact on environmental degradation and resource scarcity. Plastic recycling, especially of halogen-containing plastics, presents challenges due to potential secondary pollution and lower-value implementations. Chemical recycling via pyrolysis is the most versatile and robust approach for combating plastic waste. In this Review, we present recent advancements in halogen-plastic pyrolysis for resource utilization and the potential pathways from "reducing to recycling to upcycling" halogens. We emphasize the advanced management of halogen-plastics through copyrolysis with solid wastes (waste polymers, biomass, coal, etc.), which is an efficient method for dealing with mixed wastes to obtain high-value products while reducing undesirable substances. Innovations in catalyst design and reaction configurations for catalytic pyrolysis are comprehensively evaluated. In particular, a tandem catalysis system is a promising route for halogen removal and selective conversion of targeted products. Furthermore, we propose novel insights regarding the utilization and upcycling of halogens from halogen-plastics. This includes the preparation of halogen-based sorbents for elemental mercury removal, the halogenation-vaporization process for metal recovery, and the development of halogen-doped functional materials for new materials and energy applications. The reutilization of halogens facilitates the upcycling of halogen-plastics, but many efforts are needed for mutually beneficial outcomes. Overall, future investigations in the development of copyrolysis and catalyst-driven technologies for upcycling halogen-plastics are highlighted.
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Affiliation(s)
- Chuan Ma
- Key Laboratory of Low-grade Energy Utilization Technologies and Systems, Ministry of Education, School of Energy and Power Engineering, Chongqing University, Chongqing 400044, China
| | - Shogo Kumagai
- Graduate School of Environmental Studies, Tohoku University, 6-6-07 Aoba, Aramaki-aza, Aoba-ku, Sendai, Miyagi 980-8579, Japan
| | - Yuko Saito
- Graduate School of Environmental Studies, Tohoku University, 6-6-07 Aoba, Aramaki-aza, Aoba-ku, Sendai, Miyagi 980-8579, Japan
| | - Toshiaki Yoshioka
- Graduate School of Environmental Studies, Tohoku University, 6-6-07 Aoba, Aramaki-aza, Aoba-ku, Sendai, Miyagi 980-8579, Japan
| | - Xin Huang
- Key Laboratory of Low-grade Energy Utilization Technologies and Systems, Ministry of Education, School of Energy and Power Engineering, Chongqing University, Chongqing 400044, China
| | - Yunlin Shao
- Key Laboratory of Low-grade Energy Utilization Technologies and Systems, Ministry of Education, School of Energy and Power Engineering, Chongqing University, Chongqing 400044, China
| | - Jingyu Ran
- Key Laboratory of Low-grade Energy Utilization Technologies and Systems, Ministry of Education, School of Energy and Power Engineering, Chongqing University, Chongqing 400044, China
| | - Lushi Sun
- State Key Laboratory of Coal Combustion, Huazhong University of Science and Technology, Wuhan 430074, China
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Javaid S, Zanoletti A, Serpe A, Bontempi E, Alessandri I, Vassalini I. Glassy Powder Derived from Waste Printed Circuit Boards for Methylene Blue Adsorption. Molecules 2024; 29:400. [PMID: 38257313 PMCID: PMC10821274 DOI: 10.3390/molecules29020400] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2023] [Revised: 01/10/2024] [Accepted: 01/11/2024] [Indexed: 01/24/2024] Open
Abstract
Electronic waste (e-waste) is one of the fastest-growing waste streams in the world and Europe is classified as the first producer in terms of per capita amount. To reduce the environmental impact of e-waste, it is important to recycle it. This work shows the possibility of reusing glassy substrates, derived from the MW-assisted acidic leaching of Waste Printed Circuit Boards (WPCBs), as an adsorbent material. The results revealed an excellent adsorption capability against methylene blue (MB; aqueous solutions in the concentration range 10-5 M-2 × 10-5 M, at pH = 7.5). Comparisons were performed with reference samples such as activated carbons (ACs), the adsorbent mostly used at the industrial level; untreated PCB samples; and ground glass slides. The obtained results show that MW-treated WPCB powder outperformed both ground glass and ground untreated PCBs in MB adsorption, almost matching AC adsorption. The use of this new adsorbent obtained through the valorization of e-waste offers advantages not only in terms of cost but also in terms of environmental sustainability.
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Affiliation(s)
- Saad Javaid
- Sustainable Chemistry and Materials Laboratory, Department of Information Engineering, University of Brescia, Via Branze 38, 25123 Brescia, Italy; (S.J.); (I.A.)
| | - Alessandra Zanoletti
- Chemistry for Technologies Laboratory, Department of Mechanical and Industrial Engineering, University of Brescia, Via Branze 38, 25123 Brescia, Italy;
- Unit of National Interuniversity Consortium for Materials Science and Technology (INSTM), Research Unit of Brescia, Via Branze 38, 25123 Brescia, Italy
| | - Angela Serpe
- Department of Civil and Environmental Engineering and Architecture (DICAAR), INSTM Unit, Via Marengo 2, 09123 Cagliari, Italy;
- National Research Council of Italy, Institute of Environmental Geology and Geoengineering (CNR-IGAG), Via Marengo 2, 09123 Cagliari, Italy
| | - Elza Bontempi
- Chemistry for Technologies Laboratory, Department of Mechanical and Industrial Engineering, University of Brescia, Via Branze 38, 25123 Brescia, Italy;
- Unit of National Interuniversity Consortium for Materials Science and Technology (INSTM), Research Unit of Brescia, Via Branze 38, 25123 Brescia, Italy
| | - Ivano Alessandri
- Sustainable Chemistry and Materials Laboratory, Department of Information Engineering, University of Brescia, Via Branze 38, 25123 Brescia, Italy; (S.J.); (I.A.)
- Unit of National Interuniversity Consortium for Materials Science and Technology (INSTM), Research Unit of Brescia, Via Branze 38, 25123 Brescia, Italy
- CNR-INO (National Research Council-National Institute of Optics), Research Unit of Brescia, Via Branze 38, 25123 Brescia, Italy
| | - Irene Vassalini
- Sustainable Chemistry and Materials Laboratory, Department of Information Engineering, University of Brescia, Via Branze 38, 25123 Brescia, Italy; (S.J.); (I.A.)
- Unit of National Interuniversity Consortium for Materials Science and Technology (INSTM), Research Unit of Brescia, Via Branze 38, 25123 Brescia, Italy
- CNR-INO (National Research Council-National Institute of Optics), Research Unit of Brescia, Via Branze 38, 25123 Brescia, Italy
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Ali L, Sivaramakrishnan K, Kuttiyathil MS, Chandrasekaran V, Ahmed OH, Al-Harahsheh M, Altarawneh M. Prediction of Thermogravimetric Data in the Thermal Recycling of e-waste Using Machine Learning Techniques: A Data-driven Approach. ACS OMEGA 2023; 8:43254-43270. [PMID: 38024703 PMCID: PMC10652257 DOI: 10.1021/acsomega.3c07228] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/20/2023] [Revised: 10/12/2023] [Accepted: 10/17/2023] [Indexed: 12/01/2023]
Abstract
The release of bromine-free hydrocarbons and gases is a major challenge faced in the thermal recycling of e-waste due to the corrosive effects of produced HBr. Metal oxides such as Fe2O3 (hematite) are excellent debrominating agents, and they are copyrolyzed along with tetrabromophenol (TBP), a lesser used brominated flame retardant that is a constituent of printed circuit boards in electronic equipment. The pyrolytic (N2) and oxidative (O2) decomposition of TBP with Fe2O3 has been previously investigated with thermogravimetric analysis (TGA) at four different heating rates of 5, 10, 15, and 20 °C/min, and the mass loss data between room temperature and 800 °C were reported. The objective of our paper is to study the effectiveness of machine learning (ML) techniques to reproduce these TGA data so that the use of the instrument can be eliminated to enhance the potential of online monitoring of copyrolysis in e-waste treatment. This will reduce experimental and human errors as well as improve process time significantly. TGA data are both nonlinear and multidimensional, and hence, nonlinear regression techniques such as random forest (RF) and gradient boosting regression (GBR) showed the highest prediction accuracies of 0.999 and lowest prediction errors among all the ML models employed in this work. The large data sets allowed us to explore three different scenarios of model training and validation, where the number of training samples were varied from 10,000 to 40,000 for both TBP and TBP + hematite samples under N2 (pyrolysis) and O2 (combustion) environments. The novelty of our study is that ML techniques have not been employed for the copyrolysis of these compounds, while the significance is the excellent potential of enhanced online monitoring of e-waste treatment and extension to other characterization techniques such as spectroscopy and chromatography. Lastly, e-waste recycling could greatly benefit from ML applications since it has the potential to reduce total and operational costs and improve overall process time and efficiency, thereby encouraging more treatment plants to adopt these techniques, resulting in reducing the increasing environmental footprint of e-waste.
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Affiliation(s)
- Labeeb Ali
- Department
of Chemical and Petroleum Engineering, United
Arab Emirates University, Sheikh Khalifa Bin Zayed Street, Al-Ain 15551, United Arab
Emirates
| | - Kaushik Sivaramakrishnan
- Department
of Chemical and Petroleum Engineering, United
Arab Emirates University, Sheikh Khalifa Bin Zayed Street, Al-Ain 15551, United Arab
Emirates
| | - Mohamed Shafi Kuttiyathil
- Department
of Chemical and Petroleum Engineering, United
Arab Emirates University, Sheikh Khalifa Bin Zayed Street, Al-Ain 15551, United Arab
Emirates
| | - Vignesh Chandrasekaran
- Department
of Computer Science, University of British
Columbia, Vancouver V6T 1Z4, Canada
| | - Oday H. Ahmed
- Department
of Physics, College of Education, Al-Iraqia
University, Baghdad 10071, Iraq
| | - Mohammad Al-Harahsheh
- Chemical
Engineering Department, Jordan University
of Science and Technology, Irbid 22110, Jordan
| | - Mohammednoor Altarawneh
- Department
of Chemical and Petroleum Engineering, United
Arab Emirates University, Sheikh Khalifa Bin Zayed Street, Al-Ain 15551, United Arab
Emirates
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6
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Mir S, Dhawan N. Investigation of pyrolysis for the recovery of metallic values from ball grid arrays. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2023; 30:90180-90194. [PMID: 36692715 DOI: 10.1007/s11356-023-25494-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/20/2022] [Accepted: 01/18/2023] [Indexed: 06/17/2023]
Abstract
The massive generation of electronic waste has led to a significant interest in sustainable metal recovery and recycling. Ball grid arrays, mounted on printed circuit boards, are identified as a potentially valuable source of metals (Cu, Ni, Au, Ag, Pb, and Sn). In this study, pyrolysis is found as a promising treatment for the degradation of the epoxy resin of ball grid arrays. As a consequence, the liberation of metallic values and glass fibers is attained. The thermal analysis revealed that the major degradation occurs in the temperature range of 300-650 °C, with overall activation energy estimated as ~ 243 kJ/mol. The concentration of CO gas reaches a maximum value at a comparatively lower residence time with an increase in pyrolysis temperature. The metal enrichment was significantly influenced by the variation in pyrolysis temperatures with an optimal condition chosen as 600 °C. The metallic fractions (Cu, Ni, Ag, and Au) were separated from the glass fibers by water-based density separation and enriched in the sink product by three-fold. The recovery of Cu, Ni, Ag, and Au is achieved at 97%, 88%, 95%, and 96%, respectively. The metal fraction can be either used as a feedstock for the Cu smelting process or can be subjected to selective hydrometallurgical treatment. The glass fiber fraction comprises of Si, Al, and Ca oxides with potential application in laminate fabrication. High-quality gaseous products can be reutilized as fuel for other metallurgical processes. It can be concluded that 100 g of BGA yielded Cu ~ 23.7 g, Ni ~ 0.57 g, Ag ~ 23.4 mg, and Au ~ 73 mg after pyrolysis and density separation, which is equivalent to 1.35 kg, of primary Cu ore, 0.042 kg Ni ore, 4.68 kg Ag ore, and 14.6 kg Au ore.
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Affiliation(s)
- Shaila Mir
- Materials Recycling Laboratory, Indian Institute of Technology, Roorkee, Uttarakhand, 247667, India
| | - Nikhil Dhawan
- Materials Recycling Laboratory, Indian Institute of Technology, Roorkee, Uttarakhand, 247667, India.
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Ali L, Sivaramakrishnan K, Kuttiyathil MS, Chandrasekaran V, Ahmed OH, Al-Harahsheh M, Altarawneh M. Degradation of tetrabromobisphenol A (TBBA) with calcium hydroxide: a thermo-kinetic analysis. RSC Adv 2023; 13:6966-6982. [PMID: 36865571 PMCID: PMC9973547 DOI: 10.1039/d2ra08223c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2022] [Accepted: 02/16/2023] [Indexed: 03/04/2023] Open
Abstract
Thermal treatment of bromine-contaminated polymers (i.e., as in e-waste) with metal oxides is currently deployed as a mainstream strategy in recycling and resources recovery from these objects. The underlying aim is to capture the bromine content and to produce pure bromine-free hydrocarbons. Bromine originates from the added brominated flame retardants (BFRs) to the polymeric fractions in printed circuits boards, where tetrabromobisphenol A (TBBA) is the most utilized BFR. Among notable deployed metal oxides is calcium hydroxide, i.e., Ca(OH)2 that often displays high debromination capacity. Comprehending thermo-kinetic parameters that account for the BFRs:Ca(OH)2 interaction is instrumental to optimize the operation at an industrial scale. Herein, we report comprehensive kinetics and thermodynamics studies into the pyrolytic and oxidative decomposition of a TBBA:Ca(OH)2 mixture at four different heating rates, 5, 10, 15, and 20 °C min-1, carried out using a thermogravimetric analyser. Fourier Transform Infrared Spectroscopy (FTIR) and a carbon, hydrogen, nitrogen, and sulphur (CHNS) elemental analyser established the vibrations of the molecules and carbon content of the sample. From the thermogravimetric analyser (TGA) data, the kinetic and thermodynamic parameters were evaluated using iso-conversional methods (KAS, FWO, and Starink), which were further validated by the Coats-Redfern method. The computed activation energies for the pyrolytic decomposition of pure TBBA and its mixture with Ca(OH)2 reside in the narrow ranges of 111.7-112.1 kJ mol-1 and 62.8-63.4 kJ mol-1, respectively (considering the various models). Obtained negative ΔS values suggest the formation of stable products. The synergic effects of the blend exhibited positive values in the low-temperature ranges (200-300 °C) due to the emission of HBr from TBBA and the solid-liquid bromination process occurring between TBBA and Ca(OH)2. From a practical point of view, data provided herein are useful in efforts that aim to fine-tune operational conditions encountered in real recycling scenarios, i.e., in co-pyrolysis of e-waste with Ca(OH)2 in rotary kilns.
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Affiliation(s)
- Labeeb Ali
- United Arab Emirates University, Department of Chemical and Petroleum EngineeringSheikh Khalifa bin Zayed StreetAl-Ain 15551United Arab Emirates
| | - Kaushik Sivaramakrishnan
- United Arab Emirates University, Department of Chemical and Petroleum EngineeringSheikh Khalifa bin Zayed StreetAl-Ain 15551United Arab Emirates
| | - Mohamed Shafi Kuttiyathil
- United Arab Emirates University, Department of Chemical and Petroleum EngineeringSheikh Khalifa bin Zayed StreetAl-Ain 15551United Arab Emirates
| | | | - Oday H. Ahmed
- Department of Physics, College of Education, Al-Iraqia UniversityBaghdadIraq
| | - Mohammad Al-Harahsheh
- Chemical Engineering Department, Jordan University of Science and TechnologyIrbid 22110Jordan
| | - Mohammednoor Altarawneh
- United Arab Emirates University, Department of Chemical and Petroleum EngineeringSheikh Khalifa bin Zayed StreetAl-Ain 15551United Arab Emirates
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Cao R, Zhou R, Liu Y, Ma D, Wang J, Guan Y, Yao Q, Sun M. Research on the pyrolysis characteristics and mechanisms of waste printed circuit boards at fast and slow heating rates. WASTE MANAGEMENT (NEW YORK, N.Y.) 2022; 149:134-145. [PMID: 35728477 DOI: 10.1016/j.wasman.2022.06.008] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/20/2022] [Revised: 05/24/2022] [Accepted: 06/12/2022] [Indexed: 06/15/2023]
Abstract
The pyrolysis treatment of waste printed circuit boards (WPCBs) shows great potential for sustainable treatment and hazard reduction. In this work, based on thermogravimetry (TG), pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS), and density functional theory (DFT), the thermal weight loss, product distribution, and kinetics of WPCBs pyrolysis were studied by single-step and multi-step pyrolysis at fast (600 °C/min) and slow (10 °C/min) heating rates. The heating rates of TG and Py-GC/MS were the same for each group of experiments. In addition, the bond dissociation energy (BDE) of WPCBs polymer monomers was calculated by DFT method. Compared with slow pyrolysis, the final weight loss of fast pyrolysis is reduced by 0.76 wt%. The kinetic analysis indicates that the activation energies of main pyrolysis stages range from 98.29 kJ/mol to 177.59 kJ/mol. The volatile products of fast pyrolysis are mainly phenols and aromatics. With the increase of multi-step pyrolysis temperature, the order of the escaping volatiles is phenols, hydrocarbyl phenols, aromatics, and benzene (or diphenyl phenol). The pyrolysis residue of WPCBs may contains phenolics and polymers. Based on the free radical reactions, the mechanism and reaction pathways of WPCBs pyrolysis were deduced by the DFT. Moreover, a large amount of benzene is produced by pyrolysis, and its formation mechanism was elaborated.
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Affiliation(s)
- Rui Cao
- School of Chemical Engineering, Northwest University, International Science & Technology Cooperation Base of MOST for Clean Utilization of Hydrocarbon Resources, Chemical Engineering Research Center of the Ministry of Education for Advanced Use Technology of Shanbei Energy, Shaanxi Research Center of Engineering Technology for Clean Coal Conversion, Collaborative Innovation Center for Development of Energy and Chemical Industry in Northern Shaanxi, Xi'an 710069, Shaanxi, China
| | - Ruishi Zhou
- School of Chemical Engineering, Northwest University, International Science & Technology Cooperation Base of MOST for Clean Utilization of Hydrocarbon Resources, Chemical Engineering Research Center of the Ministry of Education for Advanced Use Technology of Shanbei Energy, Shaanxi Research Center of Engineering Technology for Clean Coal Conversion, Collaborative Innovation Center for Development of Energy and Chemical Industry in Northern Shaanxi, Xi'an 710069, Shaanxi, China
| | - Yongqi Liu
- School of Chemical Engineering, Northwest University, International Science & Technology Cooperation Base of MOST for Clean Utilization of Hydrocarbon Resources, Chemical Engineering Research Center of the Ministry of Education for Advanced Use Technology of Shanbei Energy, Shaanxi Research Center of Engineering Technology for Clean Coal Conversion, Collaborative Innovation Center for Development of Energy and Chemical Industry in Northern Shaanxi, Xi'an 710069, Shaanxi, China
| | - Duo Ma
- School of Chemical Engineering, Northwest University, International Science & Technology Cooperation Base of MOST for Clean Utilization of Hydrocarbon Resources, Chemical Engineering Research Center of the Ministry of Education for Advanced Use Technology of Shanbei Energy, Shaanxi Research Center of Engineering Technology for Clean Coal Conversion, Collaborative Innovation Center for Development of Energy and Chemical Industry in Northern Shaanxi, Xi'an 710069, Shaanxi, China
| | - Jing Wang
- School of Chemical Engineering, Northwest University, International Science & Technology Cooperation Base of MOST for Clean Utilization of Hydrocarbon Resources, Chemical Engineering Research Center of the Ministry of Education for Advanced Use Technology of Shanbei Energy, Shaanxi Research Center of Engineering Technology for Clean Coal Conversion, Collaborative Innovation Center for Development of Energy and Chemical Industry in Northern Shaanxi, Xi'an 710069, Shaanxi, China
| | - Yulei Guan
- School of Chemical Engineering, Northwest University, International Science & Technology Cooperation Base of MOST for Clean Utilization of Hydrocarbon Resources, Chemical Engineering Research Center of the Ministry of Education for Advanced Use Technology of Shanbei Energy, Shaanxi Research Center of Engineering Technology for Clean Coal Conversion, Collaborative Innovation Center for Development of Energy and Chemical Industry in Northern Shaanxi, Xi'an 710069, Shaanxi, China
| | - Qiuxiang Yao
- School of Science, Xijing University, Xi'an Key Laboratory of Advanced Photo-electronics Materials and Energy Conversion Device, Xi'an 710123, Shaanxi, China.
| | - Ming Sun
- School of Chemical Engineering, Northwest University, International Science & Technology Cooperation Base of MOST for Clean Utilization of Hydrocarbon Resources, Chemical Engineering Research Center of the Ministry of Education for Advanced Use Technology of Shanbei Energy, Shaanxi Research Center of Engineering Technology for Clean Coal Conversion, Collaborative Innovation Center for Development of Energy and Chemical Industry in Northern Shaanxi, Xi'an 710069, Shaanxi, China.
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9
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Zhang Z, Malik MZ, Khan A, Ali N, Malik S, Bilal M. Environmental impacts of hazardous waste, and management strategies to reconcile circular economy and eco-sustainability. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 807:150856. [PMID: 34627923 DOI: 10.1016/j.scitotenv.2021.150856] [Citation(s) in RCA: 23] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/01/2021] [Revised: 09/22/2021] [Accepted: 10/03/2021] [Indexed: 06/13/2023]
Abstract
The rise in living standards and the continuous development in the global economy led to the depletion of resources and increased waste generation per capita. This waste might posture a significant threat to human health or the environmental matrices (water, air, soil) when inadequately treated, transported, stored, or managed/disposed of. Therefore, effective waste management in an economically viable and environmentally friendly way has become meaningful. Prominent technology is the need of the day for circular economy and sustainable development to reduce the speed of depletion in resources and produce an alternative means for the future demands in the different sectors of science and technology. In order to meet the potential requirements for energy production or producing secondary raw material, solid waste may be the prime source. The activities of living organisms convert waste products in one form or another in which electronic waste (e-waste) is a modern-day problem that is growing by leaps and bounds. The disposal protocols of the e-waste management need to be given proper attention to avoid its hazardous impacts. The e-waste is obtained from any equipment or devices that run by electricity or batteries like laptops, palmtops, computers, televisions, mobile phones, digital video discs (DVD), and many more. E-waste is one of the rapidly growing causes of world pollution today. Plenty of research is available in the scientific literature, which shows different approaches being set up and followed to manage and dispose of waste products. These strategies to manage waste products designed by the states all over the globe revolves around minimal production, authentic techniques for the management of waste produced, reuse and recycling, etc. The virtual survey of the available literature on waste management shows that it lacks specificity regarding the management of waste products parallel to ecological sustainability. The presented review covers the sources, potential environmental impacts, and highlights the importance of waste management strategies to provide the latest and updated knowledge. The review also put forward the countermeasures that need to be taken on national and International levels addressing the sensitive issue of waste management.
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Affiliation(s)
- Zhen Zhang
- Zhejiang Provincial Key Laboratory of Evolutionary Ecology and Conservation, Taizhou University, Taizhou, Zhejiang Province 318000, China
| | - Muhammad Zeeshan Malik
- School of Electronics and Information Engineering, Taizhou University, Taizhou 318000, Zhejiang, China.
| | - Adnan Khan
- Institute of Chemical Sciences, University of Peshawar, Peshawar, Khyber Pakhtunkhwa, Pakistan
| | - Nisar Ali
- Key Laboratory for Palygorskite Science and Applied Technology of Jiangsu Province, National & Local Joint Engineering Research Center for Deep Utilization Technology of Rock-salt Resource, Faculty of Chemical Engineering, Huaiyin Institute of Technology, Huaian, China
| | - Sumeet Malik
- Institute of Chemical Sciences, University of Peshawar, Peshawar, Khyber Pakhtunkhwa, Pakistan
| | - Muhammad Bilal
- School of Life Science and Food Engineering, Huaiyin Institute of Technology, Huaian 223003, China
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Bhui B, Prabu V. Performance of electronic waste based mixed metal oxide as novel oxygen carriers for chemical looping co-combustion of high ash coal and rice straw. WASTE MANAGEMENT (NEW YORK, N.Y.) 2022; 138:199-209. [PMID: 34902682 DOI: 10.1016/j.wasman.2021.11.048] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/06/2021] [Revised: 11/23/2021] [Accepted: 11/30/2021] [Indexed: 06/14/2023]
Abstract
Electronic waste (e-waste) is one of the major pollutants accumulated due to its huge demand and short lifespan. Hence, it is essential to reuse and extract the value added components from e-waste. In this context, firstly, a printed circuit board (PCB) is used to produce calorific valuable gases by pyrolysis and gasification reactions. Secondly, the resultant residue of PCB is combusted to extract metals such as iron, copper, nickel etc. as oxygen carriers for the chemical looping combustion (CLC) process. CLC is an emerging and appealing technology for producing rich CO2 that can be directly sent for sequestration. In the present study, a detailed investigation is performed to ensure the reactivity of the e-waste based metal oxide with high ash coal, rice straw and their blends in the CLC process. CO2 yield, gas conversion, and char conversion are evaluated to assess the performance of the co-combustion based CLC process. It is found that 90.9% CO2 yield, 94.1% gas conversion and 93.2% char conversion can be obtained using the blends of coal and rice straw in the first cycle of the CLC operation. Further, a reduction of 5% to 7% of these parameters is evaluated at the end of the third consecutive cycle of CLC operations. The interaction between coal and rice straw is further studied by evaluating their synergistic effects, char-oxygen carrier interaction and kinetic parameters using a thermogravimetric analyzer under N2 and CO2 atmosphere. The co-combustion process has reduced the activation energy by 13.4% at 800-1000 °C under CO2 atmosphere.
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Affiliation(s)
- Barnali Bhui
- Department of Chemical Engineering, Indian Institute of Technology Guwahati, Assam 781039, India
| | - V Prabu
- Department of Chemical Engineering, Indian Institute of Technology Guwahati, Assam 781039, India.
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Ilyas S, Srivastava RR, Kim H, Ilyas N. Biotechnological recycling of hazardous waste PCBs using Sulfobacillus thermosulfidooxidans through pretreatment of toxicant metals: Process optimization and kinetic studies. CHEMOSPHERE 2022; 286:131978. [PMID: 34426287 DOI: 10.1016/j.chemosphere.2021.131978] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/22/2021] [Revised: 08/18/2021] [Accepted: 08/20/2021] [Indexed: 06/13/2023]
Abstract
The present study dealt with the restricted microbial tolerance for lead and tin during bioleaching of waste printed circuit boards (WPCBs) and lower extraction yields of valuable metals. Pretreatment of WPCBs in 4.0 mol/L HNO3 at 90 °C for 180 min duration prominently dissolved the toxicant metals before the microbial mobilization of valuable metals. Acid pretreatment followed the first-order kinetics that exhibiting an intermediate-controlled mechanism with the apparent activation energy determined to be Ea(Pb), 25.1 kJ/mol and Ea(Sn), 21.9 kJ/mol. Thereafter, the parametric optimization of aeration rate, O2-enrichment, external CO2 supply, temperature, and time for bioleaching of ground WPCBs was examined using Sulfobacillus thermosulfidooxidans (strain RDB). A favourable condition for Cu-bioleaching under higher oxidative environment in comparison to Ni and Zn exhibited the auto-catalytic behaviour of Cu2+ in the biological system. More than 92% of valuable metals were extracted under the optimal condition of aeration rate, 0.5 L/min; O2-enrichement dosage, 30%; external CO2 supply, 0.1%; temperature, 55 °C; and time, 18 days. The bioleaching kinetics followed shrinking core model that exhibiting the shifting of mass transfer from chemically-controlled to the diffusion-controlled mechanism. This process offers two-fold advantages that restoring the valuable metals with low-emission biotechnological route for waste valorization.
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Affiliation(s)
- Sadia Ilyas
- Department of Mineral Resources and Energy Engineering, Jeonbuk National University, Jeonju, Jeonbuk, 54896, Republic of Korea.
| | - Rajiv Ranjan Srivastava
- Center for Advanced Chemistry, Institute of Research and Development, Duy Tan University, Da Nang, 550000, Viet Nam
| | - Hyunjung Kim
- Department of Mineral Resources and Energy Engineering, Jeonbuk National University, Jeonju, Jeonbuk, 54896, Republic of Korea; Department of Environment and Energy, Jeonbuk National University, Jeonju, Jeonbuk, 54896, Republic of Korea.
| | - Nimra Ilyas
- Institute of Microbiology, University of Agriculture, Faisalabad, 38040, Pakistan
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