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Separation of plastic wastes using froth flotation - An overview. Adv Colloid Interface Sci 2022; 308:102769. [PMID: 36116142 DOI: 10.1016/j.cis.2022.102769] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2022] [Revised: 08/29/2022] [Accepted: 08/30/2022] [Indexed: 11/22/2022]
Abstract
Despite various initiatives and efforts, plastic solid waste (PSW) has become a major global problem due to decades of relentless use of plastics. Since non-biodegradable plastics can persist in the environment for hundreds of years, threatening animal and human life, discarding them into the environment is not a viable option. Plastic recycling is a critical research area that requires urgent attention since less than 10% of the seven billion tons of globally generated plastic waste has been recycled so far. With recent technological developments, it is now possible to recycle many types of PSW using a variety of methods. This review provides an overview of the froth flotation technology that is currently being researched for PSW recycling. Fundamental working principles, the current state of the development, and limitations of this technique are reviewed. It is suggested that froth flotation with continuous development has tremendous potential to result in a more efficient and environmentally friendly approach to PSW recycling.
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Chakraborty SC, Zaman MWU, Hoque M, Qamruzzaman M, Zaman JU, Hossain D, Pramanik BK, Nguyen LN, Nghiem LD, Mofijur M, Mondal MIH, Sithi JA, Shahriar SMS, Johir MAH, Ahmed MB. Metals extraction processes from electronic waste: constraints and opportunities. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2022; 29:32651-32669. [PMID: 35220520 DOI: 10.1007/s11356-022-19322-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/15/2021] [Accepted: 02/16/2022] [Indexed: 06/14/2023]
Abstract
The skyrocketing demand and progressive technology have increased our dependency on electrical and electronic devices. However, the life span of these devices has been shortened because of rapid scientific expansions. Hence, massive volumes of electronic waste (e-waste) is generating day by day. Nevertheless, the ongoing management of e-waste has emerged as a major threat to sustainable economic development worldwide. In general, e-waste contains several toxic substances such as metals, plastics, and refractory oxides. Metals, particularly lead, mercury, nickel, cadmium, and copper along with some valuable metals such as rare earth metals, platinum group elements, alkaline and radioactive metal are very common; which can be extracted before disposing of the e-waste for reuse. In addition, many of these metals are hazardous. Therefore, e-waste management is an essential issue. In this study, we critically have reviewed the existing extraction processes and compared among different processes such as physical, biological, supercritical fluid technologies, pyro and hydrometallurgical, and hybrid methods used for metals extraction from e-waste. The review indicates that although each method has particular merits but hybrid methods are eco-friendlier with extraction efficiency > 90%. This study also provides insight into the technical challenges to the practical realization of metals extraction from e-waste sources.
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Affiliation(s)
- Shovra Chandra Chakraborty
- Department of Applied Chemistry and Chemical Engineering, University of Rajshahi, Rajshahi, 6205, Bangladesh
| | - Md Wahad Uz Zaman
- Department of Applied Chemistry and Chemical Engineering, University of Rajshahi, Rajshahi, 6205, Bangladesh
| | - Mozammel Hoque
- Department of Applied Chemistry and Chemical Engineering, University of Rajshahi, Rajshahi, 6205, Bangladesh
| | - Md Qamruzzaman
- Department of Applied Chemistry and Chemical Engineering, University of Rajshahi, Rajshahi, 6205, Bangladesh
| | - Jahid Uz Zaman
- Department of Applied Chemistry and Chemical Engineering, University of Rajshahi, Rajshahi, 6205, Bangladesh
| | - Delowar Hossain
- Department of Applied Chemistry and Chemical Engineering, University of Rajshahi, Rajshahi, 6205, Bangladesh
| | | | - Luong Ngoc Nguyen
- Centre for Technology in Water and Wastewater, School of Civil and Environmental Engineering, University of Technology Sydney, 15, Broadway, Sydney, NSW, 2007, Australia
| | - Long Duc Nghiem
- Centre for Technology in Water and Wastewater, School of Civil and Environmental Engineering, University of Technology Sydney, 15, Broadway, Sydney, NSW, 2007, Australia
| | - Md Mofijur
- Centre for Technology in Water and Wastewater, School of Civil and Environmental Engineering, University of Technology Sydney, 15, Broadway, Sydney, NSW, 2007, Australia
- Mechanical Engineering Department, Prince Mohammad Bin Fahd University, Al Khobar, 31952, Saudi Arabia
| | - Md Ibrahim H Mondal
- Department of Applied Chemistry and Chemical Engineering, University of Rajshahi, Rajshahi, 6205, Bangladesh
| | - Jeni Aprazita Sithi
- Department of Applied Chemistry and Chemical Engineering, University of Rajshahi, Rajshahi, 6205, Bangladesh
| | - Sha Md Shahan Shahriar
- Department of Applied Chemistry and Chemical Engineering, University of Rajshahi, Rajshahi, 6205, Bangladesh
| | - Md Abu Hasan Johir
- Centre for Technology in Water and Wastewater, School of Civil and Environmental Engineering, University of Technology Sydney, 15, Broadway, Sydney, NSW, 2007, Australia.
| | - Mohammad Boshir Ahmed
- Department of Applied Chemistry and Chemical Engineering, University of Rajshahi, Rajshahi, 6205, Bangladesh.
- Centre for Technology in Water and Wastewater, School of Civil and Environmental Engineering, University of Technology Sydney, 15, Broadway, Sydney, NSW, 2007, Australia.
- School of Material Science and Engineering, Gwangju Institute of Science and Technology, Gwangju, 61005, Republic of Korea.
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3
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Meneses Quelal WO, Velázquez-Martí B, Ferrer Gisbert A. Separation of virgin plastic polymers and post-consumer mixed plastic waste by sinking-flotation technique. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2022; 29:1364-1374. [PMID: 34350580 PMCID: PMC8724085 DOI: 10.1007/s11356-021-15611-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/09/2021] [Accepted: 07/20/2021] [Indexed: 06/13/2023]
Abstract
The main objective of this research is to separate virgin polymers (PA, PC, PP, HDPE; PS, and ABS) and post-consumer plastic waste from municipal solid waste (MSW) using the sinking-flotation technique. Separation was carried out on a pilot scale in an 800-l useful volume container with 160 rpm agitation for one hour. Tap water, ethanol solutions, and sodium chloride at different concentrations were used as densification medium. Virgin polymers were separated into two groups: low-density (HDPE and PP) and high-density polymers groups (PS, ABS, PA, and PC). Polymers whose density was less than that of the medium solution floated to the surface, while those whose density was greater than those of the medium solution sank to the bottom. The experimental results showed that complete separation of HDPE from PP achieved 23% ethanol v/v, whereas high-density polymers separated up to 40% w/v sodium chloride. Polymer recovery ranged from 70 to 99.70%. In post-consumer recycled plastic waste, fractions of 29.6% polyolefins, 37.54% PS, 11% ABS, 8% PA, 12% PC PET, and PVC were obtained. Finally, cast plates were made of the post-consumer waste to properly identify the polymer type present in the separated fractions.
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Affiliation(s)
- Washington Orlando Meneses Quelal
- Departamento de Ingeniería Rural and Agroalimentaria, Universitat Politècnica de Valencia, 46022, Camino de Vera s/n, Valencia, Spain
| | - Borja Velázquez-Martí
- Departamento de Ingeniería Rural and Agroalimentaria, Universitat Politècnica de Valencia, 46022, Camino de Vera s/n, Valencia, Spain.
| | - Andrés Ferrer Gisbert
- Departamento de Ingeniería Rural and Agroalimentaria, Universitat Politècnica de Valencia, 46022, Camino de Vera s/n, Valencia, Spain
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Yang T, Xu J, Zhao Y, Gong T, Zhao R, Sun M, Xi B. Classification technology of domestic waste from 2000 to 2019: a bibliometrics-based review. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2021; 28:26313-26324. [PMID: 33818728 DOI: 10.1007/s11356-021-12816-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/14/2020] [Accepted: 02/01/2021] [Indexed: 05/28/2023]
Abstract
Waste classification is to reduce solid waste and its associated environmental pollution. This paper applied bibliometrics to assess publications related to classification technology of domestic waste from 2000 to 2019. A total of 466 publications were retrieved. The results showed the number of citations and papers increased rapidly. The major publication type regarding waste classification technology is article and English is the primary language for academic communication. The research is multidisciplinary and interdisciplinary, and its research directions are mainly divided into "Engineering," "Environmental Sciences Economics," and "Chemistry." It was identified that Waste Management (85) published most of papers in this topic. Meanwhile, China (93) contributed the most of publications, followed by the USA (42), France (40), Japan (36), and Italy (28). European countries are in the leading position in the study of garbage classification technology. Plastics and waste metals were the existing focus of waste classification technology, and waste identification and classification has become an important classification method. In addition, we also summarized the current mainstream technology progress and possible research challenges.
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Affiliation(s)
- Tianxue Yang
- State Key Laboratory of Environmental Criteria and Risk Assessment, State Environmental Protection Key Laboratory of Simulation and Control of Groundwater Pollution, Chinese Research Academy of Environmental Sciences, Beijing, 100012, People's Republic of China
| | - Jiangcheng Xu
- State Key Laboratory of Environmental Criteria and Risk Assessment, State Environmental Protection Key Laboratory of Simulation and Control of Groundwater Pollution, Chinese Research Academy of Environmental Sciences, Beijing, 100012, People's Republic of China
- College of Civil Engineering, Fuzhou University, Fuzhou, 350108, People's Republic of China
| | - Ying Zhao
- State Key Laboratory of Environmental Criteria and Risk Assessment, State Environmental Protection Key Laboratory of Simulation and Control of Groundwater Pollution, Chinese Research Academy of Environmental Sciences, Beijing, 100012, People's Republic of China
| | - Tiancheng Gong
- State Key Laboratory of Environmental Criteria and Risk Assessment, State Environmental Protection Key Laboratory of Simulation and Control of Groundwater Pollution, Chinese Research Academy of Environmental Sciences, Beijing, 100012, People's Republic of China
| | - Rui Zhao
- Faculty of Geosciences and Environmental Engineering, Southwest Jiaotong University, Chengdu, 611756, People's Republic of China
| | - Mengyang Sun
- State Key Laboratory of Environmental Criteria and Risk Assessment, State Environmental Protection Key Laboratory of Simulation and Control of Groundwater Pollution, Chinese Research Academy of Environmental Sciences, Beijing, 100012, People's Republic of China
| | - Beidou Xi
- State Key Laboratory of Environmental Criteria and Risk Assessment, State Environmental Protection Key Laboratory of Simulation and Control of Groundwater Pollution, Chinese Research Academy of Environmental Sciences, Beijing, 100012, People's Republic of China.
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Lee H, Lee H. Separation of auto shredder residue materials using an air table to achieve highly efficient recycling rate. SEP SCI TECHNOL 2020. [DOI: 10.1080/01496395.2020.1824239] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Affiliation(s)
- Hansol Lee
- Resources Recycling, University of Science and Technology, Daejeon, Republic of Korea
| | - Hoon Lee
- Mineral Resources Research Division, Korea Institute of Geoscience and Mineral Resources, Daejeon, Republic of Korea
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6
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Zhao Y, Yang S, Wen H, Shen Z, Han F. Adsorption behavior and selectivity mechanism of flotation reagents applied in ternary plastic mixtures. WASTE MANAGEMENT (NEW YORK, N.Y.) 2019; 87:565-576. [PMID: 31109557 DOI: 10.1016/j.wasman.2019.02.044] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/12/2018] [Revised: 02/21/2019] [Accepted: 02/23/2019] [Indexed: 06/09/2023]
Abstract
Plastic flotation attracts increasing attention in the process of recycling and will bring potential application in industry after theoretical perfection. For a separated ternary system of polyethylene terephthalate (PET), polyvinyl chloride (PVC) and polyethylene (PE), adsorption behavior and selectivity mechanism of flotation reagents were investigated by multi-characterization tests and batch equilibrium adsorption method. Quantitative adsorption results indicate that frother polyethylene glycol (PEG) only acts on gas and liquid phases in the flotation system with negligible adsorption capacity onto solid phase. For depressant sodium lignosulphonate (SL), the pseudo-first-order and Langmuir isotherm models are suitable for corresponding kinetic and equilibrium data of PET or PVC. Thermodynamic parameters further indicate that the adsorption of SL is a spontaneous and endothermic process, which neither belongs to the pure physisorption nor to the pure chemisorption. Adsorption models of SL were established based on hydrogen bond, with three clear bonding types (OH…π*, OH…O, and OH…Cl). Selectivity mechanism can be attributed to the selective hydrogen bond acceptors and donors, which are provided by specific plastic and depressant, respectively. In the light of these theoretical fundings, new targeted reagents or pre-treatments are expected to be developed towards more complex flotation system.
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Affiliation(s)
- Yue Zhao
- Shaanxi Key Laboratory of Disaster Monitoring & Mechanism Simulating, College of Geography and Environment, Baoji University of Arts and Sciences, Baoji 721013, China.
| | - Shengke Yang
- Key Laboratory of Subsurface Hydrology and Ecology in Arid Areas, Ministry of Education, School of Environmental Science and Engineering, Chang'an University, Xi'an 710054, China
| | - Hao Wen
- Key Laboratory of Subsurface Hydrology and Ecology in Arid Areas, Ministry of Education, School of Environmental Science and Engineering, Chang'an University, Xi'an 710054, China
| | - Zhou Shen
- Université de Toulouse, INSA, UPS, INP, LISBP, 135 Avenue de Rangueil, F-31077 Toulouse, France
| | - Fengrong Han
- Laboratory of Intelligent Information Processing, School of Computer, Baoji University of Arts and Sciences, Baoji 721016, China
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7
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Kangal MO, Üçerler Z. Recycling of Virgin and Post-Consumer Polypropylene and High Density Polyethylene. INT POLYM PROC 2018. [DOI: 10.3139/217.3506] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Abstract
Recycling of plastics is becoming more important nowadays due to the increasing amount of waste that is generated worldwide. Post-consumer plastics have a large volume and their harmful effects must be considered. From this perspective, the option of recycling post-consumer plastics has become more and more necessary. The main objective of this research is the selective separation of polypropylene (PP) and high density polyethylene (HDPE). On this basis, various flotation parameters were tested on virgin plastics and optimized conditions were applied to post-consumer plastics. PP particles with a purity of 96.30% were obtained with a recovery rate of 97.4% in virgin polymer separation, while HDPE particles were obtained as the sunken product with 97.38% purity and a recovery rate of 96.3%. Besides, almost all PP and HDPE particles were selectively separated with the highest recovery rates when using 500 g/t calcium lignosulfonate (CLs) as a plasticizer in post-consumer polymer separation. Moreover, water reuse was investigated to determine the recovery and economy of plasticizer without adding extra water during the experiment. Therefore, it can be concluded that this process is environmentally friendly in terms of PP and HDPE recycling and reuse of process water.
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Affiliation(s)
- M. O. Kangal
- Faculty of Mines , Mineral Processing Engineering Department, Istanbul Technical University, Istanbul , Turkey
| | - Z. Üçerler
- Faculty of Mines , Mineral Processing Engineering Department, Istanbul Technical University, Istanbul , Turkey
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8
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Markauskas D, Kruggel-Emden H, Scherer V. Numerical analysis of wet plastic particle separation using a coupled DEM-SPH method. POWDER TECHNOL 2018. [DOI: 10.1016/j.powtec.2017.11.021] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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9
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Gent M, Sierra HM, Menéndez M, de Cos Juez FJ. Evaluation of ground calcite/water heavy media cyclone suspensions for production of residual plastic concentrates. WASTE MANAGEMENT (NEW YORK, N.Y.) 2018; 71:42-51. [PMID: 29107507 DOI: 10.1016/j.wasman.2017.10.025] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/07/2017] [Revised: 09/14/2017] [Accepted: 10/20/2017] [Indexed: 06/07/2023]
Abstract
Viable recycled residual plastic (RP) product(s) must be of sufficient quality to be reusable as a plastic or source of hydrocarbons or fuel. The varied composition and large volumes of such wastes usually requires a low cost, high through-put recycling method(s) to eliminate contaminants. Cyclone separation of plastics by density is proposed as a potential method of achieving separations of specific types of plastics. Three ground calcite separation medias of different grain size distributions were tested in a cylindrical cyclone to evaluate density separations at 1.09, 1.18 and 1.27 g/cm3. The differences in separation recoveries obtained with these medias by density offsets produced due to displacement of separation media solid particles within the cyclone caused by centrifugal settling is evaluated. The separation density at which 50% of the material of that density is recovered was found to increase from 0.010 to 0.026 g/cm3 as the separation media density increased from 1.09 to 1.27 g/cm3. All separation medias were found to have significantly low Ep95values of 0.012-0.033 g/cm3. It is also demonstrated that the presence of an excess content of <10 µm calcite media particles (>75%) resulted in reduced separation efficiencies. It is shown that the optimum separations were achieved when the media density offset was 0.03-0.04 g/cm3. It is shown that effective heavy media cyclone separations of RP denser than 1.0 g/cm3 can produce three sets of mixed plastics containing: PS and ABS/SAN at densities of >1.0-1.09 g/cm3; PC, PMMA at a density of 1.09-1.18 g/cm3; and PVC and PET at a density of >1.27 g/cm3.
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Affiliation(s)
- Malcolm Gent
- School of Mines, Energy and Materials, University of Oviedo, 33004 Oviedo, Spain.
| | - Héctor Muñiz Sierra
- School of Mines, Energy and Materials, University of Oviedo, 33004 Oviedo, Spain
| | - Mario Menéndez
- School of Mines, Energy and Materials, University of Oviedo, 33004 Oviedo, Spain
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Erni-Cassola G, Gibson MI, Thompson RC, Christie-Oleza JA. Lost, but Found with Nile Red: A Novel Method for Detecting and Quantifying Small Microplastics (1 mm to 20 μm) in Environmental Samples. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2017; 51:13641-13648. [PMID: 29112813 DOI: 10.1021/acs.est.7b04512] [Citation(s) in RCA: 353] [Impact Index Per Article: 50.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
Marine plastic debris is a global environmental problem. Surveys have shown that <5 mm plastic particles, known as microplastics, are significantly more abundant in surface seawater and on shorelines than larger plastic particles are. Nevertheless, quantification of microplastics in the environment is hampered by a lack of adequate high-throughput methods for distinguishing and quantifying smaller size fractions (<1 mm), and this has probably resulted in an underestimation of actual microplastic concentrations. Here we present a protocol that allows high-throughput detection and automated quantification of small microplastic particles (20-1000 μm) using the dye Nile red, fluorescence microscopy, and image analysis software. This protocol has proven to be highly effective in the quantification of small polyethylene, polypropylene, polystyrene, and nylon-6 particles, which frequently occur in the water column. Our preliminary results from sea surface tows show a power-law increase in small microplastics (i.e., <1 mm) with a decreasing particle size. Hence, our data help to resolve speculation about the "apparent" loss of this fraction from surface waters. We consider that this method presents a step change in the ability to detect small microplastics by substituting the subjectivity of human visual sorting with a sensitive and semiautomated procedure.
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Affiliation(s)
| | - Matthew I Gibson
- Department of Chemistry, University of Warwick , Coventry CV4 7AL, U.K
- Warwick Medical School, University of Warwick , Coventry CV4 7AL, U.K
| | - Richard C Thompson
- School of Biological and Marine Sciences, Plymouth University , Plymouth PL4 8AA, U.K
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Mallampati SR, Lee BH, Mitoma Y, Simion C. Selective sequential separation of ABS/HIPS and PVC from automobile and electronic waste shredder residue by hybrid nano-Fe/Ca/CaO assisted ozonisation process. WASTE MANAGEMENT (NEW YORK, N.Y.) 2017; 60:428-438. [PMID: 28089400 DOI: 10.1016/j.wasman.2017.01.003] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/25/2016] [Revised: 01/02/2017] [Accepted: 01/02/2017] [Indexed: 06/06/2023]
Abstract
The separation of plastics containing brominated flame retardants (BFR) like (acrylonitrile-butadiene-styrene (ABS), high-impact polystyrene (HIPS), and polyvinyl chloride (PVC)) from automobile and electronic waste shredder residue (ASR/ESR) are a major concern for thermal recycling. In laboratory scale tests using a hybrid nano-Fe/Ca/CaO assisted ozonation treatment has been found to selectively hydrophilize the surface of ABS/HIPS and PVC plastics, enhancing ABS wettability and thereby promoting its separation from ASR/ESR by means of froth flotation. The water contact angles, of ABS/HIPS and PVC decreased, about 18.7°, 18.3°, and 17.9° in ASR and about 21.2°, 20.7°, and 20.0° in ESR respectively. SEM-EDS, FT-IR, and XPS analyses demonstrated a marked decrease in [Cl] and a significant increase in the number of hydrophilic groups, such as CO, CO, and (CO)O, on the PVC or ABS surface. Under froth flotation conditions at 50rpm, about 99.1% of combined fraction of ABS/HIPS in ASR samples and 99.6% of ABS/HIPS in ESR samples were separated as settled fraction. After separation, the purity of the recovered combined ABS/HIPS fraction was 96.5% and 97.6% in ASR and ESR samples respectively. Furthermore, at 150rpm a 100% PVC separation in the settled fraction, with 98% and 99% purity in ASR and ESR plastics, respectively. Total recovery of non-ABS/HIPS and PVC plastics reached nearly 100% in the floating fraction. Further, this process improved the quality of recycled ASR/ESR plastics by removing surface contaminants or impurities.
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Affiliation(s)
- Srinivasa Reddy Mallampati
- Department of Civil and Environmental Engineering, University of Ulsan, Daehak-ro 93, Nam-gu, Ulsan 680-749, Republic of Korea.
| | - Byoung Ho Lee
- Department of Civil and Environmental Engineering, University of Ulsan, Daehak-ro 93, Nam-gu, Ulsan 680-749, Republic of Korea
| | - Yoshiharu Mitoma
- Department of Environmental Sciences, Prefectural University of Hiroshima, 562 Nanatsuka-Cho, Shobara City, Hiroshima 727-0023, Japan
| | - Cristian Simion
- Politehnica University of Bucharest, Department of Organic Chemistry, Bucharest 060042, Romania.
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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: 210] [Impact Index Per Article: 26.3] [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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13
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Lupo E, Moroni M, La Marca F, Fulco S, Pinzi V. Investigation on an innovative technology for wet separation of plastic wastes. WASTE MANAGEMENT (NEW YORK, N.Y.) 2016; 51:3-12. [PMID: 26969287 DOI: 10.1016/j.wasman.2016.02.030] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/05/2016] [Revised: 02/12/2016] [Accepted: 02/23/2016] [Indexed: 06/05/2023]
Abstract
This paper presents an original device for the separation of plastic polymers from mixtures. Due to the combination of a characteristic flow pattern developing within the apparatus and density, shape and size differences among two or more polymers, this device allows their separation into two products, one collected within the instrument and the other one expelled through its outlet ducts. Experimental tests have been conducted to investigate the effectiveness of the apparatus, using two geometric arrangements, nine hydraulic configurations and three selections of polymers at three stages of a material life cycle. Tests with samples composed of a single typology of polymer have been used to understand the interaction between the particles and the carrying fluid within the apparatus in different hydraulic configurations and geometric arrangements. Multi-material tests are essential to simulate the real conditions in an industrial recycling plant. The separation results have been evaluated in terms of grade and recovery of a useful material. Under the proper hydraulic configurations, the experimentation showed that it is possible to produce an almost pure concentrate of Polyethylene Terephthalate (PET) from a mixture of 85% PET and 15% Polycarbonate (PC) (concentrate grade and recovery equal to 99.5% and 95.1%) and a mixture of 85% PET and 15% Polyvinyl Chloride (PVC) (concentrate grade and recovery equal to 97.9% and 100.0%). It is further demonstrated that almost pure concentrates of PVC and PC can be produced from a mixture of 85% PVC and 15% PC (PVC grade and recovery equal to 99.9% and 99.7%) and a mixture of 85% PC and 15% PVC (PC grade and recovery equal to 99.0% and 99.5%).
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Affiliation(s)
- Emanuela Lupo
- DICEA-Sapienza University of Rome, via Eudossiana 18, 00184 Rome, Italy.
| | - Monica Moroni
- DICEA-Sapienza University of Rome, via Eudossiana 18, 00184 Rome, Italy.
| | - Floriana La Marca
- DICMA-Sapienza University of Rome, via Eudossiana 18, 00184 Rome, Italy.
| | - Simone Fulco
- DICMA-Sapienza University of Rome, via Eudossiana 18, 00184 Rome, Italy
| | - Valentina Pinzi
- DICMA-Sapienza University of Rome, via Eudossiana 18, 00184 Rome, Italy
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Wang CQ, Wang H, Gu GH, Fu JG, Lin QQ, Liu YN. Interfacial interactions between plastic particles in plastics flotation. WASTE MANAGEMENT (NEW YORK, N.Y.) 2015; 46:56-61. [PMID: 26337962 DOI: 10.1016/j.wasman.2015.08.041] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/21/2015] [Revised: 08/25/2015] [Accepted: 08/28/2015] [Indexed: 06/05/2023]
Abstract
Plastics flotation used for recycling of plastic wastes receives increasing attention for its industrial application. In order to study the mechanism of plastics flotation, the interfacial interactions between plastic particles in flotation system were investigated through calculation of Lifshitz-van der Waals (LW) function, Lewis acid-base (AB) Gibbs function, and the extended Derjaguin-Landau-Verwey-Overbeek potential energy profiles. The results showed that van der Waals force between plastic particles is attraction force in flotation system. The large hydrophobic attraction, caused by the AB Gibbs function, is the dominant interparticle force. Wetting agents present significant effects on the interfacial interactions between plastic particles. It is found that adsorption of wetting agents promotes dispersion of plastic particles and decreases the floatability. Pneumatic flotation may improve the recovery and purity of separated plastics through selective adsorption of wetting agents on plastic surface. The relationships between hydrophobic attraction and surface properties were also examined. It is revealed that there exists a three-order polynomial relationship between the AB Gibbs function and Lewis base component. Our finding provides some insights into mechanism of plastics flotation.
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Affiliation(s)
- Chong-qing Wang
- School of Chemistry and Chemical Engineering, Key Laboratory of Resource Chemistry of Nonferrous Metals, Ministry of Education, Central South University, Changsha, Hunan 410083, China.
| | - Hui Wang
- School of Chemistry and Chemical Engineering, Key Laboratory of Resource Chemistry of Nonferrous Metals, Ministry of Education, Central South University, Changsha, Hunan 410083, China.
| | - Guo-hua Gu
- School of Minerals Processing and Bioengineering, Central South University, Changsha, Hunan 410083, China.
| | - Jian-gang Fu
- School of Chemistry and Chemical Engineering, Key Laboratory of Resource Chemistry of Nonferrous Metals, Ministry of Education, Central South University, Changsha, Hunan 410083, China.
| | - Qing-quan Lin
- School of Minerals Processing and Bioengineering, Central South University, Changsha, Hunan 410083, China.
| | - You-nian Liu
- School of Chemistry and Chemical Engineering, Key Laboratory of Resource Chemistry of Nonferrous Metals, Ministry of Education, Central South University, Changsha, Hunan 410083, China.
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15
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Wang CQ, Wang H, Fu JG, Liu YN. Flotation separation of waste plastics for recycling-A review. WASTE MANAGEMENT (NEW YORK, N.Y.) 2015; 41:28-38. [PMID: 25869841 DOI: 10.1016/j.wasman.2015.03.027] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/23/2014] [Revised: 03/16/2015] [Accepted: 03/18/2015] [Indexed: 06/04/2023]
Abstract
The sharp increase of plastic wastes results in great social and environmental pressures, and recycling, as an effective way currently available to reduce the negative impacts of plastic wastes, represents one of the most dynamic areas in the plastics industry today. Froth flotation is a promising method to solve the key problem of recycling process, namely separation of plastic mixtures. This review surveys recent literature on plastics flotation, focusing on specific features compared to ores flotation, strategies, methods and principles, flotation equipments, and current challenges. In terms of separation methods, plastics flotation is divided into gamma flotation, adsorption of reagents, surface modification and physical regulation.
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Affiliation(s)
- Chong-qing Wang
- School of Chemistry and Chemical Engineering, Key Laboratory of Resource Chemistry of Nonferrous Metals, Ministry of Education, Central South University, Changsha, 410083 Hunan, China.
| | - Hui Wang
- School of Chemistry and Chemical Engineering, Key Laboratory of Resource Chemistry of Nonferrous Metals, Ministry of Education, Central South University, Changsha, 410083 Hunan, China.
| | - Jian-gang Fu
- School of Chemistry and Chemical Engineering, Key Laboratory of Resource Chemistry of Nonferrous Metals, Ministry of Education, Central South University, Changsha, 410083 Hunan, China.
| | - You-nian Liu
- School of Chemistry and Chemical Engineering, Key Laboratory of Resource Chemistry of Nonferrous Metals, Ministry of Education, Central South University, Changsha, 410083 Hunan, China.
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16
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Serranti S, Luciani V, Bonifazi G, Hu B, Rem PC. An innovative recycling process to obtain pure polyethylene and polypropylene from household waste. WASTE MANAGEMENT (NEW YORK, N.Y.) 2015; 35:12-20. [PMID: 25458766 DOI: 10.1016/j.wasman.2014.10.017] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/09/2014] [Revised: 10/14/2014] [Accepted: 10/15/2014] [Indexed: 05/15/2023]
Abstract
An innovative recycling process, based on magnetic density separation (MDS) and hyperspectral imaging (HSI), to obtain high quality polypropylene and polyethylene as secondary raw materials, is presented. More in details, MDS was applied to two different polyolefin mixtures coming from household waste. The quality of the two separated PP and PE streams, in terms of purity, was evaluated by a classification procedure based on HSI working in the near infrared range (1000-1700 nm). The classification model was built using known PE and PP samples as training set. The results obtained by HSI were compared with those obtained by classical density analysis carried in laboratory on the same polymers. The results obtained by MDS and the quality assessment of the plastic products by HSI showed that the combined action of these two technologies is a valid solution that can be implemented at industrial level.
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Affiliation(s)
- Silvia Serranti
- DICMA, Department of Chemical Engineering, Materials and Environment, Sapienza University of Rome, Via Eudossiana 18, 00184 Rome, Italy.
| | - Valentina Luciani
- DICMA, Department of Chemical Engineering, Materials and Environment, Sapienza University of Rome, Via Eudossiana 18, 00184 Rome, Italy
| | - Giuseppe Bonifazi
- DICMA, Department of Chemical Engineering, Materials and Environment, Sapienza University of Rome, Via Eudossiana 18, 00184 Rome, Italy
| | - Bin Hu
- Faculty of Civil Engineering and Geosciences, Delft University of Technology, 2628 CN Delft, The Netherlands
| | - Peter C Rem
- Faculty of Civil Engineering and Geosciences, Delft University of Technology, 2628 CN Delft, The Netherlands
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17
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Wang CQ, Wang H, Liu Q, Fu JG, Liu YN. Separation of polycarbonate and acrylonitrile-butadiene-styrene waste plastics by froth flotation combined with ammonia pretreatment. WASTE MANAGEMENT (NEW YORK, N.Y.) 2014; 34:2656-2661. [PMID: 25266156 DOI: 10.1016/j.wasman.2014.09.002] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/04/2014] [Revised: 09/02/2014] [Accepted: 09/09/2014] [Indexed: 06/03/2023]
Abstract
The objective of this research is flotation separation of polycarbonate (PC) and acrylonitrile-butadiene-styrene (ABS) waste plastics combined with ammonia pretreatment. The PC and ABS plastics show similar hydrophobicity, and ammonia treatment changes selectively floatability of PC plastic while ABS is insensitive to ammonia treatment. The contact angle measurement indicates the dropping of flotation recovery of PC is ascribed to a decline of contact angle. X-ray photoelectron spectroscopy demonstrates reactions occur on PC surface, which makes PC surface more hydrophilic. Separation of PC and ABS waste plastics was conducted based on the flotation behavior of single plastic. At different temperatures, PC and ABS mixtures were separated efficiently through froth flotation with ammonia pretreatment for different time (13 min at 23 °C, 18 min at 18 °C and 30 min at 23 °C). For both PC and ABS, the purity and recovery is more than 95.31% and 95.35%, respectively; the purity of PC and ABS is up to 99.72% and 99.23%, respectively. PC and ABS mixtures with different particle sizes were separated effectively, implying that ammonia treatment possesses superior applicability.
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Affiliation(s)
- Chong-Qing Wang
- School of Chemistry and Chemical Engineering, Key Laboratory of Resources Chemistry of Nonferrous Metals, Ministry of Education, Central South University, Changsha 410083, Hunan, China
| | - Hui Wang
- School of Chemistry and Chemical Engineering, Key Laboratory of Resources Chemistry of Nonferrous Metals, Ministry of Education, Central South University, Changsha 410083, Hunan, China.
| | - Qun Liu
- School of Chemistry and Chemical Engineering, Key Laboratory of Resources Chemistry of Nonferrous Metals, Ministry of Education, Central South University, Changsha 410083, Hunan, China
| | - Jian-Gang Fu
- School of Chemistry and Chemical Engineering, Key Laboratory of Resources Chemistry of Nonferrous Metals, Ministry of Education, Central South University, Changsha 410083, Hunan, China
| | - You-Nian Liu
- School of Chemistry and Chemical Engineering, Key Laboratory of Resources Chemistry of Nonferrous Metals, Ministry of Education, Central South University, Changsha 410083, Hunan, China.
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18
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Wang CQ, Wang H, Wu BX, Liu Q. Boiling treatment of ABS and PS plastics for flotation separation. WASTE MANAGEMENT (NEW YORK, N.Y.) 2014; 34:1206-1210. [PMID: 24602834 DOI: 10.1016/j.wasman.2014.02.005] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/09/2013] [Revised: 01/10/2014] [Accepted: 02/06/2014] [Indexed: 06/03/2023]
Abstract
A new physical method, namely boiling treatment, was developed to aid flotation separation of acrylonitrile-butadiene-styrene (ABS) and polystyrene (PS) plastics. Boiling treatment was shown to be effective in producing a hydrophilic surface on ABS plastic. Fourier Transform Infrared analysis was conducted to investigate the mechanism of boiling treatment of ABS. Surface rearrangement of polymer may be responsible for surface change of boiling treated ABS, and the selective influence of boiling treatment on the floatability of boiling treated plastics may be attributed to the difference in the molecular mobility of polymer chains. The effects of flotation time, frother concentration and particle size on flotation behavior of simple plastic were investigated. Based on flotation behavior of simple plastic, flotation separation of boiling treatment ABS and PS with different particle sizes was achieved efficiently. The purity of ABS and PS was up to 99.78% and 95.80%, respectively; the recovery of ABS and PS was up to 95.81% and 99.82%, respectively. Boiling treatment promotes the industrial application of plastics flotation and facilitates plastic recycling.
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Affiliation(s)
- Chong-qing Wang
- School of Chemistry and Chemical Engineering, Key Laboratory of Resources Chemistry of Nonferrous Metals, Ministry of Education, Central South University, Changsha, 410083 Hunan, China
| | - Hui Wang
- School of Chemistry and Chemical Engineering, Key Laboratory of Resources Chemistry of Nonferrous Metals, Ministry of Education, Central South University, Changsha, 410083 Hunan, China.
| | - Bao-xin Wu
- School of Chemistry and Chemical Engineering, Key Laboratory of Resources Chemistry of Nonferrous Metals, Ministry of Education, Central South University, Changsha, 410083 Hunan, China
| | - Qun Liu
- School of Chemistry and Chemical Engineering, Key Laboratory of Resources Chemistry of Nonferrous Metals, Ministry of Education, Central South University, Changsha, 410083 Hunan, China
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19
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Wang H, Wang CQ, Fu JG, Gu GH. Flotability and flotation separation of polymer materials modulated by wetting agents. WASTE MANAGEMENT (NEW YORK, N.Y.) 2014; 34:309-315. [PMID: 24355830 DOI: 10.1016/j.wasman.2013.11.007] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/22/2013] [Revised: 11/17/2013] [Accepted: 11/19/2013] [Indexed: 06/03/2023]
Abstract
The surface free energy, surface tension and contact angles were performed to investigate the properties of wetting agents. Adsorption of wetting agents changes wetting behavior of polymer resins. Flotability of polymer materials modulated by wetting agents was studied, and wetting agents change significantly flotability of polymer materials. The flotability decreases with increasing the concentration of wetting agents, and the wetting ability is lignin sulfonate (LS)>tannic acid (TA)>methylcellulose (MC)>triton X-100 (TX-100) (from strong to weak). There is significant difference in the flotability between polymer resins and plastics due to the presence of additives in the plastics. Flotation separation of two-component and multicomponent plastics was conducted based on the flotability modulated by wetting agents. The two-component mixtures can be efficiently separated using proper wetting agent through simple flotation flowsheet. The multicomponent plastic mixtures can be separated efficiently through multi-stage flotation using TA and LS as wetting agents, and the purity of separated component was above 94%, and the recovery was more than 93%.
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Affiliation(s)
- Hui Wang
- School of Chemistry and Chemical Engineering, Key Laboratory of Resources Chemistry of Nonferrous Metals, Ministry of Education, Central South University, Changsha, 410083 Hunan, China.
| | - Chong-qing Wang
- School of Chemistry and Chemical Engineering, Key Laboratory of Resources Chemistry of Nonferrous Metals, Ministry of Education, Central South University, Changsha, 410083 Hunan, China
| | - Jian-gang Fu
- School of Chemistry and Chemical Engineering, Key Laboratory of Resources Chemistry of Nonferrous Metals, Ministry of Education, Central South University, Changsha, 410083 Hunan, China
| | - Guo-hua Gu
- School of Minerals Processing and Bioengineering, Central South University, Changsha, 410083 Hunan, China
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20
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21
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Vidyadhar A, Das A. Enrichment implication of froth flotation kinetics in the separation and recovery of metal values from printed circuit boards. Sep Purif Technol 2013. [DOI: 10.1016/j.seppur.2013.07.027] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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22
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Guney A, Poyraz MI, Kangal O, Burat F. Investigation of thermal treatment on selective separation of post consumer plastics prior to froth flotation. WASTE MANAGEMENT (NEW YORK, N.Y.) 2013; 33:1795-1799. [PMID: 23747135 DOI: 10.1016/j.wasman.2013.05.006] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/30/2013] [Revised: 03/26/2013] [Accepted: 05/03/2013] [Indexed: 06/02/2023]
Abstract
Plastics have become the widely used materials because of their advantages, such as cheapness, endurance, lightness, and hygiene. However, they cause waste and soil pollution and they do not easily decompose. Many promising technologies are being investigated for separating mixed thermoplastics, but they are still uneconomical and unreliable. Depending on their surface characteristics, these plastics can be separated from each other by flotation method which is useful mineral processing technique with its low cost and simplicity. The main objective of this study is to investigate the flotation characteristics of PET and PVC and determine the effect of plasticizer reagents on efficient plastic separation. For that purpose, various parameters such as pH, plasticizer concentration, plasticizer type, conditioning temperature and thermal conditioning were investigated. As a result, PET particles were floated with 95.1% purity and 65.3% efficiency while PVC particles were obtained with 98.1% purity and 65.3% efficiency.
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Affiliation(s)
- Ali Guney
- Istanbul Technical University, Faculty of Mines, Mineral Processing Engineering Department, 34469 Maslak, Istanbul, Turkey
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23
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Yenial U, Kangal O, Güney A. Selective flotation of PVC using gelatin and lignin alkali. WASTE MANAGEMENT & RESEARCH : THE JOURNAL OF THE INTERNATIONAL SOLID WASTES AND PUBLIC CLEANSING ASSOCIATION, ISWA 2013; 31:613-617. [PMID: 23439876 DOI: 10.1177/0734242x13476748] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Recycling has become one of the most important issues as a result of increasing waste mass in present day. This is especially important for polymer wastes as they are hard to degenerate in nature. Today, most of the practical methods used for the recycling of waste mass, such as hand sorting, gravity separation, etc., cannot be performed successfully owing to close densities of polymers. Froth flotation can be used successfully and economically for this purpose. The main objective of this study was to investigate the effect of plasticizer reagents and the success of froth flotation at plastic recycling. In this study, lignin alkali and gelatin were used as plasticizer reagents. The effect of these reagents was searched with the parameters of pH, concentration, conditioning and flotation time. In the case of post-consumed polyethylene terephthalate and polyvinyl chloride (PVC), 98.9% purity of PVC was obtained at optimum conditions.
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Affiliation(s)
- Unzile Yenial
- Istanbul Technical University, Faculty of Mines, Mineral Processing Engineering Department, Istanbul, Turkey.
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24
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Donaj PJ, Kaminsky W, Buzeto F, Yang W. Pyrolysis of polyolefins for increasing the yield of monomers' recovery. WASTE MANAGEMENT (NEW YORK, N.Y.) 2012; 32:840-846. [PMID: 22093704 DOI: 10.1016/j.wasman.2011.10.009] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/02/2011] [Revised: 09/09/2011] [Accepted: 10/04/2011] [Indexed: 05/28/2023]
Abstract
Pyrolysis of plastic waste is an alternative way of plastic recovery and could be a potential solution for the increasing stream of solid waste. The objective of this work was to increase the yield the gaseous olefins (monomers) as feedstock for polymerization process and to test the applicability of a commercial Ziegler-Natta (Z-N): TiCl(4)/MgCl(2) for cracking a mixture of polyolefins consisted of 46%wt. of low density polyethylene (LDPE), 30%wt. of high density polyethylene (HDPE) and 24%wt. of polypropylene (PP). Two sets of experiments have been carried out at 500 and 650°C via catalytic pyrolysis (1% of Z-N catalyst) and at 650 and 730°C via only-thermal pyrolysis. These experiments have been conducted in a lab-scale, fluidized quartz-bed reactor of a capacity of 1-3kg/h at Hamburg University. The results revealed a strong influence of temperature and presence of catalyst on the product distribution. The ratios of gas/liquid/solid mass fractions via thermal pyrolysis were: 36.9/48.4/15.7%wt. and 42.4/44.7/13.9%wt. at 650 and 730°C while via catalytic pyrolysis were: 6.5/89.0/4.5%wt. and 54.3/41.9/3.8%wt. at 500 and 650°C, respectively. At 650°C the monomer generation increased by 55% up to 23.6%wt. of total pyrolysis products distribution while the catalyst was added. Obtained yields of olefins were compared with the naphtha steam cracking process and other potentially attractive processes for feedstock generation. The concept of closed cycle material flow for polyolefins has been discussed, showing the potential benefits of feedstock recycling in a plastic waste management.
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Affiliation(s)
- Pawel J Donaj
- Royal Institute of Technology, School of Industrial Engineering and Management, Division of Energy and Furnace Technology, Brinellvagen 23, 100-44 Stockholm, Sweden.
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Park CH, Jeon HS, Yu HS, Han OH, Park JK. Application of electrostatic separation to the recycling of plastic wastes: separation of PVC, PET, and ABS. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2008; 42:249-255. [PMID: 18350904 DOI: 10.1021/es070698h] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Plastics are widely used in everyday life as a useful material, and thus their consumption is growing at a rate of about 5% per year in Korea. However, the constant generation of plastic wastes and their disposal generates environmental problems along with economic loss. In particular, mixed waste plastics are difficult to recycle because of their inferior characteristics. A laboratory-scale triboelectrostatic separator unit has been designed and assembled for this study. On the basis of the control of electrostatic charge, the separation of three kinds of mixed plastics, polyvinyl chloride (PVC), poly(ethylene terephthalate) (PET), and acrylonitrile-butadiene-styrene (ABS), in a range of similar gravities has been performed through a two-stage separation process. Polypropylene (PP) and high-impact polystyrene (HIPS) were found to be the most effective materials for a tribo-charger in the separation of PVC, PET, and ABS. The charge-to-mass ratio (nC/g) of plastics increased with increasing air velocity in the tribo charger. In the first stage, using the PP cyclone charger, the separation efficiency of particles considerably depended on the air velocity (10 m/s), the relative humidity (< 30%), the electrode potential (> 20 kV), and the splitter position (+2 cm from the center) in the triboelelctrostatic separator unit. At this time, a PVC grade of 99.40% and a recovery of 98.10% have successfully been achieved. In the second stage, using the HIPS cyclone charger, a PET grade of 97.80% and a recovery of 95.12% could be obtained under conditions of 10 m/s, over 25 kV, a central splitter position, and less than 40% relative humidity. In order to obtain 99.9% PVC grade and 99.3% PET grade, their recoveries should be sacrificed by 20.9% and 27%, respectively, with moving the splitter from the center to a (+)6 cm position.
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Affiliation(s)
- Chul-Hyun Park
- Hanyang University, Department of Geoenvironmental System Engineering, Seoul, Korea
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Carvalho MT, Agante E, Durão F. Recovery of PET from packaging plastics mixtures by wet shaking table. WASTE MANAGEMENT (NEW YORK, N.Y.) 2007; 27:1747-54. [PMID: 17118640 DOI: 10.1016/j.wasman.2006.08.015] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/21/2005] [Revised: 07/26/2006] [Accepted: 08/24/2006] [Indexed: 05/12/2023]
Abstract
Recycling requires the separation of materials appearing in a mass of wastes of heterogeneous composition and characteristics, into single, almost pure, component/material flows. The separation of materials (e.g., some types of plastics) with similar physical properties (e.g., specific gravity) is often accomplished by human sorting. This is the case of the separation of packaging plastics in municipal solid wastes (MSW). The low cost of virgin plastics and low value of recycled plastics necessitate the utilization of low cost techniques and processes in the recycling of packaging plastics. An experimental study was conducted to evaluate the feasibility of production of a PET product, cleaned from PVC and PS, using a wet shaking table. The wet shaking table is an environmentally friendly process, widely used to separate minerals, which has low capital and operational costs. Some operational variables of the equipment, as well as different feed characteristics, were considered. The results show that the separation of these plastics is feasible although, similarly to the mineral field, in somewhat complex flow sheets.
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Affiliation(s)
- M T Carvalho
- CVRM - Centro de Geosistemas, Instituto Superior Tecnico - Av. Rovisco Pais, 1049-001 Lisbon, Portugal.
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27
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Park CH, Jeon HS, Cho BG, Park JK. Triboelectrostatic separation of covering plastics in chopped waste electric wire. POLYM ENG SCI 2007. [DOI: 10.1002/pen.20810] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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28
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