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1.
Waste Manag ; 114: 53-61, 2020 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-32659687

RESUMO

Spent liquid crystal displays (LCDs) are a secondary source of precious/strategic metals, including indium (In). The present study involved optimizing the solubilization of this strategic element from samples of indium tin oxide (ITO) glass prepared from LCD screens of computer monitors and laptop screens. The influence of operating conditions on In solubilization, as well as optimum conditions for sulfuric acid leaching were defined by a Box-Behnken-type experimental design methodology. Optimum operating conditions include a leaching step for 30 min at a temperature of 70 °C in the presence of 0.4 N H2SO4 and a pulp density of 50% (w/v). Under these conditions, the quadratic model established to predict the solubilization of In from ITO glass samples provided an In solubilization efficiency of 89.7%, which was validated experimentally (99.5%). The analysis of direct operating costs and capital costs for the implementation of such a leaching process revealed that the process is conceivable for a high-capacity plant processing ~100 t/day of ITO glass.


Assuntos
Resíduo Eletrônico/análise , Cristais Líquidos , Vidro , Índio , Reciclagem
2.
Environ Sci Pollut Res Int ; 27(25): 32116-32123, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32557023

RESUMO

Plastic waste of electrical and electronic equipment (WEEE) can contain polybrominated diphenyl ethers (PBDEs) that have been used as fire retardants for a long time. PBDEs were listed in the Stockholm Convention as persistent organic pollutants, so PBDE-containing plastic waste should be separated and disposed of in an ecologically sound manner. In the article, the results of bromine and PBDE content in plastic samples of WEEE collected in Belarus are presented. The screening method for bromine identification and HRGC/HRMS for PBDE identification were applied. It is shown that bromine is present in 43% of the 111 studied samples. Most often, Br-containing plastic was found in CRT monitor, CRT TVs and LCD monitor (about 50%), printers (35%), and LCD TVs (25%). PBDEs were revealed in 12 Br-containing samples, representing TVs, monitors, and printers. The sum of ∑10PBDEs varied from 6.6 to 21,000 µg/kg. BDE-209 dominated in 9 samples (75% of cases); BDE-183, in two; and BDE-47 and BDE-99, in one sample. Based on the low content of PBDEs in the plastic, year of equipment production, and year of restriction of PBDEs applied in the countries-manufacturers, it was concluded that the presence of PBDEs in plastic is a consequence of contaminated waste recycling. Despite the relatively low concentrations of PBDEs (below the limit values established by the Stockholm and Basel conventions for POP wastes), further research is necessary with an extension of the list of analyzed types of equipment and identification of other brominated flame retardants.


Assuntos
Resíduo Eletrônico/análise , Retardadores de Chama/análise , Monitoramento Ambiental , Éteres Difenil Halogenados/análise , Plásticos , República de Belarus
3.
Sci Total Environ ; 737: 139745, 2020 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-32516663

RESUMO

E-waste is discarded and shipped mostly to developing countries located in Asian continent for disposal from other developed countries. Especially 70% of the world's e-waste ends up in Guiyu, a small town located in Guangdong Province of China. As little as 25% is recycled in formal recycling centers with adequate protection for workers and the other e-waste arrived in those areas is not handled in organized manner. As per reports only roughly 12.5% of e-waste is actually recycled, and the recycling efforts in those regions are primitive and result in toxic substances being leached into the surrounding ecosystems. In addition to persistent organic pollutants, there are many heavy metals found in the ground and river sediments in Guiyu, exceeding the threshold set to protect human health. Those areas are no longer suitable for growing food, and water is unsafe for drinking, due to the amount of toxins leached into the groundwater and land. Hazardous threats to environment and human health due to hazardous substances of e-waste all around China, as well as the current e-waste management were documented in this review. The article concludes with controlled contamination sources, and eco-friendly and efficient remediation technologies to solve e-waste problem in China.


Assuntos
Resíduo Eletrônico , Metais Pesados/análise , Eliminação de Resíduos , China , Ecossistema , Humanos , Reciclagem
4.
Waste Manag ; 112: 1-10, 2020 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-32474304

RESUMO

The possibility of a pyrolysis process as a mean of recycling the residual plastic rich fraction (WEEE residue) derived from of a material recovery facility has been evaluated. The unknown product composition of WEEE residue has been supposed through coupled thermal - infrared analysis and ultimate analysis and resulted as PP 3 wt%, PBT 3 wt%, PVC 4 wt%, styrene-based polymers (principally ABS) 50 wt%, thermosetting resins (principally, epoxy/phenolic resins) 24 wt%, inorganic fraction (principally fiber glass) 16 wt%. DSC experiments showed that the overall energy, defined as the degradation heat, needed in order to completely degrade WEEE residue was about 4% of the exploitable energy of the input material. The effect of temperature and different zeolite catalysts were investigated, in particular in terms of yield and quality of the produced oils during the pyrolysis process. Produced oils were potentially exploitable as fuels and almost all catalysts improved their quality. The best performance was reached by NaUSY(5.7) with the second highest production of light oil and the greatest total monoaromatics yield, plus 12 wt% in comparison to thermal pyrolysis experiments. Furthermore, light oil produced by NaUSY(5.7) has one of the best LHV (36 MJ/kg) and no halogenated compounds were detected by GC-MS analysis. Char or pyrolytic gas combustion could supply the energy required for the thermal degradation of WEEE Residue.


Assuntos
Resíduo Eletrônico , Plásticos , Poliestirenos , Pirólise , Reciclagem
5.
Waste Manag ; 109: 1-9, 2020 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-32361385

RESUMO

This study investigates an image recognition system for the identification and classification of waste electrical and electronic equipment from photos. Its main purpose is to facilitate information exchange regarding the waste to be collected from individuals or from waste collection points, thereby exploiting the wide acceptance and use of smartphones. To improve waste collection planning, individuals would photograph the waste item and upload the image to the waste collection company server, where it would be recognized and classified automatically. The proposed system can be operated on a server or through a mobile app. A novel method of classification and identification using neural networks is proposed for image analysis: a deep learning convolutional neural network (CNN) was applied to classify the type of e-waste, and a faster region-based convolutional neural network (R-CNN) was used to detect the category and size of the waste equipment in the images. The recognition and classification accuracy of the selected e-waste categories ranged from 90 to 97%. After the size and category of the waste is automatically recognized and classified from the uploaded images, e-waste collection companies can prepare a collection plan by assigning a sufficient number of vehicles and payload capacity for a specific e-waste project.


Assuntos
Aprendizado Profundo , Resíduo Eletrônico , Humanos , Redes Neurais de Computação
6.
Environ Sci Pollut Res Int ; 27(21): 26511-26519, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32367235

RESUMO

As observed among residents in electronic waste (e-waste) recycling areas, dioxins can disrupt the homeostasis of endocrine hormones and the balance of thyroid hormones. Few studies, however, have examined whether e-waste recycling activities influence steroid hormone equilibrium in the general adult male population. This study evaluated the association between steroid hormones and the physical burdens of dioxins in the general adult male population residing in an e-waste region. In September 2017, 74 adult males residing in an e-waste dismantling region were enrolled in the current study. Approximately 10 mL of blood was collected from each adult male, and the serum samples were separated through centrifugation. Then, the levels of dioxin and steroid hormones in the serum of the participants were measured. We treated dioxin levels as categorical variables in the general linear model according to quartiles (25, 50, and 75 percentile). Comparing the findings with a reference group (< 25th percentile), we noted significantly higher dehydroepiandrosterone (DHEA) level in men with low serum polychlorinated dibenzofuran-toxic equivalent (PCDFs-TEQ) level between 3.80 and 6.31 pg/g lipid (1933 vs. 1447 pg/ml) and low polychlorinated dibenzo-p-dioxins and dibenzofurans-TEQ (PCDD/PCDFs-TEQ) between 8.57 and 15.11 pg/g lipid (1996 vs. 1360 pg/ml). Moreover, a significantly higher androstenedione (A-dione) level was found in men whose serum PCDFs-TEQ ≥ 11.34 pg/g lipd (2404 vs. 1848). What's more, there were significantly higher 3ß-hydroxysteroid dehydrogenase (3ß-HSD) concentrations in low- and high-2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) groups (1.30-1.67 and ≥ 2.64 pg-TEQ/g lipid, respectively with 719 and 807 vs. 496, respectively). Our findings suggest that specific dioxin exposure may disturb normal DHEA, A-dione levels, and enzyme activity in the general adult male population in an e-waste region of China.


Assuntos
Dioxinas/análise , Resíduo Eletrônico , Bifenilos Policlorados/análise , Dibenzodioxinas Policloradas/análise , Adulto , China , Estudos Transversais , Dibenzofuranos Policlorados , Humanos , Masculino
7.
Chemosphere ; 251: 126632, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32443225

RESUMO

Flame retardants (FRs) from electronic waste (e-waste) are a widespread environmental concern. In our study, in vitro physiologically based extraction tests (PBETs) for FRs were conducted in three different areas where dust remained after processing of e-waste to identify the bioaccessible FRs and quantify their bioaccessibilities of gastrointestinal tract for human as well as to assess the exposure via ingestion of workers in e-waste processing workshops. All 36 FRs were measured and detected in indoor dusts. Among the FRs, the mean concentrations of polybrominated diphenyl ethers (PBDEs) in the floor dust and settled dust were highest, 65,000 ng/g, and 31,000 ng/g, respectively. In contrast, phosphorus-containing flame retardants (PFRs) presented the highest mean concentration in the workplace dust samples, 64,000 ng/g. However, the highest bioaccessible concentrations in workplace dust, floor dust, and settled dust were observed for PFRs: 5900, 1600, and 680 ng/g, respectively. This study revealed that the higher bioaccessibility of PFRs versus other compounds was related to the negative correlation between FR concentrations and log KOW (hydrophobicity) values. The fact that hazard indices calculated using measured bioaccessibilities were less than 1 suggested that the non-cancer risk to human health by the FRs exposure via dust ingestion might be low.


Assuntos
Poeira/análise , Resíduo Eletrônico/análise , Retardadores de Chama/análise , Éteres Difenil Halogenados/análise , Exposição Ocupacional/análise , Poluição do Ar em Ambientes Fechados/análise , Disponibilidade Biológica , Ingestão de Alimentos , Monitoramento Ambiental , Trato Gastrointestinal/metabolismo , Humanos , Modelos Biológicos , Medição de Risco , Vietnã
8.
Waste Manag ; 109: 222-230, 2020 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-32416564

RESUMO

The metal in the waste printed circuit boards (WPCBs) is an excellent secondary metal resource. WPCBs were ground to dissociate, and impurities in the dissociated product were removed by gradient flotation to recover valuable metals in this study. The effects of crushing methods on size composition and dissociation state of the crushed products were studied. Then the gradient flotation experiment was designed to verify the natural floatability of ground materials. Grinding test shows that impact crushing has greater grinding fineness (-0.074 mm) than shear crushing, which is 42.14% and 26.18% respectively with 5 min grinding. The flotation test results illustrate that the natural floatability of impurities increases with the grinding fineness, that is, the yield of floats increases without flotation reagents. For impact crushing and shear crushing, the floats yields are 38.48% and 31.75% respectively, accompanied by 70.53% and 65.46% impurity removal for ground materials with 5 min grinding. Subsequently, 21.61% and 26.35% of impurities can be further removed with the aid of collector. Finally, the recovery of Cu in concentrate reaches 67.84% and 65.75%, respectively. FT-IR proves that the excellent floatability of particles is caused by the significant hydrophobic group. Mechanical grinding has been proved to have double effects of improving dissociation and natural floatability.


Assuntos
Resíduo Eletrônico , Interações Hidrofóbicas e Hidrofílicas , Metais , Reciclagem , Espectroscopia de Infravermelho com Transformada de Fourier
9.
Sci Total Environ ; 734: 139286, 2020 Sep 10.
Artigo em Inglês | MEDLINE | ID: mdl-32460072

RESUMO

China is one of the countries worldwide confronted with serious e-waste pollution and associated detrimental health effects, which has aroused public, academic and governmental concerns. Most local residents are exposed to hazardous substances such as lead (Pb) and other persistent organic pollutants because of informal e-waste recycling activities. This study reviews recent studies on children exposed to e-waste Pb in China focusing on health-related effects in children (e.g. growth and development, cardiovascular, immune, nervous, respiratory, reproductive, skeletal, and urinary systems) and evaluating the evidence for the association between e-waste Pb exposure and the children health outcomes in China. Children are one of most sensitive and vulnerable groups when facing e-waste Pb exposure. Previous data indicate that exposure to e-waste Pb has adverse effect on human health such as delayed and damaged physical and nervous development. It is the time to take effective measures, such as upgrading e-waste recycling technology, enhancing government policy guidance and support, and strengthening environmental protection and health awareness of the local inhabitants, to prevent the adverse effects of e-waste.


Assuntos
Resíduo Eletrônico , Criança , Saúde da Criança , China , Exposição Ambiental , Humanos , Chumbo , Reciclagem
10.
Waste Manag ; 111: 41-50, 2020 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-32464524

RESUMO

Waste mobile phones contain significant amounts of valuable metals and non-metallic materials. Consequently, the extraction of valuable materials from discarded phones, which is a more cost-effective method compared with primary mining, is an essential step for maximizing the recovery of secondary resources and minimizing e-waste pollution. We designed a green and efficient path for recovering valuable metals from waste mobile phones and explored its technical feasibility from both environmental and economic perspectives through life cycle assessment and revenue expenditure model. The results showed that the hydrometallurgical process had three characteristics of high recovery efficiency, significant environmental friendliness and economic feasibility. The recovery efficiencies of valuable metals were higher than 90%. Simultaneously, the return on investment was 29%, indicating that the recycling enterprises can achieve self-sufficiency. Thirdly, the environmental benefits were more significant compared to environmental damage released by hydrometallurgical process, representing a significant environmental friendliness. Within the overall recycling process, the core process made the greatest contribution to the environmental burden (45.38-65.68%), followed by manual disassembly process. A comparison of sub-processes in core process revealed that the mechanical crushing and sorting phase had the greatest environmental impacts that were primarily attributed to power consumption. Consequently, future research should focus on the development of energy-efficient pretreatment techniques and energy-saving equipment. The industrial practice of recycling waste mobile phones is still in its infancy in China. Future studies should also focus on the comparing different treatment processes, with the aim of providing technical support for the advancement of industry.


Assuntos
Telefone Celular , Resíduo Eletrônico , China , Estudos de Viabilidade , Reciclagem
11.
Waste Manag Res ; 38(6): 649-659, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32471340

RESUMO

Although separate collection systems for portable batteries (PBs) have been installed years ago, high amounts of batteries still do not enter the collection systems of the member states of the European Union (EU). In Austria, the collection rate has recently dropped to the EU target value of 45%. For the purposes of this study, a comprehensive survey was conducted to identify the destinations of the other end-of-life batteries. A literature survey and an assessment of different waste streams (WSs) were followed by sampling and sorting campaigns for highly relevant WSs (residual waste, lightweight packaging waste, metal packaging waste, and small waste electrical and electronic equipment). The results underwent material flow analysis, showing that more than 800 metric tonnes of portable batteries are misplaced into non-battery-specific collection systems, 718 metric tonnes of them entering residual waste collection. Considerable amounts of batteries are stockpiled, stored or hoarded in Austrian households. Lithium-based batteries, representing a serious risk of fire to the waste industry and making up for 30% of the marketed amount, are still scarcely arriving in waste management systems.


Assuntos
Resíduo Eletrônico , Gerenciamento de Resíduos , Áustria , Fontes de Energia Elétrica , Lítio , Reciclagem
12.
Environ Pollut ; 263(Pt A): 114382, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32229371

RESUMO

Environmental distribution and concentration of tetrabromobisphenol A bis- (2-hydroxyethyl) ether (TBBPA-DHEE) and tetrabromobisphenol A mono- (hydroxyethyl) ether (TBBPA-MHEE), are obscure due to the lack of available analytical methods. Here two novel immunoassays were established to systematically investigate their distributions in Taizhou, Eastern China. Five monoclonal antibodies against pollutants were generated with two designed haptens through animal immunization. After matched with different coating antigens/antibodies, ELISAs were established (LOD for TBBPA-DHEE, 0.12 ng/mL, based on OVA-M3/mAb-D4G6; LOD for TBBPA-MHEE, 0.79 ng/mL, based on OVA-M3/mAb-D2G6) and applied for investigation of their occurrences at a typical e-waste recycling area after 2-year samples collection, where the total 33 water, 32 soil and 16 biological samples were collected with the highest concentrations of 3.46 ng/mL, 2.76 ng/g (dry weight, dw) and 5.01 ng/g (dw), respectively. Meanwhile, our study also indicated that at the centralizing e-waste recycling sites the serious pollution for both chemicals still existed despite of various efforts. Besides, obvious improvements were observed at an abandoned e-waste recycling region treated and remedied for many years by the local Chinese government. These findings highlight the importance of policy decisions in treatment of pollutants to reduce organic pollutant-related health risks.


Assuntos
Resíduo Eletrônico , Retardadores de Chama/análise , Bifenil Polibromatos/análise , Animais , China , Monitoramento Ambiental , Imunoensaio , Reciclagem
13.
Sci Total Environ ; 723: 138073, 2020 Jun 25.
Artigo em Inglês | MEDLINE | ID: mdl-32229383

RESUMO

Informal e-waste recycling leads to a contamination of the workers with several hazardous substances, in particular heavy metals and persistent organic pollutants (POPs). Polychlorinated biphenyls (PCBs) belong to the group of POPs and are suspected to be associated with adverse health effects. In particular lower chlorinated PCBs, such as the congeners PCB 28 and PCB 52 are a marker of occupational exposure. The aim of our study was to assess the occupational PCB exposure in e-waste workers in relation to their specific recycling task (e.g. dismantling, burning). Altogether, n = 88 e-waste workers and n = 196 control subjects have been included in this study. All plasma participant's samples were evaluated for the PCB congeners PCB 28, 52, 101, 138, 153, 180 and sum of NDL-indicator congeners by human biomonitoring. A significant difference could be detected for the lower chlorinated PCB congeners (PCB 28, 52, and 101) for e-waste workers in comparison to the control group. Analyzing specific recycling tasks, workers who dismantle and those who burn e-waste showed the highest plasma levels of PCB 28 and 52. In conclusion, e-waste workers showed occupational related elevated PCB levels. Although those levels did not exceed the BAT value, workers were contaminated with PCBs during their task. Occupational health and safety measure are therefore necessary to protect the worker's health.


Assuntos
Resíduo Eletrônico , Poluentes Ambientais/análise , Bifenilos Policlorados/análise , Estudos Transversais , Gana , Humanos , Reciclagem
14.
Environ Pollut ; 263(Pt A): 114461, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32251969

RESUMO

With the phase out of perfluorooctanesulfonate (PFOS) and perfluorooctanoic acid (PFOA), the composition profiles of poly- and perfluoroalkyl substance (PFAS) in our living environment are unclear. In this study, 25 PFASs were analyzed in indoor dust samples collected from urban, industrial, and e-waste dismantling areas in China. PFOS alternatives, including 6:2 chlorinated polyfluorinated ether sulfonate (6:2 Cl-PFESA) (median: 5.52 ng/g) and 8:2 chlorinated polyfluorinated ether sulfonate (8:2 Cl-PFESA) (1.81 ng/g), were frequently detected. By contrast, PFOA alternatives, such as hexafluoropropylene oxide dimer acid (HPFO-DA, Gen-X) and ammonium 4,8-dioxa-3H-perfluorononanoate (ADONA), were not found in any of the dust samples. As expected, all legacy PFASs were widely observed in indoor dust, and 4 PFAS precursors were also detected. Dust concentrations of 6:2 Cl-PFESA were strongly correlated (p < 0.05) with those of 8:2 Cl-PFESA regardless of sampling sites. 6:2 Cl-PFESA was also significantly associated with that of PFOS in industrial and e-waste (p < 0.01) areas. Association analysis suggested that the sources of PFOS and its alternatives are common or related. Although ∑Cl-PFESA concentration was lower than that of PFOS (17.4 ng/g), industrial areas had the highest 6:2 Cl-PFESA/PFOS ratio (0.63). Composition profiles of PFASs in the industrial area showed the forefront of fluorine change. Thus, the present findings suggested that Cl-PFESAs are widely used as PFOS alternatives in China, and high levels of human Cl-PFESA exposure are expected in the future. Short-chain PFASs (C4-C7) were the predominant PFASs found in dust samples, contributing to over 40% of ∑total PFASs. Furthermore, perfluoro-1-butanesulfonate/PFOS and perfluoro-n-butanoic acid (PFBA)/PFOA ratios were 2.8 and 0.72, respectively. These findings suggested shifting to the short-chain PFASs in the environment in China. To the authors knowledge this is the first study to document the levels of 6:2 Cl-PFESA, 8:2 Cl-PFESA in indoor dust.


Assuntos
Ácidos Alcanossulfônicos , Resíduo Eletrônico , Fluorcarbonetos , China , Poeira , Éteres , Humanos
15.
Environ Sci Pollut Res Int ; 27(17): 22081-22099, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32291638

RESUMO

The paper investigates the potential of circular economy of authorized e-waste collectors, dismantlers, and recyclers of Maharashtra. The study determines the drivers and barriers associated with e-waste collection in the region. Furthermore, it explores the handling techniques including dismantling, recycling, and scrap disposal. This is done through a case study of a recycling company based in Mumbai, Maharashtra. A questionnaire-based survey is used to study e-waste processing units. The qualitative analysis of the questionnaire shows that lack of awareness of environmental impact is the greatest constraint in the collection of e-waste and data security is the most crucial driver for enhancing the collection of e-waste. The case study reveals that the quantity and type of e-waste are more important than the distance between the processing unit and the collection point. It discloses that the primary factor for building trust between e-waste collectors and waste holders is data security.


Assuntos
Resíduo Eletrônico , Eliminação de Resíduos , Gerenciamento de Resíduos , Meio Ambiente , Índia , Reciclagem
16.
Waste Manag ; 107: 113-120, 2020 Apr 15.
Artigo em Inglês | MEDLINE | ID: mdl-32278216

RESUMO

Waste printed circuit boards (WPCBs) contain a variety of valuable and hazardous materials. Recycling WPCBs is an important subject not only for environmental protection but also for sustainable development of resources. In this work, a new method combined low-temperature alkaline smelting with liquid-liquid phase separation is proposed to separate and recycle metal mixture in pyrolysis residue of WPCBs of mobile phones. During the low-temperature alkaline smelting process, amphoteric metals Al, Pb, Si, Sn, and Zn are firstly separated and recycled from the metal mixture with the separation rates of 99.5%, 81.6%, 97.8%, 88.4% and 95.7%, respectively. To separate the remaining metal mixture mainly containing elements Cu, Fe, Cr, Ni, Au and Ag, a liquid-liquid phase separation system is designed. As a result, the noble metals Au and Ag are concentrated in the copper-rich substance to form a high-value group, while the elements Ni and Cr distribute in the iron-rich substance. The iron-rich substance can be reused in the liquid-liquid phase separation process. In the super-gravity field, the recycling rates of the metals Au, Ag, Cr and Ni reach 98.1%, 99.8%, 95.6% and 75.4%, respectively. Furthermore, the iron-rich substance can be reused back to the liquid-liquid separation system. The copper-rich substance enriched by the noble metals can be efficiently recovered with low energy consumption and less pollution. This work provides an environmentally friendly and efficient route for separating and recycling the metal mixture in WPCBs.


Assuntos
Telefone Celular , Resíduo Eletrônico , Cobre , Poluição Ambiental , Metais , Reciclagem
17.
Waste Manag ; 107: 285-293, 2020 Apr 15.
Artigo em Inglês | MEDLINE | ID: mdl-32330828

RESUMO

LED lamps have already conquered the market of general lighting. This new product will generate a substantial flow of e-waste requiring studies for the correct management, especially concerning recycling alternatives. This study proposes a material characterization of all the tubular and bulb LED lamp components (carcass, LEDs, printed circuit board and LED module). After manual disassembling, polymers were characterized by infrared spectroscopy (FTIR), and the metals by X-ray fluorescence (XRF) and acid leaching followed by ICP-OES analysis. By the novelty of separating and characterizing the LED lamp's components, a process which has not yet been studied, the results allow for a better interpretation of the different materials distribution within the lamps which is essential to improve the efficiency of a recycling route. To exemplify, the element gallium, which has a recycling appeal from the LEDs, is present in a larger quantity in the printed circuit boards. The study also provides an analysis of the materials recycling rates and economic values, and the comparison with the concentration of natural ores. Thus, it was possible to discuss about target components and materials and the recycling alternatives for each component. LED lamps contain interesting materials, with even higher concentrations than natural ores, such as gold, silver, copper, aluminum, tin and gallium. If recycled, tubular lamps and bulb lamps would have the economic recovery of USD 2405.99 and USD 2595.02 per ton, respectively. The gold was found to be the most valuable material, and the LEDs the most valuable component of the LED lamps.


Assuntos
Resíduo Eletrônico , Gálio , Utensílios Domésticos , Cobre , Iluminação , Reciclagem
18.
J Environ Manage ; 264: 110495, 2020 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-32250915

RESUMO

Studies on sustainable management of waste from electrical and electronic equipment (or e-waste) have gained increasing attention from researchers around the world in recent years, with investigations into various aspects of e-waste management were investigated. Studies on e-waste generation by previous papers have been reviewed to provide an overview of the current research progress and recommendations for future research. The relevant existing studies were collected from various databases. Using content analysis, three main aspects of the existing studies were evaluated: the distribution and trends of the publications, the scope and boundaries of the studies, and the current research practices and research applications. Although there was a significant increasing trend of the amount of research on the evaluation of e-waste generation, however, the number of publications based on the countries of origin was still small. Another limitation was found related to the differences in the selection of research subjects and the level of analysis resulted in variations in the scopes and boundaries of the existing studies. Various other research areas were investigated further based on their research findings, but the analysis of various methodological aspects was complicated due to the increasing number of newly developed methodologies and the lack of comprehensive and up-to-date reviews on this research area. Additionally, there was also a need to evaluate emerging and/or older technology, which led electrical appliances to be overlooked. We found that comprehensive and up-to-date reviews of the methodological aspects of e-waste generation are still lacking. Based on the research gaps and limitations discussed, recommendations for future research were made.


Assuntos
Resíduo Eletrônico , Gerenciamento de Resíduos , Eletrônica , Reciclagem , Tecnologia
19.
J Environ Manage ; 266: 110577, 2020 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-32310119

RESUMO

Recycling of plastics from e-waste can conserve resources, however, aging during the use of plastic products can cause the migration of heavy metals in additives. This study presents a methodology for evaluating the risks of heavy metals in waste plastic secondary products during long term use associated with heavy metal migration. The study processes were investigated by: (1) recycling waste plastics and producing secondary products; (2) thermal aging of secondary products; and (3) toxic leaching used to quantitatively analyse the dissolution of heavy metals. Combined with the changes in mechanical properties and microstructure, the effect of aging on the migration of heavy metals was observed. The results showed that the polymer appeared to delaminate, the adhesion of waste plastics to additives decreased, and the mechanical properties clearly decreased after the thermal aging experiment. Leaching experiments showed that the leached concentrations of Ni, Cu, Zn, Pb, and Sb in the three types waste plastic products increased over time. After 8 d of aging, the leached concentrations of Ni, Sb, and Pb exceeded the third, fourth, and third class of the groundwater quality standard, respectively. Specifically, the concentrations of Sb were 141, 289, and 21.1 times higher than the maximum permissible level. Therefore, management hierarchy and safe environmental recycling methods should be developed to reduce the risk of heavy metals in waste plastic secondary products.


Assuntos
Resíduo Eletrônico , Metais Pesados , Poluentes do Solo , Plásticos , Reciclagem
20.
Chemosphere ; 252: 126488, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32199167

RESUMO

Rare earth elements (REEs) are widely used in electronic products. But the contaminations of REEs in the e-waste sites and the related health effects were barely investigated. In the present study, we analyzed the concentrations of REEs and the hormones of the HPT axis in plasma of subjects recruited from an e-waste area and a reference area in Taizhou, China. The results showed that the concentrations of several REEs like La, Ce were much higher in the exposed group than in the control group (all p < 0.001). The thyroid hormones, FT3 and FT4, and TRH showed no significant difference between the two groups, while the concentration of TSH was significantly higher in the exposed group when compared to the control group (p = 0.002). Separate regression analysis indicated that elevated La and Ce levels were associated with higher TSH concentrations. MDA and 8-iso, the biomarkers of oxidative stress, were also significantly higher in the exposed group than that of the control group (p = 0.002 and p = 0.003, respectively). The increased oxidative stress might be the mechanism underlying the disruptive effects of REEs on TSH. Our results indicated that the quantities of internal exposure of REEs in the subjects in the e-waste area were considerable and the compositional profile of the REEs in the exposed group was different from the control group due to the e-waste dismantling. The expression of TSH were also affected by high La and Ce exposure which showed an endocrine disruption effects of REEs on HPT axis.


Assuntos
Resíduo Eletrônico/análise , Exposição Ambiental/estatística & dados numéricos , Poluentes Ambientais , Metais Terras Raras/análise , Adulto , Biomarcadores , China , Estudos Transversais , Disruptores Endócrinos/análise , Hormônios , Humanos , Masculino , Pessoa de Meia-Idade , Glândula Tireoide/efeitos dos fármacos , Hormônios Tireóideos/sangue
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