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1.
Artigo em Inglês | MEDLINE | ID: mdl-33805282

RESUMO

The recycling of electronic waste (e-waste) contaminates ecosystems with metals, though a compilation of data from across sites worldwide is lacking, without which evidence-based comparisons and conclusions cannot be realized. As such, here, a systematic review of the literature was conducted to identify peer-reviewed studies concerning e-waste sites (published between 2005 and 2017) that reported on the concentration of heavy metals (Cd, Hg, As, Pb and Cr) in soil, water and sediment. From 3063 papers identified, 59 studies from 11 countries meeting predefined criteria were included. Reported metal concentrations were summarized, and a narrative synthesis was performed. This review summarized 8286 measurements of the aforementioned metals in soils (5836), water (1347) and sediment (1103). More than 70% of the studies were conducted in Asia. In nearly all cases, the average metal concentrations in a particular medium from a given site were above guideline values; suggesting soils, water and sediment at, or near, e-waste recycling sites are contaminated. Across all media, concentrations of Pb were generally highest, followed by Cr, As, Cd and Hg. The synthesized information demonstrates that e-waste sites worldwide are contaminated with metals, that geographic data gaps exist, that the quality of most studies can be improved and that action is needed to help reduce such levels to protect human health and the environment.


Assuntos
Resíduo Eletrônico , Metais Pesados , Poluentes do Solo , Ásia , China , Ecossistema , Resíduo Eletrônico/análise , Monitoramento Ambiental , Humanos , Metais Pesados/análise , Reciclagem , Solo , Poluentes do Solo/análise
2.
J Environ Manage ; 288: 112380, 2021 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-33831638

RESUMO

This review details the current information on e-waste treatment using plasma technology. The current status of e-waste treatment via plasma technology from the scientific literature is presented herein, namely, moist paste battery, galvanic sludge, resin, printed circuit board, and semiconductor industries. The concept of plasma technology, classification of e-waste, contaminants of e-waste (metals, metalloids, and VOCs), and vitrification of the final product are presented herein. This review paper focuses on fusing flux agents to vitrify e-waste. Furthermore, this paper covers laboratory-scale investigations, plasma technology benefits, and reuse of material from plasma post-treatment. The use of plasma technology combined with flux agents could be recommended to eliminate contaminants from e-waste. Materials from plasma post-treatment may also be applied in environmental reuse applications.


Assuntos
Resíduo Eletrônico , Resíduo Eletrônico/análise , Metais , Plasma , Reciclagem , Esgotos , Tecnologia
3.
Environ Sci Technol ; 55(9): 5984-5992, 2021 05 04.
Artigo em Inglês | MEDLINE | ID: mdl-33877816

RESUMO

Liquid-crystal monomers (LCMs), especially fluorinated biphenyls and analogues (FBAs), are considered to be a new generation of persistent, bioaccumulative, and toxic organic pollutants, but their emissions from liquid-crystal display (LCD)-associated e-waste dismantling remain unknown. To fill this knowledge gap, a broad range of 46 LCMs, including 39 FBAs and 7 biphenyls/bicyclohexyls and analogues (BAs), were investigated by a dedicated target analysis in e-waste dust samples. Of 39 target FBAs, 34 were detected in LCD dismantling-associated dust. Among these 34 detectable FBAs, 9 were detected in 100% of the samples and 25 were frequently detected in >50% of the samples. The total concentrations of these 34 FBAs (∑34FBAs) detected in LCD e-waste dust were in the range of 225-976,000 (median: 18,500) ng/g, significantly higher than those in non-LCD e-waste dust (range: 292-18,500, median: 2300 ng/g). In addition to FBAs, six of seven BAs were also frequently detected in LCD e-waste dust with total concentrations (∑6BAs) of 29.8-269,000 (median: 3470) ng/g. Very strong and significant correlations (P < 0.01) were identified in all frequently detected LCMs, indicating their common applications and similar sources. Our findings demonstrate that e-waste dismantling contributes elevated emissions of FBAs and BAs to the ambient environment.


Assuntos
Resíduo Eletrônico , Poluentes Ambientais , Cristais Líquidos , Bifenilos Policlorados , China , Poeira/análise , Resíduo Eletrônico/análise , Monitoramento Ambiental
4.
J Environ Manage ; 287: 112335, 2021 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-33761368

RESUMO

The reuse of Waste Electrical and Electronic Equipment (WEEE) is deemed the best end-of-life option in terms of the environmental impact and socio-economic benefits. Taking this cue, this paper applies a systematic literature review to map the existing knowledge base to present the major and emerging themes of the reuse assessment of WEEE. In all, 12,216 articles published from 2005 to 2019 in the Web of Science, ProQuest, and Google Scholar are collected, from which 331 articles are shortlisted for review. The shortlisted articles are divided into two sub-periods 2005-2014 and 2015-2019 to draw out the development of the research themes and the contribution of the recent research articles to the literature on WEEE reuse assessment. Bibliographic coupling combined with keyword analysis is performed using SciMat and VOSViewer. The results inform that the major ongoing themes are Consumer behaviour towards use, disposal, collection, reuse, repair and recycling of WEEE; Assessing the potential of WEEE for reuse; Product recovery strategy and market analysis for WEEE remanufacturing; and Material flow analysis of WEEE in circular economy. The research themes of Informal WEEE management in developing countries; Impact of government subsidy on WEEE management; and Product service system and circular economy deserve further attention. In the articles reviewed, mobile phones and computers are extensively studied for WEEE reuse assessment followed by refrigerators and televisions. Assessing the environmental impact and legal aspects of WEEE reuse, cross-border movements and flow in secondary markets, policies and regulations on the purchase of reprocessed WEEE, and the reprocessing and revenue made by the informal sector in developing countries are possibilities for future research.


Assuntos
Resíduo Eletrônico , Gerenciamento de Resíduos , Computadores , Resíduo Eletrônico/análise , Eletrônica , Reciclagem
5.
Waste Manag ; 125: 87-97, 2021 Apr 15.
Artigo em Inglês | MEDLINE | ID: mdl-33684667

RESUMO

Waste printed circuit boards (WPCBs) constitute a hazardous material with up to 40 different metals, including numerous many heavy metals and environmentally harmful metals. Most hydrometallurgical processing approaches use high concentrations of toxic reagents and generate significant amounts of harmful effluents. This research investigates the use of cyanide-starved glycine solution containing no free cyanide in the leachate to extract precious metals from WPCBs, with most of copper and base metals pre-removed by upstream glycine-only leaching. Under the optimised conditions, 90.1% Au, 89.4% Ag and 70.1% Pd were extracted together with 81.0% Cu and 15.0% Zn. The extraction of other base metals remained low at 8.3% for Al and <5% for Pb, Ni, Co, Fe and Sn, indicating a fairly good selectivity of the leaching system. By comparing with stoichiometric and intensive cyanidation, the cyanide-starved glycine system showed comparable or better performance on precious metals extraction, but cyanide use was reduced by >70% whereas the glycine can be reused. Analysis indicates that with an initial cyanide dose of 250 ppm, the leaching solution was starved of cyanide after 4 h with no free cyanide, which minimises safety and health risks significantly compared with traditional intensive cyanidation ([CN] > 3500 ppm). Glycine and cyanide dose, pH, and particle size dominated leaching kinetics, while staged addition of cyanide did not enhance the extractions. A significant (70-90%) reduction in required cyanide use and cyanide-bearing effluents can be achieved while performing polymetallic metal removal and allowing reagent recycling.


Assuntos
Resíduo Eletrônico , Metais Pesados , Cobre , Cianetos , Resíduo Eletrônico/análise , Reciclagem
6.
Waste Manag ; 125: 163-171, 2021 Apr 15.
Artigo em Inglês | MEDLINE | ID: mdl-33706255

RESUMO

Nowadays, old electrical and electronic gadgets are being replaced constantly by newer versions resulting in huge amounts of waste electronic and electrical products that are collectively termed e-waste. It is estimated that 95% of e-waste recycling in India is done by the informal sector at the cost of their health and the environment. Very little data and no descriptions of recycling processes in the formal sector in India were available in the literature. The objective of this study was to evaluate the status of formal and informal e-waste recycling facilities in India. Seven authorized e-waste handling facilities in West Bengal, Maharashtra, Karnataka and Delhi were visited and most were involved in dismantling work only. In all cases, metals, plastic and glass are recovered from e-waste in compliance with environmental legislation. Challenges faced by the formal sector include lack of awareness among people and very few collection centers throughout the country. Quantification of e-waste generated in India was difficult as imported second-hand electrical and electronic gadgets cannot be separated for electronic waste. There is no mechanism for collecting data regarding e-waste generation in the states or at the Central government level. It is likely that published estimates are based on the indigenous production and import of electrical and electronic goods. The current installed e-waste handling capacity of 11 × 105 tons/year of e-waste in the country is woefully inadequate and needs to be enhanced as the minimum requirement is estimated to be 22 × 105 tons/year of e-waste.


Assuntos
Resíduo Eletrônico , Resíduo Eletrônico/análise , Humanos , Índia , Reciclagem
7.
Sci Total Environ ; 764: 142806, 2021 Apr 10.
Artigo em Inglês | MEDLINE | ID: mdl-33757236

RESUMO

Immunoglobulin G (IgG) is the predominant component of the humoral immune system. Epidemiological studies have shown that lead (Pb) or cadmium (Cd) exposure is associated with changes in human IgG levels, and alteration of IgG subclass production can be induced by differential modulation of Th1 and Th2 cytokines caused by Pb or Cd exposure. However, no study has focused on the adverse effects of Pb and Cd co-exposure on IgG subclass production by regulating Th1/Th2 cytokines in children living in electronic waste (e-waste) areas. This study aims to analyze the associations among Pb and Cd in blood, Th1/Th2 cytokines, and IgG subclasses in serum from children. A total of 181 healthy, 2- to 7-year-old children were examined. Of them, 104 were from Guiyu (e-waste exposed group), and the rest were from Haojiang (reference group) in China. Pb and Cd levels in whole blood, cytokines, and IgG subclasses in serum were determined. Exposed children had higher levels of blood Pb and Cd, serum IgG1, IgG1 + IgG2, serum Th1 cytokine interferon-γ (IFN-γ) and lower levels of the Th2 cytokine interleukin (IL)-13. Increased blood Pb levels were positively associated with serum levels of IFN-γ, and negatively associated with serum levels of IL-13. Adjusted linear regression analysis showed that serum levels of IL-13 were negatively associated with serum levels of IgG1 and IgG1 + IgG2. Mediation models indicated that IL-13 had significant mediating effects on the relationships between blood Pb levels and serum IgG1, as well as between blood Pb levels and serum IgG1 + IgG2. Increased blood Cd levels were positively associated with serum levels of IgG1. Our results show heavy metal (particularly Pb) exposure may affect IgG subclass production by regulating Th1/Th2 cytokines in exposed children, thus providing new evidence for a relationship between humoral immune function and environmental exposure.


Assuntos
Resíduo Eletrônico , Cádmio , Criança , Pré-Escolar , China , Resíduo Eletrônico/análise , Humanos , Imunoglobulina G , Chumbo
8.
Waste Manag ; 124: 94-101, 2021 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-33611158

RESUMO

How to realize the high value-added utilization of scrap copper from e-waste is a meaningful topic. In the study, an Ohno Continuous Casting (OCC) process is an existing method you applied to purify the copper. Based onthe model of diffusion-controlled grain growth kinetics, the redistribution of impurity of tin in the scrap copper were studied under the different continuous casting speed and mold temperature. On the centerline, macrosegregation in the axial direction of the tin was more obvious with the decrease of continuous casting speed. The small continuous casting rate was beneficial to the segregation and enrichment of tin. The axial segregation gradually decreased with the increase of the mold temperature. The flattening of the liquid-solid interface resulted in a weakening of the solute enrichment at the root of the interface with the increase of temperature. Morphology, electron backscattered diffraction (EBSD) analysis showed the structure of single crystal copper. The range of resistance of single crystal copper was from 5 × 10-6 to 3 × 10-5 Ω m. Obviously, the resistance of the single crystal copper was significantly smaller than that of ordinary copper wire (9.0 × 10-3 Ω m). This study provided a key theoretical and practical basis for the high value-added reuse of copper in e-waste.


Assuntos
Cobre , Resíduo Eletrônico , Resíduo Eletrônico/análise , Reciclagem , Soluções , Temperatura
9.
Sci Total Environ ; 773: 145623, 2021 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-33592459

RESUMO

Challenges in managing electronic waste (E-waste) arise from a lack of technical skills, poor infrastructure, inadequate financial support, and inactive community engagement. This study provides a systematic review of efforts to overcome these challenges in the context of inappropriate recycling protocols of E-waste and their toxic effects on human health and the environment. An inventory of end-of-life electronic products, which can be established through the creation of an environment friendly regulatory regime for recycling, is essential for the proper control of E-waste. An approach has been articulated to help implement effective management of E-waste in both developed and developing countries. Enforcement of systematic management measures for E-waste in developing countries coupled with best practices is expected to minimize adverse impacts while helping maintain a sustainable and resilient environment.


Assuntos
Resíduo Eletrônico , Gerenciamento de Resíduos , Resíduo Eletrônico/análise , Eletrônica , Humanos , Reciclagem
11.
Waste Manag ; 123: 42-47, 2021 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-33561768

RESUMO

The e-waste problem needs be tackled under a global framework, based upon the understanding that e-waste is a global issue and thus a shared responsibility. To illustrate this point, a cost-benefit analysis of metal recovery from e-waste was conducted with Europe, North America and China as representative regions of e-waste producers. The final profit associated with the entire e-waste recycling process was estimated by deducing the energy costs of metal recovery from the revenues of the manually dismantling stage and the metal recovery stage. Then, the potential job opportunities were estimated based on the final profit from the local e-waste recycling and average wage per year. Overall, profits of manually dismantling 1 ton of e-waste varied widely, but the final profits were positive. The potential job opportunities generated by local e-waste recycling ranged from 4.65 × 105 person/year for North America to 2.03 × 106 for China person/year. According to our study, the environmental load of 1 kg of e-waste would be 1-9 USD, indicating that this is the cost required to offset the environmental consequences of each kilogram of e-waste. By applying environmental load to per capita, the concept can act as a tool to encourage countries to fairly share the environmental responsibility of e-waste based on their e-waste generation. Based on this, we propose an e-waste emissions trading system that set a cap on the total amount of e-waste that could be generated globally and per country, to reduce e-waste and carbon emissions.


Assuntos
Resíduo Eletrônico , China , Análise Custo-Benefício , Resíduo Eletrônico/análise , Europa (Continente) , Políticas , Reciclagem
12.
Environ Res ; 194: 110728, 2021 03.
Artigo em Inglês | MEDLINE | ID: mdl-33444608

RESUMO

Recycling of electric and electronic waste products (e-waste) which amounted to more than 50 million metric tonnes per year worldwide is a massive and global operation. Unfortunately, an estimated 70-80% of this waste has not been properly managed because the waste went from developed to low-income countries to be dumped into landfills or informally recycled. Such recycling has been carried out either directly on landfill sites or in small, often family-run recycling shops without much regulations or oversights. The process traditionally involved manual dismantling, cleaning with hazardous solvents, burning and melting on open fires, etc., which would generate a variety of toxic substances and exposure/hazards to applicators, family members, proximate residents and the environment. The situation clearly calls for global responsibility to reduce the impact on human health and the environment, especially in developing countries where poor residents have been shouldering the hazardous burden. On the other hand, formal e-waste recycling has been mainly conducted in small scales in industrialized countries. Whether the latter process would impose less risk to populations and environment has not been determined yet. Therefore, the main objectives of this review are: 1. to address current trends and emerging threats of not only informal but also formal e-waste management practices, and 2. to propose adequate measures and interventions. A major recommendation is to conduct independent surveillance of compliance with e-waste trading and processing according to the Basel Ban Amendment. The recycling industry needs to be carefully evaluated by joint effort from international agencies, producing industries and other stakeholders to develop better processes. Subsequent transition to more sustainable and equitable e-waste management solutions should result in more effective use of natural resources, and in prevention of adverse effects on health and the environment.


Assuntos
Resíduo Eletrônico , Gerenciamento de Resíduos , Resíduo Eletrônico/análise , Eletrônica , Humanos , Reciclagem
13.
J Environ Manage ; 282: 111943, 2021 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-33465720

RESUMO

This paper aims to establish consumer's perception of electric waste recycling and management on a national scale in Bangladesh. The attitude, willingness to pay (WTP) and consumers' behaviour were explored by conducting a questionnaire-based survey. The conclusions are based on 915 valid responses out of 2000 online survey invitations. Interestingly, 37.9% of the respondents indicated that they would accept to pay for electronic waste recycling. Analysis also shows that the preferred WTP would cover 5-10% of the recycling cost. Factors like environmental awareness, monthly income, and education level affect the consumers' WTP. Nevertheless, most of the participants believe that the Government should share the recycling cost. The study suggests that e-waste recycling can be stimulated by promoting environmental awareness, educating the public about the benefits of recycling e-waste, and making e-waste recycling more convenient. However, additional measures will likely be needed to tackle the e-waste problem. Thus, support for environmental education is imperative in order to promote environmental awareness and increase the WTP of consumers. The study outlines key characteristics of consumer-focused e-waste management archetypes and proposes an effective road map for Bangladesh.


Assuntos
Resíduo Eletrônico , Gerenciamento de Resíduos , Bangladesh , Resíduo Eletrônico/análise , Humanos , Reciclagem , Inquéritos e Questionários
14.
Waste Manag ; 122: 26-35, 2021 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-33476959

RESUMO

In an effort to regulate waste electrical and electronic equipment (WEEE) recycling, the Chinese government has issued China-WEEE regulations and a fund policy. In accordance with the 2012 fund policy, the government collects funds from producers and subsidizes recycling enterprises. However, this policy has encountered difficulties. The 2016 White Paper on WEEE Recycling, Treatment and Reuse states that while the funds collected from producers were 2.61 billion Yuan, the subsidies provided to recycling enterprises were 4.714 billion Yuan, which is a gap of 2.104 billion Yuan. In addition, this policy did not incentivize producers to invest in WEEE recycling. Our paper aims to answering the following questions: (1) What is the impact of the current WEEE processing fund policy? (2) How can producers' green innovation in WEEE recycling be promoted? We use evolutionary game theory to investigate the strategies used by producers and recyclers and explore their evolutionary behaviors under two policies: the 2012 fund policy (the current policy) and the Fund Relief Policy (a newly designed policy). The results indicate that the Fund Relief Policy can motivate producers' green innovation behavior, improve the profitability of recyclers, and alleviate the financial pressure on government to a certain extent.


Assuntos
Resíduo Eletrônico , Gerenciamento de Resíduos , China , Resíduo Eletrônico/análise , Eletrônica , Teoria do Jogo , Reciclagem
15.
Environ Sci Pollut Res Int ; 28(9): 10503-10518, 2021 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-33438127

RESUMO

This article details the electronic waste (e-waste) generation, their composition, health, and environment hazards, and legal rules for disposal as well as their significance as a potential secondary source of metals and other components. Moreover, valuable metal extraction technologies from the e-waste are reviewed in general and waste cell phones in particular. E-waste is nowadays preferentially used for recovery of metals mainly from printed circuit boards (PCBs). Different techniques, namely pyrometallurgy, hydrometallurgy, and biohydrometallurgy used for metal extraction from e-waste are swotted. The economic and environmental valuation features of these technologies are also included. Compared to other methods, biohydrometallurgy is the method of choice, as in it natural components like air and water are used, has low operating and maintenance cost, and operate at ambient temperature and pressure. Microbial aspects of metal extraction from e-waste are summarized.


Assuntos
Telefone Celular , Resíduo Eletrônico , Resíduo Eletrônico/análise , Metais , Reciclagem , Água
16.
Chemosphere ; 269: 129409, 2021 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-33388566

RESUMO

The rise of electronic waste (e-waste) generation around the globe has become a major concern in recent times and its recycling is mostly focused on the recovery of valuable metals, such as gold, silver, and copper, etc. However, e-waste consists of a significant weight fraction of plastics (25-30%) which are either discarded or incinerated. There is a growing need for recycling of these e-waste plastics. The majority of them are made from high-quality polymers (composites), such as acrylonitrile butadiene styrene (ABS), high impact polystyrene (HIPS), polycarbonate (PC), polyamide (PA), polypropylene (PP) and epoxies. These plastics are often contaminated with hazardous materials, such as brominated flame retardants (BFRs) and heavy metals (such as Pb and Hg). Under any thermal stress (thermal degradation), the Br present in the e-waste plastics produces environmentally hazardous pollutants, such as hydrogen bromide or polybrominated diphenyl ethers/furans (PBDE/Fs). The discarded plastics can lead to the leaching of toxins into the environment. It is important to remove the toxins from the e-waste plastics before recycling. This review article gives a detailed account of e-waste plastics recycling and recovery using thermochemical processes, such as extraction (at elevated temperature), incineration (combustion), hydrolysis, and pyrolysis (catalytic/non catalytic). A basic framework of the existing processes has been established by reviewing the most interesting findings in recent times and the prospects that they open in the field recycling of e-waste plastics.


Assuntos
Resíduo Eletrônico , Retardadores de Chama , Resíduo Eletrônico/análise , Éteres Difenil Halogenados/análise , Plásticos , Reciclagem
17.
Waste Manag ; 120: 549-563, 2021 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-33308953

RESUMO

Waste electrical and electronic equipment (WEEE) comprises a globally important waste stream due to the scarcity and value of the materials that it contains; annual generation of WEEE is increasing by 3-5% per annum. The effective management of WEEE will contribute critically to progress towards (1) realisation of the United Nations' Sustainable Development Goals, (2) a circular economy, and (3) resource efficiency. This comprehensive review paper provides a critical and contemporary examination of the current global situation of WEEE management and discusses opportunities for enhancement. Trends in WEEE generation, WEEE-related policies and legislation are exemplified in detail. Four typical future WEEE management scenarios are identified, classified and outlined. The European Community is at the forefront of WEEE management, largely due to the WEEE Directive (Directive 2012/19/EU) which sets high collection and recycling targets for Member States. WEEE generation rates are increasing in Africa though collection and recycling rates are low. WEEE-related legislation coverage is increasing in Asia (notably China and India) and in Latin America. This review highlights emerging concerns, including: stockpiling of WEEE devices; reuse standards; device obsolescence; the Internet of Things, the potential for collecting space e-debris, and emerging trends in electrical and electronic consumer goods. Key areas of concern in regard to WEEE management are identified: the partial provision of formal systems for WEEE collection and treatment at global scale; further escalation of global WEEE generation (increased ownership, and acceleration of obsolescence and redundancy); and absence of regulation and its enforcement. Measures to improve WEEE management at global scale are recommended: incorporation of circular economy principles in EEE design and production, and WEEE management, including urban mining; extension of WEEE legislation and regulation, and improved enforcement thereof; harmonisation of key terms and definitions to permit consistency and meaning in WEEE management; and improvements to regulation and recognition of the informal WEEE management sector.


Assuntos
Resíduo Eletrônico , Gerenciamento de Resíduos , Ásia , China , Resíduo Eletrônico/análise , Eletrônica , Índia , Reciclagem
18.
Waste Manag ; 120: 193-201, 2021 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-33310131

RESUMO

The phenomenon of the long leaching time and low leaching rate is presented in the acid leaching process under the conventional conditions of low reaction temperature and acid concentration. In order to promote leaching rates of indium and tin in waste liquid crystal display, an optimized process combining rapid milling and acid leaching has been proposed, which is more time and energy-efficient, environmentally sound compared with the traditional acid leaching process. Leaching mechanism analysis was conducted to uncover the different leaching behavior of indium and tin. And the external factors affecting the leaching rates of indium and tin were studied to optimize. In this process, the fine powder with a weight ratio of 97.6%, which particle size less than 0.075 mm, was obtained with the optimal milling time of 30 min by rapid grinding in the planetary high energy ball milling. About -0.003 l/s of grinding rate constant was performed in the grinding size fraction from 3 mm to 0.075 mm. The research results indicated that the particle size less than 0.035 mm was agglomerated, and the addition of H2O2 reduced the leaching rate for the particle size less than 0.075 mm. Moreover, 86.3% and 76.1% of indium and tin were leached in a short leaching time of 10 min by using 3 M H2SO4 at 85 °C for particle size range from 0.075 to 0.035 mm, while 96.9% and 85.6%, respectively in 90 min.


Assuntos
Resíduo Eletrônico , Índio , Resíduo Eletrônico/análise , Peróxido de Hidrogênio , Reciclagem , Estanho
19.
J Hazard Mater ; 403: 123586, 2021 02 05.
Artigo em Inglês | MEDLINE | ID: mdl-32795820

RESUMO

Presently, biocyanidation technology is being usually adopted to recover precious metals from an increasing quantity of waste printed circuit boards. The main aim of this work was to investigate the biofilm formation of Pseudomonas and its ability to leach precious metals. Based on batch experiments, strain 113 showed the highest biofilm-forming activity in optimal culture conditions of pH 7.0, 25 °C, and 1/25 NB medium among the Pseudomonas strains isolated. Both low concentrations of Cu2+ (500 ppm) and Ag+ (2.5 ppm) promoted biofilm formation. Under the optimal culture conditions for biofilm formation, the concentration of CN- was up to 5.0 ppm. In the continuous silver leaching experiment, the Ag+ concentration reached 4.0 ppm and the leaching efficiency was 14.7 % at 7 d. The results of this study may contribute to the construction of a bioreactor used for continuous leaching of waste printed circuit boards in an attempt to recover precious metals. Our results may also aid in the industrialization of biocyanidation technology.


Assuntos
Resíduo Eletrônico , Biofilmes , Cobre , Resíduo Eletrônico/análise , Pseudomonas , Reciclagem , Prata , Tecnologia
20.
Waste Manag ; 121: 175-185, 2021 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-33360816

RESUMO

This study has attempted to ascertain the linkages between circular bio-economy (CirBioeco) and recycling of electronic (e-)waste by applying microbial activities instead of the smelter and chemical technologies. To build the research hypothesis, the advances on biotechnology-driven recycling processes for metals extraction from e-waste has been analyzed briefly. Thereafter, based on the potential of microbial techniques and research hypothesis, the structural model has been tested for a significance level of 99%, which is supported by the corresponding standardization co-efficient values. A prediction model applied to determine the recycling impact on CirBioeco indicates to re-circulate 51,833 tons of copper and 58 tons of gold by 2030 for the production of virgin metals/raw-materials, while recycling rate of the accumulated e-waste remains to be 20%. This restoration volume of copper and gold through the microbial activities corresponds to mitigate 174 million kg CO2 emissions and 24 million m3 water consumption if compared with the primary production activities. The study potentially opens a new window for environmentally-friendly biotechnological recycling of e-waste under the umbrella concept of CirBioeco.


Assuntos
Resíduo Eletrônico , Cobre , Resíduo Eletrônico/análise , Eletrônica , Ouro , Reciclagem
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