Recycling of Acrylonitrile Butadiene Styrene from Electronic Waste for the Production of Eco-Friendly Filaments for 3D Printing.

In this work, acrylonitrile butadiene styrene (ABS) copolymer from electronic waste (e-waste) was used to produce filaments for application in 3D printing. Recycled ABS (rABS) from e-waste was blended with virgin ABS (vABS) in different concentrations. By differential scanning calorimetry, it was observed that the values of the glass transition temperatures for vABS/rABS blends ranged between the values of vABS and rABS. Torque rheometry analysis showed that the processability of vABS was not compromised with the addition of rABS. Rheological measurements showed that the viscosity of vABS was higher than that of rABS at low frequencies and indicated that vABS and rABS are immiscible. Impact strength (IS) tests of the 3D printed samples showed an increase in the IS with an increase in the rABS content up to 50 wt%. Blending vABS with rABS from e-waste is promising and proved to be feasible, making it possible to recycle a considerable amount of plastics from e-waste and, thus, contributing to the preservation of the environment.

Rhodococcus erythropolis ATCC 4277 behavior against different metals and its potential use in waste biomining.

Rhodococcus erythropolis bacterium is known for its remarkable resistance characteristics that can be useful in several biotechnological processes, such as bioremediation. However, there is scarce knowledge concerning the behavior of this strain against different metals. This study sought to investigate the behavior of R. erythropolis ATCC 4277 against the residue of chalcopyrite and e-waste to verify both resistive capacities to the metals present in these residues and their potential use for biomining processes. These tests were carried out in a stirred tank bioreactor for 48 h, at 24ºC, pH 7.0, using a total volume of 2.0 L containing 2.5% (v/v) of a bacterial pre-culture. The pulp density of chalcopyrite was 5% (w/w), and agitation and oxygen flow rates were set to 250 rpm and 1.5 LO2 min-1, respectively. On the other hand, we utilized a waste of computer printed circuit board (WPCB) with a pulp density of 10% (w/w), agitation at 400 rpm, and an oxygen flow rate of 3.0 LO2 min-1. Metal concentration analyses post-fermentation showed that R. erythropolis ATCC 4277 was able to leach about 38% of the Cu present in the chalcopyrite residue (in ~ 24 h), and 49.5% of Fe, 42.3% of Ni, 27.4% of Al, and 15% Cu present in WPCB (in ~ 24 h). In addition, the strain survived well in the environment containing such metals, demonstrating the potential of using this bacterium for waste biomining processes as well as in other processes with these metals.

Chromoproduct approach to achieve environmentally sound management of e-waste plastics: Colombian project case.

Research to prevent releases of brominated flame retardants listed as persistent organic pollutants by the Stockholm Convention (POP-BFRs) was conducted through an international cooperation project in Colombia. Six waste electrical and electronic equipment (WEEE) management facilities implemented: 1) sorting e-waste by product type and color (black, white, and other; henceforth called chromoproducts), 2) sampling test products and their plastic fraction (called sets, separated by polymer type), 3) monitoring mass, bromine and antimony contents by hand-held X-ray fluorescence (XRF) and POP-BFRs such as polybrominated diphenyl ethers (PBDEs) by gas chromatography and mass spectrometry (GC-MS), and 4) differentiated treatment according to categories that used the Restriction of Hazardous Substances in Electrical and Electronic Equipment Directive (RoHS) hazardousness threshold of 1000 mg ∑PBDEs/kg. This scheme led to the proposal of a methodology for WEEE management called the "chromoproduct approach". 994,230 products were managed and grouped into 222 chromoproducts, from which 77 were analyzed: 50 below RoHS hazardousness (BRH), 16 above RoHS hazardousness (ARH), and 11 unknown RoHS hazardousness (URH). XRF indicators using bromine and antimony contents could rule out pollution in BRH chromoproducts; however, categorization still required GC-MS. One ARH plastics sample had 3620 mg ∑PBDEs/kg, while no POP-BFRs were found in the BRH plastics sample. The implementation of the chromoproduct approach traced 153.6 tonnes of ARH plastics. BRH plastics composition was estimated and used in a pilot-scale closed-loop economic activity. The chromoproduct approach seems promising for avoiding POP-BFR releases and promoting the upcycling of recyclable e-waste plastics.

Identification of yttrium oxide-specific peptides for future recycling of rare earth elements from electronic scrap.

Yttrium is a heavy rare earth element (REE) that acquires remarkable characteristics when it is in oxide form and doped with other REEs. Owing to these characteristics Y2 O3 can be used in the manufacture of several products. However, a supply deficit of this mineral is expected in the coming years, contributing to its price fluctuation. Thus, developing an efficient, cost-effective, and eco-friendly process to recover Y2 O3 from secondary sources has become necessary. In this study, we used phage surface display to screen peptides with high specificity for Y2 O3 particles. After three rounds of enrichment, a phage expressing the peptide TRTGCHVPRCNTLS (DM39) from the random pVIII phage peptide library Cys4 was found to bind specifically to Y2 O3 , being 531.6-fold more efficient than the wild-type phage. The phage DM39 contains two arginines in the polar side chains, which may have contributed to the interaction between the mineral targets. Immunofluorescence assays identified that the peptide's affinity was strong for Y2 O3 and negligible to LaPO4 :Ce3+ ,Tb3+ . The identification of a peptide with high specificity and affinity for Y2 O3 provides a potentially new strategic approach to recycle this type of material from secondary sources, especially from electronic scrap.

Challenges to implement and operationalize the WEEE reverse logistics system at the micro level.

Waste electrical and electronic equipment (WEEE) possesses unique characteristics such as its growing production and the potential for resource extraction due to its composition. The implementation and operationalization of a reverse logistics system (RLS) for WEEE is a challenge, particularly concerning the micro level. The implementation of such systems often prioritizes urban centers and their higher population densities, generally overlooking the micro level. The latter refers to ward- or village-level divisions, which can be regarded as the smallest administrative divisions of both urban and rural areas. Furthermore, it encompasses any area facing logistical challenges regarding RLS operationalization due to factors such as geographical isolation, budgetary constraints, imbalances, social isolation, environmental aspects, and even geopolitical conflicts. This study is aimed at addressing this literature gap by discussing the challenges to implement and operationalize a WEEE RLS at the micro level. A systematic literature review was employed as our methodology. We found 13 challenges for developed and developing countries without distinction between macro and micro levels. An additional approach highlighted the significance of monitoring and controlling WEEE RLS. The challenge The population and LRS entities' lack or insufficient training and awareness received the most citations in the conducted search. These challenges were organized by operational phase and discussed from the perspective of the micro level to comprehend multifactorial local challenges involving all stakeholders in the reverse logistics of WEEE in emerging nations. This can assist local administrators and constitutes the primary contribution of this study.

Formation of silver halos by Sphingomonas paucimobilis MX8 and its bioleaching of silver from computer keyboard printed circuit boards.

Silver (Ag) is currently obtained from primary and secondary sources through hydrometallurgical and pyrometallurgical processes. However, these processes consume high amounts of energy and are environmentally unfriendly. The search for bacteria tolerant with a high leaching capacity for to Ag is therefore a necessary requirement as part of the development of bioleaching technologies with reduced impact on the environment and lower energy expenditure. In this sense, the objective of this research was to evaluate the tolerance of Sphingomonas paucimobilis MX8 to Ag added to nutrient agar, and to determine whether this tolerance could favor the bioleaching of Ag present on the printed circuit boards (PCBs) of computer keyboards. The bacteria Sphingomonas paucimobilis MX8 was cultured in Petri dishes with nutrient agar and four different concentrations of AgNO3 (200, 400, 600, and 800 mg L-1) at 28 °C for 10 days. For the bioleaching experiment, the bacteria were grown in a mineral medium with computer keyboard PCBs for 30 days at room temperature (17 to 22 °C) and centrifugation at 150 rpm. The results indicate that Sphingomonas paucimobilis MX8 is tolerant to Ag and forms a silvery halo around its growth in the presence of this metal. Furthermore, Sphingomonas paucimobilis MX8 was able to bioleach 12% of the Ag found in computer keyboard PCBs. The results obtained could help generate more environmentally friendly silver bioleaching processes in which the silver bioleaching capacity of this bacterium is increased.

Estimation of lithium-ion battery scrap generation from electric vehicles in Brazil.

Among the diversity of electronic waste, lithium-ion batteries (LIB), specifically those used in the propulsion of electric vehicles (EV), are considered pollutants of significant impact. When not used and disposed of correctly, LIBs can cause damage of various types to health and the environment. The electrochemical instability inherent in these batteries releases toxic gases, risks explosion, and is always associated with a series of electronic circuits composed of various metals, including heavy metals. As a result of public policies to encourage vehicle electrification, the Brazilian EVs sector has shown high growth, even within an economic crisis scenario. In this sense, this study presents a model for estimating the production of electric vehicles and the generation of scrap LIBs, based on time series, combining battery life, car sales data, and the mileage profile covered by a car in Brazil. Around 700 thousand EVs are expected to be circulating in Brazil by 2030, with approximately 500 thousand LIBs to be converted into scrap by 2040. Finally, the delaying effect of the scrap generated from LIBs is highlighted, in line with the battery life, which, in the future, may have a very negative impact on waste management.

From E-Waste to High-Value Materials: Sustainable Synthesis of Metal, Metal Oxide, and MOF Nanoparticles from Waste Printed Circuit Boards.

The exponential growth of electronic waste (e-waste) has raised significant environmental concerns, with projections indicating a surge to 74.7 million metric tons of e-waste generated by 2030. Waste printed circuit boards (WPCBs), constituting approximately 10% of all e-waste, are particularly intriguing due to their high content of valuable metals and rare earth elements. However, the presence of hazardous elements necessitates sustainable recycling strategies. This review explores innovative approaches to sustainable metal nanoparticle synthesis from WPCBs. Efficient metal recovery from WPCBs begins with disassembly and the utilization of advanced equipment for optimal separation. Various pretreatment techniques, including selective leaching and magnetic separation, enhance metal recovery efficiency. Green recovery systems such as biohydrometallurgy offer eco-friendly alternatives, with high selectivity. Converting metal ions into nanoparticles involves concentration and transformation methods like chemical precipitation, electrowinning, and dialysis. These methods are vital for transforming recovered metal ions into valuable nanoparticles, promoting sustainable resource utilization and eco-friendly e-waste recycling. Sustainable green synthesis methods utilizing natural sources, including microorganisms and plants, are discussed, with a focus on their applications in producing well-defined nanoparticles. Nanoparticles derived from WPCBs find valuable applications in drug delivery, microelectronics, antimicrobial materials, environmental remediation, diagnostics, catalysis, agriculture, etc. They contribute to eco-friendly wastewater treatment, photocatalysis, protective coatings, and biomedicine. The important implications of this review lie in its identification of sustainable metal nanoparticle synthesis from WPCBs as a pivotal solution to e-waste environmental concerns, paving the way for eco-friendly recycling practices and the supply of valuable materials for diverse industrial applications.

Synthesis of Gold Nanoparticles from Gold Coatings Recovered from E-Waste Processors.

This work presents the synthesis of Au nanoparticles from gold coatings recovered from processor pins with minimal waste generation. The process consisted of four main steps: (1) physical recovery of pins, (2) recovery of gold coatings by acid digestion, (3) synthesis of HAuCl4 under mild conditions and, (4) synthesis of Au nanoparticles by the Turkevich method. The small dimensions of Au coatings allowed the synthesis of HAuCl4 with lower amounts of HClconc and HNO3conc than those used with aqua regia. This method has significant advantages, such as lower NO2(g) emission, easy post-treatment and purification, low synthesis cost and high yields. Gold nanoparticles synthesized from HAuCl4 were characterized by transmission electron microscopy (TEM) and UV-Vis spectroscopy. Size distribution analysis showed particles 14.23 nm in length and 12.05 nm in width, while absorption spectra showed a surface plasmon located at 523 nm; these characteristics were very similar to those observed with Au nanoparticles obtained with Aldrich's reagent. It is suggested that recycling procedures can be improved by taking into account the size and shape of the metals to be recovered, thus introducing a new field of research known as hydronanometallurgy.

Work Task Association with Lead Urine and Blood Concentrations in Informal Electronic Waste Recyclers in Thailand and Chile.

The informal recycling of electronic waste ("e-waste") is a lucrative business for workers in low- and middle-income countries across the globe. Workers dismantle e-waste to recover valuable materials that can be sold for income. However, workers expose themselves and the surrounding environment to hazardous agents during the process, including toxic metals like lead (Pb). To assess which tools, tasks, and job characteristics result in higher concentrations of urine and blood lead levels among workers, ten random samples of 2 min video clips were analyzed per participant from video recordings of workers at e-waste recycling sites in Thailand and Chile to enumerate potential predictors of lead burden. Blood and urine samples were collected from participants to measure lead concentration. Boosted regression trees (BRTs) were run to determine the relative importance of video-derived work variables and demographics, and their relationship with the urine and blood concentrations. Of 45 variables considered, five job characteristics consisting of close-toed shoes (relative importance of 43.9%), the use of blunt striking instruments (14%), bending the back (5.7%), dismantling random parts (4.4%), and bending the neck (3.5%) were observed to be the most important predictors of urinary Pb levels. A further five job characteristics, including lifting objects <20 lbs. (6.2%), the use of screwdrivers (4.2%), the use of pliers/scissors (4.2%), repetitive arm motion (3.3%), and lifting objects >20 pounds (3.2%) were observed to be among the most important factors of blood Pb levels. Overall, our findings indicate ten job characteristics that may strongly influence Pb levels in e-waste recycling workers' urine and blood.

Bibliometric analysis of studies involving e-waste: a critical review.

The correct destination of waste is an essential factor for sustainable development. Electronic waste, which is very toxic, is the type of waste with the highest rate of increase in its generation. For these reasons, the amount of research on this topic increases year by year, as shown by the literature review carried out by this study. This review aims to identify the main characteristics and proposals of the main study on electronic waste and verify how Brazil is inserted globally in the research on e-waste. Another objective is to suggest a path for researchers who want to start research on e-waste by identifying the keywords most used in the analyzed articles. The results evidenced that the most published countries on the subject are China, the USA, and India. Brazil is in a position of little prominence concerning its research production on the subject. Most of the central studies we analyzed use case study and literature review as the research method. Among the 44 articles analyzed, only one proposed a destination for e-waste. It highlights the need for more research focusing on the environmentally correct destination of e-waste. A good way to start a search on electronic waste is to use the keywords identified in this study, especially those used most frequently in the analyzed articles.

Environmental Fe, Ti, Al, Cu, Hg, Bi, and Si Nanoparticles in the Atrioventricular Conduction Axis and the Associated Ultrastructural Damage in Young Urbanites: Cardiac Arrhythmias Caused by Anthropogenic, Industrial, E-Waste, and Indoor Nanoparticles.

Air pollution exposure is a risk factor for arrhythmia. The atrioventricular (AV) conduction axis is key for the passage of electrical signals to ventricles. We investigated whether environmental nanoparticles (NPs) reach the AV axis and whether they are associated with ultrastructural cell damage. Here, we demonstrate the detection of the shape, size, and composition of NPs by transmission electron microscopy (TEM) and energy-dispersive X-ray spectrometry (EDX) in 10 subjects from Metropolitan Mexico City (MMC) with a mean age of 25.3 ± 5.9 and a 71-year-old subject without cardiac pathology. We found that in every case, Fe, Ti, Al, Hg, Cu, Bi, and/or Si spherical or acicular NPs with a mean size of 36 ± 17 nm were present in the AV axis in situ, freely and as conglomerates, within the mitochondria, sarcomeres, lysosomes, lipofuscin, and/or intercalated disks and gap junctions of Purkinje and transitional cells, telocytes, macrophages, endothelium, and adjacent atrial and ventricular fibers. Erythrocytes were found to transfer NPs to the endothelium. Purkinje fibers with increased lysosomal activity and totally disordered myofilaments and fragmented Z-disks exhibited NP conglomerates in association with gap junctions and intercalated disks. AV conduction axis pathology caused by environmental NPs is a plausible and modifiable risk factor for understanding common arrhythmias and reentrant tachycardia. Anthropogenic, industrial, e-waste, and indoor NPs reach pacemaker regions, thereby increasing potential mechanisms that disrupt the electrical impulse pathways of the heart. The cardiotoxic, oxidative, and abnormal electric performance effects of NPs in pacemaker locations warrant extensive research. Cardiac arrhythmias associated with nanoparticle effects could be preventable.

Chemical inspection and elemental analysis of electronic waste using data fusion - Application of complementary spectroanalytical techniques.

This study is focused on the development of analytical methods for characterization of printed circuit boards (PCBs) from mobile phones by direct analysis using three complementary spectroanalytical techniques: laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS), laser-induced breakdown spectroscopy (LIBS), and micro X-ray fluorescence spectroscopy (micro-XRF). These techniques were combined with principal component analysis (PCA) to investigate the chemical composition on the surface and depth profiling of PCB samples. The spatial distribution of important base metals (e.g. Al, Au, Ba, Cu, Fe, Mg, Ni, Zn), toxic elements (e.g. Cd, Cr, Pb) as well as the non-metallic fraction (e.g. P, S and Si) from conductive tracks, solder mask and integrated components were detected within the PCB samples. Univariate and multivariate approaches were also performed to obtain calibration models for Cu determination. The results were compared to reference concentrations obtained by inductively coupled plasma-optical emission spectrometry (ICP-OES) after microwave-assisted acid leaching using aqua regia. To this end, two PCB samples (50 × 34 mm2) were cut into small parts of 40 subsamples (10 × 8.5 mm2) and analyzed by ICP-OES and the Cu concentrations ranged from 13 to 45% m m-1. Partial least squares (PLS) regression was used to data fusion of analytical information from LIBS and micro-XRF analysis. The proposed calibration methods for LIBS and micro-XRF were tested for the 40 PCB subsamples, in which the best results were obtained combining both data sources though a low-level data fusion. Root mean square error of cross validation (RMSEC) and recoveries were 3.23% m m-1 and 81-119% using leave-one-out cross validation.

Calibration strategies for the direct determination of rare earth elements in hard disk magnets using laser-induced breakdown spectroscopy.

This study is dedicated to the direct determination of base (B and Fe) and some rare earth elements (REE; Dy, Gd, Nd, Pr, Sm and Tb) in hard disk magnets. Five calibration strategies were tested and compared. Two of them are related to multivariate calibration: multiple linear regression (MLR) and partial least squares (PLS). Both presented adequate trueness values within a range of 80-120% for almost all analytes. The only exception was Tb, which was probably due to matrix effects. The use of MLR and PLS permits the testing of calibration models in the presence of interference, but matrix effects are not corrected. Because of this, three other univariate calibration methods were also tested and compared: multi-energy calibration (MEC), one-point gravimetric standard addition (OP GSA) and two-point calibration transfer (TP CT). These three calibration approaches permit matrix effects corrections, but an appropriate selection of the blank and standard is mandatory. The standard error obtained ranged from 0.01 to 6% using these univariate calibration methods.

Domestic flow of e-waste in São Paulo, Brazil: Characterization to support public policies.

Understanding the domestic flow of e-waste is essential for efficient waste management in urban contexts. However, diagnosis of domestic e-waste flow is complex due to its diffuse generation and dependence on consumer behavior. Here, we characterized domestic e-waste flow in São Paulo, Brazil (a megacity with roughly 11 million inhabitants in 3.5 million households), describing the stages of product acquisition, out-of-use storage, and end-of-life destination, via a population-based cross-sectional study using a statistically representative sample. We conducted household interviews using a structured questionnaire, with questions on characteristics, quantities, and behaviors of acquisition, replacement, storage, repair, and destination for 26 electric and electronic equipment (EEE) categories. Each household had on average 21 EEE (95% confidence interval [CI]: 19.7-21.7), of which 18 were in use and 3 were out-of-use. Out-of-use storage was common, occurring in 72.6% of households. Discarded EEE (i.e., e-waste) was destined for intended reuse (59.5%; 95% CI: 57.4-61.5%), recycling (20.4%; 95% CI: 18.8-22.1%), and, particularly for small EEE, municipal waste (16.0%; 95% CI: 14.5-17.6%). Other aspects of domestic e-waste flow (e.g., place and time of acquisition, second-hand acquisition, donation, intention to repair damaged EEE, and storage) were quantified and related to actions for public policies. This research shows that household surveys are useful for obtaining primary data to verify consumer behavior toward EEE. We expect the findings of this study to support decision-making for public policies related to e-waste management, particularly in countries where reverse logistics systems are in the initial phase of implementation.

Bacterial community structure in soils contaminated with electronic waste pollutants from Delhi NCR, India

Background: Microbial community analysis of electronic waste (e-waste)-polluted environments is of interest to understand the effect of toxic e-waste pollutants on the soil microbial community and to evaluate novel microorganisms resisting the toxic environment. The present study aims to investigate the bacterial community structure in soils contaminated with e-waste from various sites of Loni and Mandoli (National Capital Region (NCR), India) where e-waste dumping and recycling activities are being carried out for many years. Results: Interferences to soil metagenomic DNA extraction and PCR amplification were observed because of the presence of inhibiting components derived from circuit boards. Whole-metagenome sequencing on the Illumina MiSeq platform showed that the most abundant phyla were Proteobacteria and Firmicutes. Deltaproteobacteria and Betaproteobacteria were the most common classes under Proteobacteria. Denaturing gradient gel electrophoresis (DGGE) analysis of the bacterial 16S rRNA gene showed that e-waste contamination altered the soil bacterial composition and diversity. There was a decrease in the number of predominant bacterial groups like Proteobacteria and Firmicutes but emergence of Actinobacteria in the contaminated soil samples. Conclusions: This is the first report describing the bacterial community structure of composite soil samples of ewaste-contaminated sites of Loni and Mandoli, Delhi NCR, India. The findings indicate that novel bacteria with potential bioremediating properties may be present in the e-waste-contaminated sites and hence need to be evaluated further.

Past and emerging topics related to electronic waste management: top countries, trends, and perspectives.

A bibliometric analysis was performed to assess historical and recent research trends regarding e-waste studies from 1998 to 2018. Documents related to e-waste were identified from the Clarivate Analytics Web of Science© (WoS) database, and a total of 3311 academic articles was retrieved. The analysis was performed from four main aspects: (1) publication activity by year, by WoS category, and by geographic distribution; (2) journals; (3) most-cited papers; and (4) top 10 countries and author keyword analysis. The number of publications concerning e-waste issues has increased substantially over the last 20 years, especially in the environmental science category, and more than a third of the publications were produced in China (1181 records). Waste Management and Environmental Science & Technology were the most sought-after journals for disseminating the results. Studies related to "e-waste flow analysis," "recycling," "recovery of precious metals," and "risk assessment of recycling areas" have been the most common for several years. The analysis of keywords suggested that there are many topics on electronic waste and that each country has presented a different focus of research. Overall, the bibliometric analysis proved to be an efficient tool with which to monitor historical and current research trends and to evaluate the sheer volume of currently existing scientific literature on e-waste topics.

Exposição ocupacional ao mercúrio em cooperativas de triagem de materiais recicláveis da região metropolitana de São Paulo, SP, Brasil / Occupational exposure to mercury in recycling cooperatives from the metropolitan region of São Paulo, Brazil

Resumo A exposição ocupacional ao mercúrio (Hg) foi avaliada em 4 cooperativas de materiais recicláveis por meio de amostragens de ar em 9 áreas (monte de triagem, balança, prensa, sala de resíduos de equipamentos eletroeletrônicos-REEE, refeitório, escritório, empilhadeira, esteira e pátio externo). Das 83 amostras, apenas 14,5% apresentaram concentrações acima do limite de quantificação (LQ) e 53% entre o LD (limite de detecção) e LQ. A maioria dos valores > LQ ocorreu na cooperativa A, no monte (0,032 µg.m -3 ) e balança (0,029 µg.m -3 ). Nos dias de amostragem houve descarregamento de lâmpadas fluorescentes, o que pode explicar os maiores teores de Hg nessa cooperativa. Na cooperativa B a concentração foi 0,033 µg.m -3 na esteira e < 0,003 µg.m -3 nas outras áreas. Nas cooperativas C e D todos os valores foram < 0,007 µg.m -3 . As áreas de REEE apresentaram baixas concentrações, provavelmente devido ao baixo volume de REEE e forma de processamento do material. Os resultados estiveram abaixo dos valores de referência ocupacional, indicando que os trabalhadores não estão expostos ao Hg. No entanto, o desenho amostral pode não ter sido abrangente devido à intermitência no processamento de REEE e à imprevisibilidade da ocorrência de lâmpadas fluorescentes no material reciclável .

Abstract The occupational exposure to mercury (Hg) was assessed in four cooperatives of recyclable materials by air sampling in nine areas (recyclable materials pile, scale, baling press machine, e-waste room, cafeteria, office, forklift, conveyor belt, and outside patio). Of the 83 samples, only 14.5% showed concentrations above the limit of quantification (LOQ) while 53% were between the LOD (limit of detection) and LOQ. Most values > LOQ occurred at Cooperative A, at the pile (0.032 μg.m-3) and scale (0.029 μg.m-3). The higher values recorded at this Cooperative might be associated with the unloading of fluorescent lamps on the day of sampling. In cooperative B, the concentration was 0.033 μg.m-3 on the conveyor belt and < 0.003 µg.m-3 in other areas. In cooperatives C and D, all samples showed values < 0.007 μg.m-3. The Hg concentrations were low in areas of e-waste handling and storage, probably due to the small amount of material and way of processing. The results were below the occupational reference values, showing that the workers are not exposed to Hg. However, the sampling design might not have been comprehensive due to the discontinuity of the e-waste processing and the unpredictable occurrence of fluorescent lamps mixed with recyclable materials .

Calibration strategies for determination of the In content in discarded liquid crystal displays (LCD) from mobile phones using laser-induced breakdown spectroscopy (LIBS).

Mobile phones are one of the fastest growing types of electronic waste disposed of world-wide. One of the main components in these devices is the LCD (liquid crystal display) panel that contains conductive electrodes made of indium tin oxide. A large amount of In, which is categorized as a critical raw element, has been used to manufacture indium tin oxide films. This study applies laser-induced breakdown spectroscopy (LIBS) for the analysis of LCD samples from mobile phones in order to determine the In content. Both conventional univariate calibration and non-traditional calibration using different transition energies (emission lines), named multi-energy calibration (MEC), were assessed. To evaluate the accuracy of the results, Method EPA 3052 was performed for acid digestion of the samples using microwave-assistance, and the In content was determined by ICP OES. Indium concentrations ranged from 35 to 47 mg kg-1 for all samples evaluated. The results showed the best accuracy for LIBS methods after the spectra were normalized by the carbon line at 193.09 nm. The univariate-LIBS model showed a standard error of calibration (SEC) about 10-fold lower than the samples' concentration, LOD and LOQ of 0.3 and 1.0 mg kg-1, respectively. MEC proved to be a fast and efficient alternative for direct solid analysis, and In concentrations were determined by LIBS using only two calibration pellets. The LOD and LOQ for MEC-LIBS method were 2.1 and 7 mg kg-1, respectively.

Estimating the generation of household e-waste in municipalities using primary data from surveys: A case study of Sao Jose dos Campos, Brazil.

Estimating the generation of Waste from Electrical and Electronic Equipment (WEEE) in municipalities is relevant for the adequate planning of take-back systems. However, current WEEE estimation studies have focused primarily at the country level, and relied mostly on secondary data from literature, especially when adopting discrete average lifespans for each type of appliance. This paper aims at developing and applying a WEEE estimation method in a Brazilian city, by obtaining primary data that reflects the differences in WEEE generation among the various social and economic profiles in the city. A survey with a stratified sample was carried out to collect representative data from each city Zone. Results show that lifespan distributions are most desirable for WEEE estimation studies than discrete averages, and that the lifespan profiles in the city are considerably different than previous values adopted in other Brazilian studies. Results also show significant variations of lifespan profiles for different types of WEEE among the different Zones of the city, which reflect the social and economic differences.