Application of soil magnetometry and geochemical methods to investigate soil contamination with antimony.

The aim of the study was an assessment of the pollution level and identification of the antimony sources in soils in areas subjected to industrial anthropopressure from: transport, metallurgy and electrical waste recycling. The combination of soil magnetometry, chemical analyzes using atomic spectrometry (ICP-OES and ICP-MS), Sb fractionation analysis, statistical analysis (Pearson's correlation matrix, factor analysis) as well as Geoaccumulation Index, Pollution Load Index, and Sb/As factor allowed not only the assessment of soil contamination degree, but also comprehensive identification of different Sb sources. The results indicate that the soil in the vicinity of the studied objects was characterized by high values of magnetic susceptibility and thus, high contents of potentially toxic elements. The most polluted area was in the vicinity of electrical waste processing plants. Research has shown that the impact of road traffic and wearing off brake blocks, i.e. traffic anthropopression in general, has little effect on the surrounding soil in terms of antimony content. Large amounts of Pb, Zn, As and Cd were found in the soil collected in the vicinity of the heap after the processing of zinc-lead ores, the average antimony (11.31 mg kg-1) content was lower in the vicinity of the heap than in the area around the electrical and electronic waste processing plant, but still very high. Antimony in the studied soils was demobilized and associated mainly with the residual fraction.

Investigating the acidophilic microbial community's adaptation for enhancement indium bioleaching from high pulp density shredded discarded LCD panels.

As part of electronic waste (e-waste), the fastest growing solid waste stream in the world, discarded liquid crystal displays (LCDs) contain substantial amounts of both valuable and potentially harmful metal, offering valuable opportunities for resource extraction but posing environmental threats. The present comprehensive study is an investigation into the bioleaching of indium from discarded LCD panels, with a particular focus on high pulp density shredded (Sh-LCDs) and powdered (P-LCDs) materials. This study involved an acidophilic consortium, with two pathways, namely the mixed sulfur-iron pathways and sulfur pathways, being explored to understand the bioleaching mechanisms. Indium bioleaching efficiencies through the mixed sulfur-iron pathway were approximately 60% and 100% for Sh-LCDs and P-LCDs, respectively. Three mechanisms were involved in the extraction of indium from LCD samples: acidolysis, complexolysis, and redoxolysis. The microbial community adapted to a pulp density of 32.5 g/L was streak-plated and it was revealed that sulfur-oxizing bacteria dominated, resulting in the minimum indium extraction of 10% and 55% for both Sh-LCDs and P-LCDs samples, respectively. It was generally accepted that ferric ions as oxidants were effective for indium bioleaching from both the Sh-LCDs and P-LCDs. This implies that the cooperation or interaction within the microbial community used in the bioleaching process had a beneficial impact, enhancing the overall effectiveness of extracting indium from LCD panels. The adapted consortium utilizes a combination of microbial transformation, efflux systems, and chelation through extracellular substances to detoxify heavy metals. The adapted microbial community demonstrated better indium leaching efficiency (50%) compared to the non-adapted microbial community which achieved a maximum of 29% and 5% respectively from Sh-LCDs and P-LCDs at a pulp density of 32.5 g/L. The advantages of an adapted microbial community for indium leaching efficiency, attributing this advantage to factors such as high metabolic activity and improved tolerance to heavy metals. Additionally, the protective role of the biofilm formed by the adapted microbial community is particularly noteworthy, as it contributes to the community's resilience in the presence of inhibitory substances. This information is valuable for understanding and optimizing bioleaching processes for indium recovery, and by extension to possibly other metals.

Spatial distribution and health risks assessment of heavy metals in e-waste dumping sites from Pakistan.

The present study focused on to determine the concentration and health risk of heavy metals (Cu, Pb, Zn, Cd, Hg, Cr) in e-waste contaminated soils collected from different provinces of Pakistan. Further, the impact of heavy metals on soil enzyme activities and microbial community was also investigated. The concentration (mg/kg) of Hg, Zn, Fe, Cu, Pb, Cd, and Cr ranged between 0-0.258, 2.284-6.587, 3.005-40.72, 8.67-36.88, 12.05-35.03, 1.03-2.43, and 33.13-60.05, respectively. The results revealed that Lahore site of Punjab province indicated more concentration of heavy metals as compared to other sites. The level of Cr at all sites whereas Hg at only two sites exceeds the World Health Organization standards (WHO) for soil. Soil enzyme activity exhibited dynamic trend among the sites. Maximum enzyme activity was observed for urease followed by phosphatase and catalase. Contamination factor (Cf), Pollution load index (PLI), and geo-accumulation index (Igeo) results showed that all the sites are highly contaminated with Cu, Cd, and Pb. Hazard index (HI) was less than 1 for children and adults suggesting non-carcinogenic health risk. Principle component analysis results depicted relation among Cr, Fr, catalase, and actinomycetes; Cd, OM, urease, and bacteria, and Pb, Cu, Zn, Hg, and phosphatase, suggesting soil enzymes and microbial community profiles were influenced by e-waste pollution. Therefore, there is a dire need to introduce sustainable e-waste recycling techniques as well as to make stringent e-waste management policies to reduce further environmental contamination.

Associations of insulin sensitivity and immune inflammatory responses with child blood lead (Pb) and PM2.5 exposure at an e-waste recycling area during the COVID-19 lockdown.

Fine particular matter (PM2.5) and lead (Pb) exposure can induce insulin resistance, elevating the likelihood of diabetes onset. Nonetheless, the underlying mechanism remains ambiguous. Consequently, we assessed the association of PM2.5 and Pb exposure with insulin resistance and inflammation biomarkers in children. A total of 235 children aged 3-7 years in a kindergarten in e-waste recycling areas were enrolled before and during the Corona Virus Disease 2019 (COVID-19) lockdown. Daily PM2.5 data was collected and used to calculate the individual PM2.5 daily exposure dose (DED-PM2.5). Concentrations of whole blood Pb, fasting blood glucose, serum insulin, and high mobility group box 1 (HMGB1) in serum were measured. Compared with that before COVID-19, the COVID-19 lockdown group had lower DED-PM2.5 and blood Pb, higher serum HMGB1, and lower blood glucose and homeostasis model assessment of insulin resistance (HOMA-IR) index. Decreased DED-PM2.5 and blood Pb levels were linked to decreased levels of fasting blood glucose and increased serum HMGB1 in all children. Increased serum HMGB1 levels were linked to reduced levels of blood glucose and HOMA-IR. Due to the implementation of COVID-19 prevention and control measures, e-waste dismantling activities and exposure levels of PM2.5 and Pb declined, which probably reduced the association of PM2.5 and Pb on insulin sensitivity and diabetes risk, but a high level of risk of chronic low-grade inflammation remained. Our findings add new evidence for the associations among PM2.5 and Pb exposure, systemic inflammation and insulin resistance, which could be a possible explanation for diabetes related to environmental exposure.

Smart e-waste management: a revolutionary incentive-driven IoT solution with LPWAN and edge-AI integration for environmental sustainability.

Managing e-waste involves collecting it, extracting valuable metals at low costs, and ensuring environmentally safe disposal. However, monitoring this process has become challenging due to e-waste expansion. With IoT technology like LoRa-LPWAN, pre-collection monitoring becomes more cost-effective. Our paper presents an e-waste collection and recovery system utilizing the LoRa-LPWAN standard, integrating intelligence at the edge and fog layers. The system incentivizes WEEE holders, encouraging participation in the innovative collection process. The city administration oversees this process using innovative trucks, GPS, LoRaWAN, RFID, and BLE technologies. Analysis of IoT performance factors and quantitative assessments (latency and collision probability on LoRa, Sigfox, and NB-IoT) demonstrate the effectiveness of our incentive-driven IoT solution, particularly with LoRa standard and Edge AI integration. Additionally, cost estimates show the advantage of LoRaWAN. Moreover, the proposed IoT-based e-waste management solution promises cost savings, stakeholder trust, and long-term effectiveness through streamlined processes and human resource training. Integration with government databases involves data standardization, API development, security measures, and functionality testing for efficient management.

Elemental characterization of electronic waste: a review of research methodologies and applicability to the practice of e-waste recycling.

Economic and environmental considerations have elucidated research interests on the best approach to managing electronic waste (e-waste), which has increasing social, environmental, and economic impacts. Proper e-waste managementis essential for resource recovery, environmental sustainability, and public health protection, and effective management of e-waste necessitates analytical techniques to assess and characterize their elemental composition. Despite expansive literature published on the topic of e-waste, there is scarce coverage of the various analytical techniques employed to characterize the inorganic contents of e-waste. This review discusses the various e-waste characterization techniques used in studies published between 2013 and 2023. Specifically, this review covers the analytical approaches employed to characterize the inorganic content of e-waste, the electronic devices or their components analyzed, the elements identified, the sample preparation methods adopted, and the merits and demerits of the analytical procedures. This review highlights the disparate approaches to e-waste characterization and the need for reliable and repeatable e-waste analysis and sample preparation methods.

Kinetic investigation on the catalytic pyrolysis of plastic fractions of waste electrical and electronic equipment (WEEE): A mathematical deconvolution approach.

Waste electrical and electronic equipment (WEEE) has become a critical environmental problem. Catalytic pyrolysis is an ideal technique to treat and convert the plastic fraction of WEEE into chemicals and fuels. Unfortunately, research using real WEEE remains relatively limited. Furthermore, the complexity of WEEE complicates the analysis of its pyrolytic kinetics. This study applied the Fraser-Suzuki mathematical deconvolution method to obtain the pseudo reactions of the thermal degradation of two types of WEEE, using four different catalysts (Al2O3, HBeta, HZSM-5, and TiO2) or without a catalyst. The main contributor(s) to each pseudo reaction were identified by comparing them with the pyrolysis results of the pure plastics in WEEE. The nth order model was then applied to estimate the kinetic parameters of the obtained pseudo reactions. In the low-grade electronics pyrolysis, the pseudo-1 reaction using TiO2 as a catalyst achieved the lowest activation energy of 92.10 kJ/mol, while the pseudo-2 reaction using HZSM-5 resulted in the lowest activation energy of 101.35 kJ/mol among the four catalytic cases. For medium-grade electronics, pseudo-3 and pseudo-4 were the main reactions for thermal degradation, with HZSM-5 and TiO2 yielding the lowest pyrolytic activation energies of 75.24 and 226.39 kJ/mol, respectively. This effort will play a crucial role in comprehending the pyrolysis kinetic mechanism of WEEE and propelling this technology toward a brighter future.

Assessment of direction changes in waste electrical and electronic equipment management in Poland.

A growing amount of waste electrical and electronic equipment (WEEE) indicates the need to verify the effectiveness of its management both nationally and globally. An analysis of the WEEE economy in Poland conducted over 5 years confirmed a 16.64% increase in the mass of collected equipment. The maximum annual mass of electrical and electronic equipment introduced to the market during this period was 607,240 Mg, with the average value exceeding 500,000 Mg. The WEEE category with the largest collected mass was waste code 20 01 36, which exceeded 235,000 Mg, whilst the highest waste weight accumulation rate of 45.98 kg per capita was recorded in one of the smallest voivodeships in Poland. This result showed the diversity of WEEE accumulation on a national scale. Overall, a noticeable increase in the WEEE accumulation rate has occurred as Poland's gross domestic product has increased, despite a decreasing population. An analysis based on the waste accumulation indicators, including socioeconomic factors, confirmed the need to develop forms of WEEE recovery and recycling to transition to a circular economy and promote the synergy of activities amongst all players in WEEE management.

Advanced granulometric characterization of shredded waste printed circuit boards for sampling.

Whether it be to measure their value before a trade, to calculate yields and optimize the recycling process or to check for the presence of harmful substances, Waste Electronic and Electric Equipments (WEEE) need to be characterized. Sampling can give an accurate assessment of the grade of a batch of WEEE, but quantifying the uncertainty around this estimate can be delicate. Pierre Gy's sampling theory of particulate matter studies how the latter is affected by the physical and chemical properties of the studied objects. However, its application requires a deep understanding of the correlations existing between their size, shape, volume, density, mass and grade, which are still unclear for WEEE fragments. Although average information is typically available on batches of WEEE, a more detailed description would be necessary to gain insight into such relationships. To start filling the gap, this paper focuses on the fine characterization of two different batches of waste printed circuit boards, crushed into pieces of about 10 mm. One by one, over 5,000 fragments were sampled, photographed and analyzed. Their individual mass, density, volume, thickness, surface, width and length were all measured separately. Based on their appearance, they were also sorted into four heuristic categories: plastic, metal, circuit boards and electronic components. Descriptive statistics of this novel granulometric database are shown here, throwing light on the unique correlations between the studied parameters and exhibiting a peculiar mass-size law. They point to new avenues on how to adapt Gy's sampling model to WEEE.

Conversion and fate of waste Li-ion battery electrolyte in a two-stage thermal treatment process.

Disposal of electrolytes from waste lithium-ion batteries (LIBs) has gained much more attention with the growing application of LIBs, yet handling spent electrolyte is challengeable due to its high toxicity and the lack of established methods. In this study, a novel two-stage thermal process was developed for treating residual electrolytes resulted from spent lithium-ion batteries. The conversion of fluorophosphate and organic matter in oily electrolyte during low-temperature rotation distillation was investigated. The distribution and migration of the concentrated electrolytes were studied and the corresponding reaction mechanisms were elucidated. Additionally, the influence of alkali on the fixation of fluorine and phosphate was further examined. The results indicated that hydrolyzed carbonate esters and lithium in the electrolyte could combine to form Li2CO3 and the hydrolysable hexafluorophosphate was proven to be stable in the concentrated electrolyte (45 rpm/85 °C, 30 min). It was found that CO2, CO, CH4, and H2 were the primary pyrolysis gases, while the pyrolysis oil consisted of extremely flammable substances formed by the dissociation and recombination of chemical bonds in the electrolyte solvent. After pyrolysis at 300 °C, fluorine and phosphate were present in the form of sodium fluoride and sodium phosphate. The stability of the residue was enhanced, and the environmental risk was reduced. By adding alkali (KOH/Ca(OH)2, 20 %), hexafluorophosphate in the electrolyte was transformed into fluoride and phosphate in the residue, thereby reducing the device's corrosion from fluorine-containing gas. This study provides a viable approach for managing the residual electrolyte in the waste lithium battery recovery process.

Contamination characteristics and dietary intake risk of brominated flame retardants in fishes around a typical e-waste dismantling site in Southern China.

Polybrominated diphenyl ethers (PBDEs) and their substitutes, novel brominated flame retardants (NBFRs), are ubiquitously present in the aquatic environment of electronic waste (e-waste) dismantling region, leading to their inevitable absorption and accumulation by aquatic organisms, which can be transferred to human via directly aquatic product consumption or through food chain, thereby posing potential health risks. This study focused on fish samples from Guiyu and its surrounding areas, and found the total PBDEs concentrations were 24-7400 ng/g lw (mean: 1800 ng/g lw) and the total NBFRs concentrations were 14 to 2300 ng/g lw (mean: 310 ng/g lw). Significant positive correlations were found among PBDE congeners, among different NBFRs, and between NBFRs and commercial PBDEs that they replace. ΣPBDEs and ΣNBFRs in the intestine were 620-350,000 and 91-81,000 ng/g lw (mean: 83000 and 12,000 ng/g lw, respectively), significantly exceeding those in the gills, where ΣPBDEs and ΣNBFRs were 14-37,000 and 39-45,000 ng/g lw (mean: 9200 and 2400 ng/g lw, respectively). The ΣPBDEs and ΣNBFRs showed no non-carcinogenic risks to the target population through dietary intake. Despite the significantly higher daily intake of decabromodiphenyl ethane (DBDPE) compared to decabromodiphenyl ether (BDE209), the non-carcinogenic risk associated with BDE209 remained higher than that of DBDPE. Our findings can assist researchers in understanding the presence of BFRs in aquatic organisms, inhabiting e-waste dismantling areas, and in evaluating the associated health risks posed to humans through dietary exposure.

Occurrence and ecotoxicological impacts of polybrominated diphenyl ethers (PBDEs) in electronic waste (e-waste) in Africa: Options for sustainable and eco-friendly management strategies.

Polybrominated diphenyl ethers (PBDEs) are persistent contaminants used as flame retardants in electronic products. PBDEs are contaminants of concern due to leaching and recalcitrance conferred by the stable and hydrophobic bromide residues. The near absence of legislatures and conscious initiatives to tackle the challenges of PBDEs in Africa has allowed for the indiscriminate use and consequent environmental degradation. Presently, the incidence, ecotoxicity, and remediation of PBDEs in Africa are poorly elucidated. Here, we present a position on the level of contamination, ecotoxicity, and management strategies for PBDEs with regard to Africa. Our review shows that Africa is inundated with PBDEs from the proliferation of e-waste due to factors like the increasing growth in the IT sector worsened by the procurement of second-hand gadgets. An evaluation of the fate of PBDEs in the African environment reveals that the environment is adequately contaminated, although reported in only a few countries like Nigeria and Ghana. Ultrasound-assisted extraction, microwave-assisted extraction, and Soxhlet extraction coupled with specific chromatographic techniques are used in the detection and quantification of PBDEs. Enormous exposure pathways in humans were highlighted with health implications. In terms of the removal of PBDEs, we found a gap in efforts in this direction, as not much success has been reported in Africa. However, we outline eco-friendly methods used elsewhere, including microbial degradation, zerovalent iron, supercritical fluid, and reduce, reuse, recycle, and recovery methods. The need for Africa to make and implement legislatures against PBDEs holds the key to reduced effect on the continent.

Pyrolytic urban mining of waste printed circuit boards: an enviro-economic analysis.

E-waste, a global environmental concern resulting from supply chain inefficiency, also offers the opportunity to recover valuable materials, including general and rare earth metals. Waste printed circuit boards (WPCBs) are integral components of e-waste that contains substantial amounts of precious metals, making them a valuable waste category. Pyrolysis has emerged as a promising method for material recovery from WPCBs. Hence, pyrolytic urban mining of WPCBs offers an excellent avenue for resource recovery, redirecting valuable materials back into the supply chain. Under the current study, experimental investigation has been conducted to explore the recovery of materials from WPCBs through pyrolysis followed by process simulation, economic analysis, and life cycle assessment (LCA). An Aspen Plus simulation was conducted to model the pyrolysis of WPCBs and subsequent product recovery using a non-equilibrium kinetic model, which represents a unique approach in this study. Another distinct aspect is the comprehensive assessment of environmental and economic sustainability. The economic analysis has been carried out using Aspen economic analyzer whereas the LCA of WPCB pyrolysis has been conducted using the SimaPro software. The experimental investigation reveals yield of solid residues are about 75-84 wt.%, liquid yields of 6-13 wt.%, and gas yields of 4-21 wt.%, which is in well agreement with the Aspen Plus simulation results. The economic analysis for an e-waste pyrolysis plant with an annual feed rate of 2000 t reveals that the total capital cost of a pyrolysis plant is nearly $51.3 million, whereas the total equipment cost is nearly $2.7 million and the total operating cost is nearly $25.6 million. The desired rate of return is 20% per year and the payback period is 6 years with a profitability index of 1.25. From the LCA, the major impact categories are global warming, fossil resource scarcity, ozone formation in human health, ozone formation in terrestrial ecosystems, fine particulate matter formation, and water consumption. The findings of this study can serve as a guideline for e-waste recyclers, researchers, and decision-makers in establishing circular economy.

Mechanism of PGMs capture from spent automobile catalyst by copper from waste printed circuit boards with simultaneous pollutants transformation.

The traditional pyrometallurgical recycling of nano-sized platinum group metals (PGMs) from spent automotive catalysts (SACs) is an energy-intensive process that requires the addition of large quantities of copper capture and slag-forming reagents. Similarly, pyro-recycling of valuable metals from waste printed circuit boards (WPCBs) is also an energy- and reagent-intensive process that and carries a risk of pollution emissions. Based on the complementarity of composition and similarity of recycling process, synergistic pyro-recycling of SACs and WPCBs allow copper in WPCBs to capture PGMs in SACs and oxides from two waste form slag jointly, which offers benefits of enhanced metal recovery, reduced reagent and energy consumption, and suppressed pollutant emissions. However, the mechanisms of PGMs capture and pollutant transformation in co-smelting remain unknown. Here, we investigated the sub-processes mechanisms of slag formation, brominates fixation, multi-metal distribution and kinetic settlement. Oxides in both wastes support SiO2-Al2O3-CaO slag formation with low melting point and viscosity, where CaO suppresses the emission of brominated pollutants. Copper (50-100 µm) from WPCBs facilitates nano-sized PGMs in SACs recovery through capture and settlement. The results of demonstration experiments indicated a recovery rate of 94.6 %, 96.8 %, 97.2 %, and 98.1 % for Cu, Pt, Pd, and Rh, respectively, with a debromination efficiency exceeding 98 %. The theoretical analysis provides support for the establishment of a synergistic pyro-recycling process for SACs and WPCBs and provides insights into the potential for a greener and more efficient co-recycling of multi urban mines.

Persistent organic pollutants in feathers of various terrestrial and aquatic bird species: Interspecies difference and source apportionment.

Feathers are regarded as important nondestructive biomonitoring tools for bird pollutants. However, external contamination of feathers by different pollutants in different bird species remains unclear. In the present study, the feathers of 16 bird species, including terrestrial, freshwater, and marine birds, were analyzed for persistent organic pollutants (POPs). Bird feathers from an abandoned e-waste recycling site had higher POP concentrations and were more correlated with the POP muscle concentrations than those from the less polluted areas. The significant and positive POP correlations between the feathers and muscles of different species indicate that feathers are a good indicator of inter-species and spatial pollution. For individual species, the most hydrophobic POPs in feathers, such as hepta- to deca-polybrominated diphenyl ethers, had higher proportions than in muscles and worse correlations with muscle POPs compared with other POPs. Results of the chemical mass balance (CMB) model revealed that the gaseous phase, internal pollution, and atmospheric particle phase were the main contributors to low-, medium-, and high-hydrophobicity POPs in feathers, respectively. Overall, this study provides a preliminary but meaningful framework for distinguishing between internal and external contamination in feathers and gives information concerning the fitness of feathers as POP indicators with specific physicochemical properties.

Anaerobic biodegradation enables zero liquid discharge of two-stage nanofiltration system for microelectronic wastewater treatment.

Nanofiltration (NF) is a promising technology in the treatment of microelectronic wastewater. However, the treatment of concentrate derived from NF system remains a substantial technical challenge, impeding the achievement of the zero liquid discharge (ZLD) goal in microelectronic wastewater industries. Herein, a ZLD system, coupling a two-stage NF technology with anaerobic biotechnology was proposed for the treatment of tetramethylammonium hydroxide (TMAH)-contained microelectronic wastewater. The two-stage NF system exhibited favorable efficacy in the removal of conductivity (96 %), total organic carbon (TOC, 90 %), and TMAH (96 %) from microelectronic wastewater. The membrane fouling of this system was dominated by organic fouling, with the second stage NF membrane experiencing a more serious fouling compared to the first stage membrane. The anaerobic biotechnology achieved a near-complete removal of TMAH and an 80 % reduction in TOC for the first stage NF concentrate. Methyloversatilis was the key genus involved in the anaerobic treatment of the microelectronic wastewater concentrate. Specific genes, including dmd-tmd, mtbA, mttB and mttC were identified as significant players in mediating the dehydrogenase and methyl transfer pathways during the process of TMAH biodegradation. This study highlights the potential of anaerobic biodegradation to achieve ZLD in the treatment of TMAH-contained microelectronic wastewater by NF system.

Alterations of gut microbiota and its metabolomics in children with 6PPDQ, PBDE, PCB, and metal(loid) exposure.

The composition and metabolites of the gut microbiota can be altered by environmental pollutants. However, the effect of co-exposure to multiple pollutants on the human gut microbiota has not been sufficiently studied. In this study, gut microorganisms and their metabolites were compared between 33 children from Guiyu, an e-waste dismantling and recycling area, and 34 children from Haojiang, a healthy environment. The exposure level was assessed by estimating the daily intake (EDI) of polybrominated diphenyl ethers (PBDEs), polychlorinated biphenyls (PCBs), 6PPD-quinone (6PPDQ), and metal(loid)s in kindergarten dust. Significant correlations were found between the EDIs of 6PPDQ, BDE28, PCB52, Ni, Cu, and the composition of gut microbiota and specific metabolites. The Bayesian kernel machine regression model showed negative correlations between the EDIs of five pollutants (6PPDQ, BDE28, PCB52, Ni, and Cu) and the composition of gut microbiota. The EDIs of these five pollutants were positively correlated with the levels of the metabolite 2,4-diaminobutyric acid, while negatively correlated with the levels of d-erythro-sphingosine and d-threitol. Our study suggests that exposure to 6PPDQ, BDE28, PCB52, Ni, and Cu in kindergarten dust is associated with alterations in the composition and metabolites of the gut microbiota. These alterations may be associated with children's health.

Copper recovery by solvent extraction for nanoparticle synthesis from waste motherboards.

Printed circuit boards, which make up part of waste from electrical and electronic equipment, contain elements that can be economically reused, such as copper, silver, gold, and nickel, as well as metals that are harmful to the environment and health, such as lead, mercury, and cadmium. Thus, through recycling this scrap, materials that would otherwise be discarded can be reinserted as secondary raw materials to produce new consumer goods through urban mining. In this context, the synthesis of nanoparticles shows promise as it allows the reinsertion of these materials in the manufacture of new products. Therefore, this study used obsolete computer motherboards as a secondary material to obtain copper to produce nanoparticles of this metal. From a solution based on the leach liquor of this scrap, a purification route using solvent extraction was defined and applied to the real leach liquor. Applying the hydroxyoxime extractant at a dilution of 20% (v/v) in kerosene, A/O of 1/1, 298 K, and 0.25 h of contact during extraction, and stripping in H2SO4 (2 M), 298 K, 0.25 h, W/O ratio of 3/1, and two theoretical countercurrent stages, a solution containing more than 95% of the copper in the leach liquor could be obtained with less than 1% of contaminants. From this purified liquor, nanoparticles containing copper and metallic copper oxides and hydroxides were produced, with an average size of 84 nm, at pH 11, 3 h of hot stirring, volume of 0.015 L of ascorbic acid (0.50 M) and 0.015 L of precursor solution (0.03 M Cu), and temperature (343 K).

Development of complete hydrometallurgical processes for gold recovery from ICs and CPUs using ionic liquids.

Integrated circuits (ICs) and central processing units (CPUs), essential components of electrical and electronic equipment (EEE), are complex composite materials rich in recyclable high-value strategic and critical metals, with many in concentrations higher than in their natural ores. With gold the most valuable metal present, increase in demand for gold for EEE and its limited availability have led to a steep rise in the market price of gold, making gold recycling a high priority to meet demand. To overcome the limitations associated with conventional technologies for recycling e-waste, the use of greener technologies (ionic liquids (ILs) as leaching agents), offers greater potential for the recovery of gold from e-waste components. While previous studies have demonstrated the efficiency and feasibility of using ILs for gold recovery, these works predominantly concentrate on the extraction stage and often utilise simulated solutions, lacking the implementation of a complete process validated with real samples to effectively assess its overall effectiveness. In this work, a simulated Model Test System was used to determine the optimal leaching and extraction conditions before application to real samples. With copper being the most abundant metal in the e-waste fractions, to access the gold necessitated a two-stage pre-treatment (nitric acid leaching followed by aqua regia leaching) to ensure complete removal of copper and deliver a gold-enriched leach liquor. Gold extraction from the leach liquor was achieved by liquid-liquid extraction using Cyphos 101 (0.1 M in toluene with an O:A = 1:1, 20 °C, 150 rpm, and 15 min) and as a second process by sorption extraction with loaded resins (Amberlite XAD-7 with 300 mg of Cyphos 101/g of resins at 20 °C, 150 rpm and 3 h). In both processes, complete stripping and desorption of gold was achieved (0.5 M thiourea in 0.5 M HCl) and gold recovered, as nanoparticles of purity ≥95%, via a reduction step using a sodium borohydride solution (0.1 M NaBH4 in 0.1 M NaOH). These two hydrometallurgical processes developed can achieve overall efficiencies of ≥95% for gold recovery from real e-waste components, permit the reuse of the IL and resins up to five consecutive times, and offer a promising approach for recovery from any e-waste stream rich in gold.

A biogenic hydrogel to recover Au(III) from electronic waste.

In the course of this investigation, we undertook the contemplation of a green chemistry paradigm with the express intent of procuring valuable metal, namely gold, from electronic waste (e-waste). In pursuit of this overarching objective, we conceived a procedural framework consisting of two pivotal stages. As an initial stage, we introduced a physical separation procedure relying on the utilization of the Eddy current separator, prior to embarking on the process of leaching from e-waste. Subsequent to the partitioning of metals from the non-metal constituents of waste printed circuit boards (PCB), we initiated an investigation into the hydrogel derived from basil seeds (Ocimum basilicum L.), utilizing it as a biogenic sorbent medium. The thorough characterization of hydrogel extracted from basil seeds involved the application of an array of analytical techniques, encompassing FTIR, XRD, SEM, and BET. The batch sorption experiments show more than 90% uptake in the pH range of 2-5. The sorption capacity of the hydrogel material was evaluated as 188.44 mg g-1 from the Langmuir Isotherm model. The potential interference stemming from a spectrum of other ions, encompassing Al, Cu, Ni, Zn, Co, Cr, Fe, Mn, and Pb was systematically examined. Notably, the sole instance of interference in the context of adsorption of gold ions was observed to be associated with the presence of lead. The application of the hydrogel demonstrated a commendable efficiency in the recovery of Au(III) from the leached solution derived from the waste PCB.