Copper Migration Research Articles

Migration of copper from nanocopper/LDPE composite films

ABSTRACTThree nanocopper/low-density polyethylene (LDPE) composite films were tested in food simulants (3% acetic acid and 10% ethanol) and real food matrices (rice vinegar, bottled water and Chinese liquor) to explore the behaviours of copper migration using ICP-OES and GFAAS. The effects of exposure time, temperature, nanocopper concentration and contact media on the release of copper from nanocopper/LDPE composite films were studied. It was shown that the migration of copper into 10% ethanol was much less than that into 3% acetic acid at the same conditions. With the increase of nanocopper concentration, exposure time and temperature, the release of copper increased. Copper migration does not appear to be significant in the case of bottled water and Chinese liquor compared with rice vinegar with a maximum value of 0.54 μg mL−1 for the CF-0.25# bags at 70°C for 2 h. The presence and morphology of copper nanoparticles in the films and the topographical changes of the films were confirmed by field emission scanning electron microscope (FE-SEM) and atomic force microscope (AFM). In this manner, copper nanoparticles of different morphologies, sizes and distribution were found, and samples with higher nanocopper concentration had a more irregular topography. In the case of Fourier transform infrared spectroscopy (FTIR), no chemical bonds formed between copper nanoparticles and LDPE. Copper nanoparticles were just as physically dispersed in LDPE.

Quantitative separation of the influence of copper (II) chloride mass migration on the chemo-responsive shape memory effect in polyurethane shape memory polymer

Chemo-responsive shape memory effect in polyurethane shape memory polymer (SMP) composite triggered by mass migration of copper (II) chloride (CuCl2) has been experimentally demonstrated. In this study, we present a comprehensive study on quantitative separation of the effect of CuCl2 particle mass migration on the chemo-responsive shape recovery behavior of polyurethane SMP composites with different concentrations of CuCl2 particles. It is found that the SMP is featured with a critical release rate of the mechanical energy storage associated with the shape recovery behavior due to mass migration of the CuCl2 particle. A sequence of molecular interactions among CuCl2 particles, polyurethane macromolecules and water molecules, i.e., assembly of the CuCl2 particle with polyurethane macromolecules, and then disassembly and dissolution of the CuCl2 particle in water, results in an acceleration of water-induced shape recovery of polyurethane SMP. This study focuses on the quantitative separation of the influence of mass migration on the chemo-responsive shape recovery behavior of polyurethane SMP in response to water. It is expected to promote and achieve the actuation of chemo-responsive SMPs in a fully controllable manner.

Safety assessment of the substance basic copper (II) carbonate for use in intelligent food contact materials

This opinion of the EFSA Panel on Food Contact Materials, Enzymes, Flavourings and Processing Aids (CEF Panel) deals with the safety assessment of basic copper (II) carbonate, CAS No 12069-69-1, for use as intelligent substance in the ink of a freshness indicator applied in labels inside trays of fresh poultry meat at temperatures from 2°C to 10°C and for a period of up to 12 days. Being a salt of carbonic acid, basic copper (II) carbonate is authorised and listed under Regulation (EU) No 10/2011 (food contact material (FCM) substance No 21: carbonic acid, salts) as, according to Article 6 of Regulation (EU) No 10/2011, salts of copper are authorised even if they are not included in the Union list. The residual amount of solvents in the printed label was determined and assuming total mass transfer from a 0.02 dm2 label into 400 g food would give a worst-case migration in the order of ■■■■■. No migration of copper is expected taking into account the nature of the application with no direct contact between the substance and the food. However, even complete transfer in case of incidental direct contact would remain several orders of magnitude lower than the migration limit applicable at the date of the assessment (5 mg/kg). The CEF Panel, having considered the above-mentioned data, concluded that the use of the substance basic copper (II) carbonate as a freshness indicator for packed poultry meat does not raise a safety concern to the consumer if the migration limit of copper is met.

Концентрація важких металів у яловичині за використання різнотипових раціонів бугайців

The complex environmental situation that arose in the Polissya region of Ukraine as a response to the Chernobyl accident and uncontrolled activities of industrial enterprises, imposes a direct threat on the pop elation’s and descendants’ health. Therefore, the scientific studies aimed at investigating into the affect of heavy metals and their concentration in the products, developed in the area of radiological contamination, on animal organisms, are essential to the population residing and running subsidiary farms in this territory. The purpose of our research was to study the quality of beef made in the area of radiological contamination, as well as the accumulation of heavy metals (Pb, Cd, Cu, Zn) in organisms of fattening bull-calves under the different ration types. In order to achieve this objective, the following tasks were set: to study the contamination of feed rations with heavy metals (Pb, Cd, Cu, Zn); to determine the concentration of heavy metals in the longest back muscles and liver; to determine coefficients of heavy metal conversion from feeds to slaughter products. The scientific-and-practical research was conducted in the physiological yard of the Polissya Institute of Agriculture NAAS (density of radioactive contamination of the territory was 5 Ci / km2) in two analogue groups of bull-calves of Ukrainian black-and-pockmarked dairy breed during the stall period –8 heads per each with an average living weight of 270-276,2 kg. The duration of the preparatory and research periods was 32 and 148 days respectively. Feeding the studied animals was carried out in groups twice daily with auto drinking bowl watering. Under the scheme of our experiment, for research and preparatory periods, fattening bull-calves in the control group (I) received the silage-and-root concentrated ration, which contained corn and clover silage in 54.9% nutritional value, concentrated feeds in 36,3%, and roughage in 8,8%. During the preparatory period, bull-calves from the experimental group (II), akin to their control analogues, were kept on the same diet. Yet, during the experimental period, their 20% (nutritional value) silage feeds were replaced with fodder and sugar beets. The structure of the feed rations was: corn and clover silage - 34.8%, beets - 20.3% and concentrated feeds - 36.0%, and roughage - 8.9%. Self-manufactured feeds were used while feeding animals. As a result, we have studied the migration of lead, cadmium, copper and zinc from ration feeds to the products for different types of bull-calve feeding. Results of heavy metal pollution (Pb, Cd, Cu, Zn) of the longest back muscle and liver of animals based on their feeding under the different ration types, were highlighted. Coefficients of heavy metal conversion into slaughter products were determined. The use of silage-root-concentrate diet had a positive impact on beef quality, lowering down the concentration of Pb in the longest back muscle by 36,2% and Cd – by 34,1%, with almost identical concentration of copper and zinc. The accumulation of cadmium and zinc in livers of the experimental animals was lower than that of the control group by 46,6% and 37,4% respectively.

Investigation on the decrease in the reduction rate of oxygen carriers for chemical looping combustion

Copper oxide on alumina is often used as oxygen carrier for chemical looping combustion owing to its very high reduction rates at lower temperatures and its very good mechanical and chemical stability at not too high temperatures. In this work, the redox kinetics of CuO/Al2O3 have been measured and analysed with many consecutive reduction (50% H2, 50% N2) and oxidation (air) cycles at different temperatures using thermogravimetric analysis. In all the redox cycles, a cyclic steady state in the redox kinetics is observed after several redox cycles, where a sudden decrease in the reaction rate is observed after a certain solids conversion, typically around 75%, depending in particular on the operating temperature. Models developed in the literature fail at predicting these redox kinetics and they are mostly shrinking core/grain type models with an ad-hoc combination and modification of chemical reaction and gas phase diffusion. The oxygen carrier was characterized in detail with different techniques including N2 physisorption, XRD and SEM-EDX to investigate morphological changes in the particle over the redox cycles in order to better understand why all the models developed in literature fail. After the study we can conclude that i) gas-phase diffusion is not playing a limiting role on the redox kinetics despite significant morphological changes in the particle; ii) migration of copper from the inside of the particle to the surface of the particle does not occur or does not influence the kinetics; iii) oxygen uncoupling is not influencing the kinetics being equally fast for Cu2O and CuO, although it can be significant for the final maximum particle conversion; iv) solid phase oxygen diffusion limitations may be responsible for the observed drop in reaction rate.

New process for copper migration by bioelectricity generation in soil microbial fuel cells.

The soil microbial fuel cell (MFC) is a promising biotechnology for the bioelectricity recovery as well as the remediation soil. Moreover, there were no studies on the heavy metal pollution in a soil MFC yet. A soil MFC was constructed to remediate the contaminated soil, and the electric field was generated from the oxidation of the acetate at the anode. We demonstrated the copper migration, the power generation, and the pH variation in the soil and the electrodes. The maximal voltage and the power density of 539mV and 65.77mW/m(2) were obtained in the soil MFC. The chemical fractionation of copper (Cu) was analyzed with a modified BCR sequential extraction method. The soluble Cu form and the total Cu contents from the anode to the cathode increased, and the difference between them kept growing over time. The Cu fractions in the soil and the electrodes were converted with the change of the dramatic pH from the anode to the cathode. There was a focusing effect leading to the change of the Cu forms, and the extractable acid form content increased in the three fifths where the acid and the alkali fronts met.

Insight of the interface of electroless Ni–P/SiC composite coating on aluminium alloy, LM24

Abstract Electroless nickel composite coatings with silicon carbide, SiC, as reinforcing particles deposited with Ni–P onto aluminium alloy, LM24, having zincating as under layer were subjected to heat treatment using air furnace. The changes at the interface were investigated using scanning electron microscope (SEM) and energy dispersive X-ray (EDX) to probe the chemistry changes upon heat treatment. Microhardness tester with various loads using both Knoop and Vickers indenters was used to study the load effect clubbed with the influence of second phase particles on the coating at the vicinity of the interface. It was observed that zinc was absent at the interface after elevated temperature heat treatment at 400–500 °C. Precipitation of copper and nickel with a distinct demarcation (copper rich belt) along the coating interface was seen with irregular thickness of the order of 1 μm. Migration of copper from the bulk aluminium alloy could have been the factor. Brittleness of the coating was confirmed on heat treatment when indented with Vickers. However, in composite coating the propagation of the microcrack was stopped by the embedded particles but the microcracks continue in the matrix when not interrupted by second phase particles (SiC).

Effects of antioxidants and acids on copper sulfide generation and migration induced by dibenzyl disulfide in oil‐immersed transformers

This study aims to explore the effect of the antioxidant 2,6‐di‐tert‐butyl‐p‐cresol (DBPC) and acids on the generation and migration of copper sulfide on insulating windings as a result of the reaction of dibenzyl disulfide (DBDS) and copper in oil‐immersed transformers. The heating experiments were conducted by adding different amounts of DBPC and different kinds of acids to the naphthenic mineral oil. The result indicates that acids can accelerate the generation of copper sulfide and that DBPC cannot effectively consume DBDS to reduce the corrosion phenomenon, but rather accelerates the deposition of copper sulfide onto the insulating paper. In particular, when the DBPC concentration is approximately 0.9% (w/w) at 130 °C for ten days, the amount of copper sulfide deposited on the insulating paper reaches its maximum. Moreover, excessive use of the antioxidant DBPC accelerates the aging of insulating oil, on the contrary, which adversely affects the mineral oil. Although the addition of DBPC can improve the antioxygenic property of mineral oil, too much of it is inadvisable because the transformers that contain DBPC and DBDS may be at high risk and suffer from breakdown. © 2015 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

Using time of flight secondary ion mass spectrometry and field emission scanning electron microscopy with energy dispersive X-ray spectroscopy to determine the role of soil components in competitive copper and cadmium migration and fixation in soils

The bioavailability of heavy metals mainly depends on their sorption in soils, as the sorption/desorption processes determine their concentration in surface or underground water. The sorption and desorption of cations predominantly involve negatively charged soil surfaces such as organic matter, clays and metallic oxides or hydroxides. The distribution of metals among the soil components depends on the intrinsic properties of the metal species involved, the properties of the soil, and the amounts of metal added. Relatively new spectroscopic imaging techniques can help determine the distribution of contaminants on soil surfaces such as natural minerals and organic matter. Competitive Cu2+ and Cd2+ sorption and desorption experiments were performed by the batch method in all of the horizons (A and B) of five natural soils: Umbric Cambisol, Endoleptic Luvisol, Mollic Umbrisol, Dystric Umbrisol, and Dystric Fluvisol. The competitive sorption and desorption capacity, hysteresis and migration throughout the profile were determined. The influence of soil components on retention capacity was investigated by means of the pairwise Pearson correlation analysis. It was found that the A horizons sorb and retain more Cu2+ than B, and more Cd2+ than A. The hysteresis indices show that the competitive sorption of Cd2+ is more irreversible than that of Cu2+. Correlation analysis shows that both Cu2+ sorption and retention capacities are positively correlated with the effective cation exchange (ECEC) and organic carbon content, while Cd2+ sorption and retention capacities are strongly correlated with the pH, the ECEC and the Fe and Mn oxide and clay contents. The migration indices indicate that the largest proportions of Cu2+, are retained in the A horizons. A small proportion of Cd2+ is retained in the B horizons, but the largest proportion migrates out of the soil profile. The time of flight secondary ion mass spectrometry (TOF-SIMS) images show that in the treated soils, the signal intensity of Cu2+ is high, while that of Cd2+ is very low, indicating that Cu2+ is retained in larger quantities than Cd2+, also demonstrating how intensively Cu2+ interacts with organic matter. The association between Cu2+ and Fe ions is very low and is not associated with the Mn ions. In contrast, the scarcely retained Cd2+ interacts with the Fe and Mn ions. Soil analysis by field emission scanning electron microscopy with energy dispersive X-ray spectroscopy (FE-SEM/EDS) showed that Cu2+ retention depends on the formation of organic matter and vermiculite aggregates or associations. Cd2+ is retained on vermiculite associated with gibbsite and amorphous Fe oxides. We confirmed the coexistence of amorphous Fe oxides, vermiculite, gibbsite and organic matter aggregates containing Cu2+, and vermiculite and gibbsite aggregates containing Cd2+. These results confirm the differences between the Cu2+ and Cd2+ sorption sites, and the competence in favour of the first, especially in the A horizons, as the organic matter has higher affinity for Cu2+ than for Cd2+. The combined use of TOF-SIMS with FE-SEM/EDS makes it possible to visualise the associations between soil components which jointly retain the metals we studied, rather than individually.

Characterization of Copper Diffusion in Silicon Solar Cells

Abstract In this work we investigate the degradation behavior of solar cells with a copper front side metallization based on a fine-line screen-printed silver seed-layer, a plated nickel diffusion barrier, a plated copper conductive layer and a silver capping. The results reveal that the cell degradation depends, besides the effectiveness of the nickel diffusion barrier, on the used seed-layer and the firing temperature of the seed-layer. The degradation behavior of cells, produced with different Ag seed-layer pastes resulting in different contact finger geometries after screen-printing and firing, was evaluated. With similar nickel diffusion barrier masses the seed-layer that generates the biggest metallized area at the cell surface shows the fastest degradation. Apart from that, the composition of the seed layer also has an impact on the degradation. The analysis of different firing temperatures shows that higher set-peak temperatures result in faster cell degradation due to copper migration.

Effect of post-treatment processing on copper migration from Douglas-fir lumber treated with ammoniacal copper zinc arsenate

Migration of heavy metals into aquatic environments has become a concern in some regions of the world. Many wood preservatives are copper based systems that have the potential to migrate from the wood and into the surrounding environment. Some wood treaters have developed “best management practices” (BMPs) that are designed to reduce the risk of migration, but there are few comparative studies assessing the efficacy of these processes. The potential for using various heating combinations to limit copper migration was assessed using ammoniacal coper zinc arsenate treated Douglas-fir lumber. Kiln drying and air drying both proved to be the most effective methods for limiting copper migration, while post-treatment steaming or hot water immersion produced more variable results. The results should provide guidance for improving the BMP processes.

Metal migration at conductor / XLPE interface subjected to partial discharges at different electrical stresses

Metal migration effects occurring at the conductor/cross-linked polyethylene (XLPE) interface are presented in the paper. The phenomenon was studied under various electrical stresses: direct current, pulse-width modulated and sinusoidal. The comparison of aging effects on specimens subjected to the stimuli was presented. The electrical stress results in partial discharges, both around the electrode in the form of surface discharges and directly at the micro air gap interface between conductor and polymeric material. In order to isolate the impact of interface discharges, the surface effects were suppressed, eliminated and compared with results containing both forms of discharges. The electrical and thermal migration mechanism was investigated in the paper and assessment was performed by means of time to breakdown and both micro morphological and elemental analysis. Migration of the conductor atoms, where metallic particles are transferred to the insulating medium, was observed. Primarily, attention was afforded to the migration of copper and aluminum electrode atoms in two zones; one zone being the direct contact area at the interface and the second zone incorporating the area surrounding the electrode which is enhanced by surface discharges. A novel aspect relates to the investigation of the metal migration depth profile and the concentration intensity at different voltage stresses. The transport phenomena were analyzed with respect to both electrical and thermal mechanisms.

The effect of chloride ion concentration on electrochemical migration of copper

The effect of chloride ion concentration of electrochemical migration (ECM) was investigated on copper applying in situ electrochemical, optical and scanning electron microscopy—energy dispersive X-ray spectroscopy methods. An unexpected phenomenon was found: copper dendrite grows not only at low chloride concentration, but also at high and even saturated chloride concentrations, although it is generally suggested that the growth of copper dendrite through ECM does not take place in high chloride concentration solutions. Reactions have been proposed to explain the ECM of copper under different chloride concentration levels.

Copper isotope fractionation in the Meiduk porphyry copper deposit, Northwest of Kerman Cenozoic magmatic arc, Iran

AbstractThe Meiduk deposit possesses three different Cu reservoirs each with a unique Cu isotope signature. δ65Cu for the leached cap minerals ranges from −2.5 to +0.49‰ to −0.45 to +0.3‰ for hypogene minerals and from +1.3 to +4.4‰ for supergene enrichment minerals. Oxidation of hypogene sulphides and effective trapping of copper (from solutions derived from the leached cap) in the supergene enrichment zone caused this relationship. A systematic pattern of low Cu isotope values close to the surface and higher isotope values with depth reveals a palaeo‐fluid pathway in the northwest–southeast direction over the deposit. Thus, the copper isotope data from leached cap and enrichment minerals can be used to monitor copper migration during supergene weathering at the Meiduk deposit.

Removal of copper ions from contaminated groundwater using waste foundry sand as permeable reactive barrier

Computer solutions Multiphysics 3.5a software was used for simulating the two-dimensional copper migration including sorption process through the saturated zone of the soil in the presence of permeable reactive barrier for equilibrium condition. The 1:3 mixture of waste foundry sand and Kerbala’s sand was used as filling material for this barrier. The waste foundry sand was represented the reactivity material, while Kerbala’s sand used to increase the permeability of reactive barrier only. However, Fourier transform infrared analysis proved that the carboxylic and alkyl halide groups are responsible for the sorption of copper onto waste foundry sand. Batch tests have been performed to characterize the equilibrium sorption properties of the waste foundry sand and Kerbala’s sand mix in copper-containing aqueous solutions. Numerical and experimental results proved that the permeable reactive barrier plays a potential role in the restriction of the contaminant plume migration. Also, predicted results showed that the thicker barrier is better than the thinner ones in copper treatment, and this barrier saturates with contaminant as a function of the travel time. However, a good agreement between the predicted and experimental results was recognized with mean error not exceeded 10 %.

Order–disorder phenomena in layered CuCrSe2 crystals

The thermal motion of Cu+ ions in a quasi-two dimensional copper ion conductor CuCrSe2 is studied in the vicinity of the order-disorder phase transition to superionic phase, basing on a single-crystal and powder X-ray diffraction, specific heat and electrical resistivity measurements. The copper ions gradually migrate with temperature decrease to empty tetrahedral sites reaching occupancy equilibrium in the disordered high-temperature phase at Ts = 365 K. The copper migration between Cuα and Cuβ tetrahedral sites occurs through the neighboring, face-sharing octahedral holes. Disorder of Cu+ ions brings perturbations in periodic potential of the crystal lattice providing additional scattering centers for electrons.

Mechanisms of Cu 2+ migration, recovery and detoxification in Cu 2+-, -containing wastewater treatment process with anaerobic granular sludge

In this study, anaerobic granular sludge with sulphate-reducing bacteria (SRB) was applied to treat Cu 2+-, -containing wastewater in an expanded granular sludge bed reactor. The migration and enrichment of copper in anaerobic granular sludge were envaluated. By analysing the sludge with X-ray diffraction, copper was determined to be present as covellite (CuS) in the sludge. Observations at the microscopic level showed that CuS precipitates were absorbed onto granules and gradually migrated from the outer to the interior layer of the granule over time and finally accumulated in the core of the granular sludge. Because of the migration of the CuS precipitates and the protection of the extracellular polymeric substances matrix, SRB were able to tolerate copper concentrations up to 10 mg/L. A copper removal efficiency of about 96% was observed at a steady state for 3 months, and copper was enriched in the granular sludge.

Evaluation and Simulation of Silver and Copper Nanoparticle Migration from Polyethylene Nanocomposites to Food and an Associated Exposure Assessment

Silver nanoparticles (nanosilver) and copper nanoparticles (nanocopper) exhibit antimicrobial activity and have been incorporated into polymers to create antimicrobial packaging materials. Their use in conjunction with food has caused concerns regarding the potential risk of particle migration, resulting in human exposure to nanoparticles. A migration experiment was carried out to investigate the effect of time and temperature on the migration of nanosilver and nanocopper particles from polyethylene (PE) nanocomposites to boneless chicken breasts. Migration of silver ranged from 0.003 to 0.005 mg/dm², while migration of copper ranged from 0.024 to 0.049 mg/dm², for a set of four different scenarios representing typical storage conditions. Effects of time and temperature were not significant (p > 0.1). A migration and exposure model was developed on the basis of mathematical relationships defining migratability and subsequent migratables using the Williams-Landel-Ferry equation for time-temperature superposition. The results of the model accurately predicted the nanosilver levels detected in the laboratory migration tests (R values ranging from 0.43 to 0.99); however, the model was less accurate in predicting nanocopper levels (R values ranging from 0.65 to 0.99), probably because of the highly variable background levels of copper observed in the real food matrix. The 95th percentile of the simulated human exposure to nanosilver based on laboratory experimental results of four scenarios ranged from 5.89 × 10⁻⁵ to 8.9 × 10⁻⁵ mg kg(bw)⁻¹ day⁻¹. For the measured migration of copper under the same storage conditions, the exposure ranged from 2.26 × 10⁻⁵ to 1.17 × 10⁻⁴ mg kg(bw)⁻¹ day⁻¹. This study highlights the potential migration of nanoparticles from PE composite packaging to a food material and the potential for simulation models to accurately capture this migration potential; however, variable background levels of copper in the food matrix can make prediction more difficult for trace migration of nanocopper.

銅薄膜配線におけるストレスマイグレーションの微細組織依存性

銅薄膜配線におけるストレスマイグレーションの微細組織依存性

Phytostabilization of moderate copper contaminated soils using co‐inoculation of Vicia faba with plant growth promoting bacteria

There is a need to conduct research on the selection of microbial isolates from rhizosphere of plants growing on heavy metal contaminated soils for specific restoration programs. This article suggest a consortium of bacteria combining Rhizobium sp. CCNWSX0481, Rhizobium leguminosarum bv. viciae, Enterobacter cloacae and Pseudomonas sp. 2(2010) that was examined for the ability to promote Vicia faba.L. growth when cultivated on the vineyard of soil moderately contaminated with copper. Data showed that inoculation was significant in nodulation; it increases the number and the weight of nodules of 50%. Co-inoculation was also found to positively influence growth and seed yield, through increasing fresh shoot and fresh root weights by 33 and 26%, respectively, and through rising numbers of seed per pod and pods per plant. In contrast, co-inoculation produced a significant reduction of accumulated copper in roots attending 35%, however, the treatment revealed no significant effects on the copper contents in pods and seeds. The tested inoculum could be an option to promote V. faba growth and to enhance soil fertilization in moderate copper contaminated soils. Further studies on the influence of co-inoculation practices on copper migration in soil-plant systems are recommended to acquire more information for evaluation of this legume safety.