Crayons and colored pencils for children may contain toxic elements (TEs) exhibiting potential risk for children?s health including cognitive development, after their ingestion, through mouthing and ...chewing and eventually, their accumulation. The aim of this study was to determine total content of As, Pb, Cr, Cd, Ni and Sb and estimate their bioaccessibility conducting artificial saliva extraction. Sixty samples of colored pencils and crayons from 10 manufacturers were analyzed. Microwave acid assisted digestion followed by inductively coupled plasma optical spectroscopy (ICP-OES) was performed for determination of total content of TEs. Simulation of extraction by artificial saliva was applied to get more reliable data when bioavailability is concerned. The total concentrations of TEs were higher in colored pencils than in crayons and their maximum levels were: 5.78, 9.36, 9.97, 0.615, and 6.63 mg kg-1 for As, Pb, Cr, Cd and Ni, respectively. Concentration of Sb was below the detection limit for all investigated samples. This study showed that concentration of As and Pb in several samples did not comply with European Union regulative. Bioaccessibility study showed the high degree of leaching of Cr and As from pencils, but regardless of extracted portions, concentrations of selected investigated TEs were below allowed levels.
Pollution with the heavy metals of Kosovo's rivers has been and continues to be a serious concern not only for the population, but also for responsible institutions that deal with environmental ...protection in our country. Based on this fact and our doubts regarding the quality of the river waters of the Municipality of Gjilan, we were motivated to conduct a study of the quality of the Mirusha, Stanishor and Morava river waters. During our research, we have set eight monitoring points for determining the exact level of concentration of heavy metals in the river waters quoted above. The heavy metals analyzed in this study were: Pb, Hg, Mn, Cu, Fe, Ni, Cr, Cd, Zn and Ba. The analytical technique used to determine the concentration of heavy metals was ICP-OES. The obtained results show that Fe, Mn and Ba exceed the allowed level at several monitoring points of the Mirusha and Stanishor rivers and appears in the degree of pollution with these metals of Morava river waters. The presence of heavy metals in the waters of these rivers negatively affects habitat waters and indirectly human health. Therefore, the identification and then suggestions regarding elimination of polluting sources are the subject of this study.
•A germanium bearing secondary zinc oxide was evaluated mineralogically.•Germanium exists in zinc and lead bearing minerals dispersedly.•Leaching behavior of Ge was revealed by leaching tests and ...residue characterization.•The limiting reasons of Ge and Zn leaching rates were found out.•99.7% of Ge and 99.4% of Zn could be leached in oxygen pressure leaching.
To improve the sulfuric-acid leaching of germanium-bearing secondary zinc oxide, the occurrence states and sulfuric-acid leaching behavior of germanium in secondary zinc oxide were investigated experimentally via inductively coupled plasma optical emission spectrometry (ICP–OES), X-ray diffraction (XRD), scanning electron microscopy and energy-dispersive spectroscopy (SEM–EDS), electron probe microanalysis (EPMA), and chemical phase analysis combined with leaching tests. The germanium-bearing secondary zinc oxide was produced via a fuming process of lead smelting slag and zinc leaching residue in a lead and zinc smelter. The results show that zincite, wurtzite, galena, and anglesite are the major minerals containing zinc and lead in the secondary zinc oxide. Further, these zinc- and lead-bearing materials contain germanium (without independent minerals). In the sulfuric-acid leaching process without oxidant, wurtzite and galena cannot be leached, which results in a loss of germanium. Anglesite, which exists originally in the secondary zinc oxide or was formed in the leaching process, contains a low amount of germanium and exhibits a loss of germanium in the residue. Moreover, the leaching efficiencies of germanium and zinc increased to 99.7% and 99.4% in the leaching process under oxygen pressure, respectively.
As a stable isotope, boron plays an important role in hydrogeology, environmental geochemistry, ore deposit geochemistry and marine paleoclimatology. However, there is no report of boron isotopic ...composition in gypsum. This is mainly confined to complete dissolution of Gypsum by water or acid. In this study, gypsum was converted to calcium carbonate (CaCO3) with ammonium bicarbonate(NH4HCO3) by two steps at 50°C. In every step, the mass ratio of NH4HCO3/CaSO4·2H2O was twice, and conversion rate reached more than 98%. Converted CaCO3 was totally dissolved with hydrochloric acid (the dissolution rate was over 99%). In order to overcome the difficulties of the matrix interference and the detection limit of Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES), we use Amberlite IRA 743 resin to purify and enrichment the boron at first, then eluting boron from the resin with 10mL 0.1mol/L hydrochloric acid at 75°C. The boron isotopic composition of natural gypsum samples was determined using positive thermal ionization mass spectrometry (P-TIMS). The boron isotopic composition of gypsum may be an excellent indicator for the formation environment.
As a stable isotope, boron plays an important role in hydrogeology, environmental geochemistry, ore deposit geochemistry and marine paleoclimatology. However, there is no report of boron isotopic composition in gypsum. This is mainly confined to complete dissolution of Gypsum by water or acid. In this study, gypsum was converted to calcium carbonate with ammonium bicarbonate by two steps at 50°C (Fig. 1). In every step, the mass ratio of NH4HCO3/CaSO4·2H2O was twice, and conversion rate reached more than 98%. It was completely dissolved with hydrochloric acid (the dissolution rate was over 99%). In order to overcome the difficulties of the matrix interference and the detection limit of Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES), we use Amberlite IRA 743 resin to purify and enrichment the boron at first, then eluting boron from the resin with 10mL 0.1mol/L hydrochloric acid at 75°C. The boron isotopic composition of natural gypsum samples was determined using positive thermal ionization mass spectrometry (P-TIMS) based on Cs2BO2+. The boron isotopic composition of gypsum may be an excellent indicator for the formation environment. Display omitted
Recently there has been an influx of silver infused food packaging materials that claim to enhance the shelf-life of stored food. We tested commercially available normal plastic packing material (S1) ...and two packing materials (S2 and S3) which claimed to contain silver to enhance shelf-life of stored food for the presence of silver and its antibacterial performance. Microwave assisted acid digestion of the plastic material and ICP-OES analysis confirmed the presence of silver in S2 (103 μg/g) and S3 (74 μg/g) but not in S1. Migration studies showed that 12–14% of silver incorporated into the plastic could leach into milk (used as a food simulant). Shelf-life studies conducted using milk showed that in comparison to normal plastic materials (S1), those containing silver (S2 and S3) had no functional advantage but slightly enhanced the microbial growth. Further studies showed that sub-lethal concentration of silver generates reactive oxygen species (ROS) within bacterial cells (Escherichia coli ATCC 25922 and Staphylococcus aureus ATCC 25923) accompanied by increased cell proliferation and biofilm formation suggestive of a hormetic effect. In short, these studies showed that the incorporation of silver at low concentration in packaging materials may not provide a functional advantage, but mitigate the migration of silver into the stored food products at sub-lethal concentration and may induce bacterial hormesis and accelerate food spoilage.
•Evaluated food packaging materials with claims on antimicrobial silver technology.•ICP-OES based determination showed nominal levels of silver in packaging material.•Low levels of silver had no functional advantage in improving shelf-life of food.•Sub-lethal levels of silver showed hormesis by inducing mild oxidative stress.•Bacterial viability and biofilm formation increased at sub-lethal levels of silver.
•Initial corrosion of carbon steel was accelerated by decreasing pH.•FeCO3 layer formation and subsequently passivation were promoted by decreasing pH.•Dissolved oxygen is shown to substantially ...affect corrosion in amine solutions.•A dominant effect of dissolved oxygen is to retard protective layer formation.•pH stabilization is a possibly effective way to reduce corrosion for CO2 capture.
A pH stabilization method was investigated to mitigate corrosion in aqueous 5M monoethanolamine for post-combustion CO2 capture. The room temperature pH of a naturally aerated CO2-loaded solution (i.e., 9.7) was adjusted with NaHCO3 powders to 9.3 and 9.1, and its effect on corrosion of A106 carbon steel was studied. Lower pH initially accelerated corrosion but promoted protective FeCO3 layer formation and subsequently A106 passivation (i.e., Fe3O4 formation). Dissolved oxygen also played a pivotal role by functioning as an additional oxidizer, retarding FeCO3 formation via preferentially oxidizing Fe2+ to form rust, and promoting passivation of A106 under the FeCO3 layer.
Simple concepts that control the amount of analyte, solvent aerosol and solvent vapor that enter the plasma are used to explain changes in analyte transport efficiency as a function of sample uptake ...rate in pneumatic nebulizer/spray chamber sample introduction systems. These include droplet-droplet collision/coalescence, evaporation of solvent from the sample aerosol and droplet impact on the walls of the spray chamber. We show that even small (2 to 5 μm diameter) droplets have a poor (<12%) transport efficiency through the spray chamber when the sample uptake rate is 1 mL/min. A dual nebulizer system and video are used to assess the role of droplet-droplet collisions/coalescence and aerosol evaporation in controlling sample transport efficiency as a function of sample uptake rate. The impact of water vapor that evaporates from the wall of the spray chamber and from evaporation of solvent from the sample aerosol are described with experimental evidence. Sample transport efficiencies for “conventional” nebulizers and micronebulizers are found to be similar when compared at the same sample uptake rates from 0.02 to 1.0 mL/min. The stability of signals when using “conventional” and micronebulizers at sample uptake rates less than 0.05 mL/min are compared. The impact of water vapor loading and water aerosol loading are investigated using a heated sample introduction system that efficiently evaporates the solvent from aerosol droplets and a vibrating mesh nebulizer than can provide virtually 100% aerosol transport efficiency at aerosol transport rates up to 0.3 mL/min, respectively.
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•Key processes that control analyte transport efficiency through spray chamber.•Extent of droplet-droplet collision/coagulation, droplet evaporation.•Video of droplet impact on spray chamber walls even at 2–10 μL/min uptake rate.•Separately assess solvent vapor, aerosol load without extinguishing plasma.•Analyte transport efficiency: micronebulizers versus “conventional” nebulizers.
The Cotopaxi Volcano is one of the most active stratovolcanoes in the world. It is located in the center of Ecuador, surrounded by densely populated cities as Latacunga, Machachi, or Sangoquí, in ...which the agricultural sector is very important for economic development. Ash emissions and phreatomagmatic eruptions characterized the eruptive process of Cotopaxi volcano in august 2015. A mineralogical study of the ashes showed the presence of heavy metals, which could have been transferred to the soil and could affect agricultural and livestock activities. To evaluate the relationship between the concentrations of Cd, Cu, Pb, Hg, Cr, Co, Ni, Zn and as between the soil, ash and the comparison with local regulations, three farms (Altamira farm, San Ramon farm and La Laguna farm) in the Canton of Mejía were defined as the study area. In those locations, the soil samples were georeferenced with a handheld GPS. The analysis was carried out before acid digestion (EPA 3050B1 method) in an ICP-OES and AMA 254 atomic absorption spectrophotometer. The metals analyzed were kept within limits defined in TULSMA Book VI: Annex 2 Soil Resource local regulations. In order to improve the visibility of the study, the presentation of the results was carried out in an open-access geoportal implemented in proprietary software. This geoportal allows the dynamic and interactive visualization of the different concentrations of heavy metals in their corresponding location.
Food security is a priority issue for sustainable global development. Metal uptake by plants could have a significant impact on crop quality in areas of rapid industrialization with high fallout of ...airborne particles. In this study, concentrations of some heavy metals (copper, Cu; zinc, Zn; and lead, Pb) in flour samples supplied in Çorum, defined as one of the “New Industry Focus”, were investigated using inductively coupled plasma-optical emission spectrometry (ICP-OES) to determine the heavy metal contamination. The results showed that the concentration of Pb in all samples examined exceeded the maximum permissible limit. To monitor the increase in Pb concentration and its relationship with air pollution, a two-year laboratory experiment was conducted. It was found that the increase in Pb concentration of about 47% and 77% for two flour samples was consistent with the increase in annual average particulate matter with diameter 10 micrometers PM10 concentrations (55% and 82%) obtained from two stations.
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