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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
11

Studies on Weathered Waterborne Treated Wood: Leaching of Metals during Service and Metals Based Detection upon Recycle

Hasan, Abdel Fattah Rasem 06 August 2009 (has links)
Weathered waterborne treated wood is believed to behave differently than new wood during service regarding the loss of its metallic-based preservatives. Also, weathered preserved wood should be separated from the unpreserved wood upon recycle. The first objective of this dissertation was to evaluate losses from weathered CCA-treated wood samples at different retention levels under normal field conditions and to compare leaching to new ACQ (as alternative to CCA). Results showed that arsenic leached at a higher rate than chromium and copper in all CCA treated wood samples, while copper leached the highest from the ACQ sample. Overall results suggest that the leaching rate of metals on a percent basis from in-service pressure treated wood may increase as the wood weathers; however due to lower retention levels of the metals in the wood as it ages the yearly mass of metals lost would be at similar or at lower quantities in comparison to new treated wood. The second objective was to evaluate the use of automated X-ray fluorescence (XRF) systems for identifying and removing As-based and Cu-based treated wood within the recovered wood waste stream. A full-scale online automated XRF-detection, conveyance and diversion system was used for experimentation. At the different applied feeding rates and belt speeds, online sorting efficiencies of waste wood by XRF technology were high (>70% for both treated wood and untreated wood). The incorrectly diverted pieces of wood were attributed to deficiencies in the wood conveyance systems and not to deficiencies in the XRF-based detection. Online sorting was shown to sort wood which would meet the residential soil cleanup target levels in Florida when an infeed is composed of 5% of treated wood pieces. Comparisons with other sorting methods show that XRF technology can potentially fulfill the need for cost-effective processing at large wood recycling facilities (> 30 tons per day). Management of weathered CCA-preserved wood, due to its continuity of leaching metals and the need to remove it upon the recycle of wood, will likely continue until complete banning and removal from the environment, a process that may extend up to the next century.
12

Tungmetallkoncentrationen i ytvatten och mark kring området Knuthöjdsmossen / Heavy metal concentration in surface water and soil surrounding the area of Knuthöjdsmossen

Brobäck, Malin, Shakespeare, Sara January 2013 (has links)
Knuthöjdsmossens naturreservat är beläget i Hällefors, Örebro län och är känd för sina unika gölar, fauna och dess sanddyna. Strax intill Knuthöjdsmossens Naturreservat finns en nerlagd industrideponi som var i bruk i början av 1800 talet fram till 1983 vid namnet avfallsupplaget Piteå. Det avfall som deponerades bestod av restprodukter, industriavfall, byggavfall, grovsopor, järnspår och slipspån. Mellan åren 1994-2009 har Bergslagens kommunalteknik utfört ytvattenprovtagningar i området, de har dock upphört, men det finns ett intresse om att återuppta provtagningarna, därtill syftet med denna uppsats; en förstudie om vilken miljöpåverkan avfallsupplaget Piteå har på området Knuthöjdsmossen. Metallkoncentrationer från ytvattenproverna från åren 1994-2009 analyserades samt så insamlades kompletterande jordprover med en XRF-skanner. Resultaten visade på metallkoncentrationer i ytvattnet där zink-, nickel- och koppar bedömdes som höga enligt Naturvårdsverkets riktvärden. Detta styrktes även genom den kompletterande jordskanningen av två områden intill avfallsupplaget Piteå. Även resterande tungmetallekoncentrationer från vattenprovtagningen visade på Tydliga till Mycket stora avvikelser utefter Naturvårdsverkets bedömningsgrunder, tungmetallhalterna jämfördes även med resultat från närliggande lokala sjöar som bedöms ha god ekologisk status. Detta gav ett tillräckligt underlag att påstå att avfallsupplaget Piteå har en miljöpåverkan på området Knuthöjdsmossen.
13

Developing a methodology for the non-destructive analysis of British soft-paste porcelain

Dunster, Joanna Margaret January 2016 (has links)
Soft-paste porcelain was produced in Britain in great quantities between the mid-18th and early 19th centuries. Due to industrial secrecy and the complexities of creating a product that would survive high-temperature firing, a range of paste recipes was employed by dozens of factories. This has resulted in an array of porcelains which vary in their elemental composition and mineralogy. This research carries out a meta-analysis of the published data for porcelain bodies and glazes and concludes that some discrimination can be achieved using the major and minor elemental composition of the bodies, and that for the glazes intra-factory variation is often greater than inter-factory variation in composition. A pilot investigation of the trace elemental composition of British porcelain is carried out using Laser Ablation Inductively Coupled Plasma Mass Spectroscopy, which finds compositional groups corresponding to different sources of clay and silica raw materials. In the interests of preserving intact objects, there is recognised a need for a non-destructive method for analysing British porcelain, in order to provenance and date objects. Such a method would rely on data from the surface of the object, which is typically covered by glaze and over-glaze coloured enamels, and this research demonstrates that the formulae used for the glaze and enamels are in some cases characteristic of the factory, or workshop, and period at which they were created. Hand-Held XRF analysis is used to analyse the glaze, underglaze blue and polychrome enamels on a selection of porcelain objects from different factories, and compositional traits are identified that allow some factories and periods to be distinguished. Glass standards are developed, which are representative of the glaze and enamel composition, and which could allow X-ray fluorescence (XRF) data to be calibrated for fully quantitative results.
14

Kartläggning av metallförekomst med XRF Väsmanstranden, Ludvika : En fördjupad riskbedömning

Qvarforth, Anna January 2020 (has links)
Abstract Centrally located in Ludvika, between the central station and the south-eastern part of Lake Väsman, the area called "Väsmanstranden" is located. The closeness to both Väsman and all its nearby natural deposits and the railroad have created excellent conditions for many businesses to flourish on the site over the years. For example, there have been sawmills, impregnation operations, a concrete plant and several oil companies. In addition, an extensive transhipment of sulphide ore resulting from the nearby mines has taken place from boat to rail near the water. Several of these historical activities have left pollution of various kinds. Investigations carried out have shown, in particular, oil pollution and metals. Today, Väsmanstranden is used to a relatively small extent. However, greater utilization of the site is to be expected, as the municipality intends to carry out extensive exploitation of the area. The purpose of this thesis was to carry out a supplementary and extended environmental risk analysis of Väsmanstranden. For practical and economic reasons, the analysis was limited to only include metals. Soil sampling, based on a sampling plan designed to supplement previous surveys, was carried out in a total of 40 points. The sampled soil was quantitatively analyzed with XRF, Xray fluorescence. The metals whose concentration was investigated were lead, barium, zinc, cobalt, arsenic, copper, chromium, cadmium, nickel and mercury. The study also included conducting a site-specific survey study in which Väsmanstranden's current visitor frequency was mapped. In the more extended part of the work, site-specific guideline values were generated using the Swedish Environmental Protection Agency's guideline value model. This was done for the metals lead, barium, zinc, nickel and arsenic, which were detected at high concentrations in many places in the area. For the same metals, a modeling of dispersion and an exposure analysis were also performed. All of the surveyed sub-areas of Väsmanstranden were found to contain at least some metal in a content that exceeds the limit for which can be tolerated when ”less sensitive landuse” is taken into consideration. In significantly more test points, the limit for ”sensitive landuse” was exceeded. Metal concentrations exceeding developed site-specific guideline values also occurred in all subareas. On a promontory in one of the northern parts of the study area that had not previously been sampled, arsenic was found in high concentrations. There is a risk that the levels of arsenic, barium, nickel and lead present can lead to unacceptable exposure in an envisaged future scenario. The dispersion modeling showed the risk of spreading to groundwater at levels that exceed assessment bases derived from the Geological Survey of Sweden. Although both model and parameter uncertainties exist in the methods used, it is clear that measures that reduce risks to humans, animals and the environment should be taken. Probably, remediation consisting of excavation is the most suited finishing option. The method is applicable to all pollution, provides a permanent risk reduction and is also one of the most economically advantageous alternatives. Concomitant use of any type of purification method could reduce the amount of waste deposited.
15

Ceramics and the Central Lydia Archaeological Survey (CLAS): a diachronic study using portable X-ray fluorescence (pXRF)

Sparling, Loren Tai 22 January 2016 (has links)
This Master's project explores the viability of portable XRF (pXRF) for the purposes of identifying the chemical signatures of ceramics collected as part of archaeological research. The work presented makes clear that this method is viable and opens the door for future opportunities with extensive research collections located in storage units and museums precisely because the analysis is portable. No longer will researchers face the hurdles of export permissions for samples. The project presents results from three separate research phases. The first data collection tested the method with a control group, corroborating results from what is traditionally seen as a far more rigorous method for chemical sourcing of archaeological ceramics, instrumental neutron activation analysis (INAA). The second and third phases handled much larger datasets, setting the stage for future research. Additionally, an investigation of data collection efficiency shows that existing protocols produce statistically consistent results, yet that protocol economy can reduce overall analysis cost (in terms of time) for certain classes of ceramics.
16

Spektrální analýza chemického kódu / Spectral analysis of chemical code

Šimončičová, Monika January 2021 (has links)
The diploma thesis deals with the study of the process of grinding aggregates of particles of a mixture of powdered lanthanide oxides in the dowanol solvent. The formed dispersions were characterised and used for the preparation of printing inks and subsequently for the printing of labels with chemical codes readable by XRF spectrometry. The aim was to study the milling process, to verify the reliability of reading and recognition of marks with the appropriate codes and to monitor the influence of the additive of the up-conversion powder on the resulting relative intensities of the elements in the chemical code. The statistical significance of the differences in the averages of relative intensities was assessed based on the Student's t test.
17

DETERMINATION OF THE FEASIBILITY OF USING THE PORTABLE X-RAY FLUOURESCENCE (XRF) ANALYZER IN THE FIELD FOR MEASURING THE LEAD CONTENT OF SIEVED SOIL

ARMSTRONG, ANDREA MARIE 21 May 2002 (has links)
No description available.
18

Central Arctic Lithostratigraphy: Implication for Sediment Transport and Paleoceanography

Council, Edward Augustus, III 08 October 2012 (has links)
No description available.
19

Determinação de elementos químicos em plásticos biodegradáveis naturais e sintéticos / Determination of chemical elements in natural and synthetic biodegradable plastics

Boscaro, Mateus Eugenio 02 September 2014 (has links)
Preocupações com o acúmulo de lixo plástico e seu consequente impacto ambiental levaram os cientistas e a indústria química, nas últimas décadas, a uma busca por plásticos biodegradáveis e plásticos produzidos com matérias-primas de fontes renováveis. Entre eles, encontram-se o poli(ácido lático), o poli(?-caprolactona), os poli(hidroxialcanoatos), os polímeros de amido e os polímeros sintéticos que recebem aditivos que facilitam a degradação, conhecidos como oxi-biodegradáveis. Em decorrência dos processos de produção e uso de aditivos e corantes, os plásticos podem conter constituintes que não fazem parte das moléculas do polímero. Por esta razão, o objetivo do trabalho foi determinar os elementos químicos presentes em amostras de polímeros biodegradáveis, sacolas oxi-biodegradáveis e sacolas de amido distribuídas em supermercados, empregando-se análise por ativação neutrônica instrumental (INAA) e espectroscopia de fluorescência de raios X (XRF). A identificação dos polímeros das sacolas de supermercado foi realizada por espectroscopia de absorção no infravermelho com transformada de Fourier (FTIR). Os resultados das análises químicas dos polímeros não processados evidenciaram baixas concentrações dos elementos químicos. Já os plásticos das sacolas apresentaram altas concentrações de cálcio, sódio, zinco e titânio, provenientes do uso de cargas minerais, corantes e outros aditivos. Em algumas amostras, as concentrações de zinco, cobalto, cromo, molibdênio e chumbo excederam os limites estabelecidos pela norma ABNT NBR 15448-2:2008 para polímeros biodegradáveis. As análises também indicaram que os aditivos pró-oxidantes utilizados nas sacolas oxi-biodegradáveis são baseados em compostos químicos que contêm ferro. Os resultados obtidos comprovam que os plásticos biodegradáveis podem ser utilizados de forma segura em embalagens e outras aplicações, desde que se evitem os aditivos contendo elementos químicos tóxicos e outras substâncias perigosas / Concerns about the accumulation of plastic waste and its consequent environmental impact have led scientists and chemical industry, in recent decades, to search for biodegradable plastics and plastics made with renewable raw materials. Among them are included poly (lactic acid), polycaprolactone, polyhydroxyalkanoates, starch polymers and synthetic polymers having additives which facilitate degradation, known as oxo-biodegradable. Due to production processes and use of additives and dyes, plastics may contain small amounts of chemical elements that are not part of the polymer molecules. For this reason, the objective of this study was to determine chemical elements in samples of biodegradable polymers, oxy-biodegradable and starch bags distributed in supermarkets by instrumental neutron activation analysis (INAA) and X-ray fluorescence spectroscopy (XRF). The polymers of plastic bags were identified by Fourier transform infrared spectroscopy (FTIR). Results of chemical analysis of unprocessed polymers have shown low concentrations of chemical elements. On the other hand, plastic bags have high concentrations of calcium, sodium, zinc and titanium, from the use of mineral fillers, dyes and other additives. In some bag samples, the concentration of zinc, cobalt, chromium, molybdenum and lead exceeded the limits established by the ABNT NBR 15448-2:2008 for biodegradable polymers. The analysis also indicated that the pro-oxidant additives used in the oxy-biodegradable bags are based on chemical compounds that contain iron. These results demonstrate that biodegradable plastics can be safely used in packaging and other applications, provided additives containing toxic chemical elements and other hazardous substances are avoided
20

Determinação de elementos químicos em plásticos biodegradáveis naturais e sintéticos / Determination of chemical elements in natural and synthetic biodegradable plastics

Mateus Eugenio Boscaro 02 September 2014 (has links)
Preocupações com o acúmulo de lixo plástico e seu consequente impacto ambiental levaram os cientistas e a indústria química, nas últimas décadas, a uma busca por plásticos biodegradáveis e plásticos produzidos com matérias-primas de fontes renováveis. Entre eles, encontram-se o poli(ácido lático), o poli(?-caprolactona), os poli(hidroxialcanoatos), os polímeros de amido e os polímeros sintéticos que recebem aditivos que facilitam a degradação, conhecidos como oxi-biodegradáveis. Em decorrência dos processos de produção e uso de aditivos e corantes, os plásticos podem conter constituintes que não fazem parte das moléculas do polímero. Por esta razão, o objetivo do trabalho foi determinar os elementos químicos presentes em amostras de polímeros biodegradáveis, sacolas oxi-biodegradáveis e sacolas de amido distribuídas em supermercados, empregando-se análise por ativação neutrônica instrumental (INAA) e espectroscopia de fluorescência de raios X (XRF). A identificação dos polímeros das sacolas de supermercado foi realizada por espectroscopia de absorção no infravermelho com transformada de Fourier (FTIR). Os resultados das análises químicas dos polímeros não processados evidenciaram baixas concentrações dos elementos químicos. Já os plásticos das sacolas apresentaram altas concentrações de cálcio, sódio, zinco e titânio, provenientes do uso de cargas minerais, corantes e outros aditivos. Em algumas amostras, as concentrações de zinco, cobalto, cromo, molibdênio e chumbo excederam os limites estabelecidos pela norma ABNT NBR 15448-2:2008 para polímeros biodegradáveis. As análises também indicaram que os aditivos pró-oxidantes utilizados nas sacolas oxi-biodegradáveis são baseados em compostos químicos que contêm ferro. Os resultados obtidos comprovam que os plásticos biodegradáveis podem ser utilizados de forma segura em embalagens e outras aplicações, desde que se evitem os aditivos contendo elementos químicos tóxicos e outras substâncias perigosas / Concerns about the accumulation of plastic waste and its consequent environmental impact have led scientists and chemical industry, in recent decades, to search for biodegradable plastics and plastics made with renewable raw materials. Among them are included poly (lactic acid), polycaprolactone, polyhydroxyalkanoates, starch polymers and synthetic polymers having additives which facilitate degradation, known as oxo-biodegradable. Due to production processes and use of additives and dyes, plastics may contain small amounts of chemical elements that are not part of the polymer molecules. For this reason, the objective of this study was to determine chemical elements in samples of biodegradable polymers, oxy-biodegradable and starch bags distributed in supermarkets by instrumental neutron activation analysis (INAA) and X-ray fluorescence spectroscopy (XRF). The polymers of plastic bags were identified by Fourier transform infrared spectroscopy (FTIR). Results of chemical analysis of unprocessed polymers have shown low concentrations of chemical elements. On the other hand, plastic bags have high concentrations of calcium, sodium, zinc and titanium, from the use of mineral fillers, dyes and other additives. In some bag samples, the concentration of zinc, cobalt, chromium, molybdenum and lead exceeded the limits established by the ABNT NBR 15448-2:2008 for biodegradable polymers. The analysis also indicated that the pro-oxidant additives used in the oxy-biodegradable bags are based on chemical compounds that contain iron. These results demonstrate that biodegradable plastics can be safely used in packaging and other applications, provided additives containing toxic chemical elements and other hazardous substances are avoided

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