Rozprawy doktorskie na temat „Metal flames”

This Thesis considers peculiarities of nanoparticle formation from the gas in different systems. The main role of the surface condensation in the nanoparticle growth in metal flames was established through a series of experiments and was described by the developed model. The stagnation of the post-nucleation nanoparticle growth was experimentally revealed and theoretically explained. The influence of generation conditions on the post-processing nanoparticle properties was examined. The non-isothermal approach to correct the homogeneous nucleation theory was developed. The results of this work can be summarized in 3 categories: (1) Nanoparticle formation in metal flames. In this work, it was demonstrated that the surface condensation is a main process responsible for nanooxides growth during metal combustion. It was shown that the rate of this condensation growth is consistent with the exponential law, which could lead to the formation of the lognormal particle size distribution in the system, where the Brownian coagulation is suppressed. The post-nucleation stagnation of the nanoparticle growth was found. The particle overheating was suggested as a cause of the growth stagnation. The found stagnation leads to the accumulation of the supercritical clusters in the system generating nanoparticles. The role of these supercritical clusters in the nanoparticle agglomeration was considered. (2) Study of properties of nanoparticles generated in different metal flames. The light absorption, photoluminescence and magnetic properties of nanoparticles produced in different metal flames were examined. The significant broadening of the absorption edge was found in nanooxides produced by direct metal combustion. This broadening allowed one to excite the unforeseen photoluminescence from these nanoparticles. The significant light absorption in the visible light found in the titania particles produced by metal combustion allows one to consider these particles as a prospective photocatalyst. The unusual optical properties revealed were related to the extreme conditions of the nanoparticle formation, namely, to high energy release (about 5 eV per condensing molecule). The stabilization of spinel structure was found in iron oxide particles synthesized by iron combustion. It allowed one to produce nanoparticles with magnetization close to the high-limit value of the bulk. (3) Approach to correct the homogeneous nucleation theory. The existing homogeneous nucleation theory implies that nucleation occurs at isothermal conditions, i.e. subcritical clusters have the same temperature as the ambient gas does. However, the theory overestimates the actual nucleation rate and underestimates the critical cluster size. It is understandable that due to release of the latent heat of condensation, the cluster temperature in the nucleating system should be higher than the environment temperature. In this work, it was suggested the method to account for the cluster overheating during nucleation. It was demonstrated that the consistent description of the detailed balance in the nucleating system may allow one to evaluate magnitudes of overestimation of the actual nucleation rate and underestimation of the number of molecules in the critical cluster, usually obtained by the isothermal nucleation theory. The numerical estimates are in good agreement with the wellknown experimental results. The implications of the results to generation of atmospheric aerosols were discussed.

This Thesis considers peculiarities of nanoparticle formation from the gas in different systems. The main role of the surface condensation in the nanoparticle growth in metal flames was established through a series of experiments and was described by the developed model. The stagnation of the post-nucleation nanoparticle growth was experimentally revealed and theoretically explained. The influence of generation conditions on the post-processing nanoparticle properties was examined. The non-isothermal approach to correct the homogeneous nucleation theory was developed. The results of this work can be summarized in 3 categories: (1) Nanoparticle formation in metal flames. In this work, it was demonstrated that the surface condensation is a main process responsible for nanooxides growth during metal combustion. It was shown that the rate of this condensation growth is consistent with the exponential law, which could lead to the formation of the lognormal particle size distribution in the system, where the Brownian coagulation is suppressed. The post-nucleation stagnation of the nanoparticle growth was found. The particle overheating was suggested as a cause of the growth stagnation. The found stagnation leads to the accumulation of the supercritical clusters in the system generating nanoparticles. The role of these supercritical clusters in the nanoparticle agglomeration was considered. (2) Study of properties of nanoparticles generated in different metal flames. The light absorption, photoluminescence and magnetic properties of nanoparticles produced in different metal flames were examined. The significant broadening of the absorption edge was found in nanooxides produced by direct metal combustion. This broadening allowed one to excite the unforeseen photoluminescence from these nanoparticles. The significant light absorption in the visible light found in the titania particles produced by metal combustion allows one to consider these particles as a prospective photocatalyst. The unusual optical properties revealed were related to the extreme conditions of the nanoparticle formation, namely, to high energy release (about 5 eV per condensing molecule). The stabilization of spinel structure was found in iron oxide particles synthesized by iron combustion. It allowed one to produce nanoparticles with magnetization close to the high-limit value of the bulk. (3) Approach to correct the homogeneous nucleation theory. The existing homogeneous nucleation theory implies that nucleation occurs at isothermal conditions, i.e. subcritical clusters have the same temperature as the ambient gas does. However, the theory overestimates the actual nucleation rate and underestimates the critical cluster size. It is understandable that due to release of the latent heat of condensation, the cluster temperature in the nucleating system should be higher than the environment temperature. In this work, it was suggested the method to account for the cluster overheating during nucleation. It was demonstrated that the consistent description of the detailed balance in the nucleating system may allow one to evaluate magnitudes of overestimation of the actual nucleation rate and underestimation of the number of molecules in the critical cluster, usually obtained by the isothermal nucleation theory. The numerical estimates are in good agreement with the wellknown experimental results. The implications of the results to generation of atmospheric aerosols were discussed.
Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
School of Environmental Engineering
Full Text

Spatially-resolved measurements of flame temperature have been demonstrated with diode lasers for the first time. The technique is based on the use of blue diode lasers to perform laser-induced fluorescence on indium atoms seeded to the flame. Temperature measurements have been carried out in laminar flames both by the two-line atomic fluorescence technique, and also by a novel line-shape thermometry method that requires the use of only a single diode laser. The first part of this work involved the development of blue extended cavity diode lasers with favourable tuning properties. Two custom-designed extended cavity diode lasers (ECDL) have been built, emitting at wavelengths of around 410 nm and 451 nm respectively. These devices are capable of mode-hop free tuning over ranges greater than 90 GHz. The performance of these devices exceeds that of commercially available systems and a patent application has been filed. High resolution fluorescence spectroscopy has been performed on both the 52P1/2→62S1/2 and 52P3/2→62S1/2 transitions of indium atoms seeded at trace quantities into atmospheric pressure flames. In both cases, the spectra obtained show excellent agreement with a theoretical fit based on the individual hyperfine components of the transition. The two ECDLs have been used to build a sensor for the measurement of temperature in combustion systems. It is much simpler, more compact, less expensive, and more versatile than any previously existing device. The two lasers were used sequentially to probe indium atoms seeded to the flame. The ratio of the resulting fluorescence signals is related to the relative populations in the two sub-levels of the spin-orbit split ground state of indium, and thus to the temperature. Temperature measurements have been successfully performed in a laminar flame and the data thus obtained do not need to be corrected by any ‘calibration constant’. This novel thermometry technique offers a robust alternative to traditional methods involving bulky high power lasers. A further development has been made by demonstrating a fluorescence line-shape thermometry technique requiring only a single diode laser excitation source. Progress has been made towards the goal of rapid temperature measurements appropriate to the study of turbulent flames. This involved the development of a simple technique for actively locking the wavelength of the blue diode laser to a resonance line of the tellurium molecule. A high-speed thermometry system would work by rapidly switching between the two locked laser beams using an optical modulator.

Chemical treatment of contaminated soils (in-situ or ex-situ) is the current most practical option for remediation. The degree of metal complexation by organic acids depends on the type, concentration, metal type, pH and temperature. The influence of pH, temperature on the extraction efficiency of lead, zinc and copper was evaluated using Sodium citrate and sodium acetate buffers. Sodium citrate buffer was selected for the soil treatment. The soil was characterized for its pH, total metal content and the distribution of target heavy metals in soil fractions. Optimal conditions for Pb extraction with 0.5M citrate buffer was used to treat soil in batches and in columns, to evaluate their extraction efficiency and possible use for in-situ remediation.
Chitosan, a derivative of chitin is a versatile biopolymer with metal uptake capabilities. Due to the large amounts of chitosan required to treat heavily contaminated leachates, magnesium (Mg) and iron (Fe) metals granules were evaluated for stripping the heavy metals from solution before the use of chitosan at optimized conditions to effectively polish the soil washing. (Abstract shortened by UMI.)

Thermal spraying is a technology, which is used for coating of components and structures in order to achieve certain tribological characteristics, or for protection against corrosion, excessive temperature and wear. Within thermal spray, there are processes, which utilise combustion of liquid fuel to obtain high velocities flows providing, therefore, good adhesion of coating materials to substrates. These include High Velocity Oxygen Flame (HVOF) and High Velocity Air Flame (HVAF) process, of which the former one is widely used as it has been developed for at least two decades, while HVAF is less common. However, some studies indicate that HVAF has a number of advantages over HVOF, including the economic benefits. The thermal spray gun, based on the HVAF process, has been developed before, but the system was controlled manually. Therefore, there is a need to develop a fully automated controller of an HVAF thermal spray system. Process control of thermal spraying is highly complex as it involves simultaneous control of a number of processes, including; ignition process, combustion process, spraying material melting, as well as control and monitoring of auxiliary equipment. This paper presents the development of a control system for an HVAF thermal spray system, based on a Microchip PIC microcontroller. The designed control system was applied for controlling of thermal spraying of carbides powders, and provided a reliable ignition and stable combustion process, powder feeding and all other functions of control.

Due to the increasing use of electronic components and the accelerated rate in which these components become obsolete, there has been a dramatic increase of discarded electronic waste (E-waste). E-waste includes obsolete electronic products such as computers, scanners, cellular phones, etc. These electronic components are manufactured using a variety of hazardous materials. As these components are discarded, the toxic and hazardous substances may become mobile and could impact human health and the environment. The toxic substances of concern contained in E-waste include heavy metals and brominated flame retardants (BFRs). This study attempts to identify the leaching potential of BFRs and metals.

Flame Atomic Absorption Spectrometry (FAAS) still keeps its importance despite the relatively low sensitivity
because it is a simple and economical technique for determination of metals. In recent years atom traps have been developed to increase the sensitivity of FAAS. Although the detection limit of FAAS is only at the level of mg/L, with the use of atom traps it can reach to ng/mL. Slotted quartz tube (SQT) is one of these atom traps, it is applied for determination of volatile elements
it is economical, commercially available and easy to use. In this study, a sensitive analytical method has been developed for the determination of lead with the help of SQT. Regarding the angle between the two slots of SQT, 120°
and 180°
configurations were used and the results were compared. There were three modes of SQT used. The first application was for providing longer residence time of analyte atoms in the measurement zone
3 fold sensitivity enhancement was observed. The second mode was the usage of SQT for preconcentration of lead atoms. In the presence of a lean air-acetylene flame, analyte atoms were trapped in the inner surface of SQT for a few minutes. Then, by the help of a small volume (10-50 &
#956
L) of Methyl isobutyl ketone (MIBK), analyte atoms were revolatilized and a rapid atomization took place. Using this mode, a sensitivity enhancement of 574 was obtained at a rather low (3.9 mL/min) suction rate
1320 fold improvement was reached at higher sample suction rate (7.4 mL/min) for 5.0 min collection. The last mode involves coating of the inner surface of SQT with several kinds of transition metals. The best sensitivity enhancement, 1650 fold, was obtained by the Ta coated SQT. In addition, effects of some elements and anions on Pb signal in Tacoated-SQT-AT-FAAS were examined. Final step consists of surface analysis
chemical nature of Pb trapped on quartz and Ta surface, and the chemical nature of Ta on quartz surface were investigated by X-ray Photoelectron Spectroscopy (XPS) and Raman Spectroscopy.

Flame Atomic Absorption Spectroscopy (FAAS) has lover sensitivity than similar analytical methods, however it has an important place for analysis due to its easy application and economic practicability especially in metal determinations. In order to increase the sensitivity of FAAS from mg/L level to ng/L level, various atom trap systems have been used. One of these atom traps, Slotted Quartz Tube (SQT), which is easy, economical and useful for volatile element determination, is used in this study as a sensitive analytical method for determination of tellurium. In the study, determination of Te by SQT is handled in three different modules. First, only with SQT itself, longer residence time for Te atoms in the measurement zone is provided and consequently 3.2 fold sensitivity enhancement is obtained both for Te (VI) and Te (IV). In the second module, SQT is used for concentration of tellurium species in a lean flame by sending the analyte into SQT for a definite time and trapping them on the inner surface of the SQT. After trapping the analyte, in order to determine the Te concentration, a small volume (10-50 µ
L) of organic solvent such as methyl ethyl ketone (MEK) is introduced to the flame for revolatilization and a rapid atomization of Te on the surface is provided. In this trapping method, for 5 minutes collection with a 6 mL/min suction rate, 143 fold enhancement for Te (VI) and 142 fold enhancement for Te (IV) were obtained. In the third module, different from the second one, the inner surface of the SQT is coated with different metals for increasing the amount of Te trapped on the surface and the best enhancement for tellurium is obtained with Tantalum-coated SQT with 252 fold enhancement for Te (VI) and 246 fold enhancements for Te (IV). All improvements are calculated according to the signals obtained in FAAS method. Separate calibration plots were used for Te (IV) and Te (VI).

The modeling of metal dust explosion phenomenon is important in order to safeguard industries from potential accidents. A key parameter of these models is the burning velocity, which represents the consumption rate of the reactants by the flame front, during the combustion process. This work is focused on the experimental determination of aluminium burning velocity, through an alternative method, called "Direct method". The study of the methods used and the results obtained is preceded by a general analysis on dust explosion phenomenon, flame propagation phenomenon, characteristics of the metals combustion process and standard methods for determining the burning velocity. The “Direct method” requires a flame propagating through a tube recorded by high-speed cameras. Thus, the flame propagation test is carried out inside a vertical prototype made of glass. The study considers two optical technique: the direct visualization of the light emitted by the flame and the Particle Image Velocimetry (PIV) technique. These techniques were used simultaneously and allow the determination of two velocities: the flame propagation velocity and the flow velocity of the unburnt mixture. Since the burning velocity is defined by these two quantities, its direct determination is done by substracting the flow velocity of the fresh mixture from the flame propagation velocity. The results obtained by this direct determination, are approximated by a linear curve and different non-linear curves, which show a fluctuating behaviour of burning velocity. Furthermore, the burning velocity is strongly affected by turbulence. Turbulence intensity can be evaluated from PIV technique data. A comparison between burning velocity and turbulence intensity highlighted that both have a similar trend.

The objective of this research is to evaluate the stiffness and strength demands on flange braces in metal building systems. This objective is accomplished by a targeted study of the effects of various attributes of metal building systems not fully addressed in existing bracing design procedures. Special emphasis is placed on attributes such as unequal brace spacing and stiffness, end brace point flexibility, nonprismatic member geometry, special requirements at knee joints and the specific configuration of combined girt/purlin, flange diagonal, diaphragm and X bracing systems used in metal building construction. A sub-objective of the research is the demonstration of how virtual test simulation via full nonlinear finite element analysis may be applied to solve a structural engineering research problem that would be difficult to address by any other means. When conducted properly, virtual test simulation can serve as a valuable companion to experimental testing since attributes such as residual stresses and critical geometric imperfections can be controlled precisely and with relative ease in virtual test simulation. Both highly simplified and more complex but relatively rigorous procedures are considered, with the ultimate goal being improved economy and safety of flange stability bracing in metal buildings.

ABSTRACT DETERMINATION OF CADMIUM USING SLOTTED QUARTZ TUBE ATOM TRAP ATOMIC ABSORPTION SPECTROMETRY AND METAL COATINGS Ö
zcan Gurbetoglu, G. Pelin M.S., Department of Chemistry Supervisor: Prof. Dr. O. Yavuz Ataman July 2010, 76 pages Flame atomic absorption spectroscopy (FAAS) is a common technique for detecting metals and metalloids in environmental, biological and metallurgical samples. Although it is a rather old technique, it is still very reliable, simple to use and inexpensive. The technique can be used to determine the concentration of over 70 different metals in a solution. However, it has detection limits at mg/L levels. Some atom trapping methods have been developed to reach the detection limits of ng/mL levels. Slotted quartz tube (SQT) is one of these atom trapping methods. It is an important technique, since it is easy to use, applicable in all laboratories, commercially available and economical. This thesis consists of development of a sensitive method for cadmium with the help of SQT atom trap. In this study, it was used for two different purposes. One was for keeping the analyte atoms more in the light path
in other words, for increasing the residence times of analyte atoms in the measurement zone. This first application was provided a 2.9 times enhancement with respect to conventional FAAS. Second application was for trapping the analyte on the surface of the SQT, in other words, for performing on-line preconcentration of cadmium in SQT. In the presence of a lean flame, analyte samples were trapped and collected for a few minutes at a low suction rate. After finishing the collection period, analyte atoms were revolatilized with the help of a small volume of (10-50 µ
L) methyl isobutyl ketone (MIBK) and a rapid atomization occurred. This introduction also altered the flame composition momentarily and analyte atoms were released from the surface of the SQT. Application of this method enhanced the sensitivity 2065 times with respect to conventional FAAS. Another approach to this type of atom trapping has been investigated also in this study, which was coating of SQT with some metals having low volatility. Therefore, some transition metals were coated to the surface of SQT and among them zirconium was selected as the best coating material as having the most sensitivity enhancement factor. That is why, rest of the study was performed with the Zr coated SQT. The enhancement was 3368 as compared with FAAS. Cd determination with this method provides LOD value of 8 pg/mL and Co value of 19 pg/mL. In order to see the effect of some other type of elements or ions on determination of cadmium, interference study was done.

Commercially available organic and conventionally grown vegetables were studied by quantitative determination of selected metals in them and to determine if any differences found are statistically significant. These findings can help the consumers to determine if the vegetable products are within the recommended maximum limits as proposed by the joint FAO/WHO Expert committee on organic foods designation. Eight edible vegetables were purchased from local stores in both the organic and conventionally grown categories. Samples were digested with concentrated nitric acid and the metals monitored were zinc, copper, lead, iron, cadmium, and nickel using flame atomic absorption. The concentration range for the heavy metals found are as follows: Zn, 2.04-69.4; Cu, 0.35-15.1; Pb, 0.00-3.99; Cd, 0.00-0.74; Fe, 2.52-319; and Ni, 39.9-53.8 μg/g. It was found that in general, conventional vegetables contain higher amounts of most of the heavy metals studied as compared to their organic counterparts. The study also showed that all vegetables products contain below the permissible limits for Zn, Cu, Ni, and Fe. For Pb all vegetables exceeded the safe limit except organic cucumber and conventional cabbage. For Cd, organic lettuce and green pepper, and conventional leafy green, green pepper, and spinach all exceeded the limit recommended by FAO/WHO.

The concentrations of heavy metals (Cd, Cu, Fe, Ni, Pb, Zn) were measured in water, and fish samples caught from the pond at Fishery Park in Unicoi County, TN. The water samples were collected once a week for 8 weeks. The amounts of metals in the muscle tissues, gill, and liver of the two fish species were measured. This was to determine if any correlation exists between the metal contents in water and those in the fish samples. The concentration ranges for the heavy metals found in the water samples are as follows: Zn 0.04-0.13; Cu, 0.00-0.00; Pb, 0.00-0.59; Cd, 0.0067-0.0071; Fe, 0.208-0.512; and Ni, 0.044-0.270 ppm. The concentration range for the heavy metals found in the fish tissues are as follows: Zn 0.0-0.48; Cu, 0.00-0.00; Pb, 0.00-0.43; Cd, 0.00-99.7; Fe, 25.7-1245.5; and Ni, 0.00-268.5 ppm. There was a strong correlation found between the water and fish tissue samples.

Based on study of documents supplied by PWO Unitools a.s. and on advices of design office staff, tool for forming flanges was designed. This tool was then manufactured and it has been used for carrying test of creating flanges of various diameters from high-strength steels. During these tests, the following parameters were optimized – force of upper and lower blank holder and the height of the main guides. Threads were created into these drown flanges. These threaded joins were later tested for maximum torque and maximum compressive strength.

Doutoramento em Biologia
Os humanos estão permanentemente expostos a vários contaminantes ambientais que têm sido produzidos pela indústria química ao longo das últimas décadas. Para além do contacto direto com produtos onde estes contaminantes são aplicados, a exposição ocorre principalmente porque estes químicos se libertam destes materiais e acumulam-se no ambiente, tornando-se desta forma disponíveis para serem consumidos involuntariamente pelos humanos. Durante muito tempo a alimentação foi considerada como a principal via da exposição dos humanos a diversas classes de contaminantes, incluindo os poluentes orgânicos persistentes (POPs) e metais tóxicos. No entanto, a exposição através do pó em ambientes interiores surgiu como uma importante via de exposição, principalmente porque estes contaminantes se acumulam no pó e devido ao facto das pessoas passarem grande parte do seu tempo em ambientes interiores. Na presente tese, foi estudada a presença de várias classes de contaminantes ambientais em amostras de duplicados de dieta e amostras de pó doméstico, de forma a caracterizar a exposição dos humanos através da ingestão de alimentos e pó doméstico em Portugal, e a avaliar os riscos associados a esta exposição. Os contaminantes estudados incluem: retardantes de chama bromados (BFRs); retardantes de chama fosforados (PFRs); bifenilos policlorados (PCBs); pesticidas organoclorados (OCs); e os metais tóxicos chumbo (Pb) e cádmio (Cd). Os níveis de BFRs, PCBs, OCs, Pb e Cd foram determinados em amostras de duplicados de dieta fornecidas por voluntários da comunidade académica da Universidade de Aveiro. No que diz respeito aos compostos orgânicos, as concentrações obtidas foram baixas. Os BFRs foram detetados em poucas amostras de dieta, sendo que o mais detetado foi o congénere BDE 209 (67%), enquanto os BFRs emergentes – 1,2-bis (2,4,6-tribromofenoxi) etano (BTBPE), decabromodifenill etano (DBDPE) – não foram detetados. Os PCBs e os OCs apresentaram as concentrações mais elevadas e foram detetados na maioria das amostras de duplicados de dieta analisadas, sendo que os diclorodifeniltricloroetanos (DDTs) e os hexaclorociclohexanos (HCHs) foram detetados em 100% das amostras. Os valores estimados das ingestões diárias foram baixos e abaixo dos valores de referência estabelecidos para a avaliação de risco em humanos. O Pb foi detetado em todas as amostras de duplicado de dieta e o seu consumo através da ingestão de alimentos foi associado a efeitos adversos para a saúde. Para 33% dos participantes a ingestão diária estimada (EDI) foi superior à dose de referência (bench mark dose level – BMDL) associada à doença renal crónica, e para um dos participantes a EDI foi 50% mais elevado do que a BMDL associada à pressão arterial sistólica elevada. A abordagem da margem de exposição (MOE - margin of exposure) foi aplicada e indicou que em pelo menos 3,3 e 26,7% dos participantes poderão surgir efeitos cardiovasculares e nefrotóxicos, respetivamente. As concentrações de Cd foram avaliadas em amostras de duplicados de dieta fornecidas por mulheres a trabalhar ou a estudar na Universidade de Aveiro. Este metal foi também detetado em todas as amostras analisadas e 35% das participantes apresentaram ingestões semanais estimadas (EWIs) mais elevadas do que a dose semanal tolerável estabelecida, sugerindo riscos de saúde elevados. No geral, os resultados obtidos através das análises feitas em amostra de duplicados de dieta demonstraram que a ingestão de alimentos é uma importante via de exposição aos contaminantes ambientais estudados. Os níveis de PFRs, BFRs and PCBs foram monitorizados em amostras de pó doméstico de casas de Aveiro e Coimbra. Estes compostos e os seus respetivos congéneres/isómeros foram detetados num grande número de amostras, sendo que os PFRs apresentaram as concentrações mais elevadas, seguidos dos BFRs e PCBs. Apesar das frequências de deteção elevadas, os EDIs foram inferiores às doses de referência (RfDs) estabelecidas. Os BFRs, PCBs, OCs foram também analisados em amostras de pó doméstico da Covilhã. Neste estudo, as amostras de pó foram recolhidas em casas de voluntários com asma e em casa de participantes sem asma. Os congéneres/isómeros dos contaminantes avaliados foram detetados na maioria das amostras, e o grupo de BFRs apresentou as concentrações mais altas, seguido de PCBs e DDTs. No entanto, para todos os contaminantes, as ingestões diárias foram inferiores às RfDs. Estes resultados confirmam que os PFRs, BFRs, PCBs e OCs estão omnipresentes nas casas Portuguesas, no entanto, o consumo diário dos contaminantes orgânicos através da ingestão de pó doméstico é baixo. Os resultados obtidos no âmbito desta tese permitiram descrever, pela primeira vez em Portugal, os níveis dos contaminantes selecionados em amostras de duplicados de dieta e pó doméstico. Estes resultados revelaram que o risco associado à ingestão de contaminantes orgânicos através da alimentação e do pó doméstico foram baixos, ao contrário do elevado risco associado à ingestão de Pb e Cd presentes nos alimentos.
Humans are permanently exposed to environmental contaminants which have been produced for decades and with numerous applications. Besides the direct contact with the consumer products in which these contaminants are applied, the exposure occurs mainly because these chemicals are released from those materials and accumulate in the environment being available for involuntary consumption. For a long time, diet has been considered the major human exposure route for several contaminants, including persistent organic pollutants (POPs) and toxic metals. However, the indoor exposure through dust emerged as important exposure route, mainly motivated by the fact that these contaminants accumulate in dust and because people in modern society spend much of their time indoors. In this thesis, several classes of environmental contaminants were analysed in duplicate diet samples and house dust in order to characterize the human exposure through the ingestion of food and the ingestion of house dust in Portugal and to access the associated risks. The contaminants studied include: brominated flame retardants (BFRs), phosphorus flame retardants (PFRs), polychlorinated biphenyls (PCBs), organochlorine pesticides (OCs), and also the toxic metals lead (Pb) and cadmium (Cd). The levels of BFRs, PCBs, OCs, Pb and Cd were assessed in duplicate diet samples obtained from volunteers from the University of Aveiro community. Regarding the organic compounds the obtained levels were low. BFRs were detected in few duplicate diet samples, with the congener BDE 209 exhibiting the higher detection frequency (67%) while the emerging BFRs – 1,2-bis (2,4,6-tribromophenoxy) ethane (BTBPE), decabromodiphenyl ethane (DBDPE) – were not detected. PCBs and OCs exhibited higher levels and were detected in most analysed duplicate diet samples, with dichlorodiphenyltrichloroethanes (DDTs) and hexachlorocyclohexanes (HCHs) being detected in 100% of the samples. The daily dietary intakes were estimated, being low and under the established guidance values for human risk assessment. Pb was detected in all duplicate diet samples and its dietary ingestion was associated with adverse health effects. For 33% of the participants, the estimated daily intakes (EDIs) were higher than the dietary intakes related to the bench mark dose level (BMDL) derived from chronic kidney disease, and for one participant the EDI was 50% higher than the BMDL derived from elevated systolic blood pressure. The margin of exposure approach (MOE) was applied and indicated that cardiovascular and nephrotoxic effects might likely occur in at least 3.3 and 26.7% of the participants, respectively. The concentrations of Cd were assessed in duplicate diet samples provided by women working or studying in University of Aveiro. This metal was also detected in all analysed samples and 35% of the participants exhibited estimated weekly intakes (EWIs) higher than the established tolerable weekly intake (TWI), suggesting increased health risks. Overall the results from the duplicate diet study demonstrate that the ingestion of food is an important pathway of exposure to these environmental contaminants. PFRs, BFRs and PCBs were monitored in house dust samples from two cities in central Portugal (Aveiro and Coimbra). These compounds and respective congeners/isomers were detected in a large number of samples, with PFRs exhibiting the highest concentrations followed by BFRs and PCBs. Despite their high detection frequencies, the EDIs were much lower than the established reference doses (RfDs). BFRs, PCBs and OCs were also analysed in house dust samples from Covilhã, Portugal. In this study, dust samples were collected from the houses of asthmatics and non-asthmatics participants. The contaminants congeners/isomers were detected in the majority of the dust samples, and the group of BFRs exhibited the higher concentrations, followed by PCBs and DDTs, however, the daily intakes were lower than the RfDs for all contaminants. These results confirm that PFRs, BFRs, PCBs and OCs are ubiquitously present in Portuguese households, however the daily intakes of these organic contaminants through house dust ingestion is low. The results obtained under the framework of this thesis allowed describing for the first time in Portugal the levels of the selected contaminants in duplicate diet samples and in house dust samples. The results disclosed that the risk associated with the ingestion of the organic contaminants through diet and house dust was low, which contrasts with the risk associated with the ingestion of Pb and Cd through diet.

Large and ever-increasing numbers of chemicals, including large quantities of a broad spectrum of organic compounds are used in modern society. More than 30 000 of the more than 100 000 chemical substances registered in the EU are estimated to be daily used, of which many will be discharged into the waste-streams handled by municipal sewage treatment plants (STPs). The main objective of the work underlying this thesis was to improve understanding of the relationships between the characteristics of sewage contaminants and their sewage treatment efficiency. Further objectives were to examine the relationships between socio-economic uses of chemicals and sludge quality, and the effects of regulatory actions on sludge quality. The quality of the sewage sludge and the levels and distribution patterns of the sludge contaminants, both within and between the STPs, seem to remain quite constant over time. The overall findings indicate that the levels of contaminants in sewage sludge seem to be largely independent of the location, size and treatment techniques applied at the STPs, and generally, of the types of human activity connected to them. The total and relative concentrations of the sludge contaminants were found to be fairly constant on a dry weight basis, with some exceptions, indicating that the pollutants originate from broad usage and diffuse dispersion rather than (industrial) point sources. The proportion of cyclic methylsiloxanes recovered in sludge seems to strongly depend on their vapour pressure, which decreases with the number of siloxane units. The higher water solubility and biodegradability of organophosphorus flame retardants and plasticizers than polybrominated diphenyl ethers (PBDEs) were also reflected in lower percentages (relative to their national use) found in sludge. Significant time-trends in levels of a-third of the sludge contaminants included in the annual national measurement program were detected over a period of seven years. The levels of compounds displaying significant time-trends generally decreased following declines in the quantities used nationally. However, a quarter of these compounds showed increasing trends, of which the linear methylsiloxanes followed the same trend as used quantities. The decaBDE was also found to be increasing in sludge, probably as a result of the phase-out of pentaBDE and octaBDE. The results indicate that the STP removal efficiency of anthropogenic substances, in Sweden, is generally good and that STPs, at least those in cold climates, do not efficiently remove certain polar contaminants. A non-targeted screening (by use of environmetrics and GCxGC-TOFMS) was performed and found to fulfil the objective to assess the STP removal efficiency, with emphasis to systematically analyse which compound classes that are not efficiently removed using the current STP technology. Many polar aromatic compounds were identified to be poorly removed. The acquired data on levels, profiles and variations in sludge contaminants (sludge quality) extend both the available information and understanding of the degree and nature of sludge contamination, which should help attempts to track changes in its contaminants and revisions, if necessary, of guideline values. This thesis also contributes to improve the knowledge base for the development of future STP technologies, and that archived sewage sludge can be used in retrospective analysis of new and emerging pollutants.

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Conselho Nacional de Pesquisa e Desenvolvimento Científico e Tecnológico - CNPq
The present study aimed to evaluate the effect of replacing fishmeal for hydrolysate fish protein (HFP) and biofloc flour (BF) in diet of marine shrimp Litopenaeus vannamei postlarvae (2mg). The present study aimed to evaluate the effect of replacing fishmeal for hydrolyzed fish protein (HFP) and biofloc flour (BF) in Litopenaeus vannamei postlarvae. The HFP used in the diets formulation were produced from fish industry waste and the biofloc used for BF production was obtained in cultivation tanks of a commercial shrimp farm. Feed for this phase was designed to be isoenergetic and isoproteic. This experiment consisted of six treatments with three replicates each, corresponding to the control treatment T0, using fish meal as the main protein source. The other treatments (T10, T20, T30, T40) were a gradual replacement of fishmeal by HFP and BF in the proportions of 10, 20, 30 and 40% respectively. In the experiment a commercial feed was used as external control. It was a 42 days assay. Shrimp survival was above 99% in all treatments. After statistical analysis to zootechnical parameters (final weight, weight gain, specific growth rate) shrimps fed with formulated diets had better results than the ones fed with commercial feed. Tested parameters had ideal points indicated by regression in levels ranging between 15 and 16% of fishmeal replacement by HFP and associated BF. In the present study we inferred that BF and HFP are potential ingredients to replace fish meal in diets for L. vannamei postlarvae.
A presente dissertação teve como objetivo avaliar o efeito da substituição da farinha de peixe por hidrolisado proteico de peixe (HPP) e farinha de biofloco (FB) na alimentação de pós-larvas (2mg) do marinho camarão Litopenaeus vannamei. O HPP utilizado na elaboração das rações foi produzido a partir de resíduos de uma indústria de pescado. O biofloco para a produção da farinha foi obtido em tanques de cultivo de uma carcinicultura comercial. As rações para esta fase foram elaboradas para serem isoproteicas e isoenergéticas. Este experimento consistiu de seis tratamentos com três repetições cada, correspondendo ao tratamento controle o T0, utilizando a farinha de peixe como principal fonte proteica, e os demais tratamentos com substituição gradual da farinha de peixe por HPP e FB nas proporções de 10, 20, 30 e 40% correspondendo aos tratamentos T10, T20, T30 e T40 respectivamente. No experimento foi utilizado um tratamento com ração comercial que serviu como controle externo. Este ensaio teve duração de 42 dias. A sobrevivência dos camarões cultivados ficou acima de 99% em todos os tratamentos. As respostas estatísticas para os parâmetros de desempenho zootécnico (peso final, ganho de peso, taxa de crescimento específico) indicaram melhores resultados para os camarões alimentados com as rações formuladas quando comparados com os camarões alimentados com ração comercial. Os parâmetros testados tiveram seus pontos ideais indicados pela regressão, em níveis que variaram entre 15 e 16% de substituição da farinha de peixe por HPP e FB associados. Os resultados encontrados neste experimento indicaram o potencial dos ingredientes testados na substituição da farinha de peixe em rações para L. vannamei.

碩士
元智大學
化學工程學系
93
The objectives of this study are two-folds: (1) develop a computational fluid dynamics (CFD) model for a low-pressure flat flame reactor and (2) the synthesis of nanostructured metal oxides particles using the low-pressure flat flame technique. A 2-dimensional CFD model was developed using the commercial CFD package FLUENT with the aim to assist in the investigation of flow behaviors and temperature distribution inside the reactor system. Parameters to be investigated in numerical experiments include fuel gas flow rate, chamber pressure, and boundary condition applied. Flame characteristics as well as temperature distribution will be studied. To validate the model, experimental measurement of flame temperature profiles at different combustion conditions (excess CH4, complete combustion, and excess O2) and operating pressures were performed. It was found that fuel/gas flow rate, combustion condition, and operating pressure influence the characteristics of the synthesized powders significantly. The average flame temperature was found to follow the relation: excess CH4＞complete combustion＞excess O2 at all three pressure conditions. At the same combustion condition, the highest achievable flame temperature occurs at 50 torr. FE-SEM and TEM results showed that most particles are with sizes in micrometer to submicrometer size range and that majority of particles obtained were spherical except for iron oxide and magnesium oxide.

When trace quantities of an alkali element are added to a flame, its optical and electrical properties change significantly. Addition of alkali seed to both premixed and diffusion flames has been used in the development of two new techniques, one for flame temperature measurement and the other for enhanced mixing. Advantage has been taken of the spectral characteristics of alkali seeds in the development of a non-invasive optical flame temperature measurement technique. The strongest resonance line of alkalis is in fact a doublet, and the two peaks can be subjected to different optical treatment. A cesium-seeded flame was exposed to radiation which was selectively filtered to yield different apparent source temperatures at the wavelengths corresponding to the doublet resonance lines. The ratio of the emission peak heights at the two wavelengths relates directly to flame temperature. This technique allows real-time measurement of flame temperatures up to 2800 K. A second process has been investigated which takes advantage of the enhanced electrical conductivity of alkali-seeded diffusion flames. The study first required a characterization of electrical discharges through planar diffusion flames. Because of the increase in conductivity, alkali-seeded diffusion flames can carry current when a transverse electric potential is applied. The behavior of diffusion flames carrying electrical current has been investigated. The dependence on electrode position and gap is reported and the behavior is contrasted with that described in the literature for premixed flames. A planar diffusion flame was subjected to a steady magnetic field parallel to the flow direction while an orthogonal, oscillating current passed through the flame sheet. A Lorentz body force was induced on the flame sheet which acted to move it alternately toward the fuel and oxidizer streams, improving bulk mixing in the flame. High-speed video images of the oscillating flame were analyzed to obtain its maximum lateral velocity. The results compared well with predictions from a simple theoretical model.
Graduation date: 1992

碩士
中正理工學院
兵器系統工程研究所
88
The objective of the study is to observe phenomenon of impacted metal surface and fire suppression and fire extinguishment by droplet impingement. The first part is to observe phenomenon of impacted metal surface by droplet impingement. The objective of the present work is systematically to study the effects of flow property and surface characteristic on the fluid dynamic by employing the high-speed CCD camera techniques and experimental measurements. The experimental work is unique in that the droplet impact factor is systematically rated in different non-dimensional numbers and parameters such as Reynolds number, Weber number. The parameter study includes the effects of the Reynolds number, Weber number, surface material (thermal diffusivity) and temperature. The dynamic behavior of droplet impingement will be mainly characterized by the splash, spread, rebound. The second objective of the study is to investigate the phenomenon of fire suppression of a kerosene lamp by water droplet impinging on the flame. The macro- and micro-photographic was used in this experimental work to obtain quantitative data. The main part of the experimental setup is the CCD camera assembled with micro- or macro-photographic. A monodisperse water droplet generator was used to generate a droplet stream. The stream was used to extinguishing the flame. The concerned parameters were flow rate, droplet size and flame size etc. The results show that the suppression of a flame without touching the lamp core could be related to the droplet size, frequency and velocity, which could cool down the flame and interfere in the structure of the flame.

碩士
文化大學
應用化學系
85
ABSTRACTThe influence of phosphorus and metal containing oligomers (P-Zn oligomer ,P-Caoligomer and P-Co oligomer) on smoke formation and flammability of variouspolymers (PVC.EPDM. Epoxy) has been studied in this work. The incorporation ofP-Zn oligomer into the PVC leads to a significant decrease of smoke evolution,but has little improvement on the fire-resistance. On the contrary, addition ofP-Ca oligomer or P-Co oligomer to PVC results in an increase of smoke evolutionalthough the OI value remains constant.Thermogravimetric studies indicate thatP-Zn oligomer exhibits a high thermal stability and gives a limited weight lossup to 800oC. The ineffectiveness of P-Zn oligmer to act as a flame retardant forPVC.EPDM. Epoxy was attributed to its' usually thermal stability. As a smokesuppressant, P-Zn oligomer shows an maximum smoke reduction at 5 phr additiveconcention in PVC formulation.

Fire presents a great risk to humans and their possessions. Polymeric compounds are highly flammable and compounds are added to increase their fire resistance. These additives are referred to as flame retardants. Intumescent flame retardants are systems that form a carbon rich foam on the surface of the polymer during thermal degradation. A new field of metal catalysed intumescence is discussed in this document. The influence of both the metal ion and organic backbone of polyhydroxylcarboxylic acid metal salts was studied. The intumescence and foaming properties of selected salts were studied in more detail. Gluconic acid proved to be the best intumescent and showed the best combination of carbon char yield, foam structure and volume, stability and open flame characteristics. As a general rule of thumb, the char volume and structure improved with an increased number of hydroxyl groups in the compound. Carbon char yield increased with an increase in the number of hydroxyl groups for a constant number of carbons in the complex. The number of acid groups in the compound played a lesser role in intumescence. Most metal complexes catalyse intumescent decomposition of polyhydric compounds such as polyhydroxylcarboxylic acids and pentaerythritol. The reduction in the volatilisation losses implies that the metal cations catalyse carbonisation reactions in the polyhydroxyl compound. Unfortunately, the resultant carbon-foams are unstable: the metal residues also catalyse the further oxidative degradation of the char. The low thermal stability of the compositions tested, as well as the afterglow effect makes them unsuitable for use as flame retardant additives in plastics. From the studies of the different metal complexes with acetylacetone and gluconic acid, it was concluded that the calcium ion exhibited the most promise. When pyrolysed in air with an open gas flame or in a furnace, calcium gluconate monohydrate produces voluminous foam. The foam is of a closed cell structure, densely packed and has no mechanical strength. The cell walls are very thin (5 to 50 nm) and the cells are between 50 µm and 200 µm in size. If the sample is compressed before heating, the resultant foam produced during pyrolysis is less voluminous than that of the loose powder. The BET surface area of the calcium gluconate monohydrate foamed at 300°C for 5 min. is 16.0 m2/g. The foam produced after 5 min heating at 300°C has a thermal conductivity similar to standard polystyrene foam. Adding leached silica to the calcium gluconate monohydrate increases mechanical strength of the foam, but influences the foam volume negatively. The optimum silica level was calculated to be 1:1 gluconate to silica on a mole ratio (11.8% SiO2 by mass). The mechanical strength of the foam can also be increased with the addition of expandable graphite. The graphite has a lesser influence on the foam volume than the silica, but also reduces the foam volume. However, the addition of the expandable graphite gives the sample more .opening. force, as the foam volume of a compressed sample pyrolysed, is similar to that of the heated loose powder. Calcium gluconate monohydrate starts to degrade at 120°C, losing its crystal water and shows a mass loss of 4% at 180°C. The exothermic peak (shown in the DSC/TGA data) associated with the metal catalysed carbon oxidation (afterglow) is observed at 570°C in air. For the calcium gluconate monohydrate the transition from CaCO3 to CaO occurs above 650°C in air. It has been shown that the foaming of polyhydroxylcarboxylic acids is due to the formation of water vapour during degradation. For calcium gluconate monohydrate, foaming starts due to the loss of crystal water and is continued by the loss of hydroxyl groups as water. The bulk of the foaming is due to the second reaction. It has been shown that compounds with crystal waters produce a more voluminous and lower density foam. The foam is an amorphous carbon rich residue. The molecular mass of the carbon residue increases up to a heating temperature of 300°C. This implies that the carbon residue crosslinks during formation, forming a stretchable cell wall for the foam. Compounds with a .free. hydroxyl group at the end of the carbon chain produce a foam of larger volume and lower density. This supports the crosslinking theory. The foam produced when calcium gluconate monohydrate is heated for 5 min at 300°C in air is of very low density . 2.5 kg/m3 based on residual mass. The density of the calcium gluconate monohydrate pyrolysed at 1000°C for 5 min in air yields a CaO with a density of 20 kg/m3 . This implies that the high temperature pyrolysis of calcium gluconate can produce an inorganic oxide of low bulk density and possible high specific surface area. The BET surface area of CaCO3 from the gluconate pyrolysed at 600°C is ~ 12 m2 /g. An intumescent coating containing calcium gluconate monohydrate, leached silica and expandable graphite as a system was prepared and compared to commercial formulations. This gluconate based system was at least as efficient as the commercial formulations when painted on balsa wood planks or aluminium plates. On cardboard sheets it did not perform as well as the commercial systems. More work should be done to overcome the afterglow effect observed with metal- based intumescent systems. The crystal structure of calcium gluconate monohydrate should be determined as to understand the decomposition better. It is unclear whether the decomposition is catalysed inter- or intramolecularly.
Thesis (PhD(Chemical Engineering))--University of Pretoria, 2005.
Chemical Engineering
unrestricted

博士
國立臺北科技大學
工程科技研究所
101
This study focused on the flame retardancy of ethylene-vinyl acetate copolymer (EVA) and ethylene-propylene-diene terpolymer (EPDM) and in combination with metal hydroxide and nanoclay. Fire tests, such as limiting oxygen index (LOI), flammability (UL-94), cone calorimeter, and smoke density chamber were employed to evaluate the effect of composition variation for the metal hydroxide and the nanoclay in EVA composites and EPDM composites. The experimental results showed that when the nanoclay of 1wt% or 2wt% was substituted for aluminum hydroxide or magnesium hydroxide in EVA blends, the LOI value was significantly improved while the V-0 rating was maintained, and when the nanoclay of 2wt% or 3wt% was substituted for the aluminum hydroxide in EPDM blends, the LOI value was a little improved but while the V-0 rating was maintained. The data obtained from the cone calorimeter test indicated that the peak heat release rate (pk-HRR) of EVA/metal hydroxide composites was reduced by about 28% to 47%, and pk-HRR of EPDM/aluminum hydroxide composites was reduced by about 51% to 65%. The smoke density data (maximal smoke density, Dm) of EVA/metal hydroxide composites showed a reduction by about 16% to 25%. The Dm of EPDM/aluminum hydroxide composites was reduced by about 3% to 12%, The thermogravimetric analysis (TGA) data also showed that the nanoclay increased the thermal stability and char residue of the EVA and EPDM samples. Hence, it is suggested that the metal oxide layer on the burning surface is reinforced by the formation of silicate layer, which is both structured and compacted and acts as the insulation, and the newly formed layer responds to the synergistic effect of flame retardancy as well as smoke suppression observed in the EVA and EPDM blends. The strength of EPDM/ATH/nanoclay composite was 2.0 times higher than that of EPDM composite. The elongation at break of EPDM/ATH/nanoclay composite increased 4%-12% as compared with EPDM/ATH composite, EVA/metal hydroxide/nanoclay composite exhibited better tensile strength and elongation at break than the corresponding EVA/metal hydroxide composite, and 2 wt% of the nanoclay inside the composite would cause the maximum of mechanical properties.

This item is only available electronically.
Background: Burnout, a work-related psychological syndrome, is highly prevalent in medical trainees. Burnout is associated with deleterious outcomes for the individual practitioner; their colleagues, patients and workplace; and broader society. Designing burnout prevention and reduction interventions for this population is therefore critical. However, burnout research with medical trainees is characterised by different conceptualisations and operationalisations of this complex construct, producing inconsistent findings. Aims: To examine individual and work-related correlates of burnout, as defined by the Maslach Burnout Inventory, in medical trainees. Methods: Thirty-three studies, comprising a pooled sample of 7,229 trainees, were identified from a systematic search of the Embase, PsycInfo, Medline, ERIC and Cochrane Library databases. Study reporting quality was examined using the QualSyst tool and Pearson’s r correlations calculated, in addition to 95% confidence intervals, p-values, heterogeneity statistics and fail-safe Ns. These analyses used a random-effects model. Training level (intern, resident, registrar) and specialty (surgical, non-surgical) were examined as potential moderators. Results: Variables with the strongest relationships across burnout dimensions included poor mental health; conflict between individual and organisational values; low job reward; and high workloads. Subgroup analyses identified emotional intelligence, specialty satisfaction, and income satisfaction as significant correlates specifically for surgical registrars. Conclusions: Interventions targeting burnout in medical trainees should focus on a combination of individual (e.g. improving mental health) and work variables (e.g. reduced workload) for maximum benefits. Observed differences between surgical and non-surgical registrars require further examination, as they may compromise transferability of interventions.
Thesis (B.PsychSc(Hons)) -- University of Adelaide, School of Psychology, 2018

碩士
國立中興大學
環境工程學系所
94
Closed-microwave method is employed in this study for digesting soil samples, and four heavy metals (Cd, Cu, Pb, and Zn) are analyzed by flame atomic absorption spectrophotometry (FAAS). The purpose of the study is to investingate the feasibility of closed-microwave method instead of traditional aqua regia hotplate reflux method for heavy metal determination in soil. In this paper, Firstly, a contaminated farm soil taken Hemei, Zanhua was used to optimize the conditions of closed-microwave method. Secondly, three standard reference materials(CRM 2003、 CRM 141 and CRM 026-050)were analyzed to evaluate the accuracy of the method. Thirdly, fourteen real soil samples were used to test the applicability of this microwave method. Finally, results obtained by sequential extraction wre used to explain why different results occurred at different digestion temperature. The optimized conditions of closed-microwave digestion method are as follows: 0.5 g soil sample, settling for 1 hour after adding oxidizing reagent(4.6 mL aqua regia),a batch of sixteen digestion bottles, power of 600 W, microwave digestion at 112℃ for 10 min. Three standard reference soil samples were analyzed by microwave digestion combined with FAAS. The results show that for Cd the recovery is 104%-106%, the precision is 0.05%-2.42%; for Cu the recovery is 102%-103%, the precision is 0.05%-0.17%; for Pb the recovery is 100%-143%, the precision is 0.47%-2.14%; for Zn the recovery is 104%-108%, the precision is 1.44%-2.81%. Three standard reference materials were also digested at 180℃. The results illustrated higher recoveries and lower variation. According to the above outcomes, temperature of 112℃ is a better choice when the microwave-digestion is applied for soil digestion instead of traditional hotplate reflux method. Fourteen real soil samples were analyzed by microwave and traditional methods. The results had good agreement and the relative difference were within ±20%. Therefore, the microwave-assisted digestion method has proved to be a viable alternative to the traditional aqua regia reflux method for rapidly determining heavy metals in farmland soil samples. In addition, the results obtained by sequential l extractions were not able to explain why the results obtained with 112℃ digestion were different from that obtained with 180℃ digestion. In sum, using closed-microwave digestion method for heavy metal determination method in soil samples has the advantages including fewer amounts of sample used , less acid required and less time consumed. Thus, the method is of great applicability. In addition, the strong-acid exposure risk of facilities and workers can be decreased significantly because of closed-microwave system.

Metal ion contamination in surface and ground water is a major threat as it has a direct implication on the health of terrestrial and aquatic flora and fauna. Lead (Pb2+), mercury (Hg2+), cadmium (Cd2+), nickel (Ni2+), copper (Cu2+) and cobalt (Co2+) are few of these metal ions which are classified under the high risk category. Of these, lead and mercury are of greater concern, as even nanomolar concentrations can be lethal, as they can be bio-accumulated and result in physiological as well as neurological disorders. In Asian countries like India and China, heavy metal pollution is more prevalent, as a consequence of poor governmental policies or ineffective or inadequate measures to combat this problem. In recent times, the monitoring and assessment of water pollution is a critical area of study, as it has a direct implication for its prevention and control. The major techniques used for metal ion detection are atomic absorption spectroscopy (AAS), X-ray fluorescence, ion chromatography, neutron activation, etc. Alternatively, the electrochemical, optical and electrical methods provide a platform for the fabrication of portable devices, which can facilitate the on-site analysis of samples in a rapid and cost-effective manner. This has led to a new field of research called chemical sensors or chemo sensory devices. The main aim of this study is to develop various chemosensory materials and test their response towards metal ion sensing. In this study, electroactive polymers have been synthesized for various sensor applications. The focus has been to design synthesize and test various functionalized electroactive polymers (FEAP) for the development of electrochemical, optical and chemoresistive sensors. Electroactive polymers like polyaniline, polypyrrole, polypyrrole grafted to exfoliated graphite oxide and dipyrromethene conjugated with p-(phenylene vinylene) have been synthesized and evaluated after functionalizing with metal coordinating ligands. These metal coordinating ligands were selected, in order to enhance their metal uptake capacity. Various metal ligands like imidazole, tertiary amine group, iminodiacetic acid, and dipyrromethene incorporated either in the polymer backbone or as a part of the backbone have been chosen for the metal binding. These functionalized electroactive polymers (FEAP) served as active material for metal ion sensing. The present investigation is subdivided into three sections. The first part includes design and chemical synthesis of the functionalized polymers by a series of organic reactions. The synthesis has been followed up by characterization using spectroscopic methods including NMR, FTIR, GCMS and Mass spectrometry. In the second part of the investigation, the synthesized polymer has been characterized for the changes in electronic, electric and optical properties after interaction with the selected metal ions. For this, the FEAP is allowed to interact with various metal ions and the changes in the relevant properties have been measured. This includes the study of changes in the conductivity, electronic properties like absorption or emission of the polymer, changes in the redox properties, etc. The third phase of investigation deals with the fabrication of the devices using the active FEAP. The sensor devices comprised of either films, or electrode modified with FEAP or solution of the FEAP, in combination with an appropriate technique has been used for the sensing. The major objectives are enumerated below 1. Functionalzation of polyaniline with imidazole functional group to get imidazole functionalized polyaniline (IMPANI) and study of the electronic, electrical and optical properties of the same. 2. Preparation of films of IMPANI and study of the change in conductivity of the film upon interaction with various metal ions, namely Cu2+, Co2+ and Ni2+ in their chloride form. 3. Synthesis of amine functionalized aniline monomer and chemical graft polymerization onto exfoliated graphite oxide as a substrate to synthesise the amine funtionalised polyaniline grafted to exfoliated graphite oxide (EGAMPANI). Modification of the carbon paste electrode (CPE) with EGAMPANI and study of the electrode characteristic. 4. Study of the electrode properties of EGAMPANI modified carbon paste electrode. 5. Evaluation of the EGAMPANI modified carbon paste electrode as a multi-elemental voltammetric sensor for Pb2+, Hg2+ and Cd2+ in aqueous system. 6. Functionalization of polypyrrole with iminodiacetic acid and characterization of the polymer to synthesis iminodiacetic acid functionalized polypyrrole (IDA-PPy). 7. Modification of the CPE with IDA-PPy by drop casting method and evaluation of the Pb2+ sensing properties. 8. Study of the effect of other metal ions say Hg2+, Co2+, Ni2+, Zn2+, Cu2+ and Cd2+ on the anodic stripping current of Pb2+ using EGAMPANI modified CPE. 9. Synthesis of dipyrromethene-p-(phenylene vinylene) conjugated polymer for heavy metal ion sensing. 10. Study of the changes in the optical absorption and emission properties of the polymer in THF and evaluation of the change in these optical properties upon interaction with the metal ions as analyte. The salient findings of the research work are highlighted as follows, In the first synthesis, aniline has been functionalized with imidazole group and this monomer has been chemical oxidatively polymerized to obtain imidazole functionalized polyaniline (IMPANI). The synthesized polymer possesses a nano-spherical structure, as confirmed from the morphological characterisation using scanning electron microscopy. The IMPANI has been interacted with a representative metal ion, copper (II) chloride, and the copper complexed polymer (Cu-IMPANI) has been subjected to various studies. The coordination of copper with IMPANI results in an increase of molecular weight of the polymer as a result of aggregation, as observed from dynamic light scattering measurements. Apart from this, a significant finding is the decrease of the pH of the system after copper ion coordination attesting to the generation of a secondary hydrochloride ion during the coordination of the copper to the imidazole side chain. This is further confirmed by an increase in conductivity of the Cu-IMPANI compared to IMPANI, measured using the four-probe technique. The increase of conductivity due to copper coordination is one order of magnitude higher. The films which have been prepared from IMPANI and Cu-IMPANI exhibit different morphology. The Cu-IMPANI film prepared by prior co-ordination of Cu ion with IMPANI powder shows a flaky structure, which is not preferable for the conductivity measurements, as a consequence of discontinuity in the medium. To overcome this problem, IMPANI films were initially prepared and then interacted with copper ions for a desired duration, before measurement of the conductivity. This latter procedure enabled the preparation of smooth films for the development of chemoresistive sensors. In continuation of the initial study highlighted above, IMPANI films of thickness 0.02 ± 0.001 mm have been prepared using IMPANI and PANI in DMPU in the ratio of 7:3 by mass. After exposure of the films with respective metal chlorides, such as Ni2+, Co2+ and Cu2+, a change in conductivity is observed in the concentration range of 10-2 to 1 M of metal chlorides. The sensor response may be arranged in the sequence: Ni2+ > Cu2+ > Co2+ at 1M concentration. On the contrary, films prepared from PANI-EB under identical conditions do not exhibit any appreciable change in conductivity. The optimum exposure time is determined to be 10 min for a maximum change in conductivity, after exposure to the chosen metal ions. In the second system taken up for investigation, a tertiary amine containing polyaniline (AMPANI) has been grafted to exfoliated graphite oxide. The amine containing polyaniline grafted to exfoliated graphite oxide (EGAMPANI) has been characterised for structural, morphological and elemental composition. The grafting percentage has been determined to be 7 % by weight of AMPANI on the EGO surface. The synthesized EGAMPANI (5 weight %) has been used to modify carbon paste electrode (CPE) for electrochemical sensor studies. Based on the differential pulse anodic stripping voltammetric studies, the electrochemical response may be arranged in the following sequence: Pb 2+>Cd 2+>Hg 2+ The minimum detection levels obtained are 5×10-6, 5×10-7, and 1.0×10-7 M for Hg2+, Cd2+ and Pb2+ ions respectively. In the next study, an iminodiacetic acid functionalized polypyrrole (IDA-PPy) has been synthesized and characterised for its elemental and structural properties. This has been further used to modify the CPE by drop casting method and used for the specific detection of Pb2+ in acetate buffer. Various parameters governing the electrode performance such as concentration of depositing solution, pH of depositing solution, deposition potential, deposition time, and scan rate, have been optimized to achieve maximum performance and found to be 20 μl, 4.5, -1.3 V, 11 min, 8 mV s-1 respectively for the chosen parameters. Additionally, the influence of other heavy metal ions on the lead response has been studied and it is observed that Co, Cu and Cd ions are found to be interfering. Further, the response of Cd, Co, Cu, Hg, Ni and Zn on IDA-PPy functionalized electrode has been evaluated. The selectivity of IDA-PPy modified electrode for Pb2+ is observed in the concentration range of 1 × 10-7 M and below. The IDA-PPy modified CPE shows a linear correlation for Pb2+ concentration in the range from 1×10-6 to 5×10-9 M and with a lowest limit of detection (LLOD) of 9.6×10-9 M concentration. The efficacy of the electrode for lead sensing has also been evaluated with an industrial effluent sample obtained from a lead battery manufacturing unit. The fourth synthesis pertained to the development of an optical sensor for Fe2+, and Co2+ ions. For this, dipyrromethene as a metal coordinating ligand in conjugation with p-phenylenevinylene has been synthesized and tested for its structural as well as optical properties. It is observed that the polymer shows three absorptions, namely at 294 nm, 357 nm and a major absorption observed as a broad band ranging from 484 to 670 nm. The emission spectrum of the polymer excited at 357 nm shows a characteristic blue emission with a maximum intensity centered at 425 nm. The emission quenching in the presence of various metal ions have been tested and are found to be quenched in presence of Fe2+ and Co2+ ions. All the other metal ions tested namely, Cr3+, Cu2+, and Zn2+ are not found to exhibit any change in the emission spectra below the concentration of 1 × 10-4 M. The linear correlation of the emission intensity with the concentration of the Co2+ and Fe2+ ions has been determined using Stern-Volmer plot. For Co2+ the Stern-Volmer regime is observed from 1×10-4 to 9×10-4 M concentration and the quenching constant Ksv is determined to be 8.67 ×103 M-1. For Fe2+, the linearity is found to be in the regime of 1×10-5 to 9×10-5 M and the quenching constant Ksv is determined to be 7.90 × 103 M-1. In conclusion, different electroactive polymers functionalized with metal coordinating ligands have been synthesized, characterised and evaluated for metal sensing applications. Techniques like electrochemical, optical and conductivity have been used to characterise the response of these FEAP towards metal sensing. It is can be concluded that the electrochemical sensors are more reliable for sensing especially at very low concentrations of metal ions such as Pb, Cd and other techniques like optical and conductimetric are good for detecting metal ions namely Fe, Co, Ni, Cu. The selectivity towards the metal ions is a function of the metal chelating ligand and the extent of sensitivity is dependent upon the technique employed.