No description available.

<P> A new preconcentration method had been developed for the determination of some trace-metal ions in lakewater. This method is based on the formation of their TPPS4 complexes at elevated temperatures in solution and adsorption of the complexes onto a column of the macroporous acrylic ester resin, XAD-7. The complexes are eluted with a methanolic solution and the metal concentration determined by graphitefurnace atomic absorption spectroscopy. Optimal conditions were established for the group preconcentration of Cd, Cu, Ni and Pb. The concentration of these trace metals in several lakewater samples were determined successfully, with a precision comparable to that of the accepted Chelex-100 method. Application of the method to natural seawater samples failed, largely because of aggregation in the highly saline medium. </p> <P> Adsorption isotherms of TPPS4 and its complexes on XAD resins were obtained. Adsorption onto XAD-2 and XAD-4 resins likely involves n-n interactions while adsorption onto XAD-7 is probably due to weak Van der Waals forces. The adsorption at high TPPS4 concentrations is complicated by aggregation. </p> <P> An attempt to create a simple chelating ion-exchange resin by adsorption of TPPS4 onto XAD resin failed. Similarly, the development of a rapid room-temperature preconcentration method specifically for Pb and Cd in natural waters was not successful. </p> / Thesis / Master of Science (MSc)

Esta tese descreve o desenvolvimento de metodologias eletroanalíticas, em especial a voltametria de onda quadrada com o eletrodo de gota pendente de Hg, para determinação de atrazina em águas de rios do Estados de São Paulo e em amostras de solo. A exatidão das metodologias foi avaliada por comparação com HPLC e estudos de recuperação. Inicialmente desenvolveu-se o método em modo estático, no qual a maior sensibilidade foi obtida em pH 2 e freqüência de 400 Hz, com limites de detecção e determinação de 2 e 10 microgramas L-1, respectivamente. O estudo do comportamento eletroquímico revelou que a atrazina comporta-se reversivelmente em altas freqüências de onda quadrada. Dentre os metabólitos da atrazina, a desetilatrazina e desiosopropilatrazina, também são eletroativas nas condições estudadas, sendo possíveis interferentes, ao contrário da hidroxiatrazina e didealquilatrazina. Sistemas em fluxo contínuo e de injeção seqüencial foram desenvolvidos para determinação de atrazina em extrato de solo e águas naturais, bem como em estudos de adsorção. Em águas, os limites de detecção e determinação obtidos por injeção seqüencial foram de 4,5 e 15 microgramas L-1. Estudos de adsorção revelaram que atrazina liga-se mais fortemente a solos em meios ácidos. As metodologias em fluxo permitiram um significativo aumento da velocidade analítica e economia de reagentes, automatizando as determinações. / This thesis describes the development of electroanalytical methodologies, especially the square wave voltammetry with the hanging mercury drop electrode, for determination of the herbicide atrazine in river waters of the São Paulo state and soil samples. The accuracy of the methodologies was evaluated by comparison with HPLC and recovery studies. Initially, a stationary method was developed, in which the highest sensitivity was attained at pH 2 and at frequency of 400 Hz, with detection and quantification limits of 2 and 10 micrograms L-1, respectively. The electrochemical behavior of atrazine was reversible at the higher square wave frequencies. Among the atrazine metabolites, deethylatrazine and deisopropylatrazine are also electroactive under the studied conditions, being possible interferences, contrary to hydroxyatrazine and didealkylatrazine. Continuous flow and sequential injection systems were developed for determination of atrazine in soil extracts and natural waters, as well as in adsorption studies. In waters, the detection and quantification limits attained by sequential injection were 4.5 and 15 micrograms L-1. Adsorption studies showed that atrazine binds more strongly to soil in acidic media. The flow analysis methodologies lead to significant increase in the sampling throughput and reagent saving, automating the determinations.

Natural organic matter (NOM), ubiquitous in natural water sources, is generated by biogeochemical processes in both the water body and in the surrounding watershed, as well as from the contribution of organic compounds that enter the water as a result of human activity. NOM significantly affects the properties of the water source, including the ability to transport metals, influence the aggregation kinetics of colloidal particles, serve as a food source for microorganisms and act as a precursor in the formation of disinfection by-products (DBPs), as well as imparting a brown colour to the water. The reactivity of NOM is closely tied to its physicochemical properties, such as aromaticity, elemental composition, functional group content and molecular weight (MW) distribution. The MW distribution is an important consideration from a water treatment perspective for several reasons. For example, low MW NOM decreases the efficiency of treatment with activated carbon, and this fraction is thought to be the portion most difficult to remove using coagulation. The efficiency of membranes in the treatment of drinking water is also influenced by the MW distribution of NOM, while some studies have shown that the low MW fraction contributes disproportionately to the formation of bioavailable organic matter, therefore promoting the formation of biofilms in the distribution system. For these reasons, understanding the MW distribution of NOM is important for the treatment of natural waters for use as drinking waters. Optimisation of a high pressure size exclusion chromatography (HPSEC) method for analysis of the MW distribution of NOM in natural waters is described (Chapter 2). Several parameters influencing the performance of HPSEC are tested and an optimised set of conditions illustrated. / These parameters included eluent composition, ionic strength of the sample, flow rate and injection volume. Firstly, it was found that increasing the ionic strength of the HPSEC eluent resulted in less exclusion of NOM from the stationary phase. Stationary phases used in HPSEC contain a residual negative charge that can repel the negatively charged regions of NOM, effectively reducing the accessible pore volume. By increasing the ionic strength, interactions between the stationary phase and eluent enabled a larger effective pore size for the NOM analytes. However, increasing ionic strength of the eluent also resulted in a loss of peak resolution for the NOM portion able to access the pore volume of the stationary phase. Determining the ideal eluent composition required the balancing of these two outcomes. Matching of the ionic strength of the sample with the eluent was also an important consideration. Retention times were slightly lower when the sample ionic strength was not matched with the eluent, especially for the lowest MW material, although the effect on chromatography was minimal. Flow rate had no effect on the resolution of the HPSEC chromatogram for the portion of material able to permeate the pore space of the stationary phase. Changes in the volume of sample injected had a marked effect on the elution profile of the NOM sample. Besides the obvious limitation of detection limit, only minor changes in elution profile were obtained up to an injection volume of 100 µL. Volumes above this value, however, resulted in significant peak broadening issues, as well as an undesirable effect on the low MW portion of detected DOC. / In Chapter 3, high pressure size exclusion chromatography with UV254 [subscript] and on-line detection of organic carbon (HPSEC-UV254[subscript]-OCD) was used to compare the removal of different apparent MW fractions of DOC by two process streams operating in parallel at the local Wanneroo groundwater treatment plant (GWTP). One of these two process streams included alum coagulation (operating in an enhanced coagulation mode (EC) for increased DOC removal) and the other stream included a magnetic ion exchange (MIEX®) process followed by alum coagulation (MIEX®-C). The MIEX® process is based on a micro-sized, macroporous, strong base anion exchange resin with magnetic properties, which has been designed to remove NOM through ion exchange of the anionic sites in NOM. Water was sampled from five key locations within these process streams, and the DOC at each location was characterised in terms of its MW distribution. HPSEC was carried out using three different on-line detector systems, namely OCD, UV absorbance detection at 254 nm, and fluorescence detection (λex[subscript]= 282 nm; λim[subscript] = 353 nm). This approach provided significant information on the chemical nature of the DOC in the various MW fractions. The MIEX®-C process was found to outperform the EC process: these two processes removed similar amounts of high and low MW DOC, but the MIEX®-C process showed greater removal of DOC from the intermediate MW fractions. The two coagulation processes (EC and coagulation following MIEX®) showed good removal of the fractions of highest MW, while the MIEX® process alone was found to remove DOC across all MW fractions. / These results seem to indicate that anionic groups, particularly susceptible to removal with MIEX® treatment, are well distributed across all MW fractions of NOM. In agreement with previous studies, MIEX®-C outperformed EC in the overall removal of DOC (MIEX®-C removed 25 % more DOC than EC). However, 70% of the additional DOC removed by MIEX®-C was comprised of a surprisingly narrow range of medium-high MW fractions. The development of a novel online organic carbon detector (OCD) for use with HPSEC for determining the MW distribution of NOM is described in Chapter 4. With UV absorbance detection, the magnitude of the signal is based on the extinction coefficient of the chromophores in the analytes being investigated; whereas the signal from an OCD is proportional to the actual organic carbon concentrations, providing significantly more information. The development of an online OCD involved the separation of analytes using HPSEC, removal of inorganic carbon species which may interfere with organic carbon determination, oxidation of the organic carbon to carbon dioxide, separation of the produced carbon dioxide from the aqueous phase and subsequent detection of the gaseous carbon dioxide. In the new instrument, following separation of components by HPSEC, the sample stream was acidified with orthophosphoric acid to a concentration of 20 mmol L-1[superscript], resulting in a pH of ≤ 2, in order to convert inorganic carbon to carbon dioxide. This acid dose was found to remove greater than 99 % of inorganic carbon once the acidified sample was passed through a hydrophobic polytetrafluoroethylene (PTFE) membrane allowing the passage of dissolved gases (under negative pressure from a vacuum pump) but restricting the flow of the mobile phase. / Several factors influenced the oxidation of the organic carbon in the next step, including the dose of persulfate, the type and intensity of UV radiation and the composition of the capillary through which the sample stream passes. Through optimisation of this process, it was found that a persulfate dose of 0.84 mmol L-1[superscript] in the sample stream was required for optimum oxidation efficiency. A medium pressure UV lamp was compared to a vacuum UV lamp for its efficiency in oxidation of organic carbon to carbon dioxide. While the medium pressure lamp produced a far smaller percentage of its total radiation at the optimum wavelength for oxidation of organic compounds, the greater overall intensity of the medium pressure lamp was shown to be superior for this application. The composition of the capillary was shown to have a considerable effect on the oxidation efficiency. A quartz capillary, internal diameter 0.6 mm, was compared with a PTFE capillary, internal diameter 0.5 mm, for the oxidation of organic carbon by external UV treatment. While peak width, an important consideration in chromatographic resolution, was greater for the larger internal diameter quartz capillary, the lower UV transparency of PTFE combined with the shorter contact time, due to the reduced internal diameter of the capillary, resulted in a less efficient oxidation step using the PTFE capillary. The quartz capillary was therefore chosen for use in the UV/persulfate oxidation step for oxidation of organic carbon to carbon dioxide. Separation of the produced carbon dioxide from the sample stream was achieved by sparging with nitrogen and contacting the gas/liquid mixture with a hydrophobic PTFE membrane, restricting the passage of the liquid while allowing the nitrogen and carbon dioxide gases to pass to the detection system. / The only factor influencing this separation was the flow of the nitrogen sparge gas, with a flow of 2 mL min-1[superscript] found to be optimum. Detection of produced carbon dioxide was via a Fourier transform infrared (FTIR) spectrometer with a Iightpipe accessory. The Iightpipe accessory was designed for use as a detector for gas chromatography and the small size of the detector cell was ideal for use with this application. Using the new system described, concentrations of a single peak could be determined with a detection limit of 31 ng and a determination limit of 68 ng. The development of the new OCD allowed characterisation of NOM in terms of its MW distribution and the UV and fluorescence spectral properties of each MW fraction. Further characterisation of MW fractions of NOM from a local groundwater bore was carried out by separation of the fractions by preparative HPSEC, followed by off-line analysis. Preparative HPSEC involved the injection of a pre-concentrated groundwater sample multiple times, using a large scale HPSEC column, then collecting and combining material of identical MW. This allowed each MW fraction of the sample to be further characterised as described in Chapter 5. Preparative HPSEC has only previously been applied to a small number of samples for the concentration and fractionation of NOM, where the structural features of the various MW fractions were studied. In the current research, more extensive studies of not only the chemical characteristics, but also the disinfection behaviour, of the MW fractions were conducted. Separation of the sample was conducted on a large diameter silica-based HPSEC column, with fraction collection based on semi-resolved peaks of the HPSEC chromatogram. Nine MW fractions were collected by this method. / After concentration and dialysis to remove the buffer salts in the HPSEC mobile phase, each fraction was re-analysed by analytical HPSEC-UV254[subscript] and showed a single Gaussian shaped peak, indicating discrete MW fractions had successfully been collected. Analysis of the collected MW fractions indicated that 57 % of the organic carbon was in Fractions 3 and 4, with 41 % in Fractions 5-9, leaving only 2 % in Fractions 1 (highest MW) and 2. For each of the nine MW fractions, chorine demand and 7 day trihalomethane formation potential (THMFP) were measured on dilute solutions of the same DOC concentration, and solid state 13[superscript]C NMR spectra were recorded on some of the solid isolates obtained after Iyophilisation of the separate or combined dialysis retentates. The larger MW Fractions 3 and 4 were found to contain a greater proportion of aromatic and carbonyl carbon, and the lower MW Fractions 5 and 6 and Fractions 7-9 contained greater proportions of aliphatic and O-aliphatic carbon, by this technique. Chlorine demand experiments on each individual fraction with a normalised DOC concentration indicated that the largest MW fraction (Fraction 1) had the lowest chlorine demand. It was concluded that material in this fraction may be associated with inorganic colloids and unavailable for reaction with chlorine. Fraction 3 had the highest chlorine demand, just over two times more than the next highest chlorine demand (Fraction 4) and approximately three times the chlorine demand of Fraction 2. The organic material in Fraction 2 was postulated to contain a mixture of the reactive material present in Fraction 3 and the colloidal associated material present in Fraction 1. / NMR analysis indicated that the difference between Fraction 3 and Fraction 4 was a reduction in reactive aromatic carbon and hence the lower chlorine demand in the latter fraction. Fractions 5-8 had similar chlorine demands, lower than Fraction 4, while Fraction 9 had a very low chlorine demand similar to that of Fraction 1. For Fractions 5-9, the lower aromatic carbon content most likely resulted in the lower chlorine demand. The 7 day THMFP experiments showed some clear trends, with Fraction 1 and Fraction 2 producing the least amounts of THMs but having the greatest incorporation of bromine. Fractions 3 and 4 produced the greatest concentration of THMs with the lowest bromine incorporation, perhaps as they contained fast reacting THM precursors and the higher chlorine concentrations resulted in greater amounts of chlorinated THMs. Fraction 5 and Fraction 6 produced similar levels of THMs over 7 days to Fractions 7-9 (approximately 75% of the amount formed by Fractions 3 and 4), however, Fractions 7-9 formed these THMs more quickly than Fractions 5 and 6, with slightly greater amounts of bromine incorporation. It was thought that the increased speed of formation was due to the smaller MW of these fractions and a simpler reaction pathway from starting material to formation of THMs, as well as some structural differences. This research marks the first report of significantly resolved MW fractions being isolated and their behaviour in the presence of a disinfectant being determined. While the high MW fractions had the greatest chlorine demands and THMFPs, these fractions are also the easiest to remove during coagulation water treatment processes, as shown in Chapter 3. The lowest MW material formed significant amounts of THMs, and also formed THMs more quickly than other MW fractions. / This has important implications from a water treatment perspective, as the lowest MW material is also the most difficult to remove during conventional treatment processes. Solid samples of NOM were isolated from water samples taken from four points at the Wanneroo GWTP using ultrafiltration and subsequent Iyophilisation of the retained fractions, as described in Chapter 6. The sampling points were following aeration (Raw), following treatment by MIEX®, following treatment by MIEX®-C and following treatment by EC. Elemental analysis, FTIR spectroscopy, solid state 13[superscript]C NMR spectroscopy and HPSEC-UV254[subscript]-0CD analysis were used to compare the four isolates. Treatment with MIEX®-C was found to remove the greatest amount of NOM. Additionally, treatment with MIEX®-C was able to remove the largest MW range of NOM, with the remaining material being depleted in aromatic species and having a greater proportion of aliphatic and O-aliphatic carbon. EC treatment completely removed the NOM components above 5000 Da, but NOM below this was not well removed. NOM remaining after the EC train had a lower aromatic content and more aliphatic oxygenated organic matter than the RW. The remaining organic matter after MIEX® treatment contained less aromatic material compared to the RW, but had a greater aromatic content than either of the EC or MIEX®-C samples. HPSEC was a significant analytical technique used throughout this research. Initial optimisation of an HPSEC method was an important development which allowed improved resolution of various MW fractions. The application of this technique and comparison of three detection systems for the study of DOC removal showed, for the first time, the performance of MIEX® treatment at a full scale groundwater treatment facility. / The use of various HPSEC detection systems allowed significant characterisation of the MW fractions, more information than had previously been gathered from such a sample set. This work demonstrated the need for OCD when applying HPSEC to the study of NOM. As such, a system was constructed that built on previously developed systems, with the use of a small detector cell enabling detection limits capable of measuring even the most dilute natural and treated water samples. To study the individual MW fractions in detail, preparative HPSEC was applied and, for the first time, the disinfection behaviour of various MW fractions was examined. Interestingly, the lowest MW fractions, acknowledged to be the most recalcitrant to conventional water treatment processes, produced significant quantities of THMs. Also the formation kinetics of THMs from the low MW fractions indicated that THMs were formed as quickly as, or perhaps even at faster rates than from the larger MW fractions. Finally, structural characterisation of NOM at four stages of the Wanneroo GWTP indicated MIEX®-C treatment was superior to EC, of significant interest for the water industry.

Orientador: Wilson de Figueiredo Jardim / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Quimica / Made available in DSpace on 2018-08-13T19:05:41Z (GMT). No. of bitstreams: 1 Guedes_NiveaCristinadeCarvalho_D.pdf: 4953955 bytes, checksum: 1152bc5a0e4999e2d110490ec6abbb2c (MD5) Previous issue date: 2009 / Resumo: Um protocolo para avaliar o mercúrio potencialmente tóxico em águas naturais foi proposto de acordo com as seguintes etapas: (i) investigação de um redutor seletivo para espécies de mercúrio potencialmente tóxicas presentes em sistemas aquáticos; (ii) otimização do método; (iii) calibração experimental do método realizada com soluções contendo 50 mg L de Hg e diferentes ligantes em diferentes razões metal:ligante, utilizando-se ácido húmico (AH), cisteina (Cys), histidina (Hys) e ácido nitrilotriacético (NTA); (iv) aplicação do método em amostras de águas naturais, provenientes de sistemas aquáticos distintos (naturais e impactados), enriquecidas com diferentes concentrações de Hg (5, 10, 25 e 50 mg L), baseado na titulação das amostras de águas com concentrações conhecidas de Hg, seguida da determinação do metal pela técnica proposta; (v) para inferir o potencial tóxico do Hg determinado a partir do metodo proposto, a relação entre os resultados analíticos e respostas dos testes de toxicidade aguda com a bactéria Escherichia coli e o microcrustaceo Daphnia similis foram avaliados. Foi utilizado um espectrofotômetro de absorção atômica do vapor frio acoplado a um sistema FIA com amostragem discreta (o reagente é adicionado na amostra e não em fluxo). Os resultados mostraram que a utilização do ácido ascórbico (AA) como redutor do Hg (HgAA), em proporções definidas em relação a quantidade da amostra, em pH 6,4 ± 0,1 (tampão fosfato), com detecção após 60 ± 10 min, apresentou LQ = 0,5 mg L, desvio padrão relativo (n= 6) em 50 mg L de Hg de 4%, para uma faixa de trabalho de 0,5 - 60,0 mg L e fator de linearidade da curva de 97,3%. Os valores de HgAA determinados nas soluções com os ligantes foram diretamente influenciados pela natureza e pela proporcao molar dos complexos formados, sendo Cys > Hys > AH > NTA. Nas amostras de águas naturais o HgAA apresentou relação direta com o material particulado e carbono orgânico total e inorgânico. Uma significativa correlação foi determinada entre os resultados analíticos e a resposta bacteriana (ANOVA, teste F95%), sendo, r = 0,97 para as soluções com os ligantes e r = 0,94 para as amostras naturais. A correlação com os resultados da D. similis nas amostras naturais em relação ao HgAA obtido, foi r = 0,65, essa correlação não foi significativa pelo teste F95%, mas pode ser considerada expressiva visto o diferente mecanismo de interação deste organismo aquático e o Hg. Considerando que o método apresentou sensibilidade na faixa de trabalho, repetibilidade analítica e significativa correlação com os resultados biológicos, essa nova proposta de determinação de Hg pode ser útil para gerar informações relacionadas com a toxicidade aguda do Hg em águas naturais / Abstract: A protocol for the assessment of potentially toxic mercury in natural waters has been developed in accordance to the following stages: (i) research for a selective reductant of potentially toxic mercury species present in natural water samples; (ii) method optimization; (iii) experimental calibration carried out with solutions containing 50 mg L of Hg and different organic ligands at different ratios metal:ligand, including humic acid (HA), cysteine (Cys), histidine (Hys) and nitrilotriacetic acid (NTA); (iv) method application in samples from distinct aquatic ecosystems (natural and impacted) were carried out using different concentrations of Hg (5, 10, 25 e 50 mg L) based on titration of water samples with known Hg concentrations and followed by the metal determination using the purposed method; (v) to infer the Hg toxic potential determined with the proposed method, the relationship between analytical results and acute toxicity test with the bacterium Escherichia coli and the microcrustacean Daphnia similis was evaluated. A cold vapor atomic absorption spectrophotometer coupled to flow injection (FIA) system with stop-flow sampling was used. The results showed that the use of ascorbic acid (AA) as a reductant (HgAA), in specifc ratios sample:reductant, at pH 6.4 ± 0.1 (phosphates buffer), with detection after 60 ± 10 min, presented a limit of quantification (LOQ) of 0.5 mg L, with a relative standard deviation (n=6) at 50 mg L of Hg of 4%, linear range of 0.5 ¿ 60.0 mg L and linearity factor of 97.3%. The values of HgAA determinated in the presence of ligands were directly dependent with the ligand nature and concentration, being Cys > Hys > HA > NTA. In natural water samples, HgAA was directly related to particulate matter, total organic and inorganic carbon. A significant correlation (ANOVA, F95% test) was observed between analytical results and bacteria response, being r = 0.97 for the synthetic solutions with ligands and r = 0.94 for natural samples. The correlation with Daphnia results and HgAA in natural samples was r = 0.65, not significance at F95%, but it can be expressive, once accepted the different mechanisms of interaction of this aquatic organism. Considering that the method has adequate sensitivity, analytical repeatability and significant correlation with biological results, this new protocol for the determination of Hg can be useful in generating information concerning the Hg acute toxicity in natural water / Doutorado / Quimica Analitica / Doutor em Ciencias Quimicas

Esta tese descreve o desenvolvimento de metodologias eletroanalíticas, em especial a voltametria de onda quadrada com o eletrodo de gota pendente de Hg, para determinação de atrazina em águas de rios do Estados de São Paulo e em amostras de solo. A exatidão das metodologias foi avaliada por comparação com HPLC e estudos de recuperação. Inicialmente desenvolveu-se o método em modo estático, no qual a maior sensibilidade foi obtida em pH 2 e freqüência de 400 Hz, com limites de detecção e determinação de 2 e 10 microgramas L-1, respectivamente. O estudo do comportamento eletroquímico revelou que a atrazina comporta-se reversivelmente em altas freqüências de onda quadrada. Dentre os metabólitos da atrazina, a desetilatrazina e desiosopropilatrazina, também são eletroativas nas condições estudadas, sendo possíveis interferentes, ao contrário da hidroxiatrazina e didealquilatrazina. Sistemas em fluxo contínuo e de injeção seqüencial foram desenvolvidos para determinação de atrazina em extrato de solo e águas naturais, bem como em estudos de adsorção. Em águas, os limites de detecção e determinação obtidos por injeção seqüencial foram de 4,5 e 15 microgramas L-1. Estudos de adsorção revelaram que atrazina liga-se mais fortemente a solos em meios ácidos. As metodologias em fluxo permitiram um significativo aumento da velocidade analítica e economia de reagentes, automatizando as determinações. / This thesis describes the development of electroanalytical methodologies, especially the square wave voltammetry with the hanging mercury drop electrode, for determination of the herbicide atrazine in river waters of the São Paulo state and soil samples. The accuracy of the methodologies was evaluated by comparison with HPLC and recovery studies. Initially, a stationary method was developed, in which the highest sensitivity was attained at pH 2 and at frequency of 400 Hz, with detection and quantification limits of 2 and 10 micrograms L-1, respectively. The electrochemical behavior of atrazine was reversible at the higher square wave frequencies. Among the atrazine metabolites, deethylatrazine and deisopropylatrazine are also electroactive under the studied conditions, being possible interferences, contrary to hydroxyatrazine and didealkylatrazine. Continuous flow and sequential injection systems were developed for determination of atrazine in soil extracts and natural waters, as well as in adsorption studies. In waters, the detection and quantification limits attained by sequential injection were 4.5 and 15 micrograms L-1. Adsorption studies showed that atrazine binds more strongly to soil in acidic media. The flow analysis methodologies lead to significant increase in the sampling throughput and reagent saving, automating the determinations.

Made available in DSpace on 2016-08-19T12:56:44Z (GMT). No. of bitstreams: 1 Dissertacao Karla.pdf: 1858742 bytes, checksum: 343bcd38edd54804af6d544de85e856d (MD5) Previous issue date: 2013-04-05 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Fluoroquinolone antibacterial agents are widely used for treatment of infectious diseases. These compounds and their metabolites are excreted through the urinary tract, reaching the environment and cause many health hazards, human and animal, besides providing bacterial resistance. Given this, it was carried out an optimization of a chromatographic method for determination of three fluoroquinolone antibiotics (CIPRO, LEVO and NORF) by HPLC/FL in waters of Anil River at São Luís City-MA. For this, the chromatographic parameters were optimized and the linear range was obtained by constructing analytical curves and subsequently calibration curves for each analyte. The most satisfactory chromatographic conditions for analysis were: Luna column (250 x 4.6 mm, 5 mm), mobile phase consisting of a mixture of Methanol/Buffer (0,04 M NaHPO4.H₂O adjusted to pH 3 with H3PO4 85%) in proportion 30/70 (v/v), isocratic mode, flow 1 mL.minˉ¹, monitored at wavelengths of 278 nm and emission 450 nm excitation. The LD of the method for compounds CIPRO, LEVO and NORF were 1,8199, 4,0967 and 0,7567 μg.Lˉ¹ respectively and LQ of the method was 5 μg.Lˉ¹ for all three analytes. The studies of recovery by SPE showed levels from 77,95 to 100,28% for all three analytes. Subsequently the methodology was applied in water samples from the Anil River, being detected none of the analytes under study. Were performed acute toxicity tests with the test organism C. silvestrii, with EC(I)50,48h average of 0,4656 mg.Lˉ¹ for CIPRO and 0,6788 mg.Lˉ¹ for LEVO. / Os antibacterianos fluoroquinolônicos são amplamente utilizados para tratamentos de doenças infecciosas. Estes compostos e seus metabólitos são excretados pelas vias urinárias, podendo alcançar o ambiente e causar diversos danos à saúde, humana e animal, além de proporcionar resistência bacteriana. Diante disto, realizou-se a otimização de um método cromatográfico para determinação de três antibacterianos fluoroquinolônicos (CIPRO, LEVO e NORF) via CLAE/FL em águas do Rio Anil da cidade de São Luís-MA. Para isto, otimizou-se os parâmetros cromatográficos e verificou-se a faixa linear através da construção de curvas analíticas e posteriormente de curvas de calibração para cada um dos analitos. As condições cromatográficas que se mostraram mais satisfatórios para análise foram: coluna Luna (250 x 4,6 mm, 5 μm), fase móvel composta por uma mistura de Metanol/tampão fosfato (NaHPO.H₂O 0,04 M ajustado á pH 3 com H3PO4 85%), na proporção 30/70 (v/v), modo isocrático, fluxo de 1 mL.minˉ¹, monitorado a com comprimentos de onda de 278 nm de emissão e 450 nm de excitação. Os LD do método para os compostos CIPRO, LEVO e NORF foram de 1,8199, 4,0967 e 0,7567 μg.Lˉ¹, respectivamente e o LQ do método foi de 5 μg.Lˉ¹ para todos os três analitos. Os estudos de recuperação por EFS apresentaram níveis de recuperação entre 77,95 a 100,28% para os três analitos. Posteriormente a metodologia foi aplicada em amostras de água do Rio Anil, não sendo detectado nenhum dos analitos em estudo. Foram realizados ensaios de toxicidade aguda com o organismo teste C. silvestrii, apresentando CE(I)50,48h médio de 0,4656 mg.Lˉ¹ para o CIPRO e de 0,6788 mg.Lˉ¹ para o LEVO.

M. Tech. (Chemical Engineering, Faculty of Engineering and Technology), Vaal University of Technology| / The co-existence of organic acids and toxic heavy metals in natural water creates harmful effects on human, plants and animals. Therefore, it is necessary to treat organic acids and toxic heavy metal contaminated wastewater prior to its discharge to the environment. The aim of this study was to apply co-treatment of industrial wastewater containing citric acid and toxic heavy metals in single and binary systems using photocatalysis process. The hydrothermal method was used to synthesise dandelion-like TiO2 structures. Modifications of the dandelion-like TiO2 by deposition of gold nanoparticles and immobilisation on calcium alginate were done using deposition precipitation and one-step encapsulation methods, respectively. Dandelion-like TiO2 and dandelion-like TiO2 immobilised on calcium alginate (Alg/TiO2) were used as photocatalysts for Cr(VI), Hg(II) and citric acid removal from water. The results showed that the production of dandelion-like TiO2 structures strongly depends on the reaction time and synthesis temperature as key process parameters. The characterisation of the dandelion-like TiO2 by X-ray diffraction (XRD), transmission electron microscope (TEM), scanning electron microscopy (SEM), energy-dispersive X-ray (EDX) and Brunauer-Emmett-Teller (BET) revealed the crystal structure, morphology, chemical composition and surface area. It was found that the efficiency of photocatalytic process depends on the type of pollutants, initial pH of the solution, photocatalyst dosage, contact time, substrate initial concentration, UV wavelength and light intensity. The reduction efficiency of Cr(VI) ion and citric acid increased with decreasing the initial pH values and initial concentration. On the other hand, Hg(II) reduction efficiency increased with increasing the initial pH values and initial concentration. In a binary system, the reduction of Cr(VI) and Hg(II) was found to be faster than in the single and ternary systems. The relationship of the chemical reaction rate of Cr(VI), Hg(II) and citric acid were expressed by the pseudo-first-order kinetic equation. Addition of ferric ions to Cr(VI)-citric acid complex and Hg(II)-citric acid complex enhanced the reduction of Cr(VI) and Hg(II), a complete reduction was accomplished within 30 and 60 minutes (min) of irradiation time, respectively. The reduction efficiency of both Cr(VI) and Hg(II) in the presence of citric acid in a solution was still significant after four times of Alg/TiO2 reuse. These results indicated that the UV/TiO2 photocatalysis process can be considered as a suitable method to reach a complete reduction of Cr(VI) and Hg(II) in the presence of citric acid in a solution.

Solid-phase microextraction (SPME) coupled with gas chromatography/mass spectrometry (GC/MS) is routinely used to analyze polycyclic aromatic hydrocarbons (PAHs) in water. A common SPME-GC/MS approach quantifies target analytes using isotopically labeled standards (IISs); one IIS is needed for each target analyte. This approach is challenging, even prohibitive since IISs are often expensive; moreover, they are generally not available for each analyte of interest. This study developed a novel SPME-GC/MS approach for the quantification of PAHs in water. The new method, which employs only a small number of IISs, uses relative response factor (RRF) (i.e., analyte corresponding to IIS) to quantify PAHs in water. Possible matrix dependency of RRFs values was examined using water that was modified concerning different physical-chemical characteristics (i.e., ionic strength, pH, suspended solids, humic acid, and biological organic carbon represented by hemoglobin). The results revealed that RRFs are not noticeably affected by changing ionic strength and pH; the other three parameters did affect the RRFs. However, the results also showed that the effect is minimal when the solution is dilute (i.e., low concentrations of suspended solids, humic acid or hemoglobin). Relatively stable RRFs for dilute water solutions indicates that this approach can be used for routine quantification of water that does not contain prohibitive amounts of suspended solids, humic acid, and biological organic matter. The developed method was employed to quantify trace levels of PAHs in three different types of water, namely river water, well water, and bottled water. PAH levels in every kind of water were less than 100 ng/L level (i.e., 0.1 ppb). Analyses of spiked water samples containing 2 ng PAHs revealed correlations between calculated RRFs and the physical-chemical properties of the PAHs investigated (i.e., vapor pressure, boiling point, octanol/water partition coefficient, octanol/air partition coefficient, GC retention time). This implies that RRFs for PAHs not examined in this study can be predicted. Overall, the results presented herein constitute a meaningful contribution to the development of SPME-GC/MS methods for quantitative analysis of PAHs and other chemicals in dilute aqueous solutions. Moreover, the development of methods that alleviate the need for IISs corresponding to each target analyte.

O presente trabalho versa sobre a gestão dos recursos hídricos sob a ótica dos princípios ambientais. O acesso à água é um direito humano fundamental. A implementação desse direito encontra-se dificultada em razão do contexto fático global de crise da água. As causas e conseqüências da escassez quali-quantitativa da água estão relacionadas diretamente ao homem, da mesma forma que seu necessário enfrentamento depende de mudanças de percepção e comportamento do próprio ser humano. Preconiza-se o rompimento do paradigma antropocentrista, que deve ser transmutado para uma visão ecocêntrica. A efetivação do direito fundamental de que se trata depende de inúmeras providências, destacando-se a publicização integral da propriedade da água pela Constituição de 1988. A finalidade dessa relevante alteração no regime de dominialidade hídrica foi dar ao Estado o meio para o adequado gerenciamento da água como forma de estabilizar ou reduzir a crise e promover justiça social. Compete ao Estado social a satisfação do bem-estar coletivo, o que é mais factível se tiver sob seu domínio o recurso atualmente escasso e de relevância pública. Os recursos hídricos ingressam no patrimônio estatal na categoria dos bens de uso comum do povo. Apesar disso, sua gestão se dá de forma descentralizada e participativa. Na tarefa de administrar as águas, o jurista utiliza-se dos princípios estruturantes do Direito Ambiental, notabilizando-se os princípios materiais do desenvolvimento sustentável, prevenção, precaução, poluidor-pagador e usuário-pagador. Todos eles estão previstos pela Constituição Federal. O desenvolvimento sustentável é um sobreprincípio, sendo mais do que um princípio. O critério de ponderação que é utilizado para solver o conflito entre princípios, no caso do ecodesenvolvimento aplica-se apenas entre seus elementos internos, não entre o desenvolvimento sustentável e outros princípios. Este princípio-reitor é muito útil na apreciação do modelo de produção de energia hidrelétrica, que causa degradações ambientais significativas, e sempre tem repercussão, também, nos planos econômico e social. Os princípios da prevenção e da precaução servem à proteção dos mananciais superficiais e subterrâneos. A precaução, porém, auxilia de forma mais apropriada na defesa das águas subterrâneas, uma vez que o estado da técnica não permite mensurar qual o impacto ambiental do consumo excessivo de água de poços, que consiste em uma realidade contemporânea crescente. Os princípios do poluidor-pagador e do usuário-pagador fundamentam teoricamente o instrumento da cobrança pela utilização dos recursos hídricos, que o legislador resolveu adotar como forma de incentivar a racionalização do uso da água. A pesquisa é do tipo bibliográfica. O método-base adotado é o analítico. Diversas formas de análise foram empregadas, registrando-se a estruturalista, a histórica e a descritiva. Como a adoção de um método-base não afasta a aplicação dos demais, pois cada trabalho científico acaba sendo construído de modo singular, utilizaram-se também, ao longo da dissertação, os métodos dialético, hermenêutico e sistêmico. / Submitted by Marcelo Teixeira (mvteixeira@ucs.br) on 2014-05-15T16:32:50Z No. of bitstreams: 1 Dissertacao Eduardo C Viegas.pdf: 909624 bytes, checksum: 5542d0380064804357b53f30abdf1bfb (MD5) / Made available in DSpace on 2014-05-15T16:32:50Z (GMT). No. of bitstreams: 1 Dissertacao Eduardo C Viegas.pdf: 909624 bytes, checksum: 5542d0380064804357b53f30abdf1bfb (MD5) / The present work concerns the natural water resource management under the evironmental principles. Access to water is a basic human right. The implementation of this right is made all the more difficult on account of the global water crisis. The causes and consequences of these quality and quantity shortages of fresh water are directly related to man, likewise, in adequately facing this problem, a change in perception and behavior must be undertaken by humankind. A move away from the pattern of anthropocentrism to a more ecocentric view is needed. Carrying out these basic laws depends on innumerable steps, clarified in the integral publication of water properties in the constitution of 1988. The objective of this relevant alteration in water property was to give the state the means for the adequate management of water as a form of stabilizing or reducing the crisis and promoting social justice. It is the responsibility of the state to see to collective well being, which is made easier when the resource, which is presently scarce, is held under it s domain of public relevance. Natural water resources are held under the category of common use resources within the patrimony of the state. Despite this, it is managed in a decentralized and collaborative fashion. In the task of managing these water resources, the jurist uses the structured principles of Environmental Law, observing the main principles of sustainable development, prevention, precaution, paying pollutant and paying user. All of which have been foreseen by the Federal constitution. Sustainable development is more than a principle. The basis of consideration used to solve the conflict between the principles, in the case of eco-development is only applied within its internal elements, not within sustainable development and other principles. This fundamental principle is very useful in the appreciation of the model of production of hydroelectric energy, which causes significant environmental degradation and always has repercussions within economic and social plans. Precaution, however, acts as a more appropriate method of protecting subterranean waters, whereby the technical state no longer permits the measuring of the environmental impact of excessive consumption of well water, which includes a growing contemporary reality. The principles of the paying pollutant and the paying user theoretically substantiate the instrument of collective use of natural water resources, which the legislator resolved to adopt in order to stimulate rationing in the use of water. The research is in a bibliographical format. The method-base is analytical. Various forms of analysis were used, including structuralistic, historic and descriptive types. As the adoption of a certain method-base does not dismiss the need of others, so each scientific project is formed in a singular fashion, including, within the dissertation, dialectic, hermeneutic and systemic methods.