In this thesis, the photochemical and photocatalytic degradation of atenolol (ATL) and 2-phenylbenzimidazole-5-sulfonic acid (PBSA) have been investigated in aqueous solutions. Our results show that direct photolysis of ATL is weak and the indirect photolysis, e.g., induced by photosensitizers such as nitrate, may contributed to its major loss process in natural sunlit waters. In the case of PBSA, direct photolysis is found to be important while the indirect photolysis may play a less important role in its elimination in natural surface waters. The photolytic reactions (either direct or indirect) generally obey pseudo-first-order kinetics and can be influence by the solution pH, the co-existence of other water constituents such as dissolved organic matter (DOM) and bicarbonate ion (HCO3-). The photolytic degradation lead to a variety of intermediates and products. However, the reduction in TOC of the photolysis is usually found to be insignificant compared to the disappearance of the mother compound. Nevertheless, the observed decrease in toxicity toward fresh water species D. magna in nitrate-induced photodegradation of ATL implies indirect photolysis of ATL is possibly an important way to reduce the toxicity to ecosystem. It should be noted that direct and indirect photodegradation may process through different pathways and mechanism as observed in the photolysis of PBSA in this work. Photocatalytic oxidation of ATL and PBSA were carried out in illuminated aqueous TiO2 suspensions. Photocatalytic reactions normally follow pseudo-first-order kinetics. The kinetics are strongly affected by the photocatalyst type, the photocatalyst dosage, the solution pH value and the substrate concentration. Hydroxyl radical (HO*) was determined to be the major reactive specie responsible for the remarkable degradation of mother compounds. The degradation efficiency is largely influenced by the water matrices as well as the formation and transformation of intermediates. It should be noted that Degussa P25 showed the highest photocatalytic activity for oxidizing ATL and PBSA compared to pure anatase or rutile catalyst such as Hombikat UV 100, Millennium PC 500 and Aldrich rutile, which is in line with previous reports. The photocatalytic degradation of mother compounds results in the formation of various intermediates (e.g., formic, oxalic, malonic acid) and inorganic ions (e.g., NH4+, NO3-, SO42-). TOC decreases much more slowly as compared to the disappearance of the mother compounds, however, complete mineralization could be obtained with longer irradiation time

Abstract: Certain cultures present especification in the assimilation of some ions, that are or not in available ways in the soil. The minerals have fundamental paper in the presence of those elements that, a lot of times, they are together originating from of the processes of meteorization of the rocks with the decomposition of the organic matter. This work had for objective to study the extraction and/or solubilization of some present chemical elements in the studied minerals and in a red latosoil, for the action of some organic acids produced starting from the decomposition of the matter ligno-cellulousic, through the microbial action, hoping to contribute in some way in the understanding of the mechanisms of fertility of the soil and, consequently, in the mineral nutrition of plants. The used minerals were: manganite [MnO(OH)], hematite (Fe2O3), pirolusite (MnO2), caolinite [Al2Si2O5(OH)4], goethite (HFeO2), bentonite [Na3(Al,Mg)2 2(Si4O10)(OH)2.H2O] e magnetite(Fe3O4), that commonly happen in areas humid intertropicals and a red latosoil, of sandy texture that, it represents more that 20% of the area of the State of Saint Paulo. The minerals and LV were triturated and drizzled in 0,05mm mesh, separately. After having examined with relationship your structure for Difratometric of Ray-X (XRD), 1g of those minerals and LV were conditioned, separately, in glass flasks. Some samples were only treated with distilled water and other with solution 0,02 mol.L-1 of the following acids: acetic, butyric, citric, carbolic, lactic, malic, oxalic, propionic and tannic, separately, for 53 days, with weekly agitations and conditions aerobics. After the digestion of the samples, they were certain the litio concentrations, sodium, potassium, magnesium, calcium, barium, vanadium, cromium, molibdenium, manganese, iron, cobalt, nickel, copper, zinc, cadmium, mercury, boron, aluminum, silicio, tin, lead, match... (Complete abstract click electronic access below) / Orientador: Ademércio Antonio Paccola / Coorientador: Pedro de Magalhães Padilha / Banca: Silas Macedo Silva / Banca: Paulo Sergio R. de Oliveira / Banca: Antonio Francisco Godinho / Banca: Rosana Cavalcante dos Santos / Doutor

Made available in DSpace on 2015-05-14T13:21:50Z (GMT). No. of bitstreams: 1 arquivototal.pdf: 2097791 bytes, checksum: ca496bec445fdfe57f7800a142dda529 (MD5) Previous issue date: 2010-10-25 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / Due to the intense activity in the textile business Piranhas River, which traverses the city of São Bento-PB is serving as the depletion for the waste generated in the steps of bleaching and dyeing of yarn, since the networks are made by artisans, many them in the backyards of residences. On this context, for this work, we collected water and sediment samples at three different points of the Piranhas, with the objective to evaluate a possible contamination of these compartments resulting from dumping of textile effluent. Were also determined the variables Dissolved Oxygen (DO), Total Dissolved Solids (TDS), OM (Organic Matter), Conductivity, pH and temperature. The results obtained for these parameters are consistent with those expected for the location of the environment under study, where the rainfall is marked by extreme irregularity. An analysis screening using the voltammetry technique was used to indicate the presence of trace metals in water, this analysis showed the possible presence of metals, Zn, Pb and Cu. Concerning the sediment samples, the quantitative analysis performed using the technique of ICP-MS (Inductively Coupled Plasma-Mass Spectrometry) showed that among the investigated metals, Cd, Pb, Cu, Cr, Ni, Cr and Ni elements were those with higher levels during the study period. Using parameters of the sediment quality evaluators, it was observed that the metals Cr and Ni had values that exceeded the lower limit TEL (Canadian guideline value) thus indicating a deleterious made occasional on aquatic biota of the environment under study. Principal components analysis (PCA) using variables such as the physical-chemical parameters and concentrations of metals investigated, highlighted the influence of parameters and STD Conductivity, pH and organic matter in the grouping of data and also showed that the differences in metal contents between months in the study (rainy and dry) were more relevant than the differences between the sampling sites investigated. From the results and taking into account the variables measured along the river, it was found that there is no evidence that the textile wastewater at the moment, is affecting the characteristics of the Piranhas. / Devido à intensa atividade no ramo têxtil o Rio Piranhas, que atravessa o município de São Bento- PB, está servindo como esgotamento para os resíduos gerados nas etapas de branqueamento e tingimento dos fios, uma vez que as redes são fabricadas de maneira artesanal, muitas delas nos quintais das residências. Neste contexto, para este trabalho, foram coletadas amostras de água e sedimento em três pontos distintos do Rio Piranhas, com o objetivo de avaliar uma possível contaminação desses compartimentos resultante do despejo do efluente têxtil. Também foram determinadas os parâmetros físico-químicos oxigênio dissolvido (O.D), sólidos totais dissolvidos (STD), matéria orgânica (M.O), condutividade, pH e temperatura. Os resultados obtidos para estes parâmetros estão de acordo com os esperados para a localização do ambiente em estudo, onde o regime pluviométrico é marcado por extrema irregularidade. Uma análise qualitativa utilizando a técnica de voltametria foi realizada para indicar a presença de metais traço na água, essa análise mostrou a possível presença dos metais Zn, Pb e Cu. Em relação às amostras de sedimento, a análise quantitativa realizada através da técnica de espectrometria de massa com plasma indutivamente acoplado (ICP-MS), mostrou que dentre os metais investigados, Cd, Pb, Cu, Cr e Ni, o Cr e o Ni foram os que apresentaram maiores teores ao longo do período em estudo. Utilizando indicadores estatísticos de qualidade do sedimento, foi observado que Cr e Ni apresentaram valores que ultrapassaram o limite inferior TEL (valor guia canadense) indicando assim, um efeito deletério ocasional sobre a biota aquática do ambiente em estudo. Análises de componentes principais (PCA) utilizando como variáveis os parâmetros físico-químicos e as concentrações dos metais investigados, ressaltou a influência dos parâmetros STD e condutividade, M.O e pH no agrupamento dos dados e mostrou ainda que, as diferenças nos teores de metais entre os meses em estudo (período chuvoso e de seca) foram mais relevantes do que as diferenças entre os pontos de coleta investigados. A partir dos resultados e levando-se em conta os parâmetros medidos no trecho do rio, verificou-se que não há evidência de que o efluente têxtil até o presente momento, esteja afetando as características do Rio Piranhas.

Este trabalho descreve o comportamento eletroquÃmico dos antibiÃticos cefuroxima (CFX) e cefalexina (CFA) por voltametria cÃclica (VC) e o desenvolvimento de metodologia eletroanalÃtica por voltametria de onda quadrada (VOQ) para a determinaÃÃo de CFX e de CFA sobre eletrodo de gota pendente de mercÃrio (HMDE, do inglÃs Hanging Mercury Drop Electrode). CFX apresentou dois processos catÃdicos irreversÃveis em -0,35 V (pico 1) e em -1,03 V (pico 2), com a participaÃÃo de dois elÃtrons e dois prÃtons tanto para o pico 1 como para o pico 2. Sugere-se que a reaÃÃo de reduÃÃo da molÃcula de CFX ocorre no grupo â C = N â para o pico 1 e no grupo â CH2 â R para o pico 2. Os parÃmetros experimentais e voltamÃtricos foram otimizados, com as respostas sendo obtidas em tampÃo BR pH 2,0,f = 90 s-1, a = 30 mV e &#916;Es = 2 mV. Os limites de detecÃÃo (LD) e de quantificaÃÃo (LQ) foram calculados utilizando-se o pico 1, com LD = 4,92x10-9 mol L-1 e LQ = 1,64x10-8 mol L-1 e recuperaÃÃo 109,15% com desvio padrÃo relativo (RSD, do inglÃs Relative Standart Deviation) de 2,39% (n = 3) em eletrÃlito de suporte. A metodologia desenvolvida foi aplicada em amostras de medicamentos, leite bovino e Ãguas naturais, com recuperaÃÃes variando de 96,40 a 129,4%. Para CFA constatou-se a presenÃa de processos catÃdicos em -0,97 V (pico 1) e em -1,2 V (pico 2). Nesse caso, tem-se que a reduÃÃo ocorre na dupla ligaÃÃo do grupo etilÃnico envolvendo a transferÃncia de dois elÃtrons e dois prÃtons. Os parÃmetros experimentais e voltamÃtricos foram avaliados com as respostas otimizadas sendo obtidas em tampÃo BR pH 2,0, f = 100 s-1, a = 30 mV e &#916;Es = 4 mV. Considerando-se o pico em -1,2 V, curvas analÃticas foram construÃdas, a partir delas os limites de detecÃÃo e de quantificaÃÃo foram calculados, LD = 1,27x10-8 mol L-1 e LQ = 4,23x10-8 mol L-1 com recuperaÃÃo de 89,19% com RSD = 1,51% (n = 3) em eletrÃlito de suporte. A metodologia foi aplicada na quantificaÃÃo de amostras de medicamentos, leite bovino e Ãguas naturais, com percentuais de recuperaÃÃo variando de 78,45 a 92,13%. Nas metodologias desenvolvidas, foram obtidos baixos valores de LD e de LQ, recuperaÃÃo entre 78,00-130,0% e precisÃo intermediÃria com RSD < 5,00%, mostrando que estas metodologias apresentam Ãtima sensibilidade, eficiÃncia e precisÃo. / The present work describes the electrochemical behavior of the antibiotic cefuroxime (CFX) and cephalexin (CFA) by cyclic voltammetry (CV) and the development of an electroanalytical methodology for CFX and CFA determination on mercury electrodes allied to the square wave voltammetry (SWV). In this work, CFX showed two irreversible reduction peak at -0.35 V (peak 1) and -1.03 V (peak 2), with the participation of two electrons and two protons for both peaks. It is suggested that the reduction reaction of the CFX occurs on the group â C = N â for the peak one and on the group â CH2 â R for the peak two. Under optimized conditions, the results were obtained in BR buffer pH 2.0, f = 90 s-1, a = 30 mV and &#916;Es = 2 mV. Considering the peak 1, analytical curves were constructed and the limits of detection (LOD) and quantitation (LOQ) were calculated with LOD = 4.92Ã10-9mol L-1and LOQ = 1.64Ã10-8mol L-1. The recovery in electrolyte was 109.15% with RSD = 2.39% (n = 3). The methodology was applied in raw natural waters, commercial formulations and bovine milk obtaining recovery values from 96.40 to 129.4%. CFA reductions waves are observed at -0.97 V (peak 1) and -1.2 V (peak 2). These reduction waves are attributed to the reduction of ethylenic bond of CFA involving the transfer of two electrons and two protons. The optimized conditions were obtained in BR buffer pH 2.0, f = 100 s-1, a = 30 mV and &#916;Es = 4 mV. Considering the peak at -1.2 V, analytical curves were constructed and were calculated with LOD = 1.27Ã10-8mol L-1and LOQ = 4.23Ã10-8 mol L-1. The recovery in electrolyte was 89.19% with RSD = 1.51% (n = 3). The methodology was applied to quantify in raw natural waters, commercial formulations and bovine milk obtaining recovery values from 78.45 to 92.13%. In developed methodologies, we obtained low values of LOD and LOQ, recovery between 78.00 to 130.00% and reproducibility below 5.00%, showing that those methods had excellent sensitivity, precision and efficiency.

Abstract Humus-rich natural water samples, containing high concentrations of dissolved organic carbon (DOC), are challenging for certain analytical methods used in trace element analysis, including hydride generation methods and electrochemical methods. In order to obtain reliable results, the samples must to be pretreated to release analytes from humic acid complexes prior to the determination. In this study, methods for both pretreatment and analysis steps were developed. Arsenic is a toxic element and therefore its determination even at low concentration levels is important in environmental monitoring. Arsenic complexed with humic substances is not likely to form volatile hydrides quantitatively during borohydride reduction. In this study, natural water samples were digested with microwave-assisted digestion method prior to analysis by hydride generation inductively coupled plasma mass spectrometry (HG-ICP-MS). In addition, a dual mode sample introduction system was used to study internal standardization in order to correct signal variations during the measurement of arsenic with HG-ICP-MS. A novel nano-TiO2 catalyzed ultraviolet light emitting diode (UV-LED) digestion device was developed to apply green chemistry principles in sample preparation. The method consumes less harmful reagents and less energy than traditional techniques. The DOC removal efficiency was studied as a function of pH, irradiation time and hydrogen peroxide concentration. Recoveries of spiked heavy metals and hydride forming elements were studied. UV-LED technology is growing rapidly, and new catalytic semiconductor materials for photocatalysis are being developed. In this study, the effects of synthesis method variables on the properties of ZnO nanopowders were investigated. / Tiivistelmä Luonnonvesinäytteet voivat sisältää suuria määriä liuennutta hiiltä (DOC), jolloin pienten alkuainepitoisuuksien määrittäminen voi olla haasteellista esimerkiksi hydridinmuodostusmenetelmillä ja sähkökemiallisilla menetelmillä. Luotettavien tulosten saavuttamiseksi näytteet täytyy esikäsitellä analyyttien vapauttamiseksi humushappokomplekseista ennen määrityksiä. Tässä tutkimuksessa kehitettiin menetelmiä humuspitoisille luonnonvesinäytteille sekä esikäsittelyvaiheeseen että analyysivaiheeseen. Arseeni on myrkyllinen alkuaine, jonka määrittäminen pienissä pitoisuuksissa on ympäristön seurannan kannalta tärkeää. Humusyhdisteisiin kompleksoitunut arseeni ei muodosta kvantitatiivisesti hydridejä borohydridipelkistyksellä. Tässä tutkimuksessa luonnonvesinäytteet hajotettiin mikroaaltoavusteisella hajotusmenetelmällä ennen arseenin mittaamista hydridinmuodostus-induktiiviplasmamassaspektrometrialla (HG-ICP-MS). Tämän lisäksi tutkittiin mittaustarkkuuden parantamista sisäisellä standardoinnilla mitattaessa arseenia HG-ICP-MS-menetelmällä. Tutkimuksessa kehitettiin myös uudenlainen näytteenkäsittelylaitteisto, jossa käytettiin säteilylähteenä ultraviolettivaloa emittoivaa diodia (UV-LED) ja katalyyttinä nanotitaanidioksidia. Uusi ympäristöystävällinen menetelmä kuluttaa vähemmän haitallisia reagensseja ja vähemmän energiaa kuin perinteiset menetelmät. Kehitetyn menetelmän hajotustehokkuutta tutkittiin pH:n, säteilytysajan ja vetyperoksidikonsentraation funktiona. Lisäksi raskasmetallien ja hydridiä muodostavien alkuaineiden saantoja tutkittiin lisäyskokeilla. UV-LED-teknologia kehittyy nopeasti ja uusia valokatalyysimateriaaleja tutkitaan jatkuvasti. Tässä tutkimuksessa tarkasteltiin synteesimuuttujien vaikutusta sinkkioksidinanojauheiden ominaisuuksiin.

Résumé : La Bretagne (France) est une région agricole où les polluants émergeants sont très susceptibles d’atteindre les eaux de surfaces. La surveillance institutionnelle montre que les sous-produits d’herbicides sont la principale pollution des eaux de surface, dans une région où 80 % des eaux potables sont produites à partir de ressources superficielles. Le comportement dans l’environnement des sous-produits d’herbicides est mal connu et, pour certains d’entre eux, les contributions de leurs différentes sources font toujours débat. Dans l’est de la Bretagne, le bassin versant de la Vilaine (10 500 km²) est d’un grand intérêt pour la recherche, car il abrite une importante usine de potabilisation (100 000 m3/j) à son extrême aval. Dans ce contexte, cette étude vise à (i) cartographier le bassin versant, (ii) évaluer la contamination et ses variations spatiales et saisonnières, (iii) comprendre les conditions favorables à l’export vers les eaux de surface, (iv) étudier les sources et le devenir de l’AMPA (acide aminométhyl phosphonique) dans les eaux usées, (v) explorer le procédé d’ozonation pour un sous-produit récalcitrant aux traitements de l’eau potable. Cette thèse consiste en trois chapitres : une revue de la littérature sur l’occurrence et le devenir des herbicides et leurs sous-produits dans les eaux de surface, eaux usées, et eau potable; le matériel et méthodes incluant, la sélection des composés d’intérêt, la stratégie d’échantillonnage, la description des méthodes d’analyses et d’assurance qualité, les outils statistiques; les résultats d’occurrence et de comportement des sous-produits d’herbicides dans les différentes eaux étudiées. Ces travaux se concluent sur un contexte plus large avec des perspectives pour acquérir une meilleure compréhension des sources et des facteurs influençant l’occurence des sous-produits d’herbicides dans les différentes eaux, dans le but d’améliorer la qualité des ressources. / Abstract : Brittany (France) is an agricultural region, where emerging pollutants are highly at risk to reach surface waters. Legal monitoring shows that herbicides metabolites are the main pollution of surface waters, in a region where 80 % of drinking water is produced with surface waters. The environmental behavior of herbicides metabolites is badly known and, for some of them, the contributions of their different sources are still debated. In east Britany, the Vilaine watershed (10 500 km²) is of great research interest, as a large drinking water treatment plant (100 000 m3/day) is located at the extreme downstream of it. In this context, this study aims to (i) map the watershed, (ii) evaluate the contamination and its spatial and seasonal variations, (iii) understand the favoring conditions resulting in metabolites export towards surface water, (iv) study sources and fate of AMPA (aminomethylphosphonic acid) in wastewaters, (v) explore ozonation treatment of a resistant metabolite in drinking water This thesis consists of three chapters: a review of the literature on herbicides and their metabolites occurrence and fate in surface waters, wastewaters, and drinking water; the materials and methods including, selection of compounds of interest, sampling strategy, description of the methods of analysis and quality assurance, statistical tools; the results of herbicides metabolites occurrences and behavior in the different waters studied. This work concludes on a broader context by providing perspectives to gain a better understanding of the sources and the factors influencing herbicides metabolites occurrences in the different waters, in order to improve the quality of water resources.

Dans ce travail, nous avons étudié la dégradation photochimique et photocatalytique de l'aténolol (ATL) et du 2-phénylbenzimidazole-5-sulfonique acide (PBSA) soit dans des solutions aqueuses de qualité milli-Q dopée ou non avec des espèces présentes dans les eaux naturelles (ions bicarbonate, nitrate, substances humiques) soit dans de l'eau naturelle (eau du Rhône). Nos résultats ont montré que la photolyse directe de l'ATL est faible, l'ATL présentant une faible absorbance pour les longueurs d'onde supérieures à 290 nm. C'est donc la photolyse induite par exemple par des photo-sensibilisateurs tels que le nitrate qui peuvent contribuer à son processus de dégradation dans les eaux naturelles ensoleillées. En revanche, dans le cas du PBSA, la photolyse directe a été jugée importante alors que la photolyse indirecte jouerait un rôle moindre dans les eaux de surface naturelles, cette dégradation étant fortement inhibé par la présence des ions hydrogénocarbonates. Dans les deux cas, les réactions de photolyse (directs ou indirects) obéissent généralement à des cinétiques de pseudo-premier ordre et peuvent être influencées par le pH de la solution, la coexistence d'autres constituants de l'eau tels que la matière organique dissoute (MOD) et de l'ion bicarbonate (HCO3-). L'oxydation photocatalytique de l'ATL et du PBSA ont également été étudiés dans des solutions aqueuses de TiO2 en suspension. Nous avons montré que les cinétiques étaient fortement dépendantes du type et de la concentration en photocatalyseur, du pH de la solution et de la concentration en substrat. Dans les deux cas, le radical hydroxyle serait la principale espèce réactive responsable de la dégradation de ces composés. Ici aussi, l'efficacité de la dégradation est largement influencée par les constituants de la matrice de l'eau. Il convient de noter que le TiO2 Degussa P25 a montré l'activité photocatalytique le plus élevée par rapport aux autres catalyseurs de type Hombikat UV 100, le PC 500 de millennium et le rutile d'Aldrich. En ce qui concerne la minéralisation des polluants, les mesures de COTmètre montrent une diminution beaucoup plus lente par rapport à la disparition des composés parents, cependant, la minéralisation complète peut être obtenue avec une plus longue durée d'irradiation / In this thesis, the photochemical and photocatalytic degradation of atenolol (ATL) and 2-phenylbenzimidazole-5-sulfonic acid (PBSA) have been investigated in aqueous solutions. Our results show that direct photolysis of ATL is weak and the indirect photolysis, e.g., induced by photosensitizers such as nitrate, may contributed to its major loss process in natural sunlit waters. In the case of PBSA, direct photolysis is found to be important while the indirect photolysis may play a less important role in its elimination in natural surface waters. The photolytic reactions (either direct or indirect) generally obey pseudo-first-order kinetics and can be influence by the solution pH, the co-existence of other water constituents such as dissolved organic matter (DOM) and bicarbonate ion (HCO3-). The photolytic degradation lead to a variety of intermediates and products. However, the reduction in TOC of the photolysis is usually found to be insignificant compared to the disappearance of the mother compound. Nevertheless, the observed decrease in toxicity toward fresh water species D. magna in nitrate-induced photodegradation of ATL implies indirect photolysis of ATL is possibly an important way to reduce the toxicity to ecosystem. It should be noted that direct and indirect photodegradation may process through different pathways and mechanism as observed in the photolysis of PBSA in this work. Photocatalytic oxidation of ATL and PBSA were carried out in illuminated aqueous TiO2 suspensions. Photocatalytic reactions normally follow pseudo-first-order kinetics. The kinetics are strongly affected by the photocatalyst type, the photocatalyst dosage, the solution pH value and the substrate concentration. Hydroxyl radical (HO•) was determined to be the major reactive specie responsible for the remarkable degradation of mother compounds. The degradation efficiency is largely influenced by the water matrices as well as the formation and transformation of intermediates. It should be noted that Degussa P25 showed the highest photocatalytic activity for oxidizing ATL and PBSA compared to pure anatase or rutile catalyst such as Hombikat UV 100, Millennium PC 500 and Aldrich rutile, which is in line with previous reports. The photocatalytic degradation of mother compounds results in the formation of various intermediates (e.g., formic, oxalic, malonic acid) and inorganic ions (e.g., NH4+, NO3-, SO42-). TOC decreases much more slowly as compared to the disappearance of the mother compounds, however, complete mineralization could be obtained with longer irradiation time

O ferro é o elemento mais abundante na Terra e tem importante papel em ciclos biogeoquímicos Neste trabalho foi desenvolvido um procedimento analítico automático para a determinação fotométrica de ferro em águas de rios, empregando um fotômetro baseado em LED e mini-bombas solenoide para o gerenciamento de soluções. O procedimento proposto foi baseado na reação do ferro (III) com o tiocianato de potássio formando um complexo avermelhado com máximo de absorção em 470 nm. Para a determinação de ferro total foi incluída uma etapa de oxidação em linha, usando uma solução de persulfato (S2O82-) como oxidante. O módulo de análises foi constituído por quatro mini-bombas solenoide e uma válvula solenoide de três vias. Para a obtenção de sinais foi construído um fotômetro composto por uma cela de fluxo com caminho óptico de 50 mm, um LED azul (\'lâmbda\'=470 nm) e um fotodetector. Visando utilizar este equipamento portátil para medidas em campo, foram empregadas duas baterias de 6 V para alimentar os dispositivos ativos. Os ensaios em laboratório mostraram que as baterias permitem uma autonomia de mais de 50 horas de trabalho sem recarregá-las. O procedimento desenvolvido apresentou as seguintes características analíticas: resposta linear entre as concentrações de 0,25 e 4,0 mg L-1, segundo a equação Y = (0,0183 ± 0,003) + (0,15326 ± 0,002)X (r=0,9997); limite de detecção 0,013 mg L-1 Fe (III) estimado com 99,7 % de confiança; desvio padrão relativo estimado em 0,95 % (n=15) obtido com uma solução de concentração de 1,5 mg L-1 Fe (III); frequência de amostragem de 50 determinações por hora. Os resultados obtidos pelo procedimento proposto e pelo de referência não apresentaram diferenças significativas com nível de confiança de 95 % / Iron is the most abundant element on Earth and plays an important role in biogeochemical cycles. In this work, an automatic analytical procedure was developed for the photometric determination of iron in river waters, employing a LED-based photometer and solenoid mini-pumps for solution handling. The proposed procedure was based on the reaction between iron (III) and potassium thiocyanate, yielding a red complex with maximum absorption at 470 nm. For the determination of total iron, an in line oxidation step was included, employing a persulfate solution (S2O82-) as oxidant. The module was constructed with four solenoid mini-pumps and a three-way solenoid valve. For data acquisition a photometer was constructed with a 50 mm optical path flow cell, a blue LED (\'lâmbda\'= 470 nm) and a photodetector. Envisioning the use of this portable equipment in field, two 6-Volt batteries were employed to supply energy to the active devices. Laboratory tests showed that the batteries provide more than 50 hours of operation without recharging. The proposed procedure showed the following analytical features: linear response between 0.25 and 4.0 mg L-1, according to the equation Y = (0.0183 ± 0.003) + (0.15326 ± 0.002) X (r = 0.9997); detection limit of 0.013 mg L-1 Fe (III), estimated with 99.7 % of confidence; relative standard deviation estimated as 0.95% (n = 15), obtained with a 1.5 mg L-1 Fe (III) solution; sampling rate of 50 determinations per hour.The results obtained with the proposed and reference procedure did not show significative differences at a 95% confidence level

Três procedimentos analíticos envolvendo microextração líquido-líquido (MELL) em fluxo foram desenvolvidos para as determinações de formaldeído em leite, detergentes aniônicos em águas de rios e bisfenol A (BPA) em águas de torneira. Microextração líquido-líquido dispersiva (MELLD) foi empregada no primeiro e no segundo procedimentos. O primeiro procedimento foi conduzido em um sistema fluxo-batelada no qual a quantificação espectrofotométrica era realizada diretamente na câmara de mistura/reação, através do acoplamento de fibras ópticas. No segundo, foi explorada a estratégia lab-in-syringe, em que a formação do par iônico entre os detergentes aniônicos e corante catiônico azul de metileno, bem como MELLD ocorriam no interior da seringa, sendo os analitos quantificados na fase orgânica por espectrofotometria. O terceiro procedimento envolveu MELL em sistema de análises por injeção sequencial (SIA), baseada na formação de um filme de 1-octanol na parede da bobina de extração. O extrato foi eluído com etanol e a quantificação de BPA foi realizada por espectrofluorimetria. As linearidades das curvas analíticas, os limites de detecção e os limites de quantificação ao nível de 95% de confiança foram: 0,5-5,0 mg L-1, 100 e 300 ?g L-1 para formaldeído, 0,03-0,5 mg L-1, 9,0 e 29,0 ?g L-1 para detergentes, e 5,0 - 100 ?g L-1, 1,8 ?g L-1 e 5,4 ?g L-1 para BPA. Os procedimentos desenvolvidos não apresentaram efeitos de matriz, e as recuperações se situaram entre 91 e 112%. A precisão e exatidão do procedimento foram concordantes com os procedimentos de referência, ao nível de 95% de confiança. Todos os procedimentos apresentaram coeficientes de variação menores do que 3,5% (n=10), frequência de amostragem de 10-17 h-1, consumiram apenas 30-40 µL de solventes orgânicos e geraram 2,7-6,7 mL de resíduos por determinação / Three analytical procedures involving flow-based liquid-liquid microextraction (LLME) were developed for the determinations of formaldehyde in milk, anionic detergents in river waters, and bisphenol A (BPA) in tap waters. The first and second procedures involved dispersive liquid-liquid microextraction (DLLME) and spectrophotometric detection. The first one was carried out in a flow-batch system, in which the spectrophotometric quantification was performed directly in the mixing/reaction chamber by coupling optical fibers. The second one exploited the lab-in-syringe strategy, in which the ion-pair formation between the anionic detergents and the methylene blue cationic dye, as well as DLLME, were carried out inside the syringe. The third procedure involved LLME in a sequential injection system based on the formation of a 1-octanol film on the inner wall of the extraction coil. The extract was eluted with ethanol and BPA was quantified by spectrofluorimetry. Linear response ranges, detection and quantification limits estimated at the 95% confidence level were: 0.5-5.0 mg L-1, 100 and 300 ?g L-1 for formaldehyde; 0.03-0.5 mg L-1, 9.0 and 29.0 ?g L-1 for detergents, and 5.0-100 ?g L-1, 1.8 and 5.4 ?g L-1 for BPA. Matrix effects were not observed for the assayed samples and recoveries ranged from 91 to 112%. Accuracy and precision of the results agreed with those attained by reference procedures at the 95% confidence level. All procedures yielded coefficients of variation lower than 3.5% (n = 10), sampling rates within 10 and 17 h-1, consumed only 30-40 ?L of organic solvents, and generated 2.7-6.7 mL of waste by determination

The thesis is a summary and discussion of eight papers. During the last decades, precipitation has become increasingly acidic due to the extensive use of fossil fuels. In areas of poorly buffered bedrocks, e.g. Scandinavia, northeastern United States, this phenomenon has resulted in elevated amounts of Al(III) being leached into streams and lakes. Recent findings reveal that these elevated Al-concentrations could cause fish death and decreasing forest production. In the present thesis, the importance of taking naturally occurring substances into consideration when discussing Al(III) in natural waters, is emphasized. On the basis of a chemical characterization of relevant ligand classes in a natural water, the complex formation between Al^+, hydroxide ions and the inorganic ligand carbonic acid, the low-molecular weight organic ligand citric acid and the high-molecular weight model substances gallic acid, 1,2-dihydroxynaphtha-lene-4-sulfonate, 1,2-naphthoquinone-4-sulfonate, pyrocatechol and salicylic acid were investigated. The investigations were performed as series of Potentiometrie titrations and data were processed by means of the least-squares computer program LETAGROPVRID using a technique called pqr-analysis, permitting an unbiased search for complex model (and corresponding equilibrium constants) to be made. In most systems studied, the complexation at high ligand excesses can be described by a series of mononuclear complexes AIL-AIL^. Tentatively, the whole series consists of octahedrally coordinated (water and ligand oxygens) AI(III). At lower ligand excesses, the significance and in some cases even predominance of ternary mono- and polynuclear hydroxo complexes is demonstrated. In two of the systems, binary aluminium hydroxo species are evaluated. The potential importance of the substances with respect to Al-com-plexation in natural waters are indicated in a number of model calculations. The solubility of the clay mineral kaolinite is calculated as a function of -lg[H+] and ligand concentration. It is shown that citric acid, gallic acid, 1,2-dihydroxynaphthalene-4-sulfonate, pyrocatechol and salicylic acid contribute quite significant to the total solubilities, even at very low concentrations. As a complement and background to the equilibrium studies, the corrosion rate for one of the naturally occurring Al-bearing minerals, corundum, is reported. In this investigation, performed with a leach-ant solution of ground-water composition, an experimental technique was employed which made it possible to divide the corrosion into chemical and mechanical losses. / <p>Diss. (sammanfattning) Umeå : Umeå universitet, 1983</p> / digitalisering@umu