Orientador: Celso Costa Lopes / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos / Made available in DSpace on 2018-08-09T15:17:24Z (GMT). No. of bitstreams: 1 Hofsetz_Kelly_D.pdf: 10880310 bytes, checksum: a6cd1fb5002b3963054fc23a04552ed4 (MD5) Previous issue date: 2007 / Resumo: Neste trabalho estudou-se a secagem de banana utilizando um pulso inicial a alta temperatura e curto tempo, combinado com uma etapa de secagem convencional a ar quente a 70°C. Numa primeira etapa, foram analisadas as mudanças de encolhimento, porosidade e estrutura ao longo da secagem com bananas de origem portuguesa e brasileira. Esses resultados foram comparados com os de uma secagem convencional feita somente a 70°C. Na segunda etapa, estudaram-se as isotermas de sorção e as transições de fase nas amostras das duas origens (Portugal e Brasil) através de Calorimetria Diferencial de Varredura. Os resultados da primeira parte mostraram que o grau de encolhimento da banana foi maior para a secagem convencional a 70°C, na qual o volume apresentou um decréscimo linear com o conteúdo de umidade, chegando a 30%, enquanto que a porosidade aumentou progressivamente até 32%. A secagem combinada resultou na formação de um produto com uma estrutura altamente porosa (45,5% a 57,5%) e menor grau de encolhimento (42% a 68,5%), quando comparada com a secagem convencional a 70°C. As observações estruturais nas amostras de banana ajudaram a explicar as mudanças na porosidade e encolhimento. Os resultados das isotermas de sorção tiveram um bom ajuste para o modelo de BET e de GAB para as amostras frescas de origem portuguesa e, para as amostras secas das duas origens, o modelo de GAB foi o mais adequado. A ocorrência da temperatura de transição vítrea foi verificada em todas as amostras estudadas e decresceu com o aumento do conteúdo de umidade, comprovando o efeito plasticizante da água. O modelo de Gordon-Taylor permitiu uma boa predição da dependência da temperatura de transição vítrea com o conteúdo de água para as amostras de origem portuguesa. No caso das amostras de origem brasileira, foi encontrada uma relação de dependência linear do parâmetro kGT do modelo de Gordon-Taylor com a temperatura de transição vítrea experimental / Abstract: This study was conducted to evaluate the drying of bananas by a high temperature and short time drying pulse combined with hot air-drying process stage at 70°C. Firstly, Portuguese and Brazilian bananas samples were dried and the changes of shrinkage, porosity and structure during drying were analyzed. This results were compared with those obtained in a conventional air-drying process at 70°C. After that, sorption isotherms of samples from Portugal and Brazil, as well the phase transitions of the Brazilian banana, were studied. The results of the first part showed that shrinkage changes during drying was more intense to the conventional air-drying process at 70°C, and a line ar decrease in volume with the decrease in moisture ratio was observed reaching 30%, while the porosity increased uniformly reaching values of about 32%. The high temperature and short time drying pulse combined with hot air- drying process stage at 70°C resulted in the formation of a highly porous structure (45,5% to 57,5%) and reduced shrinkage (42% to 68,5%) when compared with the conventional air-drying process. Structural observations of the banana samples during the processes studied were able to explain the volume and porosity changes. The BET and GAB equations gave the best fit to the experimental sorption data for Portuguese fresh bananas and the GAB model was found to be the best-fitted equation for all dried bananas (Portuguese and Brazilian samples) and both models gave information about the shelf-stability for the samples. The glass transition temperature occurred for all samples studied and decreased as water content increased, confirming the water plasticization effect. The Gordon-Taylor equation was able to predict the dependence of the glass transition temperature on moisture content for the Portuguese fresh samples. A linear dependence of the kGT (Gordon-Taylor equation¿s constant) and the experimental glass transition temperature was found for the Brazilian samples / Doutorado / Doutor em Engenharia de Alimentos

A monoetanolamina (MEA) é um composto bifuncional pertencente à classe dos amino-álcoois, muito utilizado em processos industriais envolvendo a remoção de gases ácidos como SO2 , CO2 e H2S. A resina Amberlite XAD-7 é uma resina não-iônica de polaridade intermediária muito utilizada em procedimentos de pré-concentração de compostos orgânicos e íons metálicos. Neste trabalho, estudou-se a interação entre a superfície da resina XAD-7 e a MEA. Massas conhecidas da resina foram colocadas em contato com soluções de MEA em concentrações conhecidas, sob agitação durante certo intervalo de tempo. A quantidade de MEA adsorvida foi calculada considerando-se a diferença entre a concentração inicial e a concentração remanescente no sobrenadante, ambas obtidas a partir de medidas de absorbância, com utilização da reação de Berthelot modificada. Modelos cinéticos de pseudo-primeira e -segunda ordens, além do modelo de difusão intra-partícula, foram aplicados aos dados experimentais obtidos no estudo cinético. Entre estes modelos aplicados, o de pseudo-segunda ordem apresentou excelente ajuste aos dados experimentais. O estudo realizado em um determinado tempo de contato e variando-se a concentração inicial de MEA forneceu resultados experimentais que foram aplicados a três modelos de isotermas (Langmuir, Freundlich e Dubinin-Radushkevich). Destes ajustes, que mostraram excelente concordância, foram obtidos diferentes parâmetros termodinâmicos que definiram algumas características do processo de adsorção. Finalmente, estudos preliminares evidenciaram a retenção de SO32- na superfície da resina XAD-7 modificada com MEA, mostrando a possibilidade da utilização da XAD- 2 7/MEA para extração de SO32- presente em soluções ou de SO2 recolhido em solução alcalina. / Monoethanolamine (MEA) is a bifunctional compound which belongs to the amino- alcohol group, and it is widely used in industrial \"sweetening process\", which is based on the acidic gas (such as SO2 , CO2 and H2S) absorption. Amberlite XAD-7 is a non-polar resin with an intermediate polarity used to pre-concentrate organic compounds and transition metals. In this work, the interaction between the resin surface and MEA was studied. Known amounts of the resin were kept in contact with aqueous solutions of MEA and shaked under a constant rotation and during some defined intervals of time. The amount of adsorbed MEA was calculated as the difference between the initial concentration and remained concentration in the supernatant solution, which was determined applying the Berthelot´s reaction and the spectrophotometry. Kinetic models of pseudo-first and -second orders and intra-particle diffusion model were applied on experimental data collected from the kinetic study. Among these methods, the pseudo-second order model fulled fit on those experimental data. The experiments carried out under a constant time, but by changing the initial MEA concentration, led to other experimental data which were applied to three different isotherm models (Langmuir, Freundlich e Dubinin-Radushkevich). Each model showed a good fit, and for each one, different thermodynamic parameters were calculated and used to describe some adsorption characteristics. Finally, preliminary studies on the retention of SO32- onto the resin surface, previously modified with MEA, showed the possibility to extract SO32- found in aqueous solutions or SO2 recovered in alkaline media.

Made available in DSpace on 2017-07-10T18:08:06Z (GMT). No. of bitstreams: 1 Daniel Pilatti Pereira.pdf: 801190 bytes, checksum: 28cff1ac814d5c8385ed401c7b4cd36c (MD5) Previous issue date: 2013-02-23 / The cultivation and industrialization of yerba mate (Ilex paraguariensis) have an important role in the economy of Paraná, since in most cases the plant is grown on family farming system, therefore producing thousands of jobs. Drying is one of the main processing stages of yerba mate and getting to know its variables will bring great benefits for both the processing companies and for the development of their equipment. Thus, the main motivation for developing this work, besides the direct interest on the part of the industry, was the absence of specific studies related to the drying of the species of mate grown in Brazil. This paper aims to obtain data modeling and experimental isotherms and drying kinetics of yerba mate.The equilibrium isotherms were obtained by the static method using saturated solution of sulfuric acid obtained at temperatures of 30°C, 45°C and 60°C and relative humidities in the range between 4.5 and 83%. Convective drying was performed using a fixed bed dryer for laboratory scale under different conditions of temperature: 55°C, 65°C and 75°C with air flow of 1.0 m/s, 1.5 m/s and 2.0 m/s. All experimental results were evaluated by using Maple software applied to the empirical equation that allowed the definition of the best model, which presented the highest coefficient determination (R²) and the lowest average deviation. It was concluded that the sorption isotherms of water mate in nature for the three temperatures analyzed were best fitted by the mathematical modified Halsey model. The kinetic curve for the drying temperature was 55°C better adjusted by the modified Newton model with three parameters adjusted. For temperatures of 65°C and 75°C, the modified Newton model with two adjusted parameters showed the best result. The results of this study are useful in the development of projects of industrial dryers, seeking greater savings and improved quality. / O cultivo e a industrialização da erva-mate (Ilex paraguariensis) têm um importante papel na economia do Paraná, uma vez que na maioria dos casos a planta é cultivada em sistema de agricultura familiar, gerando milhares de empregos. A secagem é uma das principais etapas do beneficiamento da erva mate. Conhecer suas variáveis trará grandes benefícios, tanto para as empresas processadoras quanto para o desenvolvimento de equipamentos. A principal motivação para o desenvolvimento deste trabalho, além do interesse direto da indústria, foi a inexistência na literatura de estudos específicos relacionados à secagem de erva-mate, das espécies cultivadas no Brasil. Este trabalho visa obter e modelar dados experimentais das isotermas e da cinética de secagem da erva-mate. As isotermas de equilíbrio foram obtidas pelo método estático, utilizando solução saturada de ácido sulfúrico, obtidas em temperaturas de 30°C, 45°C e 60°C e umidades relativas na faixa entre 4,5 e 83%. Para secagem convectiva, foi utilizado um secador de leito fixo em escala laboratorial, em diferentes condições operacionais de temperatura: 55°C, 65°C e 75 ºC, com vazões de ar de 1,00 m/s, 1,50 m/s e 2,00 m/s. Todos os resultados experimentais foram avaliados com a utilização do software Maple, aplicado às equações empíricas da literatura, o qual possibilitou a definição do melhor modelo, apresentando os melhores coeficientes de determinação (R²) e o menor desvio médio. Concluiu-se que as isotermas de sorção da água da erva-mate in natura para as três temperaturas analisadas foram melhor ajustadas pelo modelo matemático Halsey modificado. A curva de cinética de secagem para a temperatura de 55°C foi melhor ajustada pelo modelo de Newton modificado com três parâmetros ajustados. Para as temperaturas de 65°C e 75°C, o modelo de Newton modificado com dois parâmetros ajustados apresentou melhor resultado. Os resultados obtidos neste trabalho são úteis no desenvolvimento de projetos de secadores industriais, visando maior economia e qualidade aprimorada.

Submitted by Jorge Silva (jorgelmsilva@ufrrj.br) on 2017-06-20T20:25:30Z No. of bitstreams: 1 2014 - Izabella Bezerra Coutinho.pdf: 1340327 bytes, checksum: f1f665c57591a73de6229abeb35569f3 (MD5) / Made available in DSpace on 2017-06-20T20:25:30Z (GMT). No. of bitstreams: 1 2014 - Izabella Bezerra Coutinho.pdf: 1340327 bytes, checksum: f1f665c57591a73de6229abeb35569f3 (MD5) Previous issue date: 2014-09-11 / CNPq / Soils have the capacity to retain metals due to the occurrence of the phenomenon of sorption, which is the accumulation of ions or molecules on the surface of organic and mineral colloids. For their high organic matter content, therefore large amount of organic colloids, the Histosols have high adsorptive capacity. Sorption can be described by means of different models, which consist in equations that seek to describe the phenomenon with minimal loss of information. Because each model is based on different assumptions, it is essential to select the best suited to the conditions to be analyzed, thus avoiding possible contamination of the environment caused by errors in predicting the adsorption capacity of the soil. This study aimed to select the models that best describe the sorption of Zn, Cd, Cu and Pb on Histosols. The study was conducted by an adaptation of the Batch of Lab Batch, with increasing concentrations of ZnCl2, CdCl2, Pb(NO3)2 and CuCl2. After determination of the concentration of adsorbed metals, the metal levels involved in complex internal and external sphere were evalueted through by desorption studies. The parameters of the sorption isotherms were determined by the ISOFIT program. To compare the fit of the models, the correlation coefficient, determination coefficient, the Akaike Information Criterion Corrected (AICc), AICc Range (?AICc) and the Weighting of AICc (AICcw) were analyzed. It was observed that the linear model was the best to describe the sorption of Zn, while Langmuir was the best to describe the sorption of Cd and Pb and the Freundlich showed better adjustment to the sorption of Cu. In general, the concentrations of N and fulvic acids were the most important factors that influences the sorption of metals. Most of Zn, Cd and Pb is sorbed in electrostatics bonds, easily reversible. However, Cu in strong and almost irreversible bonds. / Os solos possuem a capacidade de reter metais devido ? ocorr?ncia do fen?meno da sor??o, que consiste no ac?mulo de ?ons ou mol?culas na superf?cie dos col?ides org?nicos e minerais. Por apresentarem alto teor de mat?ria org?nica, portanto grande quantidade de col?ides org?nicos, os Organossolos possuem elevada capacidade adsortiva. A sor??o pode ser descrita por meio de diferentes modelos, que s?o equa??es que buscam descrever o fen?meno com o m?nimo de perda de informa??es. Como cada modelo se baseia em diferentes pressupostos, ? fundamental selecionar o que melhor se adequa ?s condi??es que se pretende analisar, evitando, assim, poss?veis contamina??es do ambiente causadas por erros na previs?o da capacidade adsortiva do solo. Este estudo teve como objetivos selecionar os modelos que melhor descrevem a sor??o de Zn, Cd, Cu e Pb em Organossolos. O estudo foi conduzido atrav?s de uma adapta??o do M?todo Batch de Laborat?rio, com concentra??es crescentes de ZnCl2, CdCl2, Pb(NO3)2 e CuCl2. Ap?s a determina??o dos teores de metais adsorvidos, os teores de metais envolvidos em complexos de esfera interna e externa foram avaliados atrav?s de estudos de dessor??o. Os par?metros das isotermas de sor??o foram determinados pelo programa IsoFit. Para compara??o do ajuste dos modelos, foram analisados o Coeficiente de Correla??o, Coeficiente de Determina??o, o Crit?rio de Informa??o de Akaike Corrigido (AICc), Varia??o de AICc (?AICc) e a Pondera??o de AICc (AICcw). Observou-se que o modelo Linear foi o que melhor descreveu a sor??o de Zn, enquanto Langmuir foi o que melhor descreveu a sor??o de Cd e Pb e o de Freundlich apresentou melhor ajuste ? sor??o de Cu. Em geral, os teores de N e ?cidos f?lvicos foram os fatores que mais influenciaram a sor??o dos metais. A maior parte de Zn, Cd e Pb sorvidas encontra-se em liga??es eletrost?ticas, facilmente revers?veis. Entretanto, o Cu encontra-se em liga??es fortes e quase irrevers?veis.

Orientador: Susanne Rath / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Química / Made available in DSpace on 2018-08-21T08:01:07Z (GMT). No. of bitstreams: 1 Doretto_KeityMargareth_D.pdf: 2722057 bytes, checksum: d4c5a2090af2c524cc8d28125e30eaa2 (MD5) Previous issue date: 2012 / Resumo: Antimicrobianos, entre eles as sulfonamidas, têm sido amplamente utilizados em medicina veterinária para fins terapêuticos e profiláticos. Uma vez excretados os fármacos e/ou metabólitos podem levar a contaminação do meio ambiente e estudos sobre o impacto ambiental ainda são escassos. Em adição, no Brasil, ainda não existe uma fiscalização de medicamentos veterinários. A não conformidade dos medicamentos reflete diretamente na saúde animal, como também é um tópico relevante quanto à segurança alimentar. Assim sendo, métodos foram desenvolvidos e validados para a determinação de sulfadiazina (SDZ), sulfadimetoxina (SDM) e sulfaquinoxalina (SQX) em medicamentos de uso veterinário por cromatografia líquida de alta eficiência associada a um detector de arranjo de fotodiodos (HPLC-DAD). Os resultados obtidos indicam a necessidade de controle de qualidade dos fármacos de uso veterinário comercializados no Brasil. Ainda, o trabalho estudou a sorção da SDZ, SDM e SQX em quatro solos característicos do Estado de São Paulo. Os estudos foram conduzidos conforme recomendação do Guia OECD 106. As sulfonamidas foram quantificadas nas soluções de solo por um método HPLC-DAD previamente validado. Os dados de adsorção/dessorção das sulfonamidas nos quatro solos foram ajustados com isotermas de Freundlich na forma linear ou logarítmica. Um fenômeno de histerese de adsorção/dessorção foi evidente em todos os solos. Os baixos valores do coeficiente de Freundlich (KF) obtidos sugerem fraca adsorção das sulfonamidas nos solos avaliados e, portanto, estas tendem a ser lixiviados e, por sua vez apresentam potencial para contaminar águas superficiais e subterrâneas / Abstract: Antimicrobials, including sulfonamides, have been widely used in veterinary medicine for therapeutic and prophylactic purposes. Once excreted, drugs and/or metabolites can contaminate the environment. Environmental impact studies are still scarce. In addition, in Brazil, there is no surveillance of veterinary medicines. The poor quality of drugs may reflect directly on animal health and is also a topic relevant to food safety. Therefore, methods were developed and validated for the determination of sulfadiazine (SDZ), sulfadimethoxine (SDM) and sulfaquinoxaline (SQX) in veterinary drugs, using high performance liquid chromatography coupled to a photodiode array detector (HPLC-DAD). The obtained results indicate the need for a quality control program of veterinary drugs comercialized in Brazil. Moreover, the present work aim studied the sorption of sulfonamides (SDZ, SDM and SQX) in four characteristic soils of the State of São Paulo. The studies were conducted as recommended by the OECD Guidelines 106. The sulfonamides were quantified in the soil solutions by a previously validated HPLC-DAD method. Adsorption/desorption data of sulfonamides in soils were fitted to Freundlich isotherms in the linear or logarithmic forms. A hysteresis of adsorption/desorption was evident in all four soils evaluated. The low values of the Freundlich coefficient (KF) obtained suggest weak adsorption of sulfonamides in soils, and therefore they tend to be leached and present high potential to contaminate surface and groundwater / Doutorado / Quimica Analitica / Doutora em Ciências

Ce doctorat porte sur la fonctionnalisation de silices colloïdales en vue de la rétention de micropolluants métalliques dans des effluents. Les nanoparticules et microparticules ouvrent des potentialités d’application dans de nombreux secteurs industriels (chimie, environnement, pharmacie...). Ainsi, ces travaux de recherche portent sur la synthèse et la caractérisation de matériaux composites submicroniques : il s’agit de silices colloïdales sur lesquelles sont greffés des silanes ou supportés des polysaccharides. Une des applications de ces travaux de recherche porte sur l’adsorption de métaux de transition sur ces composites en solution aqueuse. Dans le cadre de ce doctorat, les caractéristiques des composites sont définies par leur morphologie de surface, par l’étude des groupements fonctionnels présents, par détermination de leurs surfaces spécifiques ainsi qu’en solution aqueuse par détermination de leurs diamètres hydrodynamiques et de leurs potentiels zéta. Dans un premier temps, la fonctionnalisation de la silice a permis le greffage de groupements carboxyliques et amines dont tes taux de greffage obtenus ont été respectivement de 0,47 µmol/m² et 3,86 µmol/m². En présence de groupements amines, le potentiel  des composites est positif jusqu’ à pH 9 alors qu’il est négatif dès pH 3 pour des silices non fonctionnalisées. Dans un second temps, la silice est supportée par du chitosane dont le degré de désacétylation est de 77%. Conjointement, l’encapsulation de la silice est réalisées par du chitosane sur lequel des fonctions carboxyliques ont été greffées. La morphologie des particules est alors modifiée, leurs diamètres hydrodynamiques sont plus élevés et leurs potentiels  sont positifs jusqu’ à pH basique. La rétention d’ions métalliques (Cu(II) et Ni(II)) par ces composites à différents pH est ensuite étudiée. Pour chacun des cations métalliques, les capacités d’adsorption sont déterminées ainsi que les cinétiques d’adsorption. L’application de plusieurs modèles d’isotherme d’équilibre a été réalisée. Dans le cas de Cu(II), à pH 5, les meilleures capacités d’adsorption sont obtenues pour des silices supportées par du chitosane greffé : la capacité de rétention des ions Cu(II) est de 270 mg/g à pH 5. De même, c’est ce composite qui permet la meilleurs rétention des ions Ni(II) à pH 7 avec une capacité d’adsorption de 263 m/g. Concernant la cinétique, le modèle de réaction de surface du pseudo-second ordre s’applique bien aux résultats expérimentaux. / This study is focused on the preparation of three types of silica-based composites for the capture of Cu(II) and Ni(II) ions. The first strategy consists in coating chitosan on colloidal fumed silica after acidic treatment yielding the composite SiO2+CS. The second strategy can be separated into two routes: the first one involves surface grafting of silica with aminopropyltriethoxysilane to obtaining silica particles covered by amino groups (SiO2(NH2)). The second one involves in surface condensation of triethoxysilylbutyronitrile, followed by acidic hydrolysis of the surface-bound nitrile groups affording silica particles covered by carboxyl groups (SiO2(CO2H)). In the last step, chitosan has been grafted on the surface bound NH2 or -CO2H groups yielding the composites SiO2(NH2)+CS or SiO2(CO2H)+CS. The third strategy involves in the modified CS surface with -CO2H groups, followed by coating onto the non-modified silica nanoparticles to obtain the composite SiO2+CS(CO2H). The novel hybrid materials were characterized by IR spectroscopy, scanning electron microscopy, atomic force microscopy, and zeta potential measurements. Batch experiments were conducted to study the sorption performance of these composites for Cu(II) and Ni(II) removal from aqueous solution at optimum pH at 298 K. The kinetics were evaluated utilizing pseudo-first-order, pseudo-second-order, and intraparticle diffusion models. The adsorption kinetics followed the mechanism of the pseudo-second-order equation for all types of adsorbents. The adsorption isotherms were evaluated utilizing Langmuir, Freundlich, and Temkin models. The best interpretation for equilibrium data was given by Langmuir isotherm model. This study demonstrates that the adsorption capacities for Cu(II) ion is more efficient for the SiO2+CS (256 mg g-1) compared to SiO2(NH2) (75 mg g-1). However, the carboxyl grafted CS-coated silica (SiO2+CS(CO2H) exhibited an excellent adsorption capacity (333 mg g-1). In case of Ni(II), based on Langmuir isotherm the maximum adsorption capacity found to be 182 mg g-1for SiO2+CS, and 210 mg g-1 for SiO2(CO2H) + CS. Using single-metal solutions, these adsorbents were found to have an affinity for metal ions in order as Cu(II) > Ni(II). The adsorption of Cu(II) ion by SiO2+CS was affected by the nature of the respective anion. Application of these composite materials to remove Cu(II) and Ni(II) from aqueous solution was shown to be more efficient than the adsorption capacities of many sorbents probed by other research groups.

M. Tech (Department of Chemistry, Faculty of Applied and Computer Sciences) Vaal University of Technology. / A simple and rapid method for determination of estrone (E1) and β-estradiol (E2) was developed and validated using high performance liquid chromatography (HPLC). The solutions of standards and sample were prepared with distilled water. HPLC separation was performed in isocratic method 50/50 (water/methanol) using 4.6 mm x 250 mm id film thickness 5 µm) XDB-C18 capillary column, detector DAD, UV on 254 nm, temperature 20 ºC with flow rate of 2 mL/min, sample volume 20 µL and run time of 10 min. Calibration curves were linear between concentration range 1.0 - 15.0 ppm. The method was validated for limit of detection and quantification, linearity, precision, trueness and specificity. Also the method was applied to directly and easily to the analysis of the E1 and E2. Adsorption experiments were carried out in batch mode using multistirrer in a series of Erlenmeyer flasks of 50 ml capacity covered to prevent contamination having concentration ranges of E1 and E2 from 1 to 10 mg/L with adsorbent dose range 0.01 to 1 g at pH range 1 to 10 and temperature range 15°C to 35°C, placed on multistirrer. The results of the batch studies showed that simultaneous adsorption shows the maximum percent (91%) removal of E1 and (86 %) E2 at optimum temperature 25 °C of adsorbent dose 0.1 g, and pH 7. The mechanism, isotherms and kinetics of removal of two endocrine disrupting chemicals, estrone (E1) and β-estradiol (E2) by activated carbon adsorption were investigated in an agitated non-flow batch adsorption studies. Mathematical models were used to describe the adsorption phenomenon with the kinetic and thermodynamic parameters evaluated using the adsorption equilibrium data at varying temperatures. Higher adsorption rates were achieved at acidic to neutral pH ranges, with the sorption kinetic data showing a good fit to the pseudo second order rate equation and the Langmuir adsorption isotherm model for both E1 and E2. The Gibbs free energy were –16.68 kJ/mol and –17.34 kJ/mol for E1 and E2 respectively. The values of enthalpy for both E1 (84.50 kJ/mol) and E2 (90 kJ/mol) indicated a chemical nature of the sorption process. Both the isotherm and thermodynamic data obtained all supported the mechanism of adsorption of E1 and E2 to be mainly chemisorption’s supported by some physical attractions.

Per- and polyfluoroalkyl substances (PFASs) have become contaminants of increasing concern to society due to the contamination of drinking water and the ecosystem. A better understanding of the sorption and transport of PFASs in soil systems is urgently needed, however there have been few studies dedicated to investigating competitive sorption among PFASs, and there is no available model to model such effects. This study investigated the sorption behaviour of PFASs of different carbon chain lengths and different functional groups to investigate potential competitive sorption effects. A multi-compound sorption model was set up based on Langmuir single sorption isotherms. By modelling the different PFASs both separately and mixed together in bi-solute and multi-solute systems, the possibility of modelling competition effects between different PFASs for sorption sites was investigated. The model could describe the general tendency of longer chained PFASs to outcompete shorter chained PFASs, and that perfluorinated sulfonic acids (PFSAs) outcompete perfluorinated carboxylic aids (PFCAs). However, the model failed to reproduce multi-solute sorption results for PFOS at concentrations near or above the critical micelle concentration (CMC), indicating micelle formation and multilayer sorption, which cannot be described by a Langmuir isotherm-based model. The study showed that it is possible to model competitive effects among some PFASs using this approach, although more advanced models may be needed to model the sorption of long-chained PFASs where micelle formation may occur, which would require further research to derive values for the parameters necessary to perform this type of modelling. / Per- och polyfluorerade alkylsubstanser (PFAS) är kolväten där alla (per-) eller vissa (poly-) avväteatomerna bytts ut mot fluoratomer. PFAS är syntetiska kemikalier som började produceras på 1950-talet och kan beså av olika långa kolkedjor och funktionella grupper vilket påverkar deras egenskaper.Den funktionella gruppen är det hydrofila (vattenälskande) ”huvudet” på molekylen vilken kan bestå avolika kemiska grupper, av vilka de två vanligast studerade grupperna är sulfonsyror (PFSA) ochkarboxylsyror (PFCA), men det finns även många andra grupper. PFAS delas också in i långa och kortaföreningar där långa PFAS har en kolkedja som är längre än 6 kol och korta PFAS har 6 kol eller färrei sin kolkedja. Den molekylära strukturen med ett hydrofilt huvud och en hydrofob (vattenhatande)fluorerad kolkedja gör att PFAS ofta används som ytaktiva ämnen. Det finns fler än 4 700 PFAS och deanvänds i många olika produkter så som vatten- och fettavstötande tyger, mattor, rengöringsmedel, plastoch non-stickbeläggningar i t.ex. stekpannor. På grund av PFAS unika egenskaper har de också använtsi brandskum där de bildar en tunn film av vatten mellan skummet och det brinnande bränslet vilketeffektivt släcker branden. Men användningen av PFAS i brandskum har visat sig särskilt problematisktdå det innebär ett direkt utsläpp av stora mängder PFAS i naturen. Kol-fluorbindningen är väldigt stark och organismer klarar inte av att bryta bindningen vilket gör attPFAS inte bryts ned utan ansamlas i naturen. Detta tillsammans med deras vattenlöslighet resulterar imånga fall i stora föroreningsplymer i grundvattnet. Livsmedelsverket har rapporterat att dricksvattnetför mer än 3,6 miljoner människor är påverkat av PFAS föroreningar i Sverige. PFAS misstänks hacancerogena och hormonstörande effekter och flera PFAS föroreningar är nu reglerade inom EU. Menäven om nya utsläpp är reglerade behöver de PFAS som redan finns i naturen åtgärdas. Det finns mångatekniker för att åtgärda PFAS-förorenade områden där man utnyttjar molekylernas förmåga att binda tillfast material (sorption). Hur starkt molekylerna binder till materialet beror på en rad faktorer så somkolkedjans längd, mängden organiskt material i vattnet och/eller materialet PFAS ska binda till,elektrostatiska interaktioner med andra närvarande joner i vattnet samt vattnets pH. I den här studien utnyttjas dessa egenskaper för att se hur effektivt olika PFAS binder till olikamaterial med hjälp av matematiska modeller. Även potentiella konkurrenseffekter undersöks då olikaPFAS binder olika starkt. Om det då finns ett begränsat antal platser för molekylerna att binda till kanen del PFAS konkurreras ut av andra PFAS som binder starkare. Det påverkar hur effektiv enåtgärdsmetod är för att rena vattnet. Studien visade att det till viss del är möjligt att modellera tävlingseffekter mellan olika PFAS, därPFAS med längre kolkedjor konkurrerar ut kortare PFAS, och PFSA är mer konkurrenskraftiga jämförtmed PFCA. Men mer avancerade modeller krävs för modellering av längre PFAS vid högrekoncentrationer då deras förmåga att bilda aggregat/miceller försvårar modelleringen. Fler studierbehövs därför för att öka mängden information som krävs för att använda dessa mer avancerademodeller.

Fluoride, the most abundant form of fluorine, is an ion released into the environment, mainly via anthropogenic sources and erosion of mineral rocks. Although the element is well known for its health benefits on teeth and bones, it can as well be a harmful pollutant. In some areas on earth, the population can not obtain drinking water that is below the guideline limits of fluoride, which is set to 1.5 mg/L by the world health organization (WHO). Therefore there is a relevance to develop methods that can clean the waters from excess fluoride. The potential problems when it comes to finding these types of methods is that they can be expensive. However, materials generated as residues in industrial processes may be low in cost. In this thesis, silicon reduced AOD-slag, a material generated as a by-product from the production of stainless steel, was examined by its fluoride adsorption behavior and adsorption capacity. The concentrations of fluoride were measured with ion chromatography (IC) and the concentration of metals were analyzed with microwave plasma atomic emission spectroscopy (MP-AES). Additionally pH and conductivity were measured. The functionality of the material surface was analyzed with isotherm modeling, where the Sips isotherm model was tested. Moreover, optimization of the slag was performed by heat treating the material, as well as a sorption kinetics test on both optimized and original slags. The results from the analysis indicated that the material corresponds well to the Sips isotherm. Considering this result it is suggested that at low concentrations, the surface can be characterized as heterogeneous, with different binding energies at different available sites. At higher concentrations the Sips-model explains the surface to be saturated when a monolayer of fluoride is formed. Therefore the binding on the slag surface can be described to have an inner-sphere and covalent character. The metal analysis showed that calcium ions are released from the slag when in aqueous solutions. The presence of calcium in the liquid samples are believed to result in formations of solid calcium fluoride (CaF2), precipitated on the slag surface. Lastly, the maximum fluoride removal is believed to differ between different types of AOD-slag, where there as well are possibilities to optimize the material.

Reversed-phase liquid chromatography (RPLC) is a commonly used separation technique in chemistry. Nevertheless, the mechanistic interactions at the molecular level among the eluent, analyte, and the stationary phase are not fully understood. Because of this limited understanding, optimization of the separation must be done experimentally. Learning more about molecular interactions should aid in improving separations. We are currently using second-harmonic generation (SHG) spectroscopy to investigate how analytes adsorb to the surface. SHG is a spectroscopic technique that produces signal only at places of non-isotropic symmetry; this typically occurs at surfaces. SHG can be used to produce surface isotherms of test analytes adsorbed to a model C18 stationary phase surface. Fitting these isotherms with a Langmuir model produces an adsorption equilibrium constant. However, the equilibrium constant can only be accurately determined if the true bulk concentration is known; this thesis describes an approach to ensure this. The equilibrium constant relates to Gibbs free energy and is the start to obtaining other thermodynamic information. The long equilibration times of analytes with the stationary phase observed in this study emphasize the importance of both thermodynamic information and kinetic values for understanding retention. Once equilibrium constants and other parameters are accurately obtained, this information can be used to improve predictions and calculations from numerical models.