Atualmente, a preocupação com a redução da poluição industrial tem motivado os pesquisadores na busca de novas tecnologias para o tratamento de resíduos industriais. Tecnologias limpas, como a eletrodiálise, são capazes de tratar alguns destes resíduos, como por exemplo o efluente da indústria de galvanoplastia, minimizando os impactos que ocorreriam caso eles fossem descartados diretamente no meio ambiente. O componente principal desta técnica é a membrana na qual ocorre a etapa de retirada dos íons da solução. Atualmente estas membranas são importadas e caras, o que justifica o desenvolvimento de membranas eficientes e acessíveis. Neste sentido, no presente trabalho membranas de poliestireno sulfonado/ poliestireno de alto impacto (SPS/HIPS), polianilina dopada com ácido canforsulfônico/ poliestireno sulfonado/ poliestireno de alto impacto (PAniCSA/SPS/HIPS), polianilina sulfonada/ poliestireno sulfonado/ poliestireno de alto impacto (SPAN/SPS/HIPS), e polianilina dopada com ácido p-tolueno sulfônico/ poliestireno sulfonado/ poliestireno de alto impacto (PAniTSA/SPS/HIPS) foram desenvolvidas usando o método de mistura química. As membranas foram caracterizadas utilizando as técnicas Análise termogravimétrica (TGA), Análise dinâmico Mecânica (DMA), e Microscopia Eletrônica de Varredura (MEV). Membranas foram submetidas a curvas corrente-potencial e ensaios de eletrodiálise em soluções de NaCl e KCl, a fim de determinar o transporte iônico através das mesmas. Os resultados foram comparados com uma membrana comercial Selemion CMT. A extração percentual média para íons de Na+ obtidos pelas membranas desenvolvidas foi superior a 20%. / Nowadays the concern with the reduction of industrial pollution has motivated researchers to found out new technologies for treatment of industrial waste. The clean technologies, as electrodialysis, are capable of treating some these residues, as for example the galvanoplasty’s waste, minimizing the impacts that would happen to them if they were discarded directly on the environment. The main component of this technique is the membrane on which occurs the ions removal stage of the solution. The membranes are imported and expensive what justifies the development of efficient and accessible membranes. In this sense, in the present work membranes of sulfonated polystyrene / high impact polystyrene (SPS/HIPS), polyaniline doped with camphorsulfonic acid / sulfonated polystyrene / high impact polystyrene (PAniCSA/SPS/HIPS), sulfonated polyaniline/ sulfonated polystyrene / high impact polystyrene (SPAN/SPS/HIPS), and polyaniline doped with p-toluenesulfonic acid / sulfonated polystyrene / high impact polystyrene (PAniTSA/SPS/HIPS) were developed using chemical mixture method. Membranes were characterized by Infrared Spectroscopy (FTIR), Thermogravimetric Analysis (TGA), Dynamic Mechanical Analysis (DMA) and Scanning Electronic Microscopy (SEM). Membranes were submitted to current-voltage curves and electrodialysis experiments with NaCl and KCl solutions, in order to determine ionic transport through them. Results were compared with a commercial membrane, Selemion CMT. The average percent extraction for Na+ ions obtained by membranes developed were beyond 20%.

Atualmente, a preocupação com a redução da poluição industrial tem motivado os pesquisadores na busca de novas tecnologias para o tratamento de resíduos industriais. Tecnologias limpas, como a eletrodiálise, são capazes de tratar alguns destes resíduos, como por exemplo o efluente da indústria de galvanoplastia, minimizando os impactos que ocorreriam caso eles fossem descartados diretamente no meio ambiente. O componente principal desta técnica é a membrana na qual ocorre a etapa de retirada dos íons da solução. Atualmente estas membranas são importadas e caras, o que justifica o desenvolvimento de membranas eficientes e acessíveis. Neste sentido, no presente trabalho membranas de poliestireno sulfonado/ poliestireno de alto impacto (SPS/HIPS), polianilina dopada com ácido canforsulfônico/ poliestireno sulfonado/ poliestireno de alto impacto (PAniCSA/SPS/HIPS), polianilina sulfonada/ poliestireno sulfonado/ poliestireno de alto impacto (SPAN/SPS/HIPS), e polianilina dopada com ácido p-tolueno sulfônico/ poliestireno sulfonado/ poliestireno de alto impacto (PAniTSA/SPS/HIPS) foram desenvolvidas usando o método de mistura química. As membranas foram caracterizadas utilizando as técnicas Análise termogravimétrica (TGA), Análise dinâmico Mecânica (DMA), e Microscopia Eletrônica de Varredura (MEV). Membranas foram submetidas a curvas corrente-potencial e ensaios de eletrodiálise em soluções de NaCl e KCl, a fim de determinar o transporte iônico através das mesmas. Os resultados foram comparados com uma membrana comercial Selemion CMT. A extração percentual média para íons de Na+ obtidos pelas membranas desenvolvidas foi superior a 20%. / Nowadays the concern with the reduction of industrial pollution has motivated researchers to found out new technologies for treatment of industrial waste. The clean technologies, as electrodialysis, are capable of treating some these residues, as for example the galvanoplasty’s waste, minimizing the impacts that would happen to them if they were discarded directly on the environment. The main component of this technique is the membrane on which occurs the ions removal stage of the solution. The membranes are imported and expensive what justifies the development of efficient and accessible membranes. In this sense, in the present work membranes of sulfonated polystyrene / high impact polystyrene (SPS/HIPS), polyaniline doped with camphorsulfonic acid / sulfonated polystyrene / high impact polystyrene (PAniCSA/SPS/HIPS), sulfonated polyaniline/ sulfonated polystyrene / high impact polystyrene (SPAN/SPS/HIPS), and polyaniline doped with p-toluenesulfonic acid / sulfonated polystyrene / high impact polystyrene (PAniTSA/SPS/HIPS) were developed using chemical mixture method. Membranes were characterized by Infrared Spectroscopy (FTIR), Thermogravimetric Analysis (TGA), Dynamic Mechanical Analysis (DMA) and Scanning Electronic Microscopy (SEM). Membranes were submitted to current-voltage curves and electrodialysis experiments with NaCl and KCl solutions, in order to determine ionic transport through them. Results were compared with a commercial membrane, Selemion CMT. The average percent extraction for Na+ ions obtained by membranes developed were beyond 20%.

O presente trabalho visou a construção e avaliação de eletrodos de membrana sólida cristalina seletivos a cobre e prata. Obteve-se o sulfeto de prata, material eletroativo usado na preparação de membranas seletivas a íons Ag+, por precipitação com gás sulfídrico em meio ácido. Eletrodos com membranas de 1,0 e 0,50 mm de espessura apresentaram respectivamente limites nernstianos de 10-4 e 10-5 Mol.L-1 e precisão de ± 0,1 e 1 mV nas leituras de potencial. Os sulfetos de cobre e prata, usados na preparação de membranas seletivas para determinação de cobre, foram obtidos por precipitação simultânea com gás sulfídrico, tioacetamida em meio ácido e tiouréia em meio amoniacal. Difratogramas de Raios X revelaram que o material obtido com tiouréia corresponde ao sulfeto ternário, Cu2S.3Ag2S ou Ag1,55Cu0,45S, responsável pela resposta seletiva do sensor em soluções de Cu2+. O eletrodo construído a partir deste sulfeto, onde o cobre aparece no estado monovalente, apresentou limite nernstiano da ordem de10-7Mol.L-1, fornecendo resultados satisfatórios na determinação deste metal em amostras de aguardente e álcool. Cálculos termodinâmicos mostraram que quando membrana é constituída de CuS, um contacto elétrico efetuado através de cobre ou prata é instável, uma vez que ocorre a formação de Cu2S. Os resultados experimentais conduziram a um novo modelo para explicar o mecanismo de resposta do eletrodo, o qual se baseia na reação: Cu2S (memb) + Cu2+ (sol) ↔ CuS (memb) + 2 Cu + (sol). A atividade de Cu+ na interface eletrodo / solução é controlada pela atividade de Cu2+ nas soluções de medida, de modo que o sensor funciona como um eletrodo de Cu2S/CuS em contacto com o sistema Cu2+/Cu+. / Present work deals with the assembling and testing of solid membrane electrodes for copper and silver. The silver sulphide used to prepare the membrane selective to Ag+ was precipitated with hydrogen sulphide in acidic medium. Electrodes 1,0 and 0,50 mm thick present Nernstian limits of 10-4 and 10-5 Mol.L-1 order with a ± 0,1 and 1 mV respectively. A mixture of silver sulphide and copper sulphides were used for the copper (II) selective electrode. This solid was prepared from Cu2+ and Ag+ in the same solution with hydrogen sulphide or thioacetamide both in acid medium and with thiourea in ammoniacal medium. X-Ray diffractograms shows that the solid prepared from thiourea solutions presents significant contribution of jalpaite Ag1,55Cu0, 45S (in fact Cu2S.3Ag2S). An important finding was the presence of copper (I) in the matrix and this has been also found to the responsible for the higher performance of this electrode with a limiting response to 10-7 Mol.L-1 copper (II). In fact thermodinamic calculation has show instability of a contact of Ag or Cu with CuS solid, as Cu2S must be formed in any case. On this basis, the theory of the electrode is based in the following reaction which takes place on the electrode surface: Cu2S (memb) +CU2+ (sol) ↔ CuS (memb) + 2 Cu+(aq) K = 10-13 M. On this basis the Cu+ activity at the electrode / solution interface is controled by the activity of Cu2+ of the solution and the Cu2+/ Cu+ system in contact with the solid matrix is defined.

Fluoride ion is an accompanying impurity in a wide variety of chemical gypsum throughout the world. In this study, the Ion Selective Electrode (ISE) method, the Ion Chromatography (IC) method and the standard Willard and Winter method of fluoride analysis were adapted and compared for use in the quantification of fluoride in South African chemical gypsum. During the use of ISE, the pH of sample solutions was found to be a critical parameter for the results to be meaningful. An operating pH of approximately 5 was suitable for consistency of results. It was important to ensure the existence of the ionised form of fluorine in solution, because the detection was based on the sensitivity of the membrane electrode to this species. In the case of the Willard and Winter method, the traditional visual indicator titration was replaced by a more sensitive spectrophotometric detection, because of low fluoride levels in the chemical gypsum. The parameter sensitive reaction rate approach was adapted, and the reaction allowed to go to completion to enable measurement with a bench top spectrophotometer. The IC method required a good separator since fluoride ions usually eluted too early for detection on common ion exchange columns. The data handling of the chromatographic software was thoroughly examined and consistent integration of the chromatograms maintained. Sample preparation of the chemical gypsum involved particle size reduction through grinding. No trend between fluoride impurity and the particle size of the sample was observed. <p. The quantity of fluoride in Kynoch and Omnia phosphogypsum were found to be 0.10% and 0.04% respectively. The Tioxide chemical gypsum, titangypsum, was found to contain in the region of 0.02% fluoride. Generally, the level of fluorine (F) has to be reduced to about 0.2% before phosphogypsum can be used as substitute for natural gypsum in the cement industry. The aim of this study is to critically evaluate three analytical methods, namely, the Willard and Winter standard method of fluoride analysis, the ISE method, and IC as applied in the quantification of fluoride in chemical gypsum. Secondly, the efficiency of treatment of the chemical gypsum with water, lime and sulphuric acid was investigated. The ISE method was found to be faster and relatively simpler versus both Willard and Winter and the IC methods. The IC method was quite superior for indicating general complexity of the sample and it was faster than the Willard and Winter method. The standard Willard and Winter method was generally found to be long and tedious. The three methods validated one another as percentages of fluoride in the chemical gypsum samples were the same. The study indicated that a sulphuric acid pretreatment of the chemical gypsum was the most effective (90%) in the removal of fluoride impurity compared to the lime treatment and water washing (9%). However, the water washing would be inexpensive for practical treatment of chemical gypsum at plant level. / Thesis (PhD(Chemistry))--University of Pretoria, 2006. / Chemistry / unrestricted

The focus of this project was to investigate the use of interdigitated electrodes (IDEs) as impedimetric ion-selective chemical sensors for the determination of several important analytes found within a freshwater aquarium. The overall aim of this research was to work towards a prototype sensing device that could eventually be developed into a commercial product for sale to aquarium owners. Polyvinyl chloride and sol-gels containing commercially-available ionophores for four aquarium-significant ions (NH4+, NO2-, NO3- and pH) were prepared and investigated for use within polymeric ion-selective membranes. Three separate IDE transducers were produced using either photolithography or screen-printing microfabrication techniques. A sinusoidal voltage was applied to the IDEs and an LCR meter was used to measure changes in the conductance and capacitance of the ion-selective membrane layer deposited over the electrode digits. Each ionophore, when tested within potentiometric ion-selective electrodes (ISEs), was found to be suitable for further investigation within IDE devices. Sol-gels were investigated as a potential membrane material for a coated wire electrode; however, poor response characteristics were observed. An IDE sensor fabricated in-house using lift-off photolithography and spin-coated with a polymeric membrane was found to produce non-selective responses caused by changes in the conductivity of the test solution. IDE devices with reduced geometric parameters were purchased and coated with a selective polymeric membrane. When the membrane was spin-coated, non-selective responses were observed; therefore, drop-coating of the membrane material was investigated. This initially resulted in an unacceptably long response time; however, this effect was reduced by decreasing the membrane solution viscosity prior to drop-coating. A fully-screen printed carbon IDE device was fabricated by incorporating the ionophore into a support matrix based on a commercial dielectric paste. Matrix interferences to the sensor response were reduced by printing ‘build-up’ layers over the sensing area prior to the ion-selective membrane. Two novel routes for monitoring the water quality of an aquarium, using IDE sensors fabricated by either photolithography or screen-printing, have been demonstrated. Due to the commercial aspect of this project, it is important to consider the final cost of producing these sensors. Both of the techniques used to produce ion-selective sensors require further experimentation to optimise the sensor response, prior to integration within a multi-analyte sensing prototype.

No description available.

A cation-responsive electrode system has been developed which incorporates aza-substituted crown ethers as ligands. In a novel application, uncomplexed crown ethers were used in the pelletized form for ionic transport. Electrodes have been produced which can be conditioned for a particular ion and following their use, be reconditioned and reused for other ions. Preparation method and lifetime studies are included. The responses of two crown ethers with plasticizers were evaluated for thirteen representative cations. The concentration range covered in each evaluation was 1 x 10-1 to 1 x 10-7 M. For those ions exhibiting Nernstian or near-Nernstian response, selectivity coefficients were derived.

Ion-selective polymeric optical sensors – ion optodes – are a promising alternative to ion-selective electrodes and fluorescent dyes for analytical and biological applications, e.g. extra- and intracellular measurements. They are non-toxic, highly selective robust probes for ionic fluxes monitoring. A large-scale fabrication of ion optodes using a solvent displacement method is introduced. This method is a single-batch process that does not require any additional steps. The influence of numerous parameters, e.g. surfactant concentration, solvent nature and membrane concentration, on the average size of the synthesized optodes was studied. The solvent displacement method allows control of the particle size in 200 nm to 30 μm range. Ion optodes selective for sodium, potassium, and calcium cations were prepared and calibrated for hydrogen (pH), sodium, potassium, and calcium. Fabricated sensors demonstrated excellent selectivity, low drift, high stability and reproducibility. Further studies of ion-optodes of different sizes but the same chemical composition revealed a significant shift in their response function. This bias is clearly seen for all fabricated optodes. A strong correlation between a calculated specific surface area and the apparent ion-exchange constant was observed. Considering this, it may be hypothesized that the surface phenomena are contributing to the overall optode response resulting in the observed effect. As a consequence, the response models, developed for the macroscopic ion optodes, cannot be easily applied to the probes at micron- and nano-scale. A primary concern for continuous sensing application of optical sensors is photobleaching of lipophilic fluorescent dye which prevents quantitative fluorescence measurements. Quantum dots, known for their high photostability, brightness and broad excitation spectra with narrow emission bands, were incorporated into polymeric matrix. They excited a fluorophore indirectly, thus, reducing its photobleaching and increasing sensors life-time. We created a composite, quantum dots doped, polymeric sensor that can be integrated into high-throughput detection platforms, such as flow cytometry, chip-based micro-total analysis system technologies, or bundled optical fiber arrays. Ultimately, a fabricated ion-optode was introduced into a Boolean logic gate serving as a reporting microparticle. It responded to the pH changes generated in situ by the enzyme logic system. The present work aimed scaling down the size of biocomputing functional units which might reach the information processing by single molecules associated with signal-transducing single nanoparticles. / Graduation date: 2012

Thesis (M.S.)--Mississippi State University. Department of Chemistry. / Title from title screen. Includes bibliographical references.

Orientadores: Carlos Emílio Levy, José Dirceu Ribeiro / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Ciências Médicas / Made available in DSpace on 2018-08-23T21:33:52Z (GMT). No. of bitstreams: 1 Goncalves_AlineCristina_M.pdf: 2485320 bytes, checksum: 5804a728c4482b025babf1bea314fbb3 (MD5) Previous issue date: 2013 / Resumo: Introdução: Fibrose cística (FC) é uma doença genética autossômica recessiva mais comum entre caucasianos. Caracterizam-se pelo defeito no transporte iônico através da membrana celular nas células epiteliais das vias aéreas, pâncreas, glândulas salivares, sudoríparas, intestino e aparelho reprodutor. As secreções mucosas ficam espessas e viscosas, causando obstrução ao nível de ductos e canalículos glandulares. Objetivo: Verificar os parâmetros bioquímicos da saliva, a saúde gengival e dental de pacientes com FC e analisar sua relação com a gravidade da doença e medicações. Casuística e método: Estudo prospectivo de pacientes atendidos no ambulatório de FC do HC Unicamp e indivíduos saudáveis. Destes pacientes foram comparados os parâmetros bioquímicos da saliva com os de indivíduos saudáveis, pela técnica de eletrodo íon seletiva, aparelho de gasometria ABL835®. Foi realizado um estudo descritivo de alguns indicadores da saúde bucal, microbiota salivar e do escarro de pacientes com FC e analisados com a gravidade da doença pelo escore de Shwachman. Resultados: Os íons cloro e sódio na saliva foram estatisticamente maiores, nos pacientes com fibrose cística que nos controles. Com aplicação da curva ROC determinamos, respectivamente para o sódio e cloro Cut-off de 13,5 mmol/L e 20 mmol/L; Sensibilidade:73,4% e 68,1% e Especificidade:70,6% e 72,9%. Com relação ao índice gengival (IG), observamos uma relação direta com o índice de placa (IP), contudo, não houve correlação entre o índice de placa ou índice gengival com o escore de Shwachman, uso crônico de antimicrobianos e de dornase alfa. Conclusões: Observou-se baixa prevalência de cárie nas crianças com FC e quantidade significativa de defeitos de esmalte, acúmulo de cálculo dental ou tártaro, que não há correlação entre IP e IG e escore de Shwachman, e entre IP e IG e uso de Dornase Alfa e uso crônico de antimicrobianos. Não houve correlação entre as concentrações de Cl- e Na+ na saliva com o escore clínico de Shwachman. No grupo FC os níveis de sódio, cloro, potássio e o pH encontraram-se aumentados e o volume de saliva foi menor que o observado no grupo controle. Novos estudos serão necessários para esclarecer a real utilidade da avaliação dos parâmetros bioquímicos na saliva para diagnóstico da FC. Na avaliação da microbiota da saliva com o material do trato respiratório, a saliva não apresenta boa relação com a presença de patógenos pulmonares crônicos e não deve ser utilizada para este fim / Abstract: Background: Cystic fibrosis (CF) is an autosomal recessive genetic disease most common among Caucasians. Characterized by a defect in ion transport across the cell membrane in airway epithelial cells, pancreas, salivary glands, sweat glands, intestine, and reproductive tract. Mucous secretions become thick and viscous, causing obstruction at the level of ducts and glandular tubules. Objective: To investigate the biochemical parameters of saliva, gingival health and dental patients with CF and analyze its relationship with disease severity and medications. Patients and methods: Prospective study of CF patients in attended of Hospital de Clínicas da Unicamp, and healthy subjects. These patients were compared biochemical parameters of saliva with healthy subjects, the technique of ionselective electrode, Radiometer blood gas analyzer ABL835®. We conducted a descriptive study of some indicators of oral health, salivary microbiota and sputum of CF patients and analyzed with the severity of the disease by the Shwachman score. Results: The chloride and sodium ions in saliva were significantly higher in patients with cystic fibrosis than in controls. With application of the ROC curve determined respectively for sodium and chlorine Cut-off 13.5 mmol/L and 20 mmol/L; Sensitivity 73.4% and 68.1% and Specificity 70.6% and 72 9%. With respect to gingival index, we observed a direct relationship with the index plaque, however, there was no correlation between plaque index and gingival index with Shwachman, chronic use of antibiotics and DNase. Conclusions: We found a low prevalence of caries in children with CF and significant amount of enamel defects, accumulation of dental calculus, no correlation between plaque index (PI) and gingival inflammation index (GI) and score Shwachman, and between PI and GI and use of dornase alpha and chronic use of antimicrobials. There was no correlation between the concentrations of Cl- and Na+ in saliva with Shwachman clinical score. In the CF group levels of sodium, chloride, potassium and pH were found increased and the volume of saliva was lower than that observed in the control group. Further studies are needed to clarify the usefulness of the assessment of biochemical parameters in saliva for diagnosis of CF. In assessing the salivary microflora with the material of the respiratory tract, saliva does not show good correlation with the presence of chronic lung pathogens and should not be used for this purpose / Mestrado / Saude da Criança e do Adolescente / Mestra em Ciências