Conselho Nacional do Desenvolvimento Científico e Tecnológico (CNPq) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Fundação Araucária de Apoio ao Desenvolvimento Científico e Tecnológico do Paraná / Universidade Tecnológica Federal do Paraná (UTFPR) / Nanopartículas (NPs) metálicas são uma classe importante de nanomateriais que têm fascinado cientistas pelas suas propriedades ópticas extraordinárias devido sua ressonância plasmônica de superfície. A frequência dessa ressonância depende fortemente do tamanho, forma, interações entre partículas vizinhas, propriedades dielétricas e meio em que as NPs se encontram. Sendo assim, as NPs tornaram-se materiais importantes para aplicações em sensoriamento óptico, pois podem melhorar a sensibilidade e, também, a seletividade desses sensores. Neste trabalho é reportado o crescimento de nanocompósitos formados por nanopartículas de prata (AgNPs) recobertas pelo complexo β-dicetonato de európio, [Eu(tta)3(H2O)2], em que o ligante tta é o β-tenoiltrifluoracetonato, em um substrato de sílica para futura aplicação em sensores de fibra óptica. Especificamente, esse trabalho oferece a oportunidade de estudar a interação entre a SPR das AgNPs e a fluorescência do complexo luminescente, bem como as mudanças nas propriedades ópticas do material como a intensificação da fluorescência pela presença da superfície metálica nanoparticulada (metal enhanced fluorescence - MEF) ou ainda a intensificação da absorção. Os resultados obtidos pelas caracterizações realizadas pelas técnicas de DRX, FT-IR e MET indicam que a rota química de síntese do nanocompósito proposta mostrou-se funcional e, além disso, os resultados obtidos por espectroscopia UV-Vis e por fotoluminescência mostraram a existência da interação entre a banda de absorção do complexo e a banda de absorção plasmônica das AgNPs. Nos espectros UV-Vis, foram observados deslocamentos para valores de maiores comprimento de onda da banda do complexo referente a transição π-π* do ligante tta, devido à interação eletromagnética entre as AgNPs e o [Eu(tta)3(H2O)2], quando as moléculas do complexo recobrem de maneira organizada a superfície das NPs, formando agregados J. Nos espectros de emissão, essa interação converteu-se em supressão da luminescência pela concentração do complexo, ou seja, pela perda de energia caracterizada pela formação de agregados J na superfície das AgNPs e, também, pela a perda de energia para a superfície metálica, competição de absorção entre as AgNPs e o complexo de európio no comprimento de onda de excitação. No entanto, quando a concentração do complexo é cerca de 10 vezes maior, foi observada a intensificação da luminescência, pois a SPR excita os emissores de luz próximo ao metal, por interações dipolo-dipolo. Sendo assim, as propriedades ópticas dos nanocompósitos estudados aqui mostram que tais materiais são excelentes candidatos para aumentar a sensibilidade dos sensores baseados em fibras ópticas. / Metallic nanoparticles (NPs) are an important class of nanomaterials that have fascinated scientists due to their extraordinary optical properties owing to their surface plasmon resonance (SPR). The SPR frequency is strongly dependent of the size, shape, interparticle interactions, dielectric properties and local environment of the nanoparticle. Therefore, NPs have been recognized in optical sensors application mainly due to their high sensitivity and selectivity displayed on devices. Herein, we report the growth of a nanocomposite formed by silver nanoparticles (AgNPs) coated with europium complex, [Eu(tta)3(H2O)2], onto the surface of silica substrate. For future application in fiber optic sensors. Specifically, this work offers the opportunity to study the interaction between the SPR of the AgNPs and the fluorescence of the luminescent complex and the changes in the optical properties of the material such as metal enhanced fluorescence (MEF) or the intensification of the absorption. The proposed route of synthesis of the nanocomposite was functional and the results showed the existence of the interaction between the complex absorption band and the surface plasmon band of the AgNPs. In the UV-Vis spectra, red shifts of the π-π* absorption were observed due to electromagnetic interaction between AgNPs and [Eu(tta)3(H2O)2] when the complex cover the surface of the NPs in an organized way (J-aggregates). In photoluminescence spectra, this interaction quenched the luminescence by concentration, that is, by the loss of energy characterized by the J-aggregation on the surface of the AgNPs and by the loss of energy for the metal surface due to absorption competition between the AgNPs and the europium complex. However, when the concentration of the complex is higher, metal enhanced fluorescence was observed because the SPR excites the light emitters near the metal, by dipole-dipole interactions. Thus, the optical properties of the nanocomposite studied here show that this material is an excellent candidate for increasing the sensitivity of the sensors.

O custo elevado na fabricação de peças pela tecnologia da Manufatura Aditiva (AM) impulsionou, nos últimos anos, várias pesquisas visando ao desenvolvimento de novos equipamentos e novos materiais. Neste contexto, uma resina fotossensível, desenvolvida anteriormente com componentes disponíveis no mercado nacional pelo grupo de pesquisa ao qual este trabalho está inserido, apresentou baixas propriedades mecânicas e alta contração do material quando comparada aos materiais disponíveis no mercado. Assim, uma alternativa para melhorar essas propriedades é a obtenção de nanocompósitos. Estes compreendem uma nova classe de materiais, em que substâncias inorgânicas de dimensões nanométricas, tais como argilas e outros argilominerais, são finamente dispersas dentro de uma matriz polimérica. Dessa forma, o presente estudo tem por objetivo preparar e caracterizar um nanocompósito fotossensível de acrílico/argila curado por exposição à radiação UV-C, com propriedades mecânicas de tração, flexão e dureza, e contrações adequadas para aplicação em processo de AM. Para tanto, a formulação original, composta pelos monômeros Trimetilpropano Triacrilato (TMPTA®) e Ácido Metacrilato Modificado (Ebecryl 171®), oligômero Amina Acrilada (Ebecryl 7100®), Co-iniciador Benzofenona 99% (Additol BP®) e o fotoiniciador Additol LX®, foi testada com o acréscimo das argilas Cloisite 20® e a BN-CT nas concentrações de 0,5%, 1,0% e 1,5% (m/m) da massa total. Após o preparo dessas formulações obtidas pela dispersão 1 (agitação magnética) e 2 (agitação magnética e ultrassom), foram preparados corpos de prova pelo princípio de adição sucessiva de camadas pela AM. A caracterização foi realizada através da análise da contração, ensaios de resistência à tração, flexão e dureza, microscopia eletrônica de varredura (MEV), difração de raios X(DRX), termogravimetria (TG) e viscosidade. O empenamento do material apresentou uma melhora média de 18,27% com argila Cloisite 20® e de 11,30% com a argila BN-CT. Os resultados dos ensaios de tração, flexão e dureza não apresentaram aumentos significativos nas propriedades mecânicas. O MEV não apresentou nenhuma delaminação entre as camadas após a realização do teste de flexão. A análise de DRX não apresentou pico de difração, sugerindo a formação de nanocompósito com estrutura intercalada e/ou esfoliada para todas as formulações com argila. O ensaio de TG mostrou que a adição de argila nas formulações não apresentou melhoras significativas na estabilidade térmica do nanocompósito. Também a viscosidade não apresentou melhoras à temperatura de 25°C, mas apresentou uma redução significativa da viscosidade a 35°C. Apesar dos resultados não muito promissores em termos de resistência mecânica, as formulações com argila podem ser empregadas na AM, considerando essas limitações. / The high cost in manufacturing parts for the of Additive Manufacturing technology (AM) boosted in recent years several studies aiming the development of new equipment and new materials. With this in mind, a photosensitive resin previously developed by the research group to which this work is inserted with components available in the domestic market, presented low mechanical properties and high shrinkage of the material compared to the materials available on the market. One alternative for improving these properties is to obtain nanocomposites. They comprise a new class of materials in which inorganic substances of nanometric dimensions, such as clays and other minerals, are finely dispersed within a polymeric matrix. Thus, this study aims to prepare and characterize a photosensitive acrylic / clay nanocomposite cured by exposure to UV-C radiation, with mechanical properties of tensile, bending and hardness, and shrinkage propers for use in AM process. Therefore, the original formulation, composed of trimethylolpropane triacrylate (TMPTA®) and Acid Methacrylate Modified (Ebecryl 171®)monomers, Amina acrylated (Ebecryl 7100®)oligomer, Co-initiator Benzophenone 99% (Additol BP®) and the photoinitiator Additol LX® was tested with the addition of the clays Cloisite 20® and BN-CT in concentrations of 0.5%, 1.0% and 1.5% (w/w) of total weight. After preparing these formulations, obtained by dispersion 1 (magnetic stirring) and 2 (magnetic stirring and ultrasound), it was prepared specimens by the principle of adding successive layers by AM. The characterization was perform by shrinkage analysis, tensile strength, bending and hardness tests, scanning electron microscopy (SEM), X-ray diffraction (XRD), thermogravimetry (TG) and viscosity. The warpage of the material showed an average improvement of 18.27% with the Cloisite 20® clay and 11.30% with the BN-CT clay. The results of the tensile, flexural and hardness testing did not show significant increases in mechanical properties. The SEM showed no delamination between the layers after the bending test was performed. The XRD analysis showed no diffraction peak, suggesting the formation of nanocomposite with intercalated and / or exfoliated structure for all formulations with clay. The TG test showed that the addition of clay in the formulations presented no significant improvements in thermal stability of the nanocomposite. The viscosity showed no improvement at a temperature of 25 °C, but showed a significant reduction in viscosity at 35 °C. Although not very promising results in terms of mechanical strength, the formulations with clay can be used in the AM considering these limitations.

Conselho Nacional do Desenvolvimento Científico e Tecnológico (CNPq) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Fundação Araucária de Apoio ao Desenvolvimento Científico e Tecnológico do Paraná / Universidade Tecnológica Federal do Paraná (UTFPR) / Nanopartículas (NPs) metálicas são uma classe importante de nanomateriais que têm fascinado cientistas pelas suas propriedades ópticas extraordinárias devido sua ressonância plasmônica de superfície. A frequência dessa ressonância depende fortemente do tamanho, forma, interações entre partículas vizinhas, propriedades dielétricas e meio em que as NPs se encontram. Sendo assim, as NPs tornaram-se materiais importantes para aplicações em sensoriamento óptico, pois podem melhorar a sensibilidade e, também, a seletividade desses sensores. Neste trabalho é reportado o crescimento de nanocompósitos formados por nanopartículas de prata (AgNPs) recobertas pelo complexo β-dicetonato de európio, [Eu(tta)3(H2O)2], em que o ligante tta é o β-tenoiltrifluoracetonato, em um substrato de sílica para futura aplicação em sensores de fibra óptica. Especificamente, esse trabalho oferece a oportunidade de estudar a interação entre a SPR das AgNPs e a fluorescência do complexo luminescente, bem como as mudanças nas propriedades ópticas do material como a intensificação da fluorescência pela presença da superfície metálica nanoparticulada (metal enhanced fluorescence - MEF) ou ainda a intensificação da absorção. Os resultados obtidos pelas caracterizações realizadas pelas técnicas de DRX, FT-IR e MET indicam que a rota química de síntese do nanocompósito proposta mostrou-se funcional e, além disso, os resultados obtidos por espectroscopia UV-Vis e por fotoluminescência mostraram a existência da interação entre a banda de absorção do complexo e a banda de absorção plasmônica das AgNPs. Nos espectros UV-Vis, foram observados deslocamentos para valores de maiores comprimento de onda da banda do complexo referente a transição π-π* do ligante tta, devido à interação eletromagnética entre as AgNPs e o [Eu(tta)3(H2O)2], quando as moléculas do complexo recobrem de maneira organizada a superfície das NPs, formando agregados J. Nos espectros de emissão, essa interação converteu-se em supressão da luminescência pela concentração do complexo, ou seja, pela perda de energia caracterizada pela formação de agregados J na superfície das AgNPs e, também, pela a perda de energia para a superfície metálica, competição de absorção entre as AgNPs e o complexo de európio no comprimento de onda de excitação. No entanto, quando a concentração do complexo é cerca de 10 vezes maior, foi observada a intensificação da luminescência, pois a SPR excita os emissores de luz próximo ao metal, por interações dipolo-dipolo. Sendo assim, as propriedades ópticas dos nanocompósitos estudados aqui mostram que tais materiais são excelentes candidatos para aumentar a sensibilidade dos sensores baseados em fibras ópticas. / Metallic nanoparticles (NPs) are an important class of nanomaterials that have fascinated scientists due to their extraordinary optical properties owing to their surface plasmon resonance (SPR). The SPR frequency is strongly dependent of the size, shape, interparticle interactions, dielectric properties and local environment of the nanoparticle. Therefore, NPs have been recognized in optical sensors application mainly due to their high sensitivity and selectivity displayed on devices. Herein, we report the growth of a nanocomposite formed by silver nanoparticles (AgNPs) coated with europium complex, [Eu(tta)3(H2O)2], onto the surface of silica substrate. For future application in fiber optic sensors. Specifically, this work offers the opportunity to study the interaction between the SPR of the AgNPs and the fluorescence of the luminescent complex and the changes in the optical properties of the material such as metal enhanced fluorescence (MEF) or the intensification of the absorption. The proposed route of synthesis of the nanocomposite was functional and the results showed the existence of the interaction between the complex absorption band and the surface plasmon band of the AgNPs. In the UV-Vis spectra, red shifts of the π-π* absorption were observed due to electromagnetic interaction between AgNPs and [Eu(tta)3(H2O)2] when the complex cover the surface of the NPs in an organized way (J-aggregates). In photoluminescence spectra, this interaction quenched the luminescence by concentration, that is, by the loss of energy characterized by the J-aggregation on the surface of the AgNPs and by the loss of energy for the metal surface due to absorption competition between the AgNPs and the europium complex. However, when the concentration of the complex is higher, metal enhanced fluorescence was observed because the SPR excites the light emitters near the metal, by dipole-dipole interactions. Thus, the optical properties of the nanocomposite studied here show that this material is an excellent candidate for increasing the sensitivity of the sensors.

O custo elevado na fabricação de peças pela tecnologia da Manufatura Aditiva (AM) impulsionou, nos últimos anos, várias pesquisas visando ao desenvolvimento de novos equipamentos e novos materiais. Neste contexto, uma resina fotossensível, desenvolvida anteriormente com componentes disponíveis no mercado nacional pelo grupo de pesquisa ao qual este trabalho está inserido, apresentou baixas propriedades mecânicas e alta contração do material quando comparada aos materiais disponíveis no mercado. Assim, uma alternativa para melhorar essas propriedades é a obtenção de nanocompósitos. Estes compreendem uma nova classe de materiais, em que substâncias inorgânicas de dimensões nanométricas, tais como argilas e outros argilominerais, são finamente dispersas dentro de uma matriz polimérica. Dessa forma, o presente estudo tem por objetivo preparar e caracterizar um nanocompósito fotossensível de acrílico/argila curado por exposição à radiação UV-C, com propriedades mecânicas de tração, flexão e dureza, e contrações adequadas para aplicação em processo de AM. Para tanto, a formulação original, composta pelos monômeros Trimetilpropano Triacrilato (TMPTA®) e Ácido Metacrilato Modificado (Ebecryl 171®), oligômero Amina Acrilada (Ebecryl 7100®), Co-iniciador Benzofenona 99% (Additol BP®) e o fotoiniciador Additol LX®, foi testada com o acréscimo das argilas Cloisite 20® e a BN-CT nas concentrações de 0,5%, 1,0% e 1,5% (m/m) da massa total. Após o preparo dessas formulações obtidas pela dispersão 1 (agitação magnética) e 2 (agitação magnética e ultrassom), foram preparados corpos de prova pelo princípio de adição sucessiva de camadas pela AM. A caracterização foi realizada através da análise da contração, ensaios de resistência à tração, flexão e dureza, microscopia eletrônica de varredura (MEV), difração de raios X(DRX), termogravimetria (TG) e viscosidade. O empenamento do material apresentou uma melhora média de 18,27% com argila Cloisite 20® e de 11,30% com a argila BN-CT. Os resultados dos ensaios de tração, flexão e dureza não apresentaram aumentos significativos nas propriedades mecânicas. O MEV não apresentou nenhuma delaminação entre as camadas após a realização do teste de flexão. A análise de DRX não apresentou pico de difração, sugerindo a formação de nanocompósito com estrutura intercalada e/ou esfoliada para todas as formulações com argila. O ensaio de TG mostrou que a adição de argila nas formulações não apresentou melhoras significativas na estabilidade térmica do nanocompósito. Também a viscosidade não apresentou melhoras à temperatura de 25°C, mas apresentou uma redução significativa da viscosidade a 35°C. Apesar dos resultados não muito promissores em termos de resistência mecânica, as formulações com argila podem ser empregadas na AM, considerando essas limitações. / The high cost in manufacturing parts for the of Additive Manufacturing technology (AM) boosted in recent years several studies aiming the development of new equipment and new materials. With this in mind, a photosensitive resin previously developed by the research group to which this work is inserted with components available in the domestic market, presented low mechanical properties and high shrinkage of the material compared to the materials available on the market. One alternative for improving these properties is to obtain nanocomposites. They comprise a new class of materials in which inorganic substances of nanometric dimensions, such as clays and other minerals, are finely dispersed within a polymeric matrix. Thus, this study aims to prepare and characterize a photosensitive acrylic / clay nanocomposite cured by exposure to UV-C radiation, with mechanical properties of tensile, bending and hardness, and shrinkage propers for use in AM process. Therefore, the original formulation, composed of trimethylolpropane triacrylate (TMPTA®) and Acid Methacrylate Modified (Ebecryl 171®)monomers, Amina acrylated (Ebecryl 7100®)oligomer, Co-initiator Benzophenone 99% (Additol BP®) and the photoinitiator Additol LX® was tested with the addition of the clays Cloisite 20® and BN-CT in concentrations of 0.5%, 1.0% and 1.5% (w/w) of total weight. After preparing these formulations, obtained by dispersion 1 (magnetic stirring) and 2 (magnetic stirring and ultrasound), it was prepared specimens by the principle of adding successive layers by AM. The characterization was perform by shrinkage analysis, tensile strength, bending and hardness tests, scanning electron microscopy (SEM), X-ray diffraction (XRD), thermogravimetry (TG) and viscosity. The warpage of the material showed an average improvement of 18.27% with the Cloisite 20® clay and 11.30% with the BN-CT clay. The results of the tensile, flexural and hardness testing did not show significant increases in mechanical properties. The SEM showed no delamination between the layers after the bending test was performed. The XRD analysis showed no diffraction peak, suggesting the formation of nanocomposite with intercalated and / or exfoliated structure for all formulations with clay. The TG test showed that the addition of clay in the formulations presented no significant improvements in thermal stability of the nanocomposite. The viscosity showed no improvement at a temperature of 25 °C, but showed a significant reduction in viscosity at 35 °C. Although not very promising results in terms of mechanical strength, the formulations with clay can be used in the AM considering these limitations.

Dan Beaty (1937-2002) was a prolific composer, pianist, researcher, educator, and writer. His large compositional output included chamber works, choral works, songs, orchestral pieces, electronic music, and keyboard works. Beaty was well versed in traditional Western music as well as the more avant-garde and perplexing idioms of the twentieth century. Beaty's compositions reflect the many fascinating, if not always popular, musical trends of his time. His music encompasses styles from serial to jazz, shows compositional influences from Arnold Schoenberg to Indonesian music, and demonstrates thought-provoking and highly intellectual craftsmanship. This document explores several of Beaty's songs through a discussion of the composer's life and compositional process. Songs included in this document are Three Weeks Songs, October, November, A Sappho Lyric, Love Song, That Night When Joy Began, and War Lyrics. This document was written to accompany the author's DMA Lecture-Recital at the University of North Texas. Unfortunately, Beaty's vocal music was never published and is mostly unknown. One goal of the project was to initiate interest in Beaty's songs. Through this document, Lecture-Recital, and additional performances, considerable strides have been made to bring Beaty's songs to new audiences throughout the United States. In addition, the author has received permission from the Beaty family to publish Dan Beaty's songs.

M. Tech. (Department of Chemistry, Faculty of Applied and Computer Sciences), Vaal University of Technology. / For centuries the contamination of surface water has been problematic, especially in third world countries whereby socio-economic issues are prevalent. With the development of various technologies for surface water rehabilitation, adsorption has been found to be the most viable due to its lower cost implications. As such the development of innovative adsorbents which are synergistic to the low cost method have been sought. Herein, the use of fossil coral limestone from Mauritius as adsorbents for the removal of Pb(II), Cr(VI) and methylene blue is presented. The pristine material (PCLS) was thermally treated by calcination to temperatures 800°C (CLS-800) and 900°C (CLS-900) and chemically treated by using an acid HCl (ACL) and base NaOH (BCL). The optimum conditions found for chemical and thermal treatment of the pristine material were used for the one pot synthesis of magnetite and maghemite calcium carbonate based nanocomposites. The pristine fossil coral limestones were characterized by scanning electron microscopy (SEM), energy dispersive X-ray (EDS), X-ray fluorescence XRF), X-ray diffractometer (XRD), Brunauer, Emmett and Teller (BET) and Fourier transformed infrared (FTIR) spectroscopy, UV visible spectrophotometer (UV/vis) and Photolumiscent spectroscopy (PL). Surface morphology of the material was found to contain an interconnected framework of pores, with a surface area of 20.45 m2/g and pore with of 4.04 nm. Thermal treatment of the material was found to increase the surface area of the materials to 64.10 and 63.28 m2/g for CLS-800 and CLS-900. The surface morphology of the calcined materials compared to the pristine were fibrous like and irregularly shaped for CLS-800 and CLS-900 respectively. The FTIR revealed the dominant surface groups to be (-C-O) and (-C=O) asymmetric stretch of the in and out of plane bend of carbonate (-CO32-), with the composition of the material being 91.76 % (-CaO) and 3.32% SrO. The thermally treated materials also exhibited vibrations of asymmetric stretch, which are characteristics of the carbonates as with the pristine material. However, EDS of the pristine compared to that of the calcined materials show a decline in the carbon and oxygen content, due to calcination. The XRD analysis confirmed the orthorhombic structure of aragonite, while CLS-800 was rhombohedral calcite with newly developed (-CaO) peaks. CLS-900 showed complete removal of CaCO3 polymorphs with more (-CaO) peaks. The surface morphology of the chemically modified samples show irregularly shaped surface. The XRD analysis confirmed that chemical treatment did convert the materials to a different polymorph. The FTIR of the chemically modified materials compared to the pristine, were found to reveal a removal of the vibrations of the asymmetric stretch associated with carbonates. However, vibrations associated with (-CaO) were observed. The SEM of the nanocomposites was observed to deviate from sphericity with variable size distribution. The materials were both red and blue shifted due to their variable sizes. Their UV/vis revealed absorption bands in the visible region. The adsorption analysis was done by varying parameters such as time, pH, concentration and temperature. The data was such that the highest capacity for the pristine material was found to be 37.24, 39.26 and 69.42 mg/g for MB, Pb(II) and Cr(VI) respectively. The removal of MB and Pb(II) pollutants were due to physical adsorption, as observed from the good fitting to pseudo first order model (PFOM). The removal of Cr(VI) was due chemisorption and the good fit on pseudo second order model (PSOM). The adsorption process was supported on a heterogeneous surface whereby multilayer adsorption could occur. Adsorption was spontaneous and feasible, exothermic for MB and Pb(II) and endothermic for Cr(VI) at all the studied temperatures as observed from thermodynamics. The adsorption of methylene blue was found to be more favourable on adsorption compared to photo-degradation Chemical modification was observed to increase adsorption and the maximum removal capacities for PCLS, ACL and BCL for Cr(VI) ions were 69.42, 65.04, 64.88 mg/g, Pb(II) ions 39.36, 74.11, 78.34 mg/g and methylene blue 37.24, 46.28, 46.39 mg/g, respectively. Uptake of Cr(VI) and methylene blue on ACL and BCL was feasible on a heterogeneous surface whereby multilayer adsorption took place. Monolayer adsorption on a homogenous surface of ACL and BCL was observed for Pb(II) uptake. The uptake of Pb(II) was exothermic on PCLS and ACL while methylene blue only on PCLS. The adsorption of Cr(VI) ions onto PCLS, ACL and BCL and methylene blue dye onto ACL and BCL were endothermic in nature. The adsorption process was spontaneous and feasible at all the studied temperatures. Thermal modification further increased the adsorption uptake of the pollutants. The recorded uptake for Cr(VI) and Pb(II) were 99.12 and 98.42 mg/g onto CLS-800 and CLS-900, respectively. The adsorption process was found to be physisorption, due to the good fit on PFOM. In addition, the adsorption occurred on a heterogeneous surface whereby multilayer adsorption was possible. The removal of Cr(VI) was found to be exothermic for both the materials and Pb(II) was found to be endothermic. The materials were tested for their reusability to up to four cycles, whereby the removal on the fourth cycle were 16.87, 63.60, 73.13 mg/g for Cr(VI), 9.87, 64.19 and 70.95 mg/g for Pb(II) on PCLS, CLS-800 and CLS-900. While the leaching test for PCLS, CLS-800 and CLS-900 for the release of Ca2+ into solution was found to be within the permissible limits of world health organisation (WHO). The as synthesized nanocomposites increase adsorption of the pollutants. Maximum capacities were found to be 345.34, 388.31, 377.92 and 375.35 mg/g for Pb(II) onto magnetite-PCLS, magnetite-CLS, maghemite-PCLS and maghemite-CLS, respectively and 308.01, 335.3, 335.29 and 335.27 mg/g for Cr(VI) onto magnetite-PCLS, magnetite-CLS, maghemite-PCLS and maghemite-CLS, respectively. From the data it was observed that the maghemite samples were much more favourable for the removal of the pollutants. The removal was due to chemical adsorption, as observed from the good fit onto PSOM and intraparticle diffusion (IPD), whereby surface adsorption was the rate limiting step. The adsorption process was heterogeneous and multilayer, while thermodynamic data reveal that adsorption was spontaneous and favourable at the studied temperature.

M. Tech. (Department of Chemistry, Faculty of Applied and Computer Sciences), Vaal University of Technology. / The presence of organic and inorganic pollutants in aqueous environments is one of the major challenges confronting man. It is therefore important to develop sensitive, versatile and cheap techniques for their detection. Arsenic (III), 2-chlorophenol (2-CP) and sulfamethoxazole (SMX) are priority pollutants that pose health threats to humans and animals. This study was thus aimed at exploring two promising carbon nanomaterials as electrode modifiers for the electrochemical sensing of arsenic (III), 2-CP and SMX in water. Glassy carbon electrode (GCE) was modified with a nanocomposite of carbon dots (CDs) and graphitic carbon nitride (g-C3N4) and used as a sensor for the analytes in aqueous media. The CDs was prepared by a facile one-pot hydrothermal method using pine cone as the carbon source; g-C3N4 and g-C3N4/CDs nanocomposite were prepared via the microwave irradiation heating method. CDs, g-C3N4 and g-C3N4/CDs were dropped-dried on the surface of bare GCE. Transmission electron microscopy (TEM), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) were used to characterize the prepared materials. GCE, g-C3N4/GCE, CDs/GCE and g-C3N4/CDs/GCE electrodes were electrochemically investigated by electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) using a ferrocyanide [Fe (CN) 6]3-/4- redox probe. The current and the reversibility of the redox probes were enhanced in the presence of modifiers. The electrochemical behavior of arsenic (III), 2-CP and SMX on different electrodes (GCE, CDs/GCE, g-C3N4/GCE and g-C3N4/CDs/GCE) were investigated by differential pulse voltammetry (DPV) under optimized conditions in a phosphate buffer solution (pH 7.6, 6 and 5 for 2-CP, As (III) and SMX respectively). The results demonstrated that the g-C3N4/CDs/GCE electrode significantly enhanced the oxidation peak current of all three analytes. The detection sensitivity of the analytes was greatly improved, suggesting that this new modified electrode has great potential in the determination of trace level of arsenic (III), 2-CP and SMX in water. The oxidation peak currents displayed a linear relationship to concentrations for 2-CP (0.5 - 2.5 μM, R2=0.958, n=5), arsenic (III) (2 - 10 μM R2=0.978, n=5) and SMX (0.3 - 1.3 μM R2=0.9906, n=5). The detection limits of 0.62 μM, 1.64 μM and 0.10 μM were obtained for 2-CP, arsenic and SMX, respectively. Phenol and 4-chloro-3-methyl-phenol were found to interfere with the detection of 2-CP, while, Cu2+, Zn2+, Pb2+ and Cd2+ were the only significant ions that interfered with the electrochemical detection of arsenic (III). EDTA was used as a ligand to mask the interference effects of copper, cadmium, lead and zinc on arsenic sensing. The modified electrode (g-C3N4/CDs/GCE) was used to determine arsenic, 2-CP and SMX in spiked tap and effluent water samples by the standard addition method and the results showed percentage recoveries varying from 93-118% for 2-CP, 98-100% for arsenic and 80-105% for SMX. The outcomes of this study established that the nanocomposite material represents an easy and sensitive sensing platform for the monitoring of arsenic (III), 2-CP and SMX in aqueous media.

D. Tech. (Department of Chemistry, Faculty of Applied and Computer Sciences), Vaal University of Technology / A novel low-cost ternary Mn-Fe-Cu (MFC) metal oxide nanocomposite adsorbent was fabricated using facile co-precipitation method and successfully applied for the sequestration of Cr(VI) and As(III) from simulated aqueous efflent. The central composite design (CCD) of the response surface methodology (RSM) optimization technique determined the optimal working parameters for the preparation of the ternary MFC metal oxide nanocomposite. The spectroscopic microstructural analysis of the ternary MFC metal oxide nanocomposite was performed using fourier transform infrared (FTIR) spectroscopy, transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) spectroscopy. The spectroscopic analyses revealed a rough surface with hydroxyl groups and the presence of mixed metal oxides in different valence states. The BET surface area, pore volume and pore size of the nanostructured MFC ternary metal oxide composite were found to be 77.2427 m2/g, 0.2409 cm3/g and 14.7560 nm, respectively. The pH drift method determined that the pHpzc of the adsorbent was 6.75. The batch technique was employed to investigate the adsorption dynamics (effects of ionic strength, co-existing anions, adsorbent regeneration and reuse) and optimum parameters (solution pH, adsorbent dosage concentration, desorption) of Cr(VI) and As(III) adsorption onto the MFC nanocomposite. The fitting of non-linear kinetic (pseudo-first-order, pseudo-second-order and Elovich), diffusion (intraparticle and Boyd) and isotherm (Langmuir, Freundlich and Dubinin-Radushkevich) models to the Cr(VI) and As(III) experimental adsorption data gave an insight into the adsorption mechanisms. The Langmuir adsorption capacities, qm (mg/g), were 168.71 at solution pH 3 and 35.07 at solution pH 9 for Cr(VI) and As(III) adsorption, respectively. The adsorption of Cr(VI) onto the ternary MFC metal oxide nanocomposite was physical and formed outer-sphere surface complexes through electrostatic interactions, while the removal of As(III) was specific due to inner-sphere surface complexation and ligand/ion exchange reactions. The results from XPS and FTIR analysis after the adsorption of Cr(VI) and As(III) showed that the surface hydroxyl groups on the MFC nanocomposite interacted with the Cr(VI) and As(III) species during the formation of the surface complexes. To facilitate ease of adsorbent removal from the treated simulated aqueous effluent, the ternary MFC metal oxide system was co-precipitated onto biochar support.

A proteção contra corrosão na indústria automotiva é um problema de alto impacto econômico. Além de características anticorrosivas, os revestimentos utilizados nas indústrias automotivas precisam apresentar boa aparência e resistência física. Os revestimentos multicamadas normalmente utilizados em indústrias automotivas são compostos por e-coat, primer, base e verniz, sendo que o primer pode ser utilizado como um substituto do e-coat em processos de retoque ou retrabalho. Sob outra perspectiva, os polímeros condutores têm sido amplamente estudados como um revestimento anticorrosivo e o compósito de Polianilina-Melamina-Zinco (PZn) apresentou resultados promissores em relação à corrosão. Então, este estudo analisou a aplicação da PZn incorporado em revestimento multicamada utilizado na indústria automotiva, substituindo o primer comercial em processo de retrabalho. Adicionalmente, os resultados de PZn foram comparados com os primers utilizados atualmente (FLASH e GLASURIT). Para a caracterização dos materiais, realizaramse ensaios de MEV e EDS para o substrato e espessura de camada nos conjuntos pintados. Para a determinação de características visuais, foram feitas medições de cor, brilho e aspecto. Para corrosão, realizaram-se ensaios eletroquímicos (OCP e Tafel) e ensaio cíclico. Por fim, para resistência física foram analisados os ensaios de umidade, flexibilidade e aderência: corte cruzado, jato d´água, impacto pontual e batida de pedra. Os resultados dos ensaios de aspecto visual foram similares para todos os conjuntos pintados. Para corrosão, os ensaios eletroquímicos apresentaram resultados similares ao ensaio químico de corrosão cíclica, nos quais os conjuntos CJ_PANI e CJ_FLASH mostraram-se semelhantes e o CJ_GLASURIT obteve melhores resultados, sendo este o conjunto mais resistente. Os ensaios de resistência física podem ser divididos em secos e úmidos. Os ensaios realizados a seco tiveram resultados similares entre todos os conjuntos pintados, porém, nos úmidos o conjunto CJ_PANI apresentou-se susceptível à defeitos. Sendo assim, concluiu-se que o compósito de PZn apresentou bons resultados em relação às características visuais, ensaios eletroquímicos de corrosão e ensaios físicos a seco, quando utilizado em sistemas de pintura multicamadas de indústrias automotivas. Contudo, a PZn apresentou-se sucetível à defeitos em abientes úmidos, perdendo aderência. / The protection against corrosion in the automotive industry is a high impact problem on the economic view. Besides of an antirust characteristic, the coatings used in the automotive industries needs to have a good appearance and phisical resistance. The multilayer coatings used normally are compound of e-coat, primer, base and clear coat, where the primer can also be used as an e-coat substitute in rework processes. In the other side, the conductive polymers has been widely discussed as an anti-rust coating material and the Polyaniline-zinc composite (PZn) had presented good results concerning the corrosion protection. Then, this study had applied the PZn in a multilayer coating used in the automotive industry, substituting the commercial primer in a common rework process. In addition, the PZn results were compared with the commercial primers used currently (FLASH and GLASURIT). To the material characterization, were done a MEV and EDS analysis of the substrate and were measured the coating thickness of the painted sets. To determinate the visual characteristics, were measured color, gloss and aspect. For corrosion, were performed electrochemical measurements (OCP and Tafel) and the cyclic test. Moreover, the phisical resistance were evaluated with humidity, flexibility and adherence tests: cross cut, steam jet, punctual impact and stone chip. The visual aspects results were similar for all the painted sets. For corrosion, the electrochemical tests presented similar results with the chemical test done by cycle test, in which the CJ_PANI and CJ_FLASH sets had showed them equivalent and the CJ_GLASURIT had better results, being the set more resistant. The phisical resistance could be divided in two types: dry and wet. The dry tests had similar results between the painted sets, but in the wet ones, the PZn set had presented susceptible for defects. In conclusion, the PZn composite had presented good results regarding visual aspects, electrochemical corrosion and dry technical tests when used in multilayer paint systems of the automotive industry. However, it presented a susceptible for defects in humidity environmental, losing adherence.

Os resíduos decorrentes da construção civil apresentam, na maioria das vezes, a predominância de materiais inertes e passíveis de reaproveitamento, que não tem em grande parte uma finalidade. Esta dissertação apresenta uma abordagem sobre destinação correta dos resíduos, utilizando resíduos de argamassa, lodo de anodização de alumínio e cal para a formação de um novo compósito. O maior objetivo desta dissertação é caracterizar os materiais como componentes de novos compósitos para a construção civil, além de identificar novas composições (ao todo são 13 composições) atendendo as normas e leis existentes, analisar os processos físico-químicos, determinar as propriedades mecânicas e adaptar tecnologias existentes no processo de fabricação, além de destinar sem danos ambientais todas as matérias primas. Para análises físico-químicas e mecânicas foram estudados os seguintes parâmetros: resistência uniaxial média, absorção de água, densidade aparente, retração linear, microscopia eletrônica de varredura (MEV), espectrometria por energia dispersiva, difração de raios-X e espectrometria de fluorescência de raios-X (FRX). Dentre as 13 composições foram escolhidas as composições 4 e 11 para analisar mais o comportamento físico-químico. A resistência à compressão média uniaxial, aos 90 dias da composição 11 alcançou 9,18 MPa, com coeficiente de absorção de água de 12%, a retração foi de 1,53% e a densidade ao longo de 180 dias de cura variou apenas 4%. Os estudos físico-químicos identificaram a presença de Carbono, Sódio, Magnésio, Alumínio, Silício e Cálcio na composição 11, e através do MEV e FRX foi possível identificar que se trata de uma estrutura amorfa. Através desses estudos propõe-se alternativas que sejam revertidas em vantagens sociais e ambientais, tais como a fabricação de blocos vazados de concreto simples para alvenaria sem função estrutural, blocos cerâmicos para alvenaria de vedação, tijolos maciços para a alvenaria em relação a categoria A, entre outros. / Waste from the construction, have in most cases the predominance of inerts materials and insusceptible reuse, which has a few purpose. This dissertation presents an approach on the correct disposal of this waste, using mortar residue, anodizing aluminum sludge and lime to form a new composite. The main objective of this project is to characterize the materials as components of new composites for the construction industry, and identify new compositions (they are 13 compositions) meet the existing standards and laws, analyze the physical and chemical processes, determine the mechanical properties and adapting existing technologies in the manufacturing process, beyond to appropriate correctly without environmental damage for all the materials. For physical-chemical and mechanical analysis, the following parameters were studied: resistance average uniaxial, water absorption, apparent density, linear retraction, environment-scanning electron microscopy, energy dispersive x-ray, x-ray diffraction and x-ray fluorescence. Between the 13 compositions, chosen compositions 4 and 11 to analyze the behavior. The average uniaxial compressive strength at 90 days composition 11 reached 9,18 MPa with 12% water absorption coefficient, the shrinkage was 1,53% and the density over 180 days varied only 4%. The physic-chemical studies have identified the presence of Carbon, Sodium, Magnesium, Aluminum, Silicon and Calcium in the composition 11 and about scanning electron microscopy and XRF identified that it is an amorphous structure. Through these studies, it was possible to propose alternatives that are reversed in social and environmental benefits, such as the manufacture of simple concrete hollow blocks brickwork without structural function, ceramic blocks for sealing brickworks and solid bricks for brickworks in relation to category A, among others.