Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Quimica / Made available in DSpace on 2013-07-15T21:13:55Z (GMT). No. of bitstreams: 0

Made available in DSpace on 2014-06-11T19:35:08Z (GMT). No. of bitstreams: 0 Previous issue date: 1997Bitstream added on 2014-06-13T20:45:54Z : No. of bitstreams: 1 martines_mau_dr_araiq.pdf: 2947884 bytes, checksum: 72629200eaa3a20a5b20f28125019cc8 (MD5) / Sílica contendo crômio faz parte de uma classe importante de materiais devido às aplicações como catalisador de polimerização e de oxidação, fibras ópticas, laseres e preparação de pigmentos. Este trabalho está dividido em duas partes. A primeira refere-se ao gel úmido e seco de sílica contendo crômio. Os géis foram preparados fazendo-se a mistura das soluções de silicato de sódio solúvel (vidrolíquido) e de soluções aquosas de nitrato de crômio em pH 4 ou 9 previamente ajustado, ou em 4 após a mistura das soluções. O gel foi caracterizado por espectroscopia eletrônica de absorção no ultravioleta -visível e por microscopia eletrônica de transmissão. A morfologia dos géis de sílica e de sílica contendo crômio é dependente do valor de pH e da ordem de mistura dos reagentes. Este efeito é atribuído às espécies poliméricas do crômio diferenciadas presentes na solução que controlam a forma da partícula. Partículas esféricas podem ser obtidas pelo colapso de microgel com alto grau de ligação cruzada. A outra parte do trabalho consiste na preparação de sílica contendo crômio por dois métodos: aquecimento convencional e banho de ultra-som nas temperaturas de 50 e 80oC. O gel obtido foi tratado por extrações com soluções ácidas, extrações com água e diálise, e seco em forno de microondas. As amostras de sílica/crômio em pó foram submetidas ao tratamento térmico em temperaturas de 200 a 1400oC, com intervalos de 200oC, sob atmosfera... / Chromium-containing silica belongs to an important class of materials having technological applications such as polymerization and oxidation catalyses, lasers, pigments and optical fibers. The chromium-containing silica and pure silica gels were obtained by mixing solutions of soluble sodium silicate (water glass) and chromium nitrate with adjusted pH 4 or 9 previously. Other method to prepare the gels was carried out by mixing water glass and chromium nitrate solutions and then the pH 4. The gel was characterized by ultraviolet-visible spectroscopy and transmission electron microscopic. The gel morphology is dependent on the pH value and the order of mixture of reagents. This effect is due to the nature of polymeric shape of chromium species in solution. Spherical particles can be obtained from microgel collapsing with high degree of cross linking . The second part of this work deals with powders obtained from gels. The chromium-containing silica and silica powders were obtained from gel by two methods: i) conventional heating at temperatures of 80 and 50oC and ii) sonication and heating at 80 and 50oC. The resultant colloidal silica was treated by continuous extraction acid solution in followed by extraction in distilled water and then dialyzed against distilled water and dried in microwave oven. The samples were...(Complete abstract, click electronic access below)

Submitted by ISAAC VAZ SOARES null (36981700867) on 2018-01-29T12:18:45Z No. of bitstreams: 1 Defesa Doutorado isaac final.pdf: 2744070 bytes, checksum: 31bc4c049671640ba917d1aba3320fb6 (MD5) / Approved for entry into archive by Cristina Alexandra de Godoy null (cristina@adm.feis.unesp.br) on 2018-01-29T12:59:53Z (GMT) No. of bitstreams: 1 soares_iv_dr_ilha.pdf: 2744070 bytes, checksum: 31bc4c049671640ba917d1aba3320fb6 (MD5) / Made available in DSpace on 2018-01-29T12:59:53Z (GMT). No. of bitstreams: 1 soares_iv_dr_ilha.pdf: 2744070 bytes, checksum: 31bc4c049671640ba917d1aba3320fb6 (MD5) Previous issue date: 2017-04-05 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Este trabalho descreve as sínteses e caracterizações de materiais à base de silício organofuncionalizados com 2-amino-5-(4-piridil)-1,3,4-tiadiazol (T8-Pr-APT e SG-Pr-APT) e 4 -amino-5-(4-piridil)-4H-1,2,4-triazol-3-tiol (T8-Pr-APTT e SG-Pr-APTT). Os materiais foram caracterizados por: espectroscopia na região do infravermelho (FTIR), ressonância magnética nuclear 29Si e 13C no estado sólido (RMN) e Microscopia eletrônica de varredura com Espectroscopia de energia dispersiva de raios-X (MEV-EDS). Nos estudos de batelada para os materiais, foram utilizados os íons metálicos de V(III), Fe(III), Cr(III), Cu(II), Pb(II) e os solventes foram água e etanol. Determinou-se a dose de adsorvente na solução e o tempo de equilíbrio, na qual, para o material T8-Pr-APT em todos os meios para os metais Cu, Pb e Cr, a capacidade máxima de adsorção ocorreu em 60 mg de adsorvente e para os metais restantes de 100 mg de adsorvente, o equilíbrio de adsorção em ambos os meios foi de aproximadamente 20 minutos para os metais Cu, Pb e Cr e 30 minutos para os demais, enquanto que, para o SGPr- APT em todos os meios para os metais Cu e Cr, a capacidade máxima de adsorção ocorreu em 60 mg de adsorvente e para os metais restantes de 100 mg de adsorvente, o equilíbrio de adsorção em ambos os meios foi de aproximadamente 40 minutos para todos os metais estudados. Estudou-se ainda a capacidade máxima de adsorção (Nf) para os solventes, na qual a capacidade máxima se deu em meio etanólico > aquoso. Em seguida, as isotermas de adsorção foram ajustadas pelos modelos Langmuir, Freundlich, Temkin e Dubinin-Radushkevich (D-R). Para cinética de adsorção dos metais, foram usados três modelos cinéticos como pseudoprimeira- ordem, pseudo-segunda-ordem e Elovich. Os modelos de Langmuir e Elovich foram os mais apropriados para descrever os dados de adsorção e cinética, respectivamente, de todos materiais. Os parâmetros termodinâmicos ΔGº, ΔHº e ΔSº foram avaliados para os materiais e observou-se que a adsorção de todos os metais, independentemente do adsorvente utilizado, foi um processo endotérmico e espontâneo, devido aos valores positivos de entalpia e negativo de energia livre de Gibbs, respectivamente. Os valores positivos da entropia indicam que o processo de adsorção é favorável e ocorre um aumento da desordem na interface sólido-solução. Estes resultados mostraram que os materiais possuem o mesmo comportamento termodinâmico. A atividade catalítica dos materiais suportados foram testados e comparados, utilizando complexo de molibdênio e tungstênio para epoxidação do 1-octeno, cicloocteno, cis-3-hexen- 1-ol, trans-3-hexen-1-ol e estireno, utilizando como oxidante o hidroperóxido de terc-butil (TBHP), onde ambos os materiais possuem semelhantes conversões e uma boa seletividade. / This work describes how syntheses and characterizations of silicon-based materials organofunctionalized with 2-amino-5- (4-pyridyl) -1,3,4-thiadiazole (T8-Pr-APT and SG-Pr- APT) and 4- Amino-5- (4-pyridyl) -4H-1,2,4-triazol-3-thiol (T8-Pr-APTT and SG-Pr-APTT). The materials were characterized by: infrared spectroscopy (FTIR), 29Si and 13C solid state nuclear magnetic resonance (NMR) and scanning electron microscopy with X-ray dispersive energy spectroscopy (SEM-EDS) V (III), Fe (III), Cr (III), Cu (II), Pb (II) and the solvents for ethanol and water. Determination of a adsorption dose in the solution and the equilibration time in quality for the T8-Pr-APT material in all media for the Cu, Pb and Cr metals, a maximum adsorption capacity occurred in 60 mg of adsorbent and for the remaining 100 mg adsorbent, the adsorption equilibrium in both media for approximately 20 minutes for the Cu, Pb and Cr metals and 30 minutes for the others, whereas for the SG-Pr-APT at all means for Cu and Cr metals, a maximum adsorption capacity occurred at 60 mg adsorbent and for other 100 mg adsorbent, the adsorption equilibrium in both media was about 40 minutes for all metals studied. A maximum adsorption capacity (Nf) was also studied for the solvents, in which a maximum capacity is given in ethanolic> aqueous medium. Then, as adsorption isotherms were adjusted by the Langmuir, Freundlich, Temkin and Dubinin-Radushkevich (D-R) models. For kinetics of adsorption of metals, three kinetic models were used as pseudo-first-order, pseudo-second order and Elovich. The Langmuir and Elovich models were more adequate to describe the adsorption and kinetic data, respectively, of all materials. The thermodynamic parameters ΔGº, ΔHº and ΔSº were evaluated for the materials and it was observed that an adsorption of all metals, independently of the adsorbent used, for an endothermic and spontaneous process, for the enthalpy and negative positive values of Gibbs free energy , respectively. The positive entropy values indicate that the adsorption process is favorable and an increase in the disorder occurs at the solid-solution interface. These results show that the materials have the same thermodynamic behavior. The catalytic activity of the supported materials was tested and compared using a molybdenum and tungsten complex for the epoxidation of 1-octene, cyclooctene, cis-3-hexen-1-ol, trans-3-hexen-1-ol and styrene, Oxidant Or tert-butyl hydroperoxide (TBHP), where both materials have conversions and good selectivity

Orientador: Claudio Airoldi / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Química / Made available in DSpace on 2018-08-20T09:35:04Z (GMT). No. of bitstreams: 1 Silva_IrleneMariaPereirae_M.pdf: 2812788 bytes, checksum: 83395128353119e4c0fa5e54a5e9748a (MD5) Previous issue date: 2012 / Resumo: O polímero inorgânico sílica gel foi usado como suporte em reações de modificações de superfície, devido à presença de grupos silanol (Si-OH) na superfície, que confere grande reatividade em processo de imobilização. A superfície da sílica gel foi organofuncionalizada com epicloridrina a partir de uma nova rota sem a presença de silano ou solvente, reduzindo assim o impacto ambiental e o custo da reação. Este método, denominado de "rota sem solvente¿, foi otimizado com a realização de um planejamento experimental 2, variando o tempo da reação, a temperatura e o volume de epicloridrina utilizado. Para fins de comparação, a sílica gel também foi funcionalizada com epicloridrina a partir de duas rotas convencionais: a homogênea e a heterogênea, utilizando tolueno como solvente, 3-aminopropiltrietoxissilano como silano, além da epicloridrina. Para aumentar a disponibilidade de sítios básicos, foi adicionada uma nova cadeia orgânica a partir da reação com a dietanolamina para favorecer a sorção de cobre. Os produtos destas reações foram denominados de SiDM, SiDT e SiD, para as rotas homogênea, heterogênea e sem solvente, respectivamente. As sílicas obtidas foram caracterizadas por de análise elementar, espectroscopia na região do infravermelho, ressonância magnética nuclear no estado sólido para os núcleos de carbono e silício, e termogravimetria. Foram determinadas as capacidades de sorção dos íons de cobre (sorbato) através das sílicas modificadas (sorvente) obtidas pelas rotas homogênea, SiDM, heterogênea, SiDT, e sem solvente, SiD. A primeira sílica apresentou maior capacidade de sorção, 0,32 mmol g, seguida pelas sílicas SiD e SiDT com os valores de capacidade de sorção de 0,27 e 0,11 mmol g. A sílica obtida sem solvente satisfaz melhor o compromisso com a Química Verde. Sua capacidade de sorção superou SiDT, mesmo tendo um centro básico de nitrogênio a menos em relação as sílicas funcionalizadas com silano. As grandezas termodinâmicas calculadas a partir da titulação calorimétrica e batelada mostraram que em todos os sistemas estudados a interação entre os íons de cobre com os centros básicos na interface sólido/líquido é energeticamente favorável, pois apresentaram valores negativos de energia de Gibbs e entalpia exotérmica, e valores positivos de entropia, exceto para SiDM. Apesar desse valor de entropia negativo, ele não tornou o processo desfavorável / Abstract: The inorganic polymer silica gel was used as support of reactions on surface modifications due to the presence of silanol (Si-OH) groups that confers greater reactivity in immobilization process. The silica gel surface was organofunctionalized with epichlorohydrin from a new route without the presence of silane or solvent, thus reducing the environmental impact and cost of the reaction. This method, called "absence solvent route¿ was optimized with the realization of an experimental planning 2, varying reaction time, temperature and amount of epichlorohydrin. For comparison, the silica gel was functionalized with epichlorohydrin also from two conventional routes: a homogeneous and heterogeneous, using toluene as solvent, 3-aminopropyltriethoxysilane and epichlorohydrin. To increase the availability of basic sites it was added a new organic chain from a reaction with diethanolamine, to favor the sorption of copper. The products of these reactions were named SIDM, SIDT and SiD for the homogeneous, heterogeneous and absence solvent routes, respectively. All silicas were characterized by elemental analysis, infrared spectroscopy, nuclear magnetic resonance in solid state for carbon and silicon nuclei and thermogravimetry. The sorption capacity of copper ions (sorbate) using the modified silicas (sorbent) obtained by the homogeneous, SIDM, heterogeneous SIDT, and without solvent, SiD, routes was determined. The first silica showed higher sorption capacity 0.31 mmol g, followed by SiD and SIDT silicas, as 0.27 and 0.11 mmol g. The silica obtained without solvent performs the best agreement to green chemistry. The sorption capacity of SIDT silica surpassed even having one basic nitrogen center less than that one functionalized with silane. The calculated thermodynamic properties from calorimetric titration and batch wire process showed that for all studied systems the interaction between copper ions with basic centers at the solid/liquid interface is energetically favorable, since they have negative Gibbs energies and exothermic enthalpies, and positive entropy values, except with SiDM. In despite of entropy with negative value, it did not make the process unfavorable / Mestrado / Quimica Inorganica / Mestra em Química

Orientador: Claudio Airoldi / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Quimica / Made available in DSpace on 2018-08-07T20:39:48Z (GMT). No. of bitstreams: 1 Oliveira_FernandoJoseVolpiEusebiode_M.pdf: 2032222 bytes, checksum: 5a4e21e8f2399cc1438c215f34681ff9 (MD5) Previous issue date: 2006 / Resumo: Novas matrizes de sílica gel organofuncionalizadas foram preparadas através da incorporação da molécula de tiouréia nos agentes sililantes comerciais de cadeias lineares contendo de um a três átomos de nitrogênio em suas estruturas, na presença de sulfato de amônio, como catalisador. Utilizou-se um novo método de preparação do novo agente modificado não envolvendo a presença de solvente na etapa inicial, o que difere daqueles que usam algum tipo de solvente orgânico, não só na etapa inicial, como também em reações sucessivas de imobilização. As matrizes foram denominadas conforme o número de nitrogênios contidos em suas superfícies, sendo S-NT, S-2NT e S-3NT, de acordo com os crescentes átomos de nitrogênio contidos no agente de origem. Através do processo sol-gel foram sintetizados os filossilicatos correspondentes às superfícies de sílica modificada. Nessa etapa, os agentes incorporados com tiouréia foram dissolvidos em etanol e adicionados a uma solução de nitrato de níquel em meio básico, obedecendo a relação molar Si/Ni como sendo 4/3. Assim, foram obtidos filossilicatos similares ao talco, que apresenta o magnésio nos sítios octaédricos, envoltos por duas camadas de silicato, onde o silício está acomodado nos sítios tetraédricos. Para a síntese da estrutura similar ao talco natural é fundamental que a razão molar mencionada seja obedecida. As técnicas de caracterização utilizadas permitiram a compreensão das estruturas, bem como algumas de suas propriedades. Para os filossilicatos, foi fundamental a análise por difração de raios-X, para observar os planos de reflexões correspondentes aos da amostra de estruturas do tipo talco e comparar os sinais e as distâncias interlamelares de todos os materiais. A capacidade de adsorção de íons cobre foi estudada para as três matrizes de sílica. Os materiais apresentaram capacidade máxima de adsorção crescente na seguinte ordem. S2NT < SNT < S-3NT, ou seja, a matriz contendo dois átomos de nitrogênio em sua estrutura apresentou menor capacidade, que por sua vez é menor do que a matriz contendo três átomos de nitrogênio nas cadeias. Esse resultado está de acordo com os percentuais de nitrogênio para cada amostra, calculados pela análise elementar. A energética da interação íons cobre/centros básicos de Lewis foi determinada por titulação calorimétrica. Os dados permitiram obter a isoterma de Langmuir e através de sua regressão linear, calcular os parâmetros termodinâmicos que se apresentaram favoráveis à complexação do cobre. / Abstract: New silica gel organofunctionalized surfaces were synthesized by incorporating the thiourea molecule in the commercial silylanting agents with linear chains containing from one to three nitrogen atoms on their structures, in presence of ammonium sulphate as catalyst. This method for new modified silylating agent preparation does not require any solvent for the first step reaction. The most usefull described processes are based on the use of solvent not only on the first step, but also on the immobilization reactions. The materiaIs were named following to the number of nitrogen atoms attached to the aliphatic organic chains containing on surfaces, as S-NT, S-2NT and S-3NT, from one to three nitrogen atoms derived from silylating agents, respectively. From sol-gel process the analogous phyllosilicates from modified silica surfaces were synthesized. In this step, the functionalized agent was dissolved in ethanol and added to a nickel nitrate solution, in basic condition, following the molar ratio Si/Ni as 4/3. Therefore, the obtained talc-like phyllosilicate, presented the magnesium atom in octahedral sites, which are located between two tetrahedral silicate layers. To synthesize a talc-like structure, the mentioned molar ratio must be obeyed. The characterization techniques allowed the understanding of the structures, as well as some of properties. For phyllosilicates, the X-ray diffraction patterns were of fundamental importance for observing the typical reflection plans associated with the samples that have a talc-like structure and to compare the signals and the interlamellar space for all materials. The copper adsorption capacity was studied for alI three silica matrices. The materials presented an increasing order of adsorption capacity as: S-2NT < SNT < S-3NT, e.g., the matrix containing two nitrogen atoms on its structure had lower capacity than the others, including that one of three nitrogen atoms. These data are in agreement with nitrogen percentage values for each sample, evaluated by elemental analysis. The energetic of the interactions between copper ions/nitrogen Lewis basic centers were followed by calorimetry. Through calorimetric titrations was possible to adjust the results to the Langmuir isotherm and by linear regression and the thermodynamic parameters were calculated and presented favorable for copper complexation. / Mestrado / Quimica Inorganica / Mestre em Química

Hybrid materials synthesized by grafting of organic molecules onto silica surface have found numerous applications in chemistry, biochemistry, and chemical engineering. In particular, the functionalization of silica gel can be accomplished by various surface reactions of immobilized boronic acids. Suzuki coupling has been chosen due to several advantages, such as mild reaction conditions, tolerance to the aqueous environment, and high yields of the products. The objective of this work was to determine the most effective reaction conditions for modifying porous hybrid materials with large specific surface areas and high density of surface organoboron reactive sites by various functional groups. Prior to modification by Suzuki coupling, the surface of silica gel was functionalized by phenylboronic acid. Two methods were tested for immobilization of phenylboronic acid: hydrosilylation and thiol-ene coupling. The later radical reaction between surface alkylthiol groups and 4-vinylphenylboronic acid was found more effective. Obtained boronated silica gel was used for further functionalization by various aryl halides. Surface Suzuki coupling reaction was catalyzed by palladium acetate in the presence of cesium carbonate as a base, while dimethylformamide was chosen as a solvent. The coupling reactions proceeded at mild heating under constant sonication. Such ultrasonic irradiation was reported earlier to have an activating effect on Suzuki coupling. The analysis of the obtained products indicated formation of surface biaryl compounds, the highest yields have been obtained in reactions with iodobenzene and bromobenzene. Thus, novel functionalized organic/inorganic hybrid materials were successfully synthesized by surface modification of mesoporous silica gel.

The reaction of base-free Chan-Lam coupling was successfully used for functionalization of surface of mesoporous silica gel. Various aromatic, aliphatic, and heterocyclic compounds were immobilized by a copper-catalyzed reaction of corresponding boronic acids with surface amino groups at mild conditions. Obtained functionalized materials were mesoporous although their surface area decreased after immobilization. The reactivity of some surface functional groups was tested in their characteristic reactions.

Lewis acids (ZnCl2, CoCl2, NiCl2, TiCl4, and CdCl2) when supported on silica gel can effectively catalyze transesterification of organophosphotriesters. In anhydrous acetonitrile and in the presence of excess alcohol, such reactions follow pseudo-first-order kinetics. Progress and efficacy of these reactions were monitored by UV-vis and 31P NMR spectroscopy.

Mesoporous silica gel was functionalized by various organic functional groups using thiol-ene coupling of surface thiol groups with 4-vinylphenylboronic acid followed by Suzuki coupling with aromatic halides. For better performance, the synthesis was conducted under sonication. The presence of surface functional groups was confirmed by thermoanalysis, FT-IR spectroscopy and characteristic reactions of these groups. Solid-phase conditions of the synthesis eliminate the risk of side reactions of boronic acids.

An adsorbent for Cs removal from contaminated water based on phosphotungstic acid (PTA) embedded in SiO 2 network was synthesized and granulated with γ-Al 2 O 3 . PTA/SiO 2 had a high adsorption capacity towards Cs while the binder provided excellent mechanical characteristics of the material. It was shown that small particles of PTA/SiO 2 with the sizes of 0.1–1 µm occupied space between larger particles of the binder (up to 5 µm). Chemical interaction between PTA and γ-Al 2 O 3 during the adsorbent preparation also took place. The obtained porous material with the specific surface area of 286.9 m 2 /g contained 4.73% of PTA. Presence of Keggin units in the structure was confirmed by solid state NMR spectroscopy. Study of the adsorbent in Cs + adsorption from solutions demonstrated its high adsorption capacity. The concentrations of Cs + in the solutions after the column tests decreased by 3.3–5.2 times. The presence of Na + and K + as competing ions did not affect the adsorption. The material was tested in clean-up of radioactive water from the shelter of Chernobyl nuclear power plant (Ukraine). A significant decrease of 137 Cs radioactivity was detected in all samples of radioactive water, especially in acidic solutions. Thus the adsorbent can be used for water treatment after incidents resulting in release of radioactive isotopes 134 Cs and 137 Cs.