A procura por fontes de energia confiáveis para motores elétricos, levou a grande esforços de síntese de novos eletrólitos para uso em baterias de íon-Li, de modo a aliar eficiência e segurança. Líquidos iônicos têm sido largamente estudados para este propósito. Misturas do sal Li(CF3SO2)2N, LiTf2N, no líquido iônico (LI) formado pelo cátion 1-butil-2,3-dimetilimidazólio, BMMI, e o ânion (CF3SO2)2N-, bis(trifluorometanosulfonil)imideto, Tf2N, foram preparadas em diferentes concentrações. A adição do sal de lítio a este liquido iônico diminuiu a mobilidade de todas as espécies, especialmente o Li+. A condutividade estimada usando os dados de difusão (NMRPGSE), os dados da espectroscopia Raman e as simulações por Dinâmica Molecular sugerem a formação de agregados compostos por ânions Tf2N em torno do Li+, com os oxigênios do Tf2N direcionados para o cátion Li+. Estes agregados aumentam conforme aumenta a concentração de LiTf2N, contribuindo para a diminuição da condutividade. Para contornar este obstáculo, foram sintetizados líquidos iônicos contendo um átomo de oxigênio na estrutura do cátion, de modo a promover a competição com os oxigênios do Tf2N pelo cátion Li+, prevenindo Li+ de formar agregados de grande massa e melhorando sua difusividade. Os cations escolhidos foram o 1,2-dimetil-imidazólio e o N-metilmorfolino. Estes LI´s serão representados por [Et2OMMI][Tf2N] e [Et2OMor][Tf2N], respectivamente. Os resultados mostraram que [Et2OMMI][Tf2N] tem uma menor janela eletroquímica (3,8V) que [BMMI][Tf2N] (4,6V), mas o potencial de redução para ambos é igual, o que os torna resistentes à redução pelo lítio metálico. Estes dois LI´s tem quase a mesma densidade e a viscosidade de [Et2OMMI][Tf2N] é 20% menor que a de [BMMI][Tf2N]. Sendo menos viscoso, é esperado que [Et2OMMI][Tf2N] tenha uma maior condutividade. De fato, sua condutividade é 40% maior que a de [BMMI][Tf2N], o que sugere que o grupo éter adiciona alguma modificação estrutural ao sistema, mostrando que neste caso, as mudanças no transporte de carga não decorrem apenas em função da fluidez. Coeficientes de difusão de [Et2OMMI][Tf2N] são maiores que aqueles de [Et2OMor][Tf2N], mas um pouco menores que aqueles de [BMMI][Tf2N]. Também foram estudadas as mudanças nas propriedades físico-químicas em [BMMI][Tf2N] decorrentes da adição do gás SO2. Todas as propriedades de transporte tiveram aumento e uma diminuição na dinâmica de formação de pares iônicos foi sugerida pelos dados experimentais / The searching for reliable power sources for electrical engines has lead to great efforts in order to synthesize new electrolytes to be used in Li-ion batteries in order to make them powerful and safe. Ionic liquids have been widely studied for this purpose. Lithium salt solutions of Li(CF3SO2)2N, LiTf2N, in a room-temperature ionic liquid (RTIL), 1-butyl-2,3-dimethyl-imidazolium cation, BMMI, and the (CF3SO2)2N-, bis(trifluoromethanesulfonyl)imide anion, Tf2N, were prepared in different concentrations. The addition of a lithium salt to this RTIL decreases the mobility of all species, especially Li+. Estimated conductivities (NMR-PGSE), Raman spectroscopy and Molecular Dynamics Simulation data suggest the formation of aggregates formed by [Tf2N] anions around Li+, with [Tf2N]´s oxygen atoms pointing toward Li+. These aggregates increase as LiTf2N content is increased, thus contributing to diminish conductivity. To overcome this obstacle, it was synthesized ionic liquids with ether-function-containing cations, so, oxygen atom from the ether group could compete for Li+ against the oxygen atoms from [Tf2N], preventing Li+ to form high mass aggregates improving the Li+ diffusion process. The chosen cations were the 1,2-dimethyl-imidazolium and N-methylmorpholine. RTILs were represented by [Et2OMMI][Tf2N] and [Et2OMor][Tf2N], respectively. Results show that [Et2OMMI][Tf2N] has a lower electrochemical window (3,8V) than [BMMI][Tf2N] (4,6V), but their reduction potential is equal, which makes them resistant to reduction by metallic lithium. These two RTIL´s have almost the same density and the viscosity of [Et2OMMI][Tf2N] is 20% lower than that of [BMMI][Tf2N]. Being less viscous, it is expected that [Et2OMMI][Tf2N] had a higher conductivity. It has in fact a conductivity 40% higher than [BMMI][Tf2N], which suggests that the ether chain add some structural modification to the system, showing that in this case, changes in charge transport is not only a function of the fluidity. Diffusion coefficients of [Et2OMMI][Tf2N] are higher than those of [Et2OMor][Tf2N], but a little bit lower than those of [BMMI][Tf2N]. It was also addressed the physical property changes in [BMMI][Tf2N] with the increasing addition of SO2. All the transport properties have improved and a decrease in ionic pair formation was suggested by experiment data

Orientador: Paulo José Samenho Moran / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Química / Made available in DSpace on 2018-08-18T09:45:27Z (GMT). No. of bitstreams: 1 Zampieri_DaviladeSouza_D.pdf: 19778215 bytes, checksum: 98414fd3042304cf48795db2917aaaac (MD5) Previous issue date: 2011 / Resumo: Neste trabalho foi realizado o estudo de biorreduções utilizando microrganismos em sistema bifásico: água/líquido iônico. As reduções de (Z)-3-cloro-4-fenil-3-buten-2-ona, (E)-3-cloro-4-fenil-3-buten-2-ona e (Z)-3-bromo-4-fenil- 3-buten-2-ona a-haloenonas foram realizadas em meio aquoso e na presença de hexaflourofosfato de 1-butil-3-metilimidazólio, usando como biocatalisadores Saccharomyces cerevisiae CCT 3019, Pichia stipitis CCT 2617, Geotrichum candidum CCT 1205, Candida albicans CCT 0776, Rhodotorula glutinis CCT 0783 e Micrococcus luteus CCT 2283. Em geral, os resultados obtidos na redução das a-haloenonas catalisadas pelos microrganismos supracitados, em sistema bifásico: água/líquido iônico, foram melhores do que em meio aquoso, obtendo-se aumentos consideráveis nos excessos enantioméricos das correspondentes haloidrinas produzidas atingindo valores de até 97% ee. Esse fato pode ser devido as constantes de partição (K = 257 a 316) das a-haloenonas que indicam a presença da maior parte dessas enonas no líquido iônico, classificando essas reações como biocatálise extrativa in situ. A determinação da configuração das haloidrinas obtidas juntamente com o monitoramento dos produtos formados durante a biorredução, permitiram a elaboração de uma proposta de mecanismo onde a ligação dupla C=C é reduzida antes da ligação da C=O. A utilizacao de P. stipitis como biocatalisador em meio aquoso levou a formação do produto desalogenado 4-fenil-2-butanona após 72 h de reação, porém, com a adição de um inibidor de radicais livres (DNB), foi observado à formação das correspondentes a-halocetonas e haloidrinas. Com base no teste dos halos de inibição dos microrganismos frente as a-haloenonas, conclui-se que as mesmas possuem efeitos inibitórios para os biocatalisadores empregados e a presença do líquido iônico diminui o efeito de inibição. Os resultados da biorredução das a- halo-cicloexenonas e a-halo-ciclopentenonas mostraram que o processo e mais reativo do que com as a-haloenonas supracitados / Abstract: In this work, the study of enantioselective reduction of a-haloenones using microorganisms was carried out in biphasic system: water/ionic liquid. Therefore, reductions of (Z)-3-chloro-4-phenyl-3-buten-2-one, (E)-3-chloro-4-phenyl-3-buten- 2-one and (Z)-3-bromo-4-phenyl-3-buten-2-one were carried out in aqueous medium, and in the presence of 1-butyl-3-methylimidazolium hexafluorophosphate, using as biocatalysts the following microorganisms: Saccharomyces cerevisiae CCT 3019, Pichia stipitis CCT 2617, Geotrichum candidum CCT 1205, Candida albicans CCT 0776, Rhodotorula glutinis CCT 0783, and Micrococcus luteus CCT 2283. In general, the results obtained in the reduction of the a-haloenones catalyzed by those microorganisms in the water/ionic liquid biphasic system were better than in aqueous medium, giving considerable increases in enantiomeric excesses of the corresponding halohydrins, reaching values up to 97% ee. This fact may be due to the constants of partition (K = 257 to 316) of a-haloenones that indicate the most quantity of the enones is in the ionic liquid phase, classifying these reactions as in situ extractive biocatalysis since the cells are in the water phase. The determination of the halohydrins¿ configuration, as well as the monitoring of intermediates and products during the reaction allowed the elaboration of a plausible mechanism, where the C=C bond is reduced before the C=O bond. The use of P. stipitis as a biocatalyst in aqueous medium gave the dehalogenated product 4-phenyl-2-butanone after 72 hours of reaction. On the other hand, the addition of a radical inhibitor (DNB) to the medium avoids the undesired dehalogetation and thus the corresponding á-haloketones and halohydrins were produced. It was observed that the haloenones have an inhibitory effect to the biocatalysts. This inhibitory effect was decreased in the biphasic system due to the decrease of enones concentration in the aqueous phase. The results for the bioreductions of a-halocyclohexenones and a-halocyclopentenones showed that these substrates are more reactive than the acyclic a-haloenones / Doutorado / Quimica Organica / Doutor em Ciências

Os líquidos iônicos (LIs) são eletrólitos promissores para uso em baterias de lítio e outros dispositivos eletroquímicos, devido às suas propriedades físico-químicas únicas como, por exemplo, ampla faixa de temperatura como liquido, boa condutividade, baixa pressão de vapor e estabilidade térmica, química e eletroquímica. Um LI é composto normalmente por um cátion orgânico e um ânion orgânico ou inorgânico. Neste trabalho, foram sintetizados novos líquidos tanto modificando o ânion como o cátion. Em ambos os casos procurou-se LIs com ótimas propriedades de transporte e que melhorassem a condutividade do lítio em relação condutividade total da mistura LI - sal de lítio. Em primeira instância, foram sintetizados e caracterizados os seguintes líquidos iônicos derivados do ânion [B(CN)4]-: [BMPYR][B(CN)4] (N-butil-N-metilpirrolidínio tetracianoborato), [BMP][B(CN)4] (N-nbutil- N-metilpiperidínio tetracianoborato) e [BMMI][B(CN)4] (1-n-butil-2,3-dimetilimidazólio tetracianoborato), sendo os dois primeiros são líquidos na temperatura ambiente. Quando comparados com os derivados de bis(trifluorometanosulfonil)imideto, [Tf2N]-, os líquidos iônicos derivados de tetracianoborato apresentam melhores valores de condutividade e viscosidade, sendo isto refletidos em um maior valor do parâmetro condutividade do lítio (σLi). Além disso, estes LI possuem maior estabilidade química e eletroquímica. Utilizou-se a técnica de espectroscopia Raman para estudar os líquidos [BMPYR][B(CN)4] e [BMP][B(CN)4] e suas misturas com sal de lítio (0,1 molL-1 de LiB(CN)4), demostrando-se que a interação entre o íon lítio e o ânion tetracianoborato é muito baixa, o que explica o altos valores do número de transporte e condutividade do lítio nestes sistemas. já através da Modificação do cátion, foram sintetizados cinco líquidos iônicos derivados de fosfônio, usando sempre o ânion [Tf2N]-. Entre eles são líquidos na temperatura unicamente os LIs [P2225][Tf2N] (Bis(trifluormetilsulfonil)imideto de trieltilpentilfosfônio) e [P222(201)][Tf2N] (Bis(trifluormetilsulfonil)imideto de trietil(2-metoxietil)fosfônio). Estes líquidos apresentaram excelentes propriedades de transporte e estabilidade eletroquímica quando comparados com seus equivalentes derivados de nitrogênio. Quando se adicionou o sal de lítio, LiTf2N, em concentrações de 1 e 2 molL-1 , os líquidos apresentaram um decréscimo das propriedades de transporte, embora demostrarem efeito menor em comparação com os líquidos iônicos derivados de nitrogênio, apresentando inclusive maiores valores nos números de transporte e de condutividade do lítio nas misturas estudadas. / Ionic liquids (ILs), are of great interest nowadays as electrolytes for lithium ion batteries due their unique characteristics, which include: liquid state over a wide temperature range; nonvolatility, which assures thermal stability and nonflammability; high ion content, which results in high ionic conductivity; and excellent chemical and electrochemical stability. ILs consists of an organic cation and an inorganic or organic anion. In order to improve the transport properties, the cation and anion of the ionic liquid were changed. Three ionic liquids derived from the anion [B(CN)4]- were synthetized and chararacterized: [BMPYR][B(CN)4] (N-n-butyl-N-methylpyrrolidinium tetracyanoborate) [BMP][B(CN)4] (N-n-butyl-Nmethylpiperidinium tetracyanoborate) and [BMMI][B(CN)4] (1-n-butyl-2,3-dimethylimidazolium tetracyanoborate). The first two are liquid at room temperature. When comparing these ionic liquid with the analogous ones containing the anion Tf2N, it was found that ILs derivates from tetracyanoborate have better transport properties which is reflected in a larger value of parameter conductivity of lithium (σLi). Moreover these ILs have higher chemical and electrochemical stability. The Raman spectroscopy was employed to study the BMPYRB(CN)4 and BMPB(CN)4 liquids and their mixtures with lithium salt (0.1 mol L-1 of LiB(CN)4); it was demonstrated that the interaction between the lithium ion and anion tetracyanoborate is very low, which explains the high values of conductivity and transport numbers of lithium in these systems. Furthermore five ionic liquids from the phosphonium cation was synthesized always using the anion [Tf2N]-; being liquid at room temperature only the ILs [P2225][Tf2N] (triethyln-pentylphosphonium bis(trifluoromethylsulfonyl)imide) and [P222(201)][Tf2N] (triethyl (2- methoxyethyl) phosphonium bis(trifluoromethylsulfonyl imide) imide). It was found that these liquids have excellent transport properties and electrochemical stability when compared with their counterparts derived from nitrogen; furthermore, when lithium salt LiTf2N, was added at concentrations of 1 and 2 mol L-1, the ILs containing the phosphonium cations have also shown a decrease in the transport properties, however, the effect is less pronounced when compared to ionic liquids derived from nitrogen, presenting higher transport number and lithium ion conductivity.

Membrane processes are considered energy-efficient for water desalination and treatment. However most membranes are based on polymers prepared from fossil petrochemical sources. The development of multilayer membranes for nanofiltration and ultrafiltration, with thin selective layers of naturally available cellulose, has been hampered by the availability of non-aggressive solvents. We propose the manufacture of cellulose membranes based on two approaches: (i) silylation, coating from solutions in tetrahydrofuran, followed by solvent evaporation and cellulose regeneration by acid treatment; (ii) casting from solution in 1-ethyl-3-methylimidazolum acetate ([C2mim]OAc), an ionic liquid, followed by phase inversion in water. In the search for less harsh, greener membrane manufacture, the combination of cellulose and ionic liquid is of high interest. Due to the abundance of OH groups and hydrophilicity, cellulose-based membranes have high permeability and low fouling tendency. Membrane fouling is one of the biggest challenges in membrane industry and technology. Accumulation and deposition of foulants onto the surface reduce membrane efficiency and requires harsh chemical cleaning, therefore increasing the cost of maintenance and replacement. In this work the resistance of cellulose 5 membranes towards model organic foulants such as Suwanee River Humic Acid (SRHA) and crude oil have been investigated. Cellulose membrane was tested in this work for oil-water (o/w) separation and exhibited practically 100 % oil rejection with good flux recovery ratio and membrane resistivity. The influence of anionic, cationic and ionic surfactant as well as pH and crude oil concentration on oil separation was investigated, giving a valuable insight in experimental and operational planning.

京都大学 / 0048 / 新制・課程博士 / 博士(エネルギー科学) / 甲第19090号 / エネ博第314号 / 新制||エネ||64(附属図書館) / 32041 / 京都大学大学院エネルギー科学研究科エネルギー基礎科学専攻 / (主査)教授 萩原 理加, 教授 佐川 尚, 教授 野平 俊之 / 学位規則第4条第1項該当 / Doctor of Energy Science / Kyoto University / DFAM

Room temperature ionic liquids (ILs) are a unique class of solvents which are characterized by non-volatility, non-flammability, electrochemical stability and high ionic conductivity. These properties are highly desirable for ion-conducting electrolytes, and much work has focused on realizing their application in practical devices. In addition, hydrophilic and ionophilic polymers are generally miscible with ILs. The miscibility of ILs with ion-coordinating polymers makes ILs effective plasticizers for gel polymer electrolytes. Due to their unique properties, ILs present a means to realize the next generation of energy storage technology. In this dissertation, the fundamental interactions between poly(ethylene oxide) (PEO) and a variety of room temperature ILs were investigated. ILs with acidic protons were demonstrated to form a stronger interaction with PEO than ILs without such protons, suggesting that hydrogen bonding plays a dominant role for PEO miscibility with ILs. The hydrogen bonding interaction is selective for the PEO block of a PEO-b-PPO-b-PEO block copolymer (BCP). Therefore, blending these copolymers with the strongly interacting IL 1-butyl-3-methylimidazolium hexafluorophosphate ([BMI][PF6]) induced microphase separation into a well-ordered structure, whereas the neat copolymer is phase mixed. At sufficient quantities, the interaction between [BMI][PF6] and PEO suppresses PEO crystallinity entirely. In addition, the induced microphase separation may prove beneficial for ion conduction. Therefore, microphase separated copolymer/IL blends were investigated as potential gel polymer electrolytes. Cross-linkable block copolymers which microphase separate when blended with [BMI][PF6] were synthesized by modifying PPO-b-PEO-b-PPO copolymers with methacrylate end-groups. Cross-linking these copolymers while swollen with an IL generates ion gels with high ionic conductivities. The copolymer/IL blends vary from a well-ordered, strongly microphase separated state to a poorly ordered and weakly microphase separated state, depending upon the molecular weight. Stronger microphase separation results in higher mechanical strength upon cross-linking. However, this does not greatly affect ion conductivity. Nor is conductivity affected by forming gels from cross-linked PEO homopolymers when compared to BCPs. It was found that BCPs can be beneficial in producing gel electrolytes by allowing sequestration of phase selective cross-linkers away from the conducting block. Cross-linker molecules that are selective for the PPO blocks can be used to increase the mechanical strength of the gels with only a small effect on the conductivity. When cross-linkers that partition to the mixed PEO/IL block are used, the conductivity decreases by nearly a factor of 2. These studies show how ILs interact with PEO and how gel polymer electrolytes can be constructed with the IL [BMI][PF6]. While BCPs cannot directly be used to increase ion conductivity, they do allow for greater mechanical strength without sacrificing conductivity. This suggests many new approaches that may be used to simultaneously achieve high ionic conductivity and mechanical strength in solid and gel polymer electrolytes.

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