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Submitted by José Henrique Lazaro de Carvalho (jose.carvalho@fc.unesp.br) on 2018-04-26T14:52:46Z No. of bitstreams: 1 merged.pdf: 3543516 bytes, checksum: 94a6da42fee42b5469644d670ca0dddc (MD5) / Approved for entry into archive by Minervina Teixeira Lopes null (vina_lopes@bauru.unesp.br) on 2018-04-26T17:33:49Z (GMT) No. of bitstreams: 1 carvalho_jhl_me_bauru.pdf: 3133645 bytes, checksum: 07b206851bb163d2aab65e55f0340aea (MD5) / Made available in DSpace on 2018-04-26T17:33:49Z (GMT). No. of bitstreams: 1 carvalho_jhl_me_bauru.pdf: 3133645 bytes, checksum: 07b206851bb163d2aab65e55f0340aea (MD5) Previous issue date: 2018-02-26 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Os hidrocarbonetos se constituem na função mais simples da química orgânica. Mesmo sendo formados apenas por carbono e hidrogênio, esta classe é uma das mais diversas, onde se destacam os hidrocarbonetos alquil aromáticos (HAA) e os hidrocarbonetos aromáticos policíclicos (HAP). Por possuírem baixa reatividade e serem lipossolúveis, os HAA e HAP tendem a se acumular na natureza e nos tecidos vivos podendo levar a mutações genéticas e ao câncer. Funcionalizações oxigenadas nestes hidrocarbonetos ampliam suas aplicações industriais e auxiliam na sua remediação ambiental. A oxidação radicalar utilizando radicais hidroxila via TBHP (t-butil-hidroperóxido) é uma rota promissora devido à ausência de resíduos metálicos nocivos no processo. Paralelamente, o uso de metais do bloco-d, como o nióbio, como catalisadores heterogêneos, que são conhecidos por apresentarem boa estabilidade térmica, porosidade, maior superfície de contato e podendo ser recuperado e reutilizado, vem sendo descrito como bons catalisadores para a reação, permitindo rendimentos maiores e condições reacionais mais brandas. O nióbio tem despertado o interesse de muitos grupos de pesquisa devido às suas propriedades e aplicabilidades na metalurgia, supercondutores e supercapacitores, e na síntese orgânica. Este trabalho focou no estudo da aplicação do óxido de nióbio como catalisador heterogêneo em reações de oxidação de HAA e HAP usando o TBHP como oxidante. Diferentes variáveis reacionais como o solvente, a concentração e morfologia do catalisador, temperatura, dentre outras, foram investigadas a fim de otimizar a reação para a melhor conversão no derivado oxigenado. A melhor condição obtida foi utilizando Nb2O5 amorfo em 10% em mol de reagente, em acetonitrila e em refluxo com mais de 40 % de conversão em derivado oxigenado para qualquer substrato de hidrocarboneto estudado. / Hydrocarbons are the simplest function of organic chemistry. Although formed only by carbon and hydrogen, this class is one of the most diverse, in which the alkyl aromatic hydrocarbons (AAHs) and the polycyclic aromatic hydrocarbons (PAHs) stand out. These substances are mostly fossil raw materials widely used in industry in diverse applications. Because they have low reactivity and are liposoluble, AAHs and PAHs tend to accumulate in nature and in living tissues, leading to genetic mutations and cancer. Oxygenated functionalities in these hydrocarbons broaden their industrial applications and assist in their environmental remediation. Radical oxidation using hydroxyl radicals via TBHP (t-butylhydroperoxide) is a promising route due to the absence of noxious metal residues in the process. At the same time, the use of d-block metals, such as niobium, as heterogeneous catalysts, which are known to have good thermal stability, porosity, larger contact surface and be able to be recovered and reused, have been described as good catalysts for the reaction, allowing for higher yields and softer reaction conditions. Niobium has attracted the interest of many research groups because of its properties and applications in metallurgy, superconductors and supercapacitors, and in organic synthesis. This work focused on the study of the application of niobium oxide as a heterogeneous catalyst in oxidation reactions of AAHs and HAP using TBHP as oxidant. Many reactional variables like the solvent, the catalyst concentration and morphology, as well as temperature have been investigated in order to optimize the reaction for the better conversion to oxygen derivatives. The best obtained condition was using 10 % in mol amorphous Nb2O5 in acetonitrile under reflux with a conversion yield of more than 40 % for any studied hydrocarbon substrate.

Ce travail est consacré à l’étude de l’impact des lavages chimiques à l’hypochlorite de sodium (NaOCl) effectués sur des membranes polymères polyéthersulfone (PES)/polyvinylpyrolidonne (PVP) (95%/5%) utilisées pour la filtration de l’eau ou du lait. Sur les sites d’exploitation les lavages chimiques sont nécessaires pour maintenir les propriétés de filtration des membranes qui se colmatent au cours de leur utilisation. L’objectif de cette étude est de déterminer les mécanismes de dégradation de ces deux polymères au contact de l’agent nettoyant, puis de corréler ces évolutions aux changements de propriétés macroscopiques des membranes en réalisant une analyse multi-échelle. Dans un premier temps, l’étude de l’impact de NaOCl sur des polymères modèles, le PES d’une part et la PVP d’autre part, a montré que la PVP s’oxyde lorsqu’elle est dissoute dans NaOCl ce qui n’est pas le cas de films de PES. A partir de l’identification des produits d’oxydation, un mécanisme d’oxydation radicalaire de la PVP mettant en jeu les radicaux hydroxyles provenant de la solution de NaOCl a été proposé. Dans un deuxième temps, afin de s’affranchir de l’hétérogénéité des membranes PES/PVP, des films de mélanges modèles PES/PVP à différents pourcentages de PVP ont été préparés. Leur immersion dans une solution de NaOCl provoque non seulement l’oxydation de la PVP mais aussi celle du PES montrant sans ambiguïté l’effet pro-dégradant de la PVP sur le PES. Dans un troisième temps, il a été montré que le vieillissement des membranes PES/PVP peut être explicité à partir des résultats obtenus sur les mélanges modèles, et que l’évolution de la structure chimique de la PVP pouvait être corrélée avec la perte des propriétés mécaniques des membranes permettant de faire le lien entre l’évolution de la structure chimique et la perte des propriétés macroscopiques. Il apparait donc au final que l’additif ajouté au PES pour rendre les membranes hydrophiles est le talon d’Achille de la structure. Le suivi de l’oxydation de la PVP contenue dans les membranes exposées à NaOCl a été proposé pour servir de marqueur moléculaire de vieillissement. / This work was devoted to the study of the impact that chemical cleaning with sodium hypochlorite (NaOCl) has on polyethersulfone (PES)/polyvinylpyrrolidone (PVP) (95%/5%) membranes, commonly used for water and milk filtration processes. In onsite plants, chemical cleanings are widely used to maintain membranes filtration properties. The aim of this thesis is to determine the degradation mechanisms of these two polymers in contact with NaOCl and to correlate this information with the evolution of the macroscopic properties of the membrane through a multi scale analysis. Firstly, the study of NaOCl impact on both PVP and PES, treated separately as “model polymers”, showed us that dissolved PVP is oxidised, whereas PES film remains stable. Thanks to the identification of PVP oxidation products, a radical degradation mechanism by means of hydroxyl radicals from NaOCl solution has been proposed. Secondly, in order to overcome membrane heterogeneities, several films with different PES/PVP ratios were prepared by varying the amount of PVP. The immersion of these films in NaOCl solutions provoked the oxidation of both PVP and PES, allowing us to clearly identify the degrading effect that PVP has in PES oxidation. Thirdly, the evolution of PVP chemical structure was correlated with the loss of the membrane mechanical properties, demonstrating that PVP, used as an additive (5%), is the weak point of PES/PVP membranes. The monitoring of PVP oxidation in membranes in contact with NaOCl was proposed as a molecular marker of ageing.