This thesis is submitted in a format of published papers by the candidate. Advanced methods of electron microscopy and X-ray spectroscopy have been used to study the relationship between the pillars and the silicate structure ranging from Al13 and Ga13 complexes to the final products Al- and Ga-pillared clays. The Al13 and Ga13 pillared montmorillonites have been prepared by conventional and ultrasonic methods. The ultrasonic method has been proven to be effective and showed very good catalytically activity. Transmission electron microscopy combined with elemental mapping by EDS showed the distribution of the Ga and Al pillars in the clay structure. The use of gallium allowed the independent observation of the Ga pillar distribution from the Al distribution in the clay structure. XPS spectra of the Ga13 pillared montmorillonites showed that the pillars has been changed from the original Keggin structure with a 7+ charge to something more stable with a lower charge upon intercalation. No direct evidence of the inverted silicon tetrahedron structure bonding to the pillar structure, as suggested by Plee in his original thesis, was observed. For comparative reasons the major aluminium hydroxide minerals in bauxite (gibbsite, bayerite and (pseudo-) boehmite) were studied. Detailed information about the Al13 structure was obtained by studying the basic sulphate and nitrate salts with XPS. The XPS results of a set of starting clays in comparison to the pillared clays indicated that small changes in the binding energy could explain the changes in the pillar structure and the formation of chemical bonds to the clay tetrahedral sheets during the calcination leading to the final products.

Neste estudo, investigaram-se mudanças nas propriedades coloidais de uma esmectita pilarizada com polihidroxicátion de alumínio. A solução pilarizante foi preparada mediante gotejamento de solução NaOH 0,4 mol L-1 em solução de AlCl3.6H2O 0,2 mol L-1, a qual foi adicionada à suspensão de argila de 1% m/m. Para avaliar mudanças nas propriedades das argilas, recorreu-se às técnicas de titulação potenciométrica descontínua, análise química total, DRX, FTIR, CTC e isotermas de adsorção/dessorção de N2. Além disso, foram realizados ensaios de adsorção de Cu2+ para avaliar a capacidade de remoção do metal de soluções aquosas pelas argilas pilarizadas e gerar informações relacionadas à interação entre adsorvente e adsorbato. Naturalmente, a argila apresentou espaçamento basal de 1,26 nm, ao passo que as pilarizadas apresentaram valores de 1,78 nm (500 oC) e 1,80 nm (350 oC). Dados da análise química total mostraram se tratar de uma montmorillonita com altos teores de Fe3+, e confirmou o aumento nos teores de Al3+ na estrutura da argila após pilarização. Os valores de área superficial específica e volume de microporos foram maiores para as argilas pilarizadas, enquanto que a CTC foi maior para a argila natural. A titulação potenciométrica mostrou modificação nas curvas de titulação com o processo de pilarização, em que nas argilas pilarizadas surgiram novos sítios de reação. Dentre as equações de adsorção aplicadas, Langmuir, Freundlich e Temkin, a primeira apresentou valores de r2 das equações linearizadas maior para todas as argilas e menor desvio médio (?g%) para argila natural, ao passo que a equação de Temkin mostrou valores de ?g(%) menores para as argilas pilarizadas. Parâmetros termodinâmicos confirmaram que a reação de adsorção de Cu2+ é espontânea para todas as argilas, principalmente para as argilas pilarizadas. Além disso, cálculos baseados em equações de Dubinin-Radushkevich evidenciam que a ligação é fraca entre metal e argila, caracterizando reações de fisissorção. / In this study, an Al-pillared smectite was synthesized and changes in its colloidal properties were investigated. The pillaring solution was prepared adding dropwise adequate volume of NaOH 0,4M to AlCl3.6H2O 0,2M solution. Then, the pillaring solution was added to a 1% w/w clay slurry with constant stirring. Potentiometric titration, chemical analysis, XRD, FTIR, CEC and N2 sorption/dessoption isotherms analysis were done to characterize the changes in clay properties. Moreover, adsorption experiments were carried out in order to evaluate the capacity of the pillared clays to remove Cu2+ from aqueous solution and to characterize the interaction between adsorbent and adsorbate. The natural clay has a basal spacing of 1.26 nm whereas the pillared clays reached 1.78 nm (500 oC) and 1.80 nm (350 oC) after calcination. Chemical analysis revealed that the montmorillonite used has high content of Fe3+ and the increase in the Al3+ amount in the structure of the pillared clays after pillaring process. The surface area and micropore volume were higher for the pillared clays and the CEC was higher for the natural clay. The pillaring process changed the potentiometric titration curves, wherein the pillared clays exhibited new reactive site. Experimental data were fit to Langmuir, Freundlich and Temkin adsorption equations, being the the first one the best (highest r2 value) for all the clays and lower standard deviation (?g%) for the natural clay. On the other hand, Temkin equation exhibited ?g% value lower for the pillared clays. Thermodynamics parameters demonstrate that the Cu2+ adsorption process is spontaneous for all the clays, but with higher values for the pillared materials. In addition, application of the Dubinin-Radushkevich equation revealed that the bond between the metal and the clay are weak, characterizing a physisorption.

Neste estudo, investigaram-se mudanças nas propriedades coloidais de uma esmectita pilarizada com polihidroxicátion de alumínio. A solução pilarizante foi preparada mediante gotejamento de solução NaOH 0,4 mol L-1 em solução de AlCl3.6H2O 0,2 mol L-1, a qual foi adicionada à suspensão de argila de 1% m/m. Para avaliar mudanças nas propriedades das argilas, recorreu-se às técnicas de titulação potenciométrica descontínua, análise química total, DRX, FTIR, CTC e isotermas de adsorção/dessorção de N2. Além disso, foram realizados ensaios de adsorção de Cu2+ para avaliar a capacidade de remoção do metal de soluções aquosas pelas argilas pilarizadas e gerar informações relacionadas à interação entre adsorvente e adsorbato. Naturalmente, a argila apresentou espaçamento basal de 1,26 nm, ao passo que as pilarizadas apresentaram valores de 1,78 nm (500 oC) e 1,80 nm (350 oC). Dados da análise química total mostraram se tratar de uma montmorillonita com altos teores de Fe3+, e confirmou o aumento nos teores de Al3+ na estrutura da argila após pilarização. Os valores de área superficial específica e volume de microporos foram maiores para as argilas pilarizadas, enquanto que a CTC foi maior para a argila natural. A titulação potenciométrica mostrou modificação nas curvas de titulação com o processo de pilarização, em que nas argilas pilarizadas surgiram novos sítios de reação. Dentre as equações de adsorção aplicadas, Langmuir, Freundlich e Temkin, a primeira apresentou valores de r2 das equações linearizadas maior para todas as argilas e menor desvio médio (?g%) para argila natural, ao passo que a equação de Temkin mostrou valores de ?g(%) menores para as argilas pilarizadas. Parâmetros termodinâmicos confirmaram que a reação de adsorção de Cu2+ é espontânea para todas as argilas, principalmente para as argilas pilarizadas. Além disso, cálculos baseados em equações de Dubinin-Radushkevich evidenciam que a ligação é fraca entre metal e argila, caracterizando reações de fisissorção. / In this study, an Al-pillared smectite was synthesized and changes in its colloidal properties were investigated. The pillaring solution was prepared adding dropwise adequate volume of NaOH 0,4M to AlCl3.6H2O 0,2M solution. Then, the pillaring solution was added to a 1% w/w clay slurry with constant stirring. Potentiometric titration, chemical analysis, XRD, FTIR, CEC and N2 sorption/dessoption isotherms analysis were done to characterize the changes in clay properties. Moreover, adsorption experiments were carried out in order to evaluate the capacity of the pillared clays to remove Cu2+ from aqueous solution and to characterize the interaction between adsorbent and adsorbate. The natural clay has a basal spacing of 1.26 nm whereas the pillared clays reached 1.78 nm (500 oC) and 1.80 nm (350 oC) after calcination. Chemical analysis revealed that the montmorillonite used has high content of Fe3+ and the increase in the Al3+ amount in the structure of the pillared clays after pillaring process. The surface area and micropore volume were higher for the pillared clays and the CEC was higher for the natural clay. The pillaring process changed the potentiometric titration curves, wherein the pillared clays exhibited new reactive site. Experimental data were fit to Langmuir, Freundlich and Temkin adsorption equations, being the the first one the best (highest r2 value) for all the clays and lower standard deviation (?g%) for the natural clay. On the other hand, Temkin equation exhibited ?g% value lower for the pillared clays. Thermodynamics parameters demonstrate that the Cu2+ adsorption process is spontaneous for all the clays, but with higher values for the pillared materials. In addition, application of the Dubinin-Radushkevich equation revealed that the bond between the metal and the clay are weak, characterizing a physisorption.

Orientador: Heloise de Oliveira Pastore / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Química / Made available in DSpace on 2018-08-22T16:48:58Z (GMT). No. of bitstreams: 1 Moura_HipassiaMarcondesde_M.pdf: 6781457 bytes, checksum: b05858e45bf4d0bdf564a43406440fc9 (MD5) Previous issue date: 2013 / Resumo: O estudo da inserção de alumínio na estrutura lamelar da magadiita assim como o acompanhamento de sua cristalização permitiu elucidar os mecanismos de incorporação deste metal neste tipo de silicato, ainda pouco investigado na literatura. Através do monitoramento por técnicas espectroscópicas (RMN de Si e Al, IV-TF e XPS) e não espectroscópicas (DRX, análise elementar e TGA) das etapas de formação da [Al]-magadiita, notou-se que sua obtenção em laboratório pode ser otimizada devido ao uso de sementes do próprio material. Os experimentos de XPS elucidam a [Al]-magadiita como uma estrutura do tipo `coreshell¿, constituída de magadiita silícica sobre a qual encontra-se depositada uma camada de aluminossilicato. Seguido por estudos de adsorção de CO à baixas temperaturas, avaliou-se os sítios ácidos dos materiais obtidos pelo uso de sementes de cristalização assim como a homogeneidade da distribuição da camada de aluminossilicato. A [Al]-magadiita pode apresentar aplicações descritas na literatura como precursora de outras estruturas zeolíticas. Porém, pouco se explora seu uso em outros tipos de modificações como é feita para sua forma livre de alumínio, a magadiita. Nesse sentido, algumas modificações na superfície do aluminossilicato foram investigadas. Dentre elas, a organossililação ("grafting") com grupos aminopropil (APTS), a pilarização com tetraetilortosilicato (TEOS) e a modificação com ambas as fontes de silício, permitindo a formação de novos materiais mesoporosos e/ou funcionalizados contendo alumínio em sua rede cristalina e grupos orgânicos ativos na captura de gases ácidos como o carbônico. / Abstract: The synthesis of [Al]-magadiite was monitored during preparation and crystallization by the Aluminum-Induced Crystallization method developed previously. A systematic study of the physicochemical and thermal properties of the products obtained at each step in [Al]-magadiite synthesis was performed by combining different experimental techniques [infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetric analysis (TGA) and solid-state magic-angle spinning nuclear magnetic resonance (MAS-NMR)]. The results obtained showed that the hydrothermal treatment before aluminum insertion served essentially for the creation of magadiite seeds. Thus, induced crystallization by introduction of magadiite seeds directly in the synthesis gel showed that the synthesis duration could be reduced into a single step. XPS spectroscopy allowed designing the [Al]- magadiite structure as a pure silicon magadiite core with a thin layer of aluminosilicate deposited on top of it. Using the CO adsorption at low temperature with IR-FT, the acid sites of the SIC-[Al]-magadiites were evaluated as the aluminosilicate shell distribution over the magadiite crystal. [Al]-magadiite found applications described in the literature as a precursor to other zeolites structures. However, little is explored about its use in other types of surface modifications such as done for its aluminum free form, magadiite. In this sense, some modifications on the aluminosilicate surface were investigated. Among them, the grafting with aminopropyl groups (APTS), the pillaring with tetraethylorthosilicate (TEOS) and the modification with both silicon sources, allowing the formation of novel mesoporous and/or functionalized materials containing aluminum in its crystalline lamella and active organic groups in acid gases uptake such as carbon dioxide. / Mestrado / Quimica Inorganica / Mestra em Química

Neste trabalho, fracionou-se e tratou-se a argila Brasgel. Esta argila foi pilarizada em vários estágios de facionamento e/ou tratamento com 5 meq de Al / g de argila: (i) Al-PILC, a argila passou por todos os estágios de fracionamento e tratamento (ARG), (ii) Al-PILCFe, a argila não passou pela etapa de retirada de Fe livre (ARGFe) e (iii) Al-PILCFe/silte, a argila não passou pelas etapas de retirada de silte e Fe livre (ARGFE/silte). Em análise por DRX observou-se que as Al-PILCs apresentaram uma distância basal maior que as argilas de partida. A análise textural indicou que as argilas Al-PILCs e ARGs são materiais mesoporosos, com poros do tipo fenda estreita e do tipo fenda, respectivamente. Além disso, as Al-PILCs apresentaram área superficial razoavelmente maior que as ARGs correspondentes. Outras análises feitas nas argilas foram: teor de Si, Fe e Al; CTC; FTIR; TGA e TGD. As argilas Brasgel pilarizadas foram usadas como catalisador na reação de isomerização do óxido de estireno em hexano sob refluxo. A reação foi seletiva na formação de fenilacetaldeído. As argilas Al-PILCFe e Al-PILCFe/silte apresentaram melhor desempenho catalítico (100 % de conversão em 20 min de reação). Assim, as argilas Brasgel pilarizadas se apresentaram como uma Tecnologia Limpa na reação de isomerização do óxido de estireno ao fenilacetaldeído. Palavras-chave: Desenvolvimento Sustentável. Tecnologia Limpa. Química Verde. Argilas Pilarizadas. Isomerização de Epóxidos. / This work, the Brasgel clay was fractionated and treated. The clay was pillared in several stages of fractionation and / or treatment with Al 5 meq / g of clay: (i) Al- PILC, the clay has passed through all stages of treatment and fractionation (ARG), (ii) Al-PILCFe, the clay would not pass the step of removal of free Fe (ARGFe) and (iii) Al-PILCFe/silt, clay has not gone through the steps of removing silt and free Fe (ARGFE/silt). XRD analysis showed that the Al-PILCs showed a basal spacing greater than the starting clays. The textural analysis indicated that the Al-PILCs and ARGs are mesoporous materials, with pore narrow slit type and slit type, respectively. Moreover, the Al-PILCs showed reasonable surface area greater than the corresponding ARGs. Other analyzes were made on clays: the content of Si, Fe and Al; CEC, FTIR, TGA and TGD. Brasgel pillared clays have been used as catalyst in the isomerization reaction of the styrene oxide in refluxing. The reaction was selective for the formation of phenylacetaldehyde. Al-PILCFe and Al-PILCFe/silt clays showed better catalytic performance (100% conversion in 20 min of reaction). Thus, the pillared clays Brasgel presented as a Clean Technology in the isomerization reaction of styrene oxide to phenylacetaldehyde. Keywords: Sustainable Development. Clean Technology. Green Chemistry. Pillared Clays. Isomerization of Epoxides.

Neste trabalho, fracionou-se e tratou-se a argila Brasgel. Esta argila foi pilarizada em vários estágios de facionamento e/ou tratamento com 5 meq de Al / g de argila: (i) Al-PILC, a argila passou por todos os estágios de fracionamento e tratamento (ARG), (ii) Al-PILCFe, a argila não passou pela etapa de retirada de Fe livre (ARGFe) e (iii) Al-PILCFe/silte, a argila não passou pelas etapas de retirada de silte e Fe livre (ARGFE/silte). Em análise por DRX observou-se que as Al-PILCs apresentaram uma distância basal maior que as argilas de partida. A análise textural indicou que as argilas Al-PILCs e ARGs são materiais mesoporosos, com poros do tipo fenda estreita e do tipo fenda, respectivamente. Além disso, as Al-PILCs apresentaram área superficial razoavelmente maior que as ARGs correspondentes. Outras análises feitas nas argilas foram: teor de Si, Fe e Al; CTC; FTIR; TGA e TGD. As argilas Brasgel pilarizadas foram usadas como catalisador na reação de isomerização do óxido de estireno em hexano sob refluxo. A reação foi seletiva na formação de fenilacetaldeído. As argilas Al-PILCFe e Al-PILCFe/silte apresentaram melhor desempenho catalítico (100 % de conversão em 20 min de reação). Assim, as argilas Brasgel pilarizadas se apresentaram como uma Tecnologia Limpa na reação de isomerização do óxido de estireno ao fenilacetaldeído. Palavras-chave: Desenvolvimento Sustentável. Tecnologia Limpa. Química Verde. Argilas Pilarizadas. Isomerização de Epóxidos. / This work, the Brasgel clay was fractionated and treated. The clay was pillared in several stages of fractionation and / or treatment with Al 5 meq / g of clay: (i) Al- PILC, the clay has passed through all stages of treatment and fractionation (ARG), (ii) Al-PILCFe, the clay would not pass the step of removal of free Fe (ARGFe) and (iii) Al-PILCFe/silt, clay has not gone through the steps of removing silt and free Fe (ARGFE/silt). XRD analysis showed that the Al-PILCs showed a basal spacing greater than the starting clays. The textural analysis indicated that the Al-PILCs and ARGs are mesoporous materials, with pore narrow slit type and slit type, respectively. Moreover, the Al-PILCs showed reasonable surface area greater than the corresponding ARGs. Other analyzes were made on clays: the content of Si, Fe and Al; CEC, FTIR, TGA and TGD. Brasgel pillared clays have been used as catalyst in the isomerization reaction of the styrene oxide in refluxing. The reaction was selective for the formation of phenylacetaldehyde. Al-PILCFe and Al-PILCFe/silt clays showed better catalytic performance (100% conversion in 20 min of reaction). Thus, the pillared clays Brasgel presented as a Clean Technology in the isomerization reaction of styrene oxide to phenylacetaldehyde. Keywords: Sustainable Development. Clean Technology. Green Chemistry. Pillared Clays. Isomerization of Epoxides.

Στην παρούσα διατριβή ειδίκευσης παρασκευάσθηκαν νανοσύνθετα υλικά αργιλικών ορυκτών/διοξειδίου του τιτανίου (TiO2) για την περιγραφή και μελέτη των νέων βελτιωμένων χαρακτηριστικών τους και την εφαρμογή τους σαν φωτοκαταλύτες στη διάσπαση ανόργανων αέριων ρύπων οξειδίων του αζώτου (NOX). Τρία αργιλικά ορυκτά (σαπωνίτης, παλυγορσκίτης και αλλοϋσίτης) χρησιμοποιήθηκαν για την διεξαγωγή των πειραμάτων. Δείγματα σαπωνίτη και παλυγορσκίτη συλλέχθηκαν από τη λεκάνη του Βεντζίου στα Γρεβενά και αλλοϋσίτη από τη νήσο Λήμνο. Δύο διαφορετικές μορφές νανοσύνθετων αργιλικού ορυκτού/TiO2 παρήχθησαν με δύο διαφορετικές μεθόδους και χρησιμοποιήθηκαν για τη μελέτη της φωτοαποικοδόμησης ανόργανων αέριων ρύπων NOX : Υποστυλωμένα με TiO2 νανοσύνθετα σαπωνίτη (Ti-sap1, Ti-sap2) παρήχθησαν με τη μέθοδο της «solvothermal synthesis” χρησιμοποιώντας TiCl3 σαν πρόδρομο TiO2 και νανοσύνθετα TiO2/ παλυγορσκίτη (Ti-pal) και TiO2/ αλλοϋσίτη (Ti-hall) παρήχθησαν με τη μέθοδο κολλοειδούς διαλύματος σε πήκτωμα (sol-gel) χρησιμοποιώντας Titanium Tetraisopropoxide (Ti(OC3H7)4) σαν διάλυμα διασποράς-επικάθησης. Για τον χαρακτηρισμό των ιδιοτήτων των φυσικών και τροποποιημένων δειγμάτων εφαρμόστηκαν διαφορετικές τεχνικές (XRD, FTIR-ATR, SEM-EDS, TEM, DLS, BET, porosimetry). Τα νανοσύνθετα αποδείχθηκαν αρκετά αποτελεσματικά για τη φωτοδιάσπαση των αέριων ρύπων NOX συγκριτικά με τον standard τύπο διοξειδίου του τιτανίου, Degussa P25, που χρησιμοποιείται γιαυτό το σκοπό. Tα υποστυλωμένα νανοσύνθετα Ti-sap1 και Ti-sap2 (με αναλογίες μάζας TiO2:σαπωνίτη = 0.2:1 και 0.1:1 αντίστοιχα) έδειξαν αύξηση της ειδικής τους επιφάνειας συγκριτικά με το φυσικό δείγμα σαπωνίτη και μεσοπορώδη δομή με κατανομή πόρων 5.7-9.8nm για το Ti-sap1 και 3.8nm για το Ti-sap2. Και τα δύο νανοσύνθετα απέκτησαν αυξημένη φωτοκαταλυτική ικανότητα βάση του περιεχόμενου ποσοστού TiO2 συγκριτικά με τον standard P25 λόγω της ομοιογενούς διασποράς των σωματιδίων TiO2 στον σαπωνίτη αλλά συγκρίνοντας τα δύο δείγματα Tisap1 και Tisap2, το Tisap2 είχε καλύτερη φωτοκαταλυτική δράση από το Tisap1. Όσον αφορά τα νανοσύνθετα TiO2-pal και TiO2-hall τα αποτελέσματα έδειξαν τη δημιουργία μεσοπορώδους δομής με πόρους 6.5 και 5.6 nm αντίστοιχα για το κάθε υλικό ενώ η μακροπορώδης δομή (lumen) του αλλοϋσίτη δεν υπήρχε στο τροποποιημένο δείγμα λόγω του ότι καλύφθηκε από τα νανοσωματίδια του TiO2 με αποτέλεσμα να προκύψει ένα υλικό με μικρότερο μέγεθος πόρων. Τα δύο δείγματα έδειξαν υψηλή φωτοκαταλυτική ικανότητα στη διάσπαση των αέριων ρύπων NOX υπό την επίδραση ορατής (λ>510nm) και υπεριώδους (λ>290nm) ακτινοβολίας σε σύγκριση με τα αποτελέσματα που έδωσε ο standard τύπος TiO2 P25. / In this thesis TiO2/clay nanocomposites have been synthesized and characterized as photocatalysts in the decomposition of NOx gases. Three different clay minerals (saponite, palygorskite and halloysite) have been used. The saponite and palygorskite samples were collected from Western Macedonia (Grevena, Ventzia basin) and halloysite from Lemnos island. The two different forms of nanocomposites that synthesized by two different methods were: TiO2 -pillared saponite (Ti-sap1, Tisap2) were successfully prepared by solvothermal synthesis using titanium trichloride as the precursor and TiO2- Palygorskite (Ti-pal) and TiO2-Halloysite (Ti-hall) nanocomposites were prepared by deposition of anatase form of TiO2 on the clay surfaces using a sol–gel method with titanium isopropoxide as a precursor. The characterization of the natural and modified samples was done by using different techniques (XRD, FTIR-ATR, SEMEDS, TEM, DLS, BET, porosimetry) The photocatalytic properties of the TiO2-clay nanocomposites were found to be better than that of the standard titania, Degussa P25 in decomposing NOX gases. The pillared TiO2 nanocomposites Ti-sap1, Tisap2 (mass ratio of TiO2:saponite= 0.2:1 and 01:1 respectively) showed a mesoporous structure compared to the natural saponite, with the distribution of pore diameters centered at 5.7-9.8 and at 3.8 nm, with high specific surface areas. Both TiO2-saponite nanocomposites showed higher photocatlytic activity than the standard (Degussa P25) based on TiO2 content because the TiO2 was well dispersed on saponite. By comparing the two modified samples Ti-sap1, Ti-sap2, the second one showed better photocatalytic activity than Ti-sap1 The results of the other two nanocomposites, Ti-hall and Ti-pal, showed mesopores of about 5.6 and 6.5 nm, respectively, while the macropores of halloysite (lumen) disappeared. The latter is attributed to the covering of the lumen of halloysite tubes by TiO2 nanoparticles and for that reason the pore size of the TiO2–treated halloysite was significantly smaller. The clay minerals- TiO2 samples showed significantly higher activity in decomposing NOx gas under visible-light irradiation (λ> 510 nm) and UV light irradiation (λ> 290 nm) compared to that of the standard commercial TiO2, P 25.