Síntese e caracterizaçăo de metaloporfirinas aniônicas imobilizadas em suportes inorgânicos : estudo de diferentes estratégias de imobilizaçăo e investigaçăo da atividade catalítica /

Inclui apęndiceOrientadora : Shirley NakagakiCo-orientador : Fernando WypychInclui bibliografiaÁrea de concentraçăo : Química inorgânic

Preparation of catalysts based on iron(III) porphyrins heterogenized on silica obtained by the Sol-Gel process for hydroxylation and epoxidation reactions

Solid catalysts have been prepared by chemical interaction of iron(III) porphyrins with the surface of the pores of a silica matrix obtained by the sol-gel method. The presence of the complexes in the silica matrix and the morphology of the obtained particles were studied by UV-Vis spectroscopy, powder X-ray diffractometry, infrared spectroscopy, transmission electron microscopy, electron paramagnetic resonance and thermogravimetric analysis. The catalytic activity of the immobilized iron(III) porphyrins in the oxidation of (Z)-cyclooctene, cyclohexene and cyclohexane was evaluated in dichloromethane/acetonitrile 1:1 solvent mixture (v/v) using iodosylbenzene as oxidant. Results were compared with those achieved with the homogeneous counterparts

Síntese e caracterização de metaloporfirinas aniônicas imobilizadas em suportes inorgânicos : estudo de diferentes estratégias de imobilização e investigação da atividade catalítica

Orientadora: Prof.ª Dr.ª Shirley NakagakiCoorientador: Prof. Dr. Fernando WypychTese (doutorado) - Universidade Federal do Paraná, Setor de Exatas, Programa de Pós-Graduação em Química. Defesa: Curitiba, 27/06/2008Inclui referências: p. 133-143Área de concentração: Química InorgânicaResumo: O objetivo principal deste trabalho está focado na obtenção de catalisadores heterogêneos capazes de promover reações de oxidação de diferentes substratos orgânicos, de forma seletiva e eficiente. Diferentes porfirinas de ferro de primeira geração {[Fe(TSPP)] (aniônica) e [Fe(TMPyP] (catiônica)} e de segunda geração {[Fe(TDFSPP)], [Fe(TCFSPP)] e [Fe(TDCSPP], todas aniônicas} foram sintetizadas e submetidas à diferentes processos de imobilização em diferentes suportes. Diferentes materiais inorgânicos foram utilizados como suporte para as ferroporfirinas: (1 ) a crisotila, usada na sua forma natural e quimicamente modificada pelo processo de funcionalização; (2 ) a sílica fibrosa desordenada obtida a partir da crisotila lixiviada e funcionalizada; (3) as esferas de sílica obtidas pelo processo sol-gel; (4) os hidróxidos duplos lamelares e (5) os hidróxidos duplos lamelares macroporosos. As ferroporfirinas foram imobilizadas nos diferentes suportes pelos seguintes processos (a) interação das ferroporfirinas aniônicas com o grupo NH2 protonado, proveniente do grupo funcionalizante 3-APTS; (b) síntese das esferas de sílica na presença da ferroporfirina catiônica; (c) intercalação de anions ferroporfirínicos em HDL; (d) reestruturação de óxidos mistos macroporosos na presença do ânion ferroporfirínico e (e) troca iônica direta com anions DDS intercalados no HDL macroporoso. Todos os sólidos obtidos foram caracterizados por: difratometria de raios-X (pó), ressonância paramagnética eletrônica, espectroscopia eletrônica na região do ultravioleta e visível e vibracional na região do infravermelho com transformada de Fourier ou atenuação de refletância, microscopia eletrônica de transmissão, microscopia eletrônica de varredura, análise elementar e análise térmica. Os sólidos obtidos pelos processos de heterogenização foram utilizados como catalisadores (catálise heterogênea) na oxidação de alcenos cíclicos e de alcanos cíclico e linear. Como oxidante foi utilizado o Iodosilbenzeno. As ferroporfirinas utilizadas neste trabalho também foram utilizadas como catalisadores antes de serem imobilizadas (catálise homogênea). Os catalisadores heterogêneos que foram utilizados na oxidação do cicloocteno apresentaram bons rendimentos catalíticos (até 100 % do epóxido correspondente). Para a ferroporfirina [Fe(TCFSPP)], melhores rendimentos foram obtidos em catálise heterogênea, quando comparados à catálise homogênea, efetuadas nas mesmas condições. Quando os catalisadores foram utilizados na oxidação do cicloexano, uma grande seletividade para o álcool foi observada para todos os sistemas. Cada sistema apresentou resultados particulares para a formação dos produtos. A partir dos diferentes sistemas obtidos, foi possível investigar algumas das inúmeras variáveis que interferem no rendimento catalítico quando se utiliza ferroporfirinas como catalisador. Observou-se que o desempenho do catalisador pode ser controlado pelo suporte, dependendo em qual ambiente o catalisador se encontra (intercalado, aprisionado em esferas ou imobilizado na superfície). A proporção FePor/oxidante também é importante. Observou-se, também, que o tamanho dos substituintes pode facilitar ou bloquear o acesso dos reagentes ao sítio catalítico ativo. Os sistemas FePor/HDL macro e FePor/HDL-DDS foram utilizados na oxidação de um alcano linear, o heptano, apresentando seletividade para formação de álcoois, principalmente para o 1-heptanol, raramente formado. Estudos realizados utilizando-se os sistemas FePor/HDL-ZnxAl como catalisadores e cicloexeno como substrato mostraram que produtos alílicos (álcool + cetona) podem ser formados por diferentes rotas. Os catalisadores utilizados nas reações de catálise foram recuperados, lavados, secos e reutilizados apresentando rendimentos semelhantes ou superiores à primeira utilização.Abstract: The main goal of this work was focused on obtaining heterogeneous catalysts capable of promoting selective and efficient oxidation reactions of different organic substrates. Different iron(III)porphyrins of first generation {[Fe(TSPP)] (anionic ion) and [Fe(TMPyP] (cationic ion)} and of second generation {[Fe(TDFSPP)], [Fe(TCFSPP)] and [Fe(TDCSPP], anionic ions} were synthesized and immobilized in different supports by several methods. Different inorganic materials were used as support for the iron(III)porphyrins immobilization: (1) the raw chrysotile and chrysotile chemically modified by the functionalization process (2 ) the fibrous disordered silica obtained from the leached chrysotile and functionalized; (3) the silica spheres obtained by the sol-gel process; (4) the layered double hydroxides and (5) the macroporous layered double hydroxides. The iron(III)porphyrins were immobilized in different supports by the following processes (a) electrostatic interaction of the negative groups of the iron(III)porphyrins with the protoned NH2 from the 3-APTS group; (b) synthesis of the silica spheres in the presence of a cationic iron(III)porphyrins; (c) synthesis of the LDH with the iron(III)porphyrins anions by a co-precipitation reaction; (d) restructuring of the macroporous mixed oxides in the presence of the iron(III)porphyrins anions and (e) direct ionic exchange with the DDS anions intercalated into macroporous LDHs. The solids obtained by the immobilization processes were characterized by: powder X-ray diffraction, electron paramagnetic resonance, ultraviolet-visible spectroscopy, Fourier transform infrared spectroscopy or attenuated total reflection Fourier transform infrared, transmission electronic microscopy, scanning electron microscopy, elementar and thermal analysis. The resulting solids were used as catalysts (heterogeneous catalysis) in the oxidation of the alkenes and cyclic and linear alkanes. The Iodosilbenzeno was used as oxidant. The iron(III)porphyrins used in this work were used also as catalysts before their immobilization (homogeneous catalysis). The heterogeneous catalysts were used in the oxidation reactions of the cyclooctene, presenting a good catalytic yield (up to 100 % of the corresponding epoxide). For the iron(III)porphyrin [Fe(TCFSPP)], better yields were obtained in heterogeneous catalysis, when compared to the homogeneous catalysis. When the catalysts were used in the cyclohexane oxidation, a big selectivity for the alcohol was observed for all of the systems. Each system presented special results for the formation of the products. From the different obtained systems, it was possible to investigate some of the numerous variables that interfere in the catalytic yield when iron(III)porphyrins are used as catalysts. It was observed that the action of the catalyst can be controlled by the support, depending on the atmosphere the catalyst is retained in the support (intercalated, confined in spheres or immobilized in the surface). It was also observed, that the size of the substituent groups on the iron(III)porphyrins rings can facilitate or block the access of the reagents to the catalytic active site. The macroporous FePor/LDH and FePor /LDH-DDS systems were used for a linear alkane oxidation (heptane), presenting selectivity for alcohols formation, mainly for the 1 - heptanol, rarely formed. Catalytic studies using the systems FePor/LDH-ZnxAl as catalysts and cyclohexene as substrat showed that alilic products (alcohol + ketone) can be formed by the different means. The catalysts used in the catalysis reactions were recovered, washed, dried and reused presenting similar or superior yields to the first use.Résumé: L'objectif principal du travail présenté dans ce mémoire est l'obtention de catalyseurs hétérogènes pour les réactions d'oxydation sélective et effective de différents substrats organiques. Différentes porphyrines de fer de première génération {[Fe(TSPP)] (anionique) et [Fe(TMPyP] (cationique)} et de deuxième génération {[Fe(TDFSPP)], [Fe(TCFSPP)] et [Fe(TDCSPP], anioniques} ont été synthétisées et immobilisées dans différents supports par diverses méthodes. Différents matériaux inorganiques ont été utilisés comme support pour l’immobilisation des porphyrines de fer: (1 ) la chrysotile, utilisée dans sa forme naturelle et modifiée chimiquement par la fonctionnalisation; (2 ) la silice fibreuse, obtenue à partir d’un traitement chimique de la chrysotile et functionnalisée; (3) les sphères de silice, obtenues par le processus sol-gel; (4) les hydroxydes doubles lamellaires et (5) les hydroxydes doubles lamellaires macroporeux. Les porphyrines de fer ont été immobilisées dans les supports par les méthodes suivantes (a) interaction des porphyrines de fer anioniques avec le NH2 (protoné) du groupe 3-APTS; (b) synthèse des sphères de silice avec la porphyrine de fer cationique; (c) synthèse des HDL avec l’anion porphyrine de fer par co-précipitation à pH constant; (d) restructuration des oxydes mixtes macroporeux avec la porphyrine de fer (e) échange ionique avec les anions DDS intercalés dans des HDL macroporeux. Les matériaux obtenus ont été caractérisés par les techniques suivantes: diffraction des rayons-X (poudre), résonance paramagnétique electronique, caractérisation par UV-visible et infrarouge, microscopie électronique de transmission, microscopie électronique de balayage, analyse chimique et thermique. Les solides obtenus ont été utilisés en catalyse hétérogène pour l'oxydation d’alcènes et d'alcanes cyclique et linéaire. Le Iodosylbenzene a été utilisé comme donneur d’oxygène pour les réactions d’oxydation. Les porphyrines de fer ont aussi été usées dans la catalyse homogène. Les catalyseurs hétérogènes qui ont été utilisés pour l'oxydation du cyclooctène, ont présentanté de bons résultats catalytiques (jusqu'à 100% de formation pour l'époxyde correspondant). Pour la porphyrine de fer [Fe(TCFSPP)], les meilleurs rendements ont été obtenus dans la catalyse hétérogène en comparison avec la catalyse homogène. Quand les catalyseurs ont été utilisés pour l'oxydation du cyclohexane, une grande sélectivité pour l'alcool a été observée dans tous les systèmes. Chaque système a présenté des résultats différents pour la formation des produits d’oxydation. A partir des systèmes obtenus il a été possible d'enquêter sur quelques-unes des variables qui perturbent les résultats catalytiques quand les porphyrines de fer sont utilisées comme catalyseurs. Il a été observé que l’action du catalyseur peut-être commandée par le support, selon l’atmosphère que le catalyseur est retenu (intercalé, emprisonné dans des sphères ou immobilisé dans des surfaces). Le rapport FePor/oxydant est aussi important. Il a été observé, aussi, que la dimension des groupes présents dans les structures de porphyrines de fer peut faciliter ou bloquer l'accès des réactifs au site catalytique. Les systèmes de catalyseurs hétérogènes FePor/HDL macroporeux et FePor/HDL-DDS ont été utilisés pour l'oxydation d'un alcane linéaire, l'heptane, en présentant une sélectivité pour la formation d'alcools, principalement pour le 1-heptanol, rarement formé. Les études de la catalyse du cyclohexène en utilisant les systèmes FePor/ HDL-ZnxAl ont montré que les produits alcool + ketone, présents parmi les produits d’oxydation, peuvent être formés pour de différentes manières.Les catalyseurs utilisés ont été lavés, séchés et réutilisés. Le recyclage, par exemple, pour les systèmes FePor/HDL macroporeux et FePor/HDL-DDS, a présenté des rendements semblables ou supérieurs au premier usage

Síntese e caracterizaçao de ferroporfirinas imobilizadas em hidróxidos duplos lamelares : estudo de diferentes estratégias de imobilizaçao e investigaçao da atividade catalítica

Orientadora : Shirley NakagakiCo-orientador : Fernando WypychDissertaçao (mestrado) - Universidade Federal do Paraná, Setor de Ciencias Exatas, Programa de Pós-Graduaçao em Química. Defesa: Curitiba, 2004Inclui bibliografiaÁrea de concentraçao: Química inorgânic

Síntese e caracterizaçao de metaloporfirinas aniônicas imobilizadas em suportes inorgânicos : estudo de diferentes estratégias de imobilizaçao e investigaçao da atividade catalítica

Inclui apendiceOrientadora : Shirley NakagakiCo-orientador : Fernando WypychTese (doutorado) - Universidade Federal do Paraná, Setor de Exatas, Programa de Pós-Graduaçao em Química. Defesa: Curitiba, 27/06/2008Inclui bibliografiaÁrea de concentraçao : Química inorgânicaResumo: O objetivo principal deste trabalho está focado na obtenção de catalisadores heterogêneos capazes de promover reações de oxidação de diferentes substratos orgânicos, de forma seletiva e eficiente. Diferentes porfirinas de ferro de primeira geração {[Fe(TSPP)] (aniônica) e [Fe(TMPyP] (catiônica)} e de segunda geração {[Fe(TDFSPP)], [Fe(TCFSPP)] e [Fe(TDCSPP], todas aniônicas} foram sintetizadas e submetidas à diferentes processos de imobilização em diferentes suportes. Diferentes materiais inorgânicos foram utilizados como suporte para as ferroporfirinas: (1 ) a crisotila, usada na sua forma natural e quimicamente modificada pelo processo de funcionalização; (2 ) a sílica fibrosa desordenada obtida a partir da crisotila lixiviada e funcionalizada; (3) as esferas de sílica obtidas pelo processo sol-gel; (4) os hidróxidos duplos lamelares e (5) os hidróxidos duplos lamelares macroporosos. As ferroporfirinas foram imobilizadas nos diferentes suportes pelos seguintes processos (a) interação das ferroporfirinas aniônicas com o grupo NH2 protonado, proveniente do grupo funcionalizante 3-APTS; (b) síntese das esferas de sílica na presença da ferroporfirina catiônica; (c) intercalação de anions ferroporfirínicos em HDL; (d) reestruturação de óxidos mistos macroporosos na presença do ânion ferroporfirínico e (e) troca iônica direta com anions DDS intercalados no HDL macroporoso. Todos os sólidos obtidos foram caracterizados por: difratometria de raios-X (pó), ressonância paramagnética eletrônica, espectroscopia eletrônica na região do ultravioleta e visível e vibracional na região do infravermelho com transformada de Fourier ou atenuação de refletância, microscopia eletrônica de transmissão, microscopia eletrônica de varredura, análise elementar e análise térmica. Os sólidos obtidos pelos processos de heterogenização foram utilizados como catalisadores (catálise heterogênea) na oxidação de alcenos cíclicos e de alcanos cíclico e linear. Como oxidante foi utilizado o Iodosilbenzeno. As ferroporfirinas utilizadas neste trabalho também foram utilizadas como catalisadores antes de serem imobilizadas (catálise homogênea). Os catalisadores heterogêneos que foram utilizados na oxidação do cicloocteno apresentaram bons rendimentos catalíticos (até 100 % do epóxido correspondente). Para a ferroporfirina [Fe(TCFSPP)], melhores rendimentos foram obtidos em catálise heterogênea, quando comparados à catálise homogênea, efetuadas nas mesmas condições. Quando os catalisadores foram utilizados na oxidação do cicloexano, uma grande seletividade para o álcool foi observada para todos os sistemas. Cada sistema apresentou resultados particulares para a formação dos produtos. A partir dos diferentes sistemas obtidos, foi possível investigar algumas das inúmeras variáveis que interferem no rendimento catalítico quando se utiliza ferroporfirinas como catalisador. Observou-se que o desempenho do catalisador pode ser controlado pelo suporte, dependendo em qual ambiente o catalisador se encontra (intercalado, aprisionado em esferas ou imobilizado na superfície). A proporção FePor/oxidante também é importante. Observou-se, também, que o tamanho dos substituintes pode facilitar ou bloquear o acesso dos reagentes ao sítio catalítico ativo. Os sistemas FePor/HDL macro e FePor/HDL-DDS foram utilizados na oxidação de um alcano linear, o heptano, apresentando seletividade para formação de álcoois, principalmente para o 1-heptanol, raramente formado. Estudos realizados utilizando-se os sistemas FePor/HDL-ZnxAl como catalisadores e cicloexeno como substrato mostraram que produtos alílicos (álcool + cetona) podem ser formados por diferentes rotas. Os catalisadores utilizados nas reações de catálise foram recuperados, lavados, secos e reutilizados apresentando rendimentos semelhantes ou superiores à primeira utilização.Abstract: The main goal of this work was focused on obtaining heterogeneous catalysts capable of promoting selective and efficient oxidation reactions of different organic substrates. Different iron(III)porphyrins of first generation {[Fe(TSPP)] (anionic ion) and [Fe(TMPyP] (cationic ion)} and of second generation {[Fe(TDFSPP)], [Fe(TCFSPP)] and [Fe(TDCSPP], anionic ions} were synthesized and immobilized in different supports by several methods. Different inorganic materials were used as support for the iron(III)porphyrins immobilization: (1) the raw chrysotile and chrysotile chemically modified by the functionalization process (2 ) the fibrous disordered silica obtained from the leached chrysotile and functionalized; (3) the silica spheres obtained by the sol-gel process; (4) the layered double hydroxides and (5) the macroporous layered double hydroxides. The iron(III)porphyrins were immobilized in different supports by the following processes (a) electrostatic interaction of the negative groups of the iron(III)porphyrins with the protoned NH2 from the 3-APTS group; (b) synthesis of the silica spheres in the presence of a cationic iron(III)porphyrins; (c) synthesis of the LDH with the iron(III)porphyrins anions by a co-precipitation reaction; (d) restructuring of the macroporous mixed oxides in the presence of the iron(III)porphyrins anions and (e) direct ionic exchange with the DDS anions intercalated into macroporous LDHs. The solids obtained by the immobilization processes were characterized by: powder X-ray diffraction, electron paramagnetic resonance, ultraviolet-visible spectroscopy, Fourier transform infrared spectroscopy or attenuated total reflection Fourier transform infrared, transmission electronic microscopy, scanning electron microscopy, elementar and thermal analysis. The resulting solids were used as catalysts (heterogeneous catalysis) in the oxidation of the alkenes and cyclic and linear alkanes. The Iodosilbenzeno was used as oxidant. The iron(III)porphyrins used in this work were used also as catalysts before their immobilization (homogeneous catalysis). The heterogeneous catalysts were used in the oxidation reactions of the cyclooctene, presenting a good catalytic yield (up to 100 % of the corresponding epoxide). For the iron(III)porphyrin [Fe(TCFSPP)], better yields were obtained in heterogeneous catalysis, when compared to the homogeneous catalysis. When the catalysts were used in the cyclohexane oxidation, a big selectivity for the alcohol was observed for all of the systems. Each system presented special results for the formation of the products. From the different obtained systems, it was possible to investigate some of the numerous variables that interfere in the catalytic yield when iron(III)porphyrins are used as catalysts. It was observed that the action of the catalyst can be controlled by the support, depending on the atmosphere the catalyst is retained in the support (intercalated, confined in spheres or immobilized in the surface). It was also observed, that the size of the substituent groups on the iron(III)porphyrins rings can facilitate or block the access of the reagents to the catalytic active site. The macroporous FePor/LDH and FePor /LDH-DDS systems were used for a linear alkane oxidation (heptane), presenting selectivity for alcohols formation, mainly for the 1 - heptanol, rarely formed. Catalytic studies using the systems FePor/LDH-ZnxAl as catalysts and cyclohexene as substrat showed that alilic products (alcohol + ketone) can be formed by the different means. The catalysts used in the catalysis reactions were recovered, washed, dried and reused presenting similar or superior yields to the first use.L'objectif principal du travail présenté dans ce mémoire est l'obtention de catalyseurs hétérogènes pour les réactions d'oxydation sélective et effective de différents substrats organiques. Différentes porphyrines de fer de première génération {[Fe(TSPP)] (anionique) et [Fe(TMPyP] (cationique)} et de deuxième génération {[Fe(TDFSPP)], [Fe(TCFSPP)] et [Fe(TDCSPP], anioniques} ont été synthétisées et immobilisées dans différents supports par diverses méthodes. Différents matériaux inorganiques ont été utilisés comme support pour l’immobilisation des porphyrines de fer: (1 ) la chrysotile, utilisée dans sa forme naturelle et modifiée chimiquement par la fonctionnalisation; (2 ) la silice fibreuse, obtenue à partir d’un traitement chimique de la chrysotile et functionnalisée; (3) les sphères de silice, obtenues par le processus sol-gel; (4) les hydroxydes doubles lamellaires et (5) les hydroxydes doubles lamellaires macroporeux. Les porphyrines de fer ont été immobilisées dans les supports par les méthodes suivantes (a) interaction des porphyrines de fer anioniques avec le NH2 (protoné) du groupe 3-APTS; (b) synthèse des sphères de silice avec la porphyrine de fer cationique; (c) synthèse des HDL avec l’anion porphyrine de fer par co-précipitation à pH constant; (d) restructuration des oxydes mixtes macroporeux avec la porphyrine de fer (e) échange ionique avec les anions DDS intercalés dans des HDL macroporeux. Les matériaux obtenus ont été caractérisés par les techniques suivantes: diffraction des rayons-X (poudre), résonance paramagnétique electronique, caractérisation par UV-visible et infrarouge, microscopie électronique de transmission, microscopie électronique de balayage, analyse chimique et thermique. Les solides obtenus ont été utilisés en catalyse hétérogène pour l'oxydation d’alcènes et d'alcanes cyclique et linéaire. Le Iodosylbenzene a été utilisé comme donneur d’oxygène pour les réactions d’oxydation. Les porphyrines de fer ont aussi été usées dans la catalyse homogène. Les catalyseurs hétérogènes qui ont été utilisés pour l'oxydation du cyclooctène, ont présentanté de bons résultats catalytiques (jusqu'à 100% de formation pour l'époxyde correspondant). Pour la porphyrine de fer [Fe(TCFSPP)], les meilleurs rendements ont été obtenus dans la catalyse hétérogène en comparison avec la catalyse homogène. Quand les catalyseurs ont été utilisés pour l'oxydation du cyclohexane, une grande sélectivité pour l'alcool a été observée dans tous les systèmes. Chaque système a présenté des résultats différents pour la formation des produits d’oxydation. A partir des systèmes obtenus il a été possible d'enquêter sur quelques-unes des variables qui perturbent les résultats catalytiques quand les porphyrines de fer sont utilisées comme catalyseurs. Il a été observé que l’action du catalyseur peut-être commandée par le support, selon l’atmosphère que le catalyseur est retenu (intercalé, emprisonné dans des sphères ou immobilisé dans des surfaces). Le rapport FePor/oxydant est aussi important. Il a été observé, aussi, que la dimension des groupes présents dans les structures de porphyrines de fer peut faciliter ou bloquer l'accès des réactifs au site catalytique. Les systèmes de catalyseurs hétérogènes FePor/HDL macroporeux et FePor/HDL-DDS ont été utilisés pour l'oxydation d'un alcane linéaire, l'heptane, en présentant une sélectivité pour la formation d'alcools, principalement pour le 1-heptanol, rarement formé. Les études de la catalyse du cyclohexène en utilisant les systèmes FePor/ HDL-ZnxAl ont montré que les produits alcool + ketone, présents parmi les produits d’oxydation, peuvent être formés pour de différentes manières.Les catalyseurs utilisés ont été lavés, séchés et réutilisés. Le recyclage, par exemple, pour les systèmes FePor/HDL macroporeux et FePor/HDL-DDS, a présenté des rendements semblables ou supérieurs au premier usage

Bacteria encapsulated in Layered Double Hydroxides: an efficient Bionanohybrid for remediation processes.

International audienceA soft chemical process was successfully used to immobilize Pseudomonas sp. strain ADP (ADP), a well-known atrazine (herbicide) degrading bacterium, within a Mg2Al-layered double hydroxide host matrix. This approach is based on a simple, quick and ecofriendly direct coprecipitation of metal salts in the presence of a colloidal suspension of bacteria in water. It must be stressed that by this process the mass ratio between inorganic and biological components was easily tuned ranging from 2 to 40. This ratio strongly influenced the biological activity of the bacteria towards atrazine degradation. The better results were obtained for ratios of 10 or lower, leading to an enhanced atrazine degradation rate and percentage compared to free cells. Moreover the biohybrid material maintained this biodegradative activity after four cycles of reutilization and 3 weeks storage at 4 °C. The ADP@MgAl-LDH bionanohybrid materials were completely characterized by X-ray diffraction (XRD), FTIR spectroscopy, thermogravimetric analysis and scanning and transmission electronic microscopy (SEM and TEM) evidencing the successful immobilization of ADP within the inorganic matrix. This synthetic approach could be readily extended to other microbial whole-cell immobilization of interest for new developments in biotechnological systems

H2O2 oxidation of lignin model dimers catalyzed by copper(II)– phenanthroline

International audienc

Layered double hydroxides: Efficient fillers for waterborne nanocomposite films.

International audienceUsing Layered double hydroxides (LDH) nanoparticles and film-forming latexes, waterborne nanocomposite films were produced by simply a heterocoagulation and solvent casting process. Self-standing and transparent films with LDH contents from 2.5 to 15 vol% were prepared. The structure, microstructure and mechanical behavior were thoroughly investigated by powder X-ray diffraction (PXRD), infrared spectroscopy (IR), transmission electron microscopy (TEM), scanning electron microscopy (FIB–SEM) and dynamic mechanical analysis (DMA). Favorable electrostatic interactions between pristine LDH and the latex ensured a good dispersion of the bidimensional LDH platelets in the films. Above a certain content of LDH, the formation of a well-defined cellular LDH network following the starting latex morphology was observed. Such a percolating microstructure induces a large mechanical reinforcement significant of a mechanical percolation behavior

Thin bacteria/Layered Double Hydroxide films using a layer-by-layer approach.

International audienceThis paper reports the design of thin bacteria/Layered Double Hydroxides (LDH) films in which bacterial cells of Pseudomonas sp. strain ADP were assembled alternatively with Mg2Al-NO3 LDH nanosheets by a layer-by-layer deposition method. The UV–Vis spectroscopy was used to monitor the assembly process, showing a progressive increase in immobilized bacteria amount upon deposited cycles. The {ADP/LDH}n film was characterized by X-ray diffraction, infrared spectroscopy, scanning electron microscopy and atomic force microscopy. The metabolic activity of immobilized bacteria was determined using chronoamperometry by measuring the biochemical oxygen demand in presence of glucose using an artificial electron acceptor (Fe(CN)63−) at 0.5 V/Ag-AgCl. A steady current of 0.250 μA cm−2 was reached in about 30 s after the addition of 5 mM glucose