12 research outputs found

    Ultrasonic-assisted removal of cationic and anionic dyes residues from wastewater using functionalized triptycene-based polymers of intrinsic microporosity (PIMs)

    Get PDF
    In this work, a series of hypercrosslinked polymers of intrinsic microporosity (HCP-PIMs), namely nitro-triptycene (TRIP-NO2), amino-triptycene (TRIP-NH2), sulfonated-triptycene (TRIP-SO3H) and hydrocarbon-triptycene (TRIP-HC), are employed for the adsorption of organic dyes from wastewater. The materials show the efficient removal of cationic (malachite green, MG) and anionic (methyl orange, MO) dyes. The adsorption parameters herein investigated include the initial pH, the adsorbate concentration and the contact time, with the aim to elucidate their effect on the adsorption process. Furthermore, the adsorption kinetic and isotherms are studied, and the findings suggest the results fit well with pseudo-second-order kinetics and Langmuir model. The reported maximum adsorption capacity is competitive for all the tested polymers. More specifically, TRIP-SO3H and TRIP-HC exhibit adsorptions of ~ 303 and ~ 270 mg g−1 for MG and MO, respectively. The selectivity toward cationic and anionic dyes is assessed by mixing the two dyes, and showing that TRIP-HC completely removes both species, whereas TRIP-NO2, TRIP-NH2 and TRIP-SO3H show an enhanced selectivity toward the cationic MG, compared to the anionic MO. The effect of the type of water is assessed by performing ultrasonic-assisted adsorption experiments, using TRIP-SO3H and TRIP-HC in the presence of either tap or seawater. The presence of competing ions and their concentrations is evaluated by ICP-MS. Our study shows that tap water does not have a detrimental effect on the adsorption of both polymers, whereas, in the presence of seawater, the performance of TRIP-HC toward MO proved to be more stable than MG with TRIP-SO3H, which is probably due to a larger concentration of competing ions. Comparison between ultrasonic-assisted and magnetic stirring adsorption demonstrates that the former exhibits a greater efficiency. This seems due to a more rapid mass transfer, driven by the formation of high velocity micro-jets, acoustic microstreaming and shock waves, at the polymer surface. Reusability studies show a good stability up to five adsorption–desorption cycles

    Síntese e investigação da atividade catalítica de estruturas poliméricas baseadas em metaloporfirinas

    Get PDF
    Orientador : Shirley NakagakiCoorientador : SĂŽnia Faria ZawadzkiCoorientador : Neil B. McKeown (The University of Edinburgh)Tese (doutorado) - Universidade Federal do ParanĂĄ, Setor de CiĂȘncias Exatas, Programa de PĂłs-Graduação em QuĂ­mica. Defesa: Curitiba, 20/09/2016Inclui referĂȘncias : f. 114-127Área de concentração : QuĂ­mica inorgĂąnicaResumo: Porfirinas sĂŁo compostos macrociclos, aromĂĄticos, altamente conjugados, que estĂŁo presentes em diversos sistemas biolĂłgicos. Esses compostos podem ser sintetizados com grande versatilidade estrutural e possuem aplicação em diversas ĂĄreas do conhecimento. Metaloporifinas (MP) sintĂ©ticas tĂȘm sido amplamente investigadas como catalisadores em reaçÔes de oxidação, principalmente para mimetização das enzimas do citocromo P-450, tanto em estudos de catĂĄlise homogĂȘnea como heterogĂȘnea, apresentando resultados promissores. A catĂĄlise heterogĂȘnea possui vantagens em relação Ă  homogĂȘnea, citando-se principalmente a possibilidade de reuso do catalisador em diversos ciclos catalĂ­ticos. Nesse sentido, MP tĂȘm sido imobilizadas em diferentes tipos de suportes, tais como sĂ­licas, zeĂłlitas, materiais lamelares e polĂ­meros orgĂąnicos. AlĂ©m disso, MP tĂȘm sido utilizadas como blocos construtores na formação de sĂłlidos polimĂ©ricos porosos tais como MOFs (Metal Organic Framework), COFs (Covalent Organic Framework) e PIMs (Polymer of Intrinsic Microporosity). PIMs sĂŁo materiais altamente rĂ­gidos, nĂŁo cristalinos, no qual a microporosidade se deve a rigidez dos monĂŽmeros empregados em sua sĂ­ntese. PIMs insulĂșveis contendo porfirinas em suas estruturas foram previamente preparados. A elevada ĂĄrea superficial (~ 1000 m2 g-1) e a estabilidade quĂ­mica destes materiais estimulam a sĂ­ntese de novos PIMs para uso em catĂĄlise heterogĂȘnea. Assim, no presente trabalho, porfirinas e metaloporfirinas (simĂ©tricas e nĂŁo simĂ©tricas) foram sintetizadas, caracterizadas e empregadas como monĂŽmeros na formação de treze novos PIMs, os quais foram caracterizados por diferentes tĂ©cnicas. A microporosidade dos sĂłlidos polimĂ©ricos foi confirmada por meio de medidas de adsorção de nitrogĂȘnio utilizando-se o mĂ©todo BET (Brunauer-Emmett-Teller), apresentando valores de ĂĄrea superficial entre 300 a 1270 m2g-1. Estudos catalĂ­ticos com estes polĂ­meros, em reaçÔes de oxidação do cicloocteno e cicloexano e na presença de PhIO revelou resultados surpreendentes e interessantes. Os polĂ­meros apresentaram atividade catalĂ­tica similar, ou superior, ao obtido empregando-se a metaloporfirina MnP1 em solução. Tais polĂ­meros tambĂ©m apresentaram capacidade de reuso e mantiveram excelente atividade catalĂ­tica e seletividade para o ĂĄlcool em pelo menos quatro ciclos catalĂ­ticos frente Ă  oxidação do cicloexano. AlĂ©m disso, um dos PIMs sintetizados foi selecionado para testes iniciais para a oxidação do cicloocteno na presença de perĂłxido de hidrogĂȘnio e os resultados indicam que estes polĂ­meros podem ser bons candidatos na presença deste oxidante, proporcionando assim uma tecnologia mais limpa aos processos catalĂ­ticos. PorĂ©m, estudos para o aprimoramento da atividade catalĂ­tica do polĂ­mero na presença de perĂłxido de hidrogĂȘnio ainda devem ser conduzidos. Palavras-Chaves: Porfirina, PolĂ­meros de IntrĂ­nseca Microporosidade (PIM), CatĂĄlise HomogĂȘnea, CatĂĄlise HeterogĂȘnea, Oxidação.Abstract: Porphyrins are highly conjugated aromatic macrocyclic compounds that are present in many biological systems. These compounds can be synthesized with great structural versatility leading to a wide range of applications in different fields. Synthetic metalloporphyrins (MP) have been widely used as catalysts in many oxidation processes as models for cytochrome P-450 enzymes, in both homogeneous and heterogeneous catalysis showing promising catalytic results. Heterogeneous catalysis has a number of advantages when compared to its homogeneous analogue, especially regarding the possibility of catalyst recovery and reuse in many catalytic cycles. Hence, seeking heterogeneous catalysts, MP have been immobilized on a wide range of supports, such as silica, zeolites, lamellar materials and organic polymers. Moreover, these macrocyclic compounds have been used as building blocks for the design of porous polymers, such as MOFs (Metal Organic Frameworks), COFS (Covalent Organic Frameworks) and PIMs (Polymers of Intrinsic Microporosity). PIMs are highly rigid amorphous materials for which the microporosity is generated from the rigidity of the monomers used in their synthesis. Insoluble networks PIMs have been prepared previously using porphyrins as monomers. The high surface area (up to 1000 m2g-1) and the chemical stability of these materials encourage the synthesis of new network PIMs and their assessment for heterogeneous catalysis. Then, in the present work, porphyrins and metalloporphyrins (symmetric and unsymmetric) were synthesized, characterized and used as monomers to prepare thirteen new PIMs, which were characterized by different techniques. The microporosity of the prepared PIMs was confirmed by nitrogen adsorption, with the calculated Brunauer-Emmett-Teller (BET) surface areas showing values from 300 to 1270 m2 g-1. Catalytic studies showed surprising and interesting results for the oxidation reactions of the substrates cyclooctene and cyclohexane using PhIO as oxidant. The catalytic activity of these polymers were similar or better compared to the ones obtained using the metalloporphyrin MnP1 in solution. The polymers also showed reuse capacity and preserved their excellent catalytic activity and alcohol selectivity in at least four catalytic cycles on cyclohexane oxidation reaction. Furthermore, one of the synthesized PIMs has been selected for initial tests on cyclooctene oxidation reactions using hydrogen peroxide as the oxidant. The results showed that these polymers can also be good catalysts when employing this oxidant, thus providing a cleaner technology process in catalytic reactions. However, studies still should be conducted to improve the catalytic activity of the polymer using hydrogen peroxide. Keywords: Porphyrin, Polymers of Intrinsc Microporosity (PIMs), Homogeneous Catalysis, Heterogeneous Catalysis, Oxidation

    Adjustable Functionalization of Hyper-Cross-Linked Polymers of Intrinsic Microporosity for Enhanced CO2 Adsorption and Selectivity over N2 and CH4

    Get PDF
    In this paper, we report the design, synthesis, and characterization of a series of hyper-cross-linked polymers of intrinsic microporosity (PIMs), with high CO2 uptake and good CO2/N2 and CO2/CH4 selectivity, which makes them competitive for carbon capture and biogas upgrading. The starting hydrocarbon polymers’ backbones were functionalized with groups such as −NO2, −NH2, and −HSO3, with the aim of tuning their adsorption selectivity toward CO2 over nitrogen and methane. This led to a significant improvement in the performance in the potential separation of these gases. All polymers were characterized via Fourier transform infrared (FTIR) spectroscopy and 13C solid-state NMR to confirm their molecular structures and isothermal gas adsorption to assess their porosity, pore size distribution, and selectivity. The insertion of the functional groups resulted in an overall decrease in the porosity of the starting polymers, which was compensated with an improvement in the final CO2 uptake and selectivity over the chosen gases. The best uptakes were achieved with the sulfonated polymers, which reached up to 298 mg g–1 (6.77 mmol g–1), whereas the best CO2/N2 selectivities were recorded by the aminated polymers, which reached 26.5. Regarding CH4, the most interesting selectivities over CO2 were also obtained with the aminated PIMs, with values up to 8.6. The reason for the improvements was ascribed to a synergetic contribution of porosity, choice of the functional group, and optimal isosteric heat of adsorption of the materials

    A porphyrin-based microporous network polymer that acts as an efficient catalyst for cyclooctene and cyclohexane oxidation under mild conditions

    Get PDF
    The highly efficient dibenzodioxin-forming reaction between the (pentafluorophenyl)porphyrin manganese(III) (MnP) and hexahydroxytriptycene (HHT) provide a new microporous network polymer (P1), which demonstrated a large surface area (1080 m2 g− 1) and proved to be an efficient solid for heterogeneous catalysis for cyclooctene and cyclohexane oxidation under mild conditions and with high capacity of recovery and reuse in many catalytic cycles

    CO2 Separation by Imide/Imine Organic Cages

    Get PDF
    Two novel imide/imine-based organic cages were prepared and studied as materials for the selective separation of CO 2 from N 2 and CH 4 in Vacuum Swing Adsorption conditions. Gas adsorption on the new compounds showed selectivity for CO 2 over N 2 and CH 4 . The cages were also tested as fillers in mixed-matrix membranes for gas separation. Dense and robust membranes were obtained by loading the cages in either Matrimid Âź or PEEK-WC polymers. Improved gas transport properties and selectivity for CO 2 were achieved compared to the neat polymer membranes

    Hydrosilylation and Silane Polymerization Catalyzed by Group 4 Amidometallocene Cations

    No full text
    Four cationic amidotitanocene complexes [Cp2Ti(NRRâ€Č)][B(C6F5)4] (Cp = η5-C5H5; 1a: R = Râ€Č = p-anisyl; 1b: R = p-fluorophenyl, Râ€Č = p-anisyl; 1c: R = p-fluorophenyl, Râ€Č = phenyl; 1d: R = phenyl, Râ€Č = 2-pyridyl) were synthesized. Complexes 1a–d undergo Ti–N bond homolysis under visible light irradiation. Complexes 1a–c catalyze the polymerization of phenylsilane to yield branched polysilane polymers with molecular weights (Mw) up to approximately 3000 and dispersity indexes (Đ) of 1.4–1.6. Previously reported Group 4 cationic amidometallocene complexes [Cp2Ti(NPh2)][B(C6F5)4] (Ia) and Cp2Zr(NPh2)][MeB(C6F5)3] (IIa) were also tested in the hydrosilylation of carbonyl compounds with triethylsilane (Et3SiH). In some cases, complex Ia afforded completely reduced products (e.g., ethylbenzene from acetophenone), while IIa was generally more selective (e.g., (1-phenylethoxy)triethylsilane from acetophenone) but also more active. Complex IIa could also convert anisole derivatives to phenoxysilanes with high efficiency (TON = 2000)

    Highly active manganese porphyrin-based microporous network polymers for selective oxidation reactions

    No full text
    New microporous polymer networks, constructed by a nucleophilic substitution reaction between two different porphyrins and metalloporphyrins are reported. The meso-tetrakis-(pentafluorophenyl)porphyrin HP1 (monomer A1) and/or its manganese complex MP1 (monomer A2) was reacted with the meso-tetrakis-(3,4-dihydroxyphenyl)porphyrin HP2 (monomer B1) and/or its manganese complex MP2 (monomer B2), giving rise to four new porphyrin-based microporous network polymers (P1-P4) with apparent BET surface areas in the range 600–1200 m2 g−1. The catalytic performance of the polymers was evaluated by oxidation reactions using cyclooctene and cyclohexane as substrates and Iodosylbenzene as oxidant in cytochrome P-450 model reactions. The catalytic activity and selectivity of these porous polymer networks are similar or superior to those of the analogous homogeneous manganese porphyrins MP1 and MP2. The robustness of the materials in terms of thermal stability and good recyclability showed that they hold great promise as biomimetic heterogeneous catalysts
    corecore