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Synthesis of Gold Nanoparticles over CoAl Mixed Oxide for Ethanol Oxidation Reaction. Molecules 2024; 29:2285. [PMID: 38792146 PMCID: PMC11123866 DOI: 10.3390/molecules29102285] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2024] [Revised: 04/27/2024] [Accepted: 05/08/2024] [Indexed: 05/26/2024] Open
Abstract
Catalytic total oxidation is an effective technique for the treatment of industrial VOCs principally resulting from industrial processes using solvents and usually containing mono-aromatics (BTEX) and oxygenated compounds (acetone, ethanol, butanone). The aim of this work is to deposit gold nanoparticles on CoAl mixed oxide issued from layered double hydroxide (LDH) precursor by using the deposition precipitation (DP) method, which is applied with two modifications, labeled method (A) and method (B), in order to enhance the interaction of the HAuCl4 precursor with the support. Method (A) involves the hydrolysis of the HAuCl4 precursor after addition of the support, while in method (B), the gold precursor is hydrolyzed before adding the support. The two methods were applied using as support the CoAl mixed oxide and the LDH precursor. Samples were characterized by several physical chemical techniques and evaluated for ethanol total oxidation. Method (B) allowed the ethanol oxidation activity to be enhanced for the resulting Au/CoAlOx catalysts thanks to the high surface concentration of Co2+ and improved reducibility at low temperature. The presence of gold permits to minimize the formation of by-products, notably, methanol, allowed for a total oxidation of ethanol at lower temperature than the corresponding support.
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A Prato Tour on Carbon Nanotubes: Raman Insights. Chemistry 2023; 29:e202302476. [PMID: 37788975 DOI: 10.1002/chem.202302476] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2023] [Revised: 09/27/2023] [Accepted: 09/28/2023] [Indexed: 10/05/2023]
Abstract
The functionalisation of carbon nanotubes has been instrumental in broadening its application field, allowing especially its use in biological studies. Although numerous covalent and non-covalent functionalisation methods have been described, the characterisation of the final materials has always been an added challenge. Among the various techniques available, Raman spectroscopy is one of the most widely used to determine the covalent functionalisation of these species. However, Raman spectroscopy is not a quantitative technique, and no studies are reported comparing its performance when the same number of functional groups are added but using completely different reactions. In this work, we have experimentally and theoretically studied the functionalisation of carbon nanotubes using two of the most commonly used reactions: 1,3-dipolar cycloaddition of azomethylene ylides and diazonium-based radical addition. The number of groups introduced onto the tubes by these reactions has been determined by different characterisation techniques. The results of this study support the idea that data obtained by Raman spectra are only helpful for comparing functionalisations produced using the same type of reaction. However, they should be carefully analysed when comparing functionalisations produced using different reaction types.
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Highly Functionalized SWCNTs with a Dopamine Derivative as a Support for Pd Nanoparticles: A Recyclable Catalyst for the Reduction of Nitro Compounds and the Heck Reaction. Chemistry 2023; 29:e202301238. [PMID: 37518681 DOI: 10.1002/chem.202301238] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2023] [Revised: 07/29/2023] [Accepted: 07/30/2023] [Indexed: 08/01/2023]
Abstract
Single-walled carbon nanotubes (SWCNTs) were functionalized with a dopamine derivative in which the amine group was converted to azide (dopamine azide). The direct reaction of SWCNTs and dopamine azide in o-dichlorobenzene at high temperature (160 °C) led to very highly functionalized CNTs (≈60 wt.%). Surprisingly, despite this high degree of functionalization, Raman spectroscopy detected a low disruption of the π-network of the carbonaceous support. This finding was justified by the rehybridization from sp3 to sp2 of the sidewall carbon atoms of CNTs involved in the functionalization process. Further characterization by means of different techniques such as X-ray photoelectron spectroscopy (XPS) analysis and transmission electron microscopy (TEM) allowed to shed some light on the chemical composition and morphology of the obtained material. Moreover, the estimation of the total content of phenolic units and their reducing potential after CNTs functionalization was also assessed using Folin and Ciocalteu and 2,2-diphenyl-1-picryl hydrazide (DPPH) assays. The functionalization of CNTs was exploited to immobilize palladium(II) species that were subsequently reduced with NaBH4 leading to the formation of Pd nanoparticles (NPs). The so obtained hybrid material was used as a recyclable heterogeneous catalyst for the reduction of nitro compounds and the Heck reaction.
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Ni-Based SBA-15 Catalysts Modified with CeMnO x for CO 2 Valorization via Dry Reforming of Methane: Effect of Composition on Modulating Activity and H 2/CO Ratio. NANOMATERIALS (BASEL, SWITZERLAND) 2023; 13:2641. [PMID: 37836282 PMCID: PMC10574277 DOI: 10.3390/nano13192641] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/14/2023] [Revised: 09/07/2023] [Accepted: 09/22/2023] [Indexed: 10/15/2023]
Abstract
Dry reforming of methane with ratio CH4/CO2 = 1 is studied using supported Ni catalysts on SBA-15 modified by CeMnOx mixed oxides with different Ce/Mn ratios (0.25, 1 and 9). The obtained samples are characterized by wide-angle XRD, SAXS, N2 sorption, TPR-H2, TEM, UV-vis and Raman spectroscopies. The SBA-15 modification with CeMnOx decreases the sizes of NiO nanoparticles and enhances the NiO-support interaction. When Ce/Mn = 9, the NiO forms small particles on the surface of large CeO2 particles and/or interacts with CeO2, forming mixed phases. The best catalytic performance (at 650 °C, CH4 and CO2 conversions are 51 and 69%, respectively) is achieved over the Ni/CeMnOx/SBA-15 (9:1) catalyst. The peculiar CeMnOx composition (Ce/Mn = 9) also improves the catalyst stability: In a 24 h stability test, the CH4 conversion decreases by 18 rel.% as compared to a 30 rel.% decrease for unmodified catalyst. The enhanced catalytic stability of Ni/CeMnOx/SBA-15 (9:1) is attributed to the high concentration of reactive peroxo (O-) and superoxo (O2-) species that significantly lower the amount of coke in comparison with Ni-SBA-15 unmodified catalyst (weight loss of 2.7% vs. 42.2%). Ni-SBA-15 modified with equimolar Ce/Mn ratio or Mn excess is less performing. Ni/CeMnOx/SBA-15 (1:4) with the highest content of manganese shows the minimum conversions of reagents in the entire temperature range (X(CO2) = 4-36%, X(CH4) = 8-58%). This finding is possibly attributed to the presence of manganese oxide, which decorates the Ni particles due to its redistribution at the preparation stage.
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Batch and Flow Green Microwave-Assisted Catalytic Conversion Of Levulinic Acid to Pyrrolidones. CHEMSUSCHEM 2023:e202301200. [PMID: 37672358 DOI: 10.1002/cssc.202301200] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/15/2023] [Accepted: 09/04/2023] [Indexed: 09/08/2023]
Abstract
This paper reports a new sustainable protocol for the microwave-assisted catalytic conversion of levulinic acid into N-substituted pyrrolidones over tailor-made mono (Pd, Au) or bimetallic (PdAu) catalysts supported on either highly mesoporous silica (HMS) or titania-doped HMS, exploiting the advantages of dielectric heating. MW-assisted reductive aminations of levulinic acid with several amines were first optimized in batch mode under hydrogen pressure (5 bar) in solvent-free conditions. Good-to-excellent yields were recorded at 150 °C in 90 min over the PdTiHMS and PdAuTiHMS, that proved recyclable and almost completely stable after six reaction cycles. Aiming to scale-up this protocol, a MW-assisted flow reactor was used in combination with different green solvents. Cyclopentyl methyl ether (CPME) provided a 99 % yield of N-(4-methoxyphenyl) pyrrolidin-2-one at 150 °C over PdTiHMS. The described MW-assisted flow synthesis proves to be a safe procedure suitable for further industrial applications, while averting the use of toxic organic solvents.
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Beneficial effect of cerium excess on in situ grown Sr 0.86Ce 0.14FeO 3-CeO 2 thermocatalysts for the degradation of bisphenol A. RSC Adv 2023; 13:21459-21470. [PMID: 37465574 PMCID: PMC10351217 DOI: 10.1039/d3ra03404f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2023] [Accepted: 07/10/2023] [Indexed: 07/20/2023] Open
Abstract
Ce-doped SrFeO3 perovskite-type compounds are known as good thermocatalysts for the abatement of wastewater contaminants of emerging concern. In this work, Sr0.86Ce0.14FeO3-CeO2 perovskite-oxide systems with increasing amounts of cerium excess (0, 5, 10 and 15 mol% Ce), with respect to its maximum solubility in the perovskite, were prepared in one-pot by solution combustion synthesis and the effects of cerium excess on the chemical physical properties and thermocatalytic activity in the bisphenol A degradation were evaluated. The powders were characterized by powder X-ray diffraction combined with Rietveld refinement, X-ray photoelectron spectroscopy, thermal gravimetry, temperature programmed reduction, nitrogen adsorption, scanning electron microscopy and energy dispersive X-ray spectroscopy techniques. Results highlight that the perovskite structural, redox, surface, and morphological properties are affected by the in situ co-growth of the main perovskite phase and ceria and that a larger cerium excess has a beneficial effect on the thermocatalytic performance of the perovskite oxide-ceria biphasic system, although ceria is not active as a thermocatalyst itself. Perovskite properties and performance are enhanced by the tetragonal distortion induced by the introduction of cerium excess in the synthesis. It is supposed that a larger oxygen mobility and an easier reducibility are among the most relevant features that contribute to superior thermocatalytic properties of these perovskite oxide-based systems. These results also suggest new perspectives in the nanocomposite preparation and their catalytic applications.
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Catechol‐Functionalized Carbon Nanotubes as Support for Pd Nanoparticles: A Recyclable System for the Heck Reaction. European J Org Chem 2022. [DOI: 10.1002/ejoc.202201364] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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8
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Heterogenizing palladium tetraiodide catalyst for carbonylation reactions. J Catal 2022. [DOI: 10.1016/j.jcat.2022.08.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/15/2022]
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9
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Catechol‐Functionalized Carbon Nanotubes as Support for Pd Nanoparticles: a Recyclable System for the Heck Reaction. European J Org Chem 2022. [DOI: 10.1002/ejoc.202200497] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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10
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Antifouling and antimicrobial activity of Ag, Cu and Fe nanoparticles supported on silica and titania. Inorganica Chim Acta 2022. [DOI: 10.1016/j.ica.2021.120636] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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11
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CO 2 Reforming of CH 4 over SiO 2-Supported Ni Catalyst: Effect of Sn as Support and Metal Promoter. Ind Eng Chem Res 2021. [DOI: 10.1021/acs.iecr.1c02193] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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12
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TiO 2/Ag 2O immobilized on cellulose paper: A new floating system for enhanced photocatalytic and antibacterial activities. ENVIRONMENTAL RESEARCH 2021; 198:111257. [PMID: 33974837 DOI: 10.1016/j.envres.2021.111257] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/29/2020] [Revised: 03/06/2021] [Accepted: 04/26/2021] [Indexed: 06/12/2023]
Abstract
Paper-TiO2-Ag2O floating photocatalysts were produced under mild condition and their photocatalytic activity for the degradation of aromatic amine under sunlight stimulant was investigated. Characterizations by Raman, XRD, XPS, DRS and PL confirmed the presence of TiO2 and Ag2O, and the morphology of the appended TiO2/Ag2O layer was probed by FE-SEM. The photocatalytic activity of the prepared samples was investigated by the degradation of aniline (AN) in water under simulated sun-light illumination and constrained conditions, i.e. non-stirring and non-oxygenation. The presence of Ag2O combined with TiO2 was shown to improve the resistance of paper to bacteria attack, thus increasing the durability of the photocatalyst. Thanks to its hydrophobic character, the paper-TiO2-Ag2O NPs can be employed as useful floating photocatalyst and can be reused in continuous cycles.
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Microwave-Assisted Glycerol Etherification Over Sulfonic Acid Catalysts. MATERIALS 2020; 13:ma13071584. [PMID: 32235560 PMCID: PMC7178245 DOI: 10.3390/ma13071584] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/10/2020] [Revised: 03/25/2020] [Accepted: 03/27/2020] [Indexed: 11/16/2022]
Abstract
Glycerol is the main by-product of biodiesel production. For this reason, its valorization into value-added products, by using green procedures, represents an important goal. Different sulfonic acid silica- or titania-based catalysts were prepared, characterized and tested in the glycerol etherification process, assisted by microwaves, in order to obtain biodiesel additives. The surface and structural properties of the catalysts were investigated by means of N2 adsorption isotherms, thermogravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS) and acid capacity measurements by X-Ray Fluorescence Spectroscopy (XRF). The best performance in terms of activity was achieved in the presence of the sulfonic function directly linked to the amorphous silica. By the correlation of the structure properties of the materials and their activity, the performance of the catalysts was shown to be influenced mainly by the surface area, pore volume and acidity. Recycling experiments performed over the most active systems showed that the sulfonic silica-based materials maintained their performance during several cycles.
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Dehydration of Fructose to 5-HMF over Acidic TiO 2 Catalysts. MATERIALS (BASEL, SWITZERLAND) 2020; 13:E1178. [PMID: 32155730 PMCID: PMC7085090 DOI: 10.3390/ma13051178] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/23/2020] [Revised: 02/12/2020] [Accepted: 03/04/2020] [Indexed: 11/17/2022]
Abstract
Different solid sulfonic titania-based catalysts were investigated for the hydrothermal dehydration of fructose to 5-hydroxymethylfurfural (5-HMF). The catalytic behavior of the materials was evaluated in terms of fructose conversion and selectivity to 5-HMF. The surface and structural properties of the catalysts were investigated by means of X-ray diffraction (XRD), N2 adsorption isotherms, thermo-gravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS) and acid capacity measurements. Special attention was focused on the reaction conditions, both in terms of 5-HMF selectivity and the sustainability of the process, choosing water as the solvent. Among the various process condition studied, TiO2-SO3H catalyzed a complete conversion (99%) of 1.1M fructose and 5-HMF selectivity (50%) and yield (50%) at 165 °C. An important improvement of the HMF selectivity (71%) was achieved when the reaction was carried out by using a lower fructose concentration (0.1M) and lower temperature (140 °C). The catalytic activities of the materials were related to their acid capacities as much as their textural properties. In particular, a counterbalance between the acidity and the structure of the pores in which the catalytic sites are located, results in the key issue for switch the selectivity towards the achievement of 5-HMF.
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Templating effect of carbon nanoforms on highly cross‐linked imidazolium network: Catalytic activity of the resulting hybrids with Pd nanoparticles. Appl Organomet Chem 2019. [DOI: 10.1002/aoc.4848] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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17
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Sustainable Recycling of Insoluble Rust Waste for the Synthesis of Iron-Containing Perovskite-Type Catalysts. ACS OMEGA 2019; 4:6994-7004. [PMID: 31459812 PMCID: PMC6647980 DOI: 10.1021/acsomega.8b03522] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/15/2018] [Accepted: 01/30/2019] [Indexed: 05/07/2023]
Abstract
Insoluble rust waste from the scraping of rusted iron-containing materials represents a cheap, eco-friendly, and available source of iron. LaFeO3 perovskite-type powders were successfully prepared by solution combustion synthesis using rust waste from an electricity transmission tower manufacturer. Solution combustion synthesis enabled introduction of this insoluble iron precursor directly into the final product, bypassing complex extraction procedures. Catalytic activity in the propylene oxidation of the waste-derived LaFeO3 with stoichiometric Fe/La ratio was almost identical to the commercial iron nitrate-derived LaFeO3, thus demonstrating the viability of this recycling solution. The amount of waste iron precursor was varied and its effect on the powder properties was investigated. A lesser stoichiometric amount of precursor produced a LaFeO3-La2O3 binary system, whereas a higher stoichiometric amount led to a LaFeO3-Fe2O3 binary system. Catalytic activity of iron-rich compositions in the propylene oxidation was only slightly lower than the stoichiometric one, whereas iron-poor compositions were much less active. This eco-friendly methodology can be easily extended to other iron perovskites with different chemical compositions and to other iron-containing compounds.
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Salmeterol Xinafoate (SX) loaded into mucoadhesive solid lipid microparticles for COPD treatment. Int J Pharm 2019; 562:351-358. [PMID: 30935915 DOI: 10.1016/j.ijpharm.2019.03.059] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2018] [Revised: 03/25/2019] [Accepted: 03/27/2019] [Indexed: 01/12/2023]
Abstract
Chronic obstructive pulmonary disease (COPD) is one of the main health problems worldwide. It is characterised by chronic inflammation in the lungs that leads to progressive, chronic, largely irreversible airflow obstruction. The use of long-acting β agonists remain today the frontline treatment for COPD with the aim of minimizing side effects and enhancing therapeutic usefulness. To this purpose, in this paper, mucoadhesive solid lipid microparticles (SLMs) containing a long-acting β-2 agonist, Salmeterol Xinafoate (SX) were prepared, characterised (size, z-potential, aerodynamic diameter, turbidimetric evaluations, drug loading and entrapping efficiency) and tested in a model of bronchial epithelial cells. It was demonstrated that the incorporation of SX into SLMs led to the production of particles suitable for inhalation and more efficient than the free molecule at increasing the cAMP expression in bronchial epithelial cells. In conclusion, the prepared systems, due to their aerodynamic behaviour and mucoadhesive properties, could improve the retention time of SX in the lung epithelium and its therapeutic effect, thus representing a good strategy for the treatment of COPD patients.
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Au/Co promoted CeO2 catalysts for formaldehyde total oxidation at ambient temperature: role of oxygen vacancies. Catal Sci Technol 2019. [DOI: 10.1039/c9cy00436j] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Cobalt enables formation of additional oxygen vacancies in Au/Co–CeO2 and significantly boosts the ambient oxidation of formaldehyde.
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20
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Gold nanoparticles stabilized by modified halloysite nanotubes for catalytic applications. Appl Organomet Chem 2018. [DOI: 10.1002/aoc.4665] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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22
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Paper-TiO2 composite: An effective photocatalyst for 2-propanol degradation in gas phase. J Photochem Photobiol A Chem 2018. [DOI: 10.1016/j.jphotochem.2017.09.074] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Amorphous boron-doped sodium titanates hydrates: Efficient and reusable adsorbents for the removal of Pb 2+ from water. JOURNAL OF HAZARDOUS MATERIALS 2017; 324:168-177. [PMID: 27776867 DOI: 10.1016/j.jhazmat.2016.10.046] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/06/2016] [Revised: 10/19/2016] [Accepted: 10/20/2016] [Indexed: 06/06/2023]
Abstract
Amorphous titanium hydroxide and boron-doped (B-doped) sodium titanates hydrates were synthetized and used as adsorbents for the removal of Pb2+ from water. The use of sodium borohydride (NaBH4) and titanium(IV) isopropoxide (TTIP) as precursors permits a very easy synthesis of B-doped adsorbents at 298K. The new adsorbent materials were first chemically characterized (XRD, XPS, SEM, DRIFT and elemental analysis) and then tested in Pb2+ adsorption batch experiments, in order to define kinetics and equilibrium studies. The nature of interaction between such sorbent materials and Pb2+ was also well defined: besides a pure adsorption due to hydroxyl interaction functionalities, there is also an ionic exchange between Pb2+ and sodium ions even working at pH 4.4. Langmuir model presented the best fitting with a maximum adsorption capacity up to 385mg/g. The effect of solution pH and common ions (i.e. Na+, Ca2+ and Mg2+) onto Pb2+ sorption were also investigated. Finally, recovery was positively conducted using EDTA. Very efficient adsorption (>99.9%) was verified even using tap water spiked with traces of Pb2+ (50ppb).
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Single-Walled Carbon Nanotube-Polyamidoamine Dendrimer Hybrids for Heterogeneous Catalysis. ACS NANO 2016; 10:4627-36. [PMID: 26974262 DOI: 10.1021/acsnano.6b00936] [Citation(s) in RCA: 75] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
We report the synthesis and catalytic properties of single-walled carbon nanotube-polyamidoamine dendrimers hybrids (SWCNT-PAMAM), prepared via a convergent strategy. The direct reaction of cystamine-based PAMAM dendrimers (generations 2.5 and 3.0) with pristine SWCNTs in refluxing toluene, followed by immobilization and reduction of [PdCl4](2-), led to the formation of highly dispersed small palladium nanoparticles homogeneously confined throughout the nanotube length. One of these functional materials proved to be an efficient catalyst in Suzuki and Heck reactions, able to promote the above processes down to 0.002 mol % showing a turnover number (TON) of 48 000 and a turnover frequency (TOF) of 566 000 h(-1). In addition, the hybrid material could be recovered and recycled for up to 6 times. No leaching of the metal has been detected during the Suzuki coupling. Additional experiments carried out on the spent catalyst permitted to suggest that a "release and catch" mechanism is operative in both reactions, although during Heck reaction small catalytically active soluble Pd species are also present.
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Hybrid paper–TiO2 coupled with a Cu2O heterojunction: an efficient photocatalyst under sun-light irradiation. RSC Adv 2016. [DOI: 10.1039/c6ra20248a] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Hybrid paper–TiO2, paper–Cu2O–TiO2 and paper–TiO2–Cu2O photocatalysts were prepared via a non-hydrolytic sol–gel process followed by mild hydrothermal treatment to generate the TiO2 layer, and a reduction process to form the Cu2O nanoparticles.
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Fullerene-ionic-liquid conjugates: a new class of hybrid materials with unprecedented properties. Chemistry 2015; 21:3327-34. [PMID: 25589382 DOI: 10.1002/chem.201406067] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2014] [Indexed: 11/10/2022]
Abstract
A modular approach has been followed for the synthesis of a series of fullerene-ionic-liquid (IL) hybrids in which the number of IL moieties (two or twelve), anion, and cation have been varied. The combination of C60 and IL give rise to new unique properties in the conjugates such as solubility in water, which was higher than 800 mg mL(-1) in several cases. In addition, one of the C60 -IL hybrids has been employed for the immobilization of palladium nanoparticles through ion exchange followed by reduction with sodium borohydride. Surprisingly, during the reduction several carbon nanostructures were formed that comprised nano-onions and nanocages with few-layer graphene sidewalls, which have been characterized by means of thermogravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), scanning electron microscopy/energy-dispersive X-ray analysis (SEM-EDAX), and high-resolution transmission electron microscopy (HRTEM). Finally, the material thus obtained was successfully applied as catalyst in Suzuki and Mizoroki-Heck reactions in a concentration of just 0.2 mol %. In the former process it was recyclable for five runs with no loss in activity.
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Transesterification of short chain esters using sulfonic acid-functionalized hybrid silicas: Effect of silica morphology. Catal Today 2014. [DOI: 10.1016/j.cattod.2013.09.029] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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Abstract
A pH-sensitive azo-dye covalently grafted onto cellulose nanocrystals yields nanostructured optodes in the form of membranes, sticks, and water-based inks for optical pH detection.
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Palladium local structure of La1−xSrxCo1−yFey−0.03Pd0.03O3−δ perovskites synthesized using a one pot citrate method. Phys Chem Chem Phys 2014; 16:22677-86. [DOI: 10.1039/c4cp03214d] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Pd local environment in the LSCF perovskite phase.
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Co/SiO2 catalysts for Fischer–Tropsch synthesis; effect of Co loading and support modification by TiO2. Catal Today 2012. [DOI: 10.1016/j.cattod.2012.05.042] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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32
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Multiwalled Carbon Nanotubes Drive the Activity of Metal@oxide Core–Shell Catalysts in Modular Nanocomposites. J Am Chem Soc 2012; 134:11760-6. [DOI: 10.1021/ja304398b] [Citation(s) in RCA: 97] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Interaction of Gold with Co‐Condensed and Grafted HMS‐SH Silica: A
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Si {
1
H} CP‐MAS NMR Spectroscopy, XRD, XPS and Au L
III
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