For the first time, we report calorimetric measurements of intrusion of aqueous LiCl solutions in a hydrophobic pure siliceous MFI zeolite (silicalite-1) under high pressure. Our results show that the intrusion heats are strongly dependent on the LiCl concentration. The intrusion process is endothermic for diluted solutions (molar HO/LiCl = 12) as well as for water, but it becomes exothermic for a concentration close to saturation (molar HO/LiCl = 4).
View Article and Find Full Text PDFThe fabrication of structured zeolite adsorbents through photopolymerization-based 3D printing which offers a solution to the limitations of conventional shaping techniques has been demonstrated but many parameters still need to be optimized. In this study, we studied the influence of zeolite compensation cations on the photopolymerization and the composite's properties. Modified zeolites (LTA 4 A and FAU 13X exchanged with K , Li , Sr , Ca or Mg ) were incorporated in PEGDA with BDMK as photoinitiator, and the formulation was cured under mild conditions (LED@405 nm, room temperature, under air).
View Article and Find Full Text PDFThe development of antimicrobial devices and surfaces requires the setup of suitable materials, able to store and release active principles. In this context, zeolites, which are microporous aluminosilicate minerals, hold great promise, since they are able to serve as a reservoir for metal-ions with antimicrobial properties. Here, we report on the preparation of Linde Type A zeolites, partially exchanged with combinations of metal-ions (Ag, Cu, Zn) at different loadings (0.
View Article and Find Full Text PDFThe influence of the charge compensating cation nature (Na, Mg) on the water adsorption properties of LTA-type zeolites used as filler in composite materials (zeolite/polymers) was investigated. Large scale cation exchanges were performed on zeolite powder at 80 °C for 2 h using 1 M magnesium chloride (MgCl) aqueous solutions. XRF, ICP, and EDX analyses indicate a successful cationic exchange process without the modification of the zeolite structure as shown by XRD and solid-state NMR analyses.
View Article and Find Full Text PDFIn this study, a layer of a pure and dense phase of FAU-type zeolite was synthesized directly on the surface of α-AlO plane macroporous support. Before hydrothermal synthesis, a step of cleaning of the support by an anionic detergent was performed, a roughness surface is created, allowing the anchoring of the zeolite nuclei and then their growth, favoring in this sense the formation of a homogeneous zeolite layer. The obtained membranes were fully characterized using X-ray diffraction analysis (XRD), nitrogen sorption, scanning electron microscopy (SEM), and mercury porosimetry.
View Article and Find Full Text PDFSilicone and pure organic binders were used to develop FAU-type zeolite coatings applied on pre-treated aluminum substrates by using a spraying method and then cured under specific conditions. The influence of the amount of binder on adhesion properties of zeolite coatings was first investigated to determine the optimum ratio between zeolite and binder. Zeolite coatings were then elaborated with a high zeolite content (between 70 and 80 wt.
View Article and Find Full Text PDFAn overview of all the studies on high-pressure intrusion-extrusion of LiCl aqueous solutions in hydrophobic pure silica zeolites (zeosils) for absorption and storage of mechanical energy is presented. Operational principles of heterogeneous lyophobic systems and their possible applications in the domains of mechanical energy storage, absorption, and generation are described. The intrusion of LiCl aqueous solutions instead of water allows to considerably increase energetic performance of zeosil-based systems by a strong rise of intrusion pressure.
View Article and Find Full Text PDFThe influence of the compensating cation (Na, Li, Mg) nature on the water adsorption properties of LTA and FAU-type zeolites was investigated. Cation exchanges were performed at 80 °C for 2 h using 1 M aqueous solutions of lithium chloride (LiCl) or magnesium chloride (MgCl). XRF and ICP-OES analyses indicate that the cation exchange yields reach values between 59 to 89% depending on the number of exchange cycles and the nature of the zeolite and cation, while both zeolites structures are preserved during the process, as shown by XRD and solid state NMR analyses.
View Article and Find Full Text PDFThe high pressure intrusion-extrusion process of different electrolyte aqueous solutions (NaCl and CaCl2, 2 M and 3 M) in a hydrophobic pure-silica LTA zeolite was investigated for energetic purposes by means of in situ X-ray powder diffraction, porosimeter tests, thermogravimetric analysis and NMR spectroscopy. The intrusion pressure of the saline solutions was proved to be higher than that of pure water, with the highest value measured for CaCl2, thus increasing the energetic performance of the system. The intrusion of NaCl solutions was irreversible (bumper behavior), whereas that of CaCl2 solutions is partially reversible (shock absorber behavior).
View Article and Find Full Text PDFA mixture of SO and air was continuously injected in a fixed bed reactor containing a CuO/SBA-15 sorbent material and submitted to an isothermal temperature between 325 and 400 °C. The SO emissions were measured at the exit of the reactor. Different isothermal temperatures, different injected SO concentrations and different sorbent masses, all representative of industrial conditions, were tested.
View Article and Find Full Text PDFThree different alumina-based Ni, Cu, Co oxide catalysts with metal loading of 10 wt %, and labeled 10Ni⁻Al, 10Co⁻Al and 10Cu⁻Al, were prepared by microwave-assisted solution combustion. Their morphological, structural and surface properties were deeply investigated by complementary physico-chemical techniques. Finally, the three materials were tested in CO oxidation used as test reaction for comparing their catalytic performance.
View Article and Find Full Text PDFHierarchical *BEA-type nanosponges zeolite with a high external surface area (116 m.g) and small crystal size, synthesized in the presence of a dual-porogenic organic compound, were modified with a cationic surfactant (HDTMABr: hexadecyltrimethyl ammonium bromide) in order to create a new anion exchanger system: the surfactant-modified zeolite nanosponges (SMZ). For comparison, two other surfactant-modified *BEA-type zeolite materials, SMZ and SMZ, were obtained by modifying the synthesized conventional micron-size microcrytals and nanocrystals *BEA-type zeolite with HDTMABr, respectively.
View Article and Find Full Text PDFBinderless zeolite macrostructures in the form of ZK-4 microspheres were prepared using anion-exchange resin beads as shape-directing macrotemplates. The particles were synthesized under hydrothermal conditions at different temperatures and treatment times. The influence of the different synthesis parameters was investigated by X-ray diffraction, scanning electron microscopy, fluorescence X, nitrogen adsorption measurements and Si solid-state NMR.
View Article and Find Full Text PDFThe number of studies on the capture of radioactive iodine compounds by porous sorbents has regained major importance in the last few years. In fact, nuclear energy is facing major issues related to operational safety and the treatment and safe disposal of generated radioactive waste. In particular during nuclear accidents, such as that in 2011 at Fukushima, gaseous radionuclides have been released in the off-gas stream.
View Article and Find Full Text PDF-COK-14 zeolite, the variant of COK-14 (OKO topology) with a systematically interrupted framework, exhibits unusual behaviour in high pressure intrusion-extrusion cycles of 20 M LiCl solution. After the first cycle with deviating behaviour and partially irreversible intrusion, subsequent cycles show stable reversible behaviour. The system behaves like a spring with unique progressive intrusion in the range of 10-120 MPa followed by enhanced uptake before saturation.
View Article and Find Full Text PDFThe energetic performances of seven SOD or RHO-topology ZIFs, with zinc or cobalt metal cation (ZIF-8, ZIF-90, Zn(dcim)2-SALE, ZIF-67, ZIF-7, ZIF-71, ZIF-11) were evaluated using water intrusion-extrusion under high pressure. The relationship between the structural parameters (in particular the pore system SOD or RHO, the type of linker, the metal cation nature) and the intrusion pressure was studied to better understand the mechanism of water intrusion and the energetic behaviour for a given ZIF crystal type. "ZIF-8-water", "ZIF-67-water" and "ZIF-71-water" systems display a shock-absorber behaviour.
View Article and Find Full Text PDFExperimental water intrusion-extrusion isotherms were obtained at room temperature on pure silica ITW-type zeolites (ITQ-12 zeosil). The water intrusion is obtained by applying a high hydraulic pressure corresponding to the intrusion step. When the pressure is released, the water extrusion occurs at a similar pressure to that of the intrusion one.
View Article and Find Full Text PDFThe "ZIF-8-water" system displays reproducible shock-absorber behaviour over several cycles with a stored energy of 13.3 J g(-1) and an energy yield close to 85%. The combination of the main features evidenced for ZIF-8, i.
View Article and Find Full Text PDFPIC (Phase Inversion Composition) O-W nanoemulsions was used as a template for the synthesis of Hierarchical Porous Silica (HPS), and the oil phase of the nanoemulsion was used as a nanoreactor for the preparation of magnetic gamma-Fe(2)O(3) nanoparticles, confined within the silica matrix.
View Article and Find Full Text PDFMeasurements of 8-hour time-weighted average NO(2) concentrations are reported at 7 different locations in the region of Dunkirk over 5 consecutive days using PiezOptic monitoring badges previously calibrated for the range 0-70 ppb together with data from chemiluminescent analysers in 5 sites (4 fixed and one mobile). The latter facilities also provided data on ozone and NO concentrations and meteorological conditions. Daily averages from the two pairs of badges in different types of sampling cover in each site have been compared with data from the chemiluminescent analysers, and found largely to agree within error margins of +/-30%.
View Article and Find Full Text PDF