Pierre Emile Levitz

Sorbonne Université | UPMC · PHENIX

The peak parking method was applied to evaluate the surface diffusivity Ds of polystyrenes dissolved in a THF/heptane mixture and transported through porous silica materials with various morphologies. With this method, the overall effective diffusivity D is measured experimentally with coarse-grained models like Maxwell equation allowing one to inf...

A multiscale 3D approach combining three advanced volumetric imaging techniques was employed for obtaining direct information on the hierarchical porosity in Coscinodiscus sp. diatoms having an internal organization ranging from micrometer to nanometer.

We propose a set of simple formulae for interpreting “mercury cyclic porosimetry” measurements where multiple intrusion–extrusion cycles are carried out. By employing two parameters α∈[0,1] and κ∈[0,1], our theory quantitatively breaks down any hysteresis observed in cyclic porosimetry data into contributions due to connectivity effects and contact...

Owing to their complex morphology and surface, disordered nanoporous media possess a rich diffusion landscape leading to specific transport phenomena. The unique diffusion mechanisms in such solids stem from restricted pore relocation and ill-defined surface boundaries. While diffusion fundamentals in simple geometries are well-established, fluids...

Owing to their complex pore morphology and strong surface heterogeneity, disordered nanoporous media possess a rich underlying diffusion landscape that gives rise to specific transport phenomena. The unique diffusion mechanisms in such heterogeneous, ultra-confining solids stem from restricted pore relocation and blurred, i.e. ill-defined, pore/sur...

Wax deposition is one of the major concerns for waxy crude oil production and transportation. A better understanding and prediction of fluid properties related to this issue require knowledge of the medium structuration at scales ranging from nanometers (molecules) to a few micrometers (crystals). For this purpose, the behavior of a waxy crude oil...

The data presented here are related to the research paper entitled "Green Earth pigments dispersions: water dynamics at the interfaces". The nuclear magnetic resonance (NMR) relaxometry data are provided for various aqueous Green Earth (GE) pigments dispersions with volume fraction spanning approximately from 0.1 to 0.5. For two of them (Cyprus GE...

In this study, the flocculation and the subsequent decantation step of mixed suspensions of 10 nm-sized γ-Fe2O3 magnetic nanoparticles and 500 nm-sized beidellite clay platelets was investigated. This work may find application in the field of water treatment, specifically the flocculation processes with magnetically assisted sedimentation. After a...

Source rocks are expected to become increasingly important in the upcoming years for oil and gas production as well as for the storage of greenhouse gases. These rocks are bedded and heterogeneous media, composed of minerals, kerogen and pore space. One of the most challenging issue is to better define the pore space, including pore size distributi...

Hypothesis The objective is to elucidate the multiscale dynamics of water within natural mixtures of minerals, green earth pigments that are mainly composed of phyllosilicates containing large amount of iron. In particular, the interaction of water with the different kinds of surfaces has to be probed. One issue is to examine the influence of surfa...

During cement hydration, C-S-H nanoparticles precipitate and form a porous and heterogeneous gel that glues together the hardened product. C-S-H nucleation and growth is driven by dissolution of the cement grains, posing the question of how cement grain surfaces induce spatial heterogeneities in the formation of C-S-H and affect the overall microst...

Two dimensional ultra thin CdSe nanoplatelets have attracted a large interest due to their optical properties but their formation mechanism is not well understood. Several different mechanisms have been proposed: confined growth in a surfactant mesophase acting as a template, anisotropic ripening of small seeds into 2D nanoplatelets or continuous a...

We study the aggregation of charged plate-like colloids, Na-montmorillonite clays, in the presence of ionenes, oppositely charged polymer chains. The choice of the charged polymer allows tuning its linear charge density to match/mismatch the average charge separation on the clay surfaces. We assess the nanoscale structure of the aggregates formed b...

div>Two dimensional ultra thin CdSe nanoplatelets have attracted a large interest due to their optical properties but their formation mechanism is not yet well understood. Several different mechanisms and models have been proposed but quantitative in situ data that could validate or disprove them are lacking. We use synchrotron-based small-angle an...

Nowadays, one of the main studied reservoirs corresponds to source rock systems. This is due to the fact that such rocks are self-sourced systems and are known as the second biggest geological formation for CO2 storage. In these rocks, gas is stored within two forms, as a free gas in both pores and fractures and as an absorbed gas in nanopores. Det...

Organic matter is responsible for the generation of hydrocarbons during the thermal maturation of source rock formation. This geochemical process engenders a network of organic hosted pores that governs the flow of hydrocarbons from the organic matter to fractures created during the stimulation of production wells. Therefore, it can be reasonably a...

Analysing the structure and microstructure of compacted swelling clay minerals is important because of the applications of these minerals in engineering and environmental sciences. Given the typical sub-micrometre size of the particles and pores in clays, small-angle scattering techniques are well suited for such analysis. Interpretation of the int...

The effect of polymer coating on MNR relaxometry of maghemite nanoparticles has been studied. The samples were carefully sorted by size in order to reach narrow size distribution (<0.2) with size ranging from 4.5 to 12.5 nm. Relaxation dispersion profile as well as studies at a fixed Larmor frequency, were recorded for numerous either uncoated or p...

The confined dynamics of water molecules inside a pore involves an intermittence between adsorption steps near the interface and surface diffusion and excursions in the pore network. Depending on the strength of the interaction in the layer(s) close to the surface and the dynamical confinement of the distal bulk liquid, exchange dynamics can vary s...

This contribution couples (1) Small Angle X‐ray Scattering (SAXS) experiments of a High Performance Concrete (HPC) at the millimetric scale, and (2) Focused Ion Beam/Scanning Electron Microscopy (FIB/SEM) of the cement paste of the HPC, with 10‐20 nm voxel size. The aim is to improve the understanding of the 3D pore network of the HPC at the mesosc...

Imaging the distribution of reactive molecules in an internal diffusion-limited catalyst is of primary importance in the comprehension and modeling of these systems. Mesoporous alumina supports were impregnated with asphaltenes in a self-pressurized autoclave at high pressure (5 MPa) and high temperature (523 K). Extrudates were then analyzed by la...

Interactions between kaolinite (KGa-2) and a typical anionic surfactant bis(2-ethylhexyl) sulfosuccinate sodium (AOT) have been study to obtain a better knowledge of this system. Firstly, adsorption isotherms of AOT on kaolinite are realized as a function of pH. Stability experiments have been performed between the surfactant and the clay mineral a...

The rheology of modern Portland cement (PC) concrete critically depends on the correct dosage of gypsum (calcium sulfate hydrate) to control the hydration of the most reactive phase - tricalcium aluminate (C3A). The underlying physio-chemical mechanism, however, remains unsolved mainly due to the lack of high-spatial-resolved and chemistry-sensitiv...

This chapter presents several experimental examples in which the water dynamics close to a colloidal interface can be probed by nuclear magnetic relaxation dispersion (NMRD). Three classes of systems are presented: a porous plaster exhibiting large flat surfaces, a colloidal gel of finite clay particles and a suspension of very long and rigid nanor...

Refining heavy or extra heavy oil is still an important challenge for petroleum chemistry. The research performed in the field of hydroprocessing technologies covers different sides of the domain laying from the reactor and process aspects to heterogeneous catalysts development. Historically, at a large scale of time, the worldwide trend seems to i...

Numerous geomaterials, manufactured porous materials have a complex structure with a multiscale organization of the pore network, ranging from nm to μm and above. A good knowledge of the structure at these different scales is a cornerstone to properly understand transport properties (diffusion-permeation) and mechanical strength. In this context, m...

Flocculation and its tuning is of utmost importance in the optimization of the several industrial protocols, in areas such as purification of waste-water or civil engineering. We study polyelectrolyte-induced flocculation of clay colloids on a model system, consisting of purified clay colloids of well-defined size fractions and ionene polyelectroly...

This study deals with the role of the alumina nanoporous texture on the accessibility of the asphaltene molecules to the active sites of resid hydrotreatment catalysts. We have proposed in this contribution to investigate the diffusion and adsorption process into the porosity of various monomodal and bimodal alumina supports. It consists in immersi...

The upgrading of heavy petroleum fractions needs the development of more and more efficient heterogeneous catalysts. One of the major issues of these processes is the diffusion of asphaltenes to the active site through the porous network of the alumina support. The catalytic efficiency is deeply impacted by the transport phenomena and the interfaci...

Mechanical behavior of concrete crucially depends on cement hydrates, the “glue” of cement. The design of high performance and more environmentally friendly cements demands a deeper understanding of the formation of the multiscale structure of cement hydrates, when they precipitate and densify. We investigate the precipitation and setting of nano-g...

This paper discusses the applicability of neutron imaging techniques for probing the internal microstructure of several fossil woods upon wetting and drying, two phenomena occurring in museum cabinets and endangering the fossil woods. Investigations were carried out using lignites (fossil woods) from two French localities (Rivecourt, Parisian Basin...

The wettability of three swelling clays (beidellite, nontronite and montmorillonite) exchanged with different interlayer ions (Li⁺, Na⁺, K⁺ and Ca²⁺) was investigated by using the static sessile drop method for contact angle measurements. The results show that water contact angles on clay films vary as a function of the nature of the ion with a spe...

Relaxivities r1 and r2 of cobalt ferrite magnetic nanoparticles (MNPs) have been investigated in the aim of improving the models of NMR relaxation induced by magnetic nanoparticles. On one hand a large set of relaxivity data has been collected for cobalt ferrite MNP dispersions. On the other hand the relaxivity has been calculated for dispersions o...

Strength and other mechanical properties of cement and concrete rely upon the formation of calcium-silicate-hydrates (C-S-H) during cement hydration. Controlling structure and properties of the C-S-H phase is a challenge, due to the complexity of this hydration product and of the mechanisms that drive its precipitation from the ionic solution upon...

We show that nuclear magnetic relaxation experiments at variable magnetic fields (NMRD) provide non-invasive means for probing the spatial dependence of liquid diffusion close to solid interfaces. These experiments performed on samples of cylindrical and spherical nanopore geometries demonstrate that average diffusion coefficient parallel to the in...

Calcium-silicate hydrate (C-S-H) is the main binder in cement and concrete. It starts forming from the early stages of cement hydration and it progressively densifies as cement sets. C-S-H nanoscale building blocks form a cohesive gel, whose structure and mechanics are still poorly understood, in spite of its practical importance. Here we review a...

Current advances in micro and nano X-ray tomography allow to image multiscale porous materials with spatial resolutions up to about 10 nm. This is particularly the case of natural or industrial geo-materials like sedimentary rocks, shale or cement pastes. These experiments reveal complex multiscale morphologies and raise the question to couple thes...

Supercapacitors are electrochemical devices which store energy by ion adsorption on the surface of a porous carbon. They are characterized by high power delivery. The use of nanoporous carbon to increase their energy density should not hinder their fast charging. However, the mechanisms for ion transport inside electrified nanopores remain largely...

Heavy oil fractions can be upgraded through various processes, such as catalytic residue hydrotreatments. Mass transfer of macromolecules present in the heavy oil fraction, so-called asphaltenes, from feedstock to catalytic active sites is limited during hydroprocesses. Mechanisms of the diffusion of asphaltenes through pore network, adsorption, an...

Morphological details of calcium silicate hydrate (C–S–H) stemming from the hydration process of Portland cement (PC) phases are crucial for understanding the PC-based systems but are still only partially known. Here we introduce the first soft X-ray ptychographic imaging of tricalcium silicate (C3S) hydration products. The results are compared usi...

Natural and manufactured disordered systems are ubiquitous and often involve hierarchical structures. This structural organization optimizes defined physical properties at several scales from molecular to representative volumes where the usual homogenization approach becomes efficient. For studying a particular physical property on these systems it...

Swelling clay minerals play a key role in the control of water and pollutant migration in natural media such as soils. Moreover, swelling clay particles' orientational properties in porous media have significant implications for the directional dependence of fluid transfer. Herein we investigate the ability to mimic the organization of particles in...

This investigation was designed to explore the possibility of using transmission electron microscope (TEM) tomography on cement-based systems gain a greater understanding of their nanostructure and pore network. The preliminary results show a clearly a well-defined pore network at the nanoscale, with pore size approximately 1.7–2.4 nm in diameter a...

Motivated by the intriguing phase behavior of charged colloidal platelets, we investigate the structure and dynamics of charged repulsive disks by means of Monte-Carlo simulations. The electrostatic interactions are taken into account through an effective two-body potential, obtained within the non-linear Poisson-Boltzmann formalism, which has the...

Charged platelet suspensions, such as swelling clays, disc-like mineral crystallites or exfoliated nanosheets are ubiquitous in nature. Their phase behaviours are nevertheless still poorly understood: while some clay suspensions form arrested states at low densities, others exhibit an equilibrium isotropic-nematic transition at moderate densities....

The phase behaviour of aqueous suspensions of NAu1 nontronite was studied on size-selected particles by combining osmotic pressure measurements, visual observations under polarized light, rheological experiments and Small Angle X-ray Scattering (SAXS). NAu1 suspensions display a liquid crystalline behaviour as they exhibit a Isotropic/Nematic (I/N)...

Clay minerals, like beidellite or nontronite, spontaneously exfoliate in water and form colloidal suspensions of nanosheets. In a given range of concentration, these suspensions display a nematic liquid–crystalline phase whose structure and properties can be conveniently studied in detail by polarized-light microscopy and small-angle X-ray scatteri...

Numerous natural and manufactured systems such as colloidal suspensions, geological pore networks, catalysts, and nanofluidic devices develop a large and sometimes complex interface strongly influencing the dynamics of the fluid entrapped inside these materials. A coarse grain picture of this molecular dynamics can be considered as an intermittence...

Small-angle X-ray scattering (SAXS) and small-angle neutron scattering (SANS) are widespread experimental tools for the investigation of the microstructure of random heterogeneous materials such as granular porous media. Such experiments allow operating on macroscopic samples and provide quantitative 3D information at length-scales between 1 and 50...

A multiscale NMR method is used for probing the proton dynamics in control pore glasses (CPG) standing in the meso and macro scale ranges. The porous material has been synthetized in our laboratory following the sol-gel route as well as spinodal decomposition. Special heat treatment has modified the proton species at the pore surface. 1H high field...

Recent advances in cell therapy and tissue engineering open new windows for regenerative medicine, but still necessitate innovative non invasive imaging technologies. We demonstrate that high resolution Magnetic Resonance Imaging (MRI) allows combining cellular-scale resolution with the ability to detect several cell types simultaneously at any tis...

Recent developments in magnetic resonance imaging (MRI) have led the community to consider more complex nanostructures than the regular superparamagnetic iron oxide nanoparticles (NPs) as potential efficient contrast agents. These nanostructures present a magnetic dynamical behavior that may stand beyond the superparamagnetic regime and then affect...

The material characteristics and elastic properties of aluminum-substituted 11 Å tobermorite in the relict lime clasts of 2000-year-old Roman seawater harbor concrete are described with TG-DSC and 29Si MAS NMR studies, along with nanoscale tomography, X-ray microdiffraction, and high pressure X-ray diffraction synchroton radiation applications. The...

We report various synchrotron radiation laboratory based techniques used to characterize cement based materials in nanometer scale. High resolution X-ray transmission imaging combined with a rotational axis allows for rendering of samples in three dimensions revealing volumetric details. Scanning transmission X-ray microscope combines high spatial...

The coagulation of sodium montmorillonite by inorganic salts (NaNO3, Ca(NO3)2 and La(NO3)3) was studied by combining classical turbidity measurements with wide-angle-X-ray scattering (WAXS), small-angle-X-ray scattering (SAXS), and transmission X-ray microscopy (TXM). Using size-selected samples, such a combination, associated with an original quan...

There is currently a growing interest in nano-structured silica based materials due to their remarkable thermal properties. These materials are notably used in Vacuum Insulating Panels (VIP). Their exceptional insulating performances have been demonstrated experimentally for a relatively long time. But the heat transfer mechanisms occurring in this...

Small-angle x-ray and neutrons scattering is a widespread experimental tool for the investigation of the microstructure of random heterogeneous materials. Validation of (computer-generated) model microstructures often requires the numerical computation of the scattering intensity, which must be carried out with great care due to finite size effects...

We investigate the competition between anisotropic excluded-volume and repulsive electrostatic interactions in suspensions of thin charged colloidal discs, by means of Monte-Carlo simulations and dynamical characterization of the structures found. We show that the original intrinsic anisotropy of the electrostatic potential between charged platelet...

Charged platelet suspensions, such as swelling clays, disc-like mineral crystallites or exfoliated nanosheets, are ubiquitous in nature. Their puzzling phase behaviours are nevertheless still poorly understood: while Laponite and Bentonite clay suspensions form arrested states at low densities, others, like Beidellite and Gibbsite, exhibit an equil...

Morphological and topological quantification of complex pore networks is of great relevance for environmental engineering, earth science and industry. Recent developments of 3D imaging techniques such as X-ray microtomography or X-ray microscopy provide an opportunity to perform a comprehensive analysis of the pore network topology. Such an analysi...

Cellular processing of nanomaterials may affect their physical properties at the root of various biomedical applications. When nanoparticles interact with living cells, their spatial distribution is progressively modified by cellular activity, which tends to concentrate them into intracellular compartments, changing in turn their responsivity to ph...

Morphological quantification of the complex structure of hierarchical geomaterials is of great relevance for Earth science and environmental engineering, among others. To date, methods that quantify the 3D morphology on length scales ranging from a few tens of nanometers to several hundred nanometers have had limited success. We demonstrate, for th...

We studied pattern formation in granular media in two distinct states: in the dry and non-cohesive (powder) state, on the one hand, and in the wet and cohesive (paste) state, on the other. In the first case, we have shown that gas injection in a thin layer of powder within a Hele Shaw cell leads to fractal patterns remarkably similar to viscous fin...