Hyper-cross-linked polystyrene-like polymers (HCPs) represent a cost-effective, highly stable, and scalable class of porous materials with significant potential for environmental remediation, catalysis, gas storage, and separation applications. Herein, we demonstrate that the introduction of pentafluorostyrene in the precursor HCP formulation and the subsequent para-fluoro-thiol reaction is an efficient and energy-saving strategy to functionalize these materials. The important quantity of thiol compounds available in the market offers a wide variety of chemical functions accessible for microporous materials and tailors the properties of HCPs to the specific sorption application. In this study, the proportion of the three building blocks used in the polymerization is first optimized to obtain HCPs exhibiting high microporosity, large Brunauer-Emmett-Teller surface areas, and pore volumes independent of the incorporated functional groups (hexyl, alcohol, amine, or sulfonate). The efficiency and versatility of the para-fluoro-thiol coupling reaction are then demonstrated. Finally, the HCPs′ CO2 adsorption capacity was accessed, as an analyte example, using a manometric setup. At ambient pressure, uptake capacity is predominantly governed by surface chemistry alongside textural properties, while at higher pressure, the uptake capacity is correlated with pore volume, with a probable influence of the swelling of the material upon adsorption.

The growing concern over water pollution and waste management requires innovative solutions that promote resource efficiency within a circular economy. This study aims to utilize rice husk (RH) as a sustainable feedstock to develop highly porous silica particles and generate valuable by-products, addressing the dual challenges of waste reduction and water contamination. We hypothesize that optimizing the production of amorphous silica from acid-washed RH will enhance its adsorptive properties and facilitate the concurrent generation of bio-oil and syngas. Amorphous silica particles were extracted from acid-washed RH with a yield of 15 wt% using a combination of acid washing at 100 • C, pyrolysis at 500 • C, and calcination at 700 • C with controlled heating at 2 • C/min. The optimized material (RH2-SiO 2 ), composed of small (60-200 nm) and large (50-200 µm) particles, had a specific surface area of 320 m 2 /g, with funnel-shaped pores with diameters from 17 nm to 4 nm and showed a maximum cadmium adsorption capacity of 407 mg Cd/g SiO 2 . Additionally, the pyrolysis process yielded CO-rich syngas and bio-oil with an elevated phenolic content, demonstrating a higher bio-oil yield and reduced gas production compared to untreated RH. Some limitations were identified, including the need for bio-oil upgrading, further research into the application of RH2-SiO 2 for wastewater treatment, and the scaling-up of adsorbent production. Despite the challenges, these results contribute to the development of a promising adsorbent for water pollution control while enhancing the value of agricultural waste and moving closer to a circular economy model.

Avec le soutien d’une unité du CNRS de Montpellier, une équipe de recherche de l’Université de Pau et des Pays de l’Adour (UPPA) s’intéresse à la valorisation de la balle de riz, la cosse qui entoure ces petits grains bien connus. Leurs objectifs ? Récupérer bio-huile et silice, deux super ingrédients présents dans ce déchet, qui pourraient servir de biocarburant ou encore d’agent décontaminant de l’eau.

In this paper, the non-local density functional theory is used in combination with SAFT-VR, to investigate the pore pressure behaviour of water confined in various nanopores. Due to the efficiency and low computational cost of the method, many configurations and thermodynamic conditions are explored. In particular, capillary condensation and evaporation of water, their impact on the pore pressure, and the effect of surface activation are evaluated. Successive first-order phase transitions of ultra-confined water monolayer are also highlighted.

This study aims at characterising the adsorption-induced pore pressure and confinement in nanoscopic pores by molecular non-local density functional theory (DFT). Considering its important potential industrial applications, the adsorption of methane in graphitic slit pores has been selected as the test case. While retaining the accuracy of molecular simulations at pore scale, DFT has a very low computational cost that allows obtaining highly resolved pore pressure maps as a function of both pore width and thermodynamic conditions. The dependency of pore pressure on these parameters (pore width, pressure and temperature) is carefully analysed in order to highlight the effect of each parameter on the confined fluid properties that impact the solid matrix.

Natural and synthesised porous media are generally composed of a double porosity: a microporosity where the fluid is trapped as an adsorbed phase and a meso or a macro porosity required to ensure the transport of fluids to and from the smaller pores. Zeolites, activated carbon, tight rocks, coal rocks, source rocks, cement paste or construction materials are among these materials. In nanometer-scale pores, the molecules of fluid are confined. This effect, denoted as molecular packing, induces that fluid- fluid and fluid-solid interactions sum at the pore scale and have significant consequences at the macroscale, such as instantaneous deformation, which are not predicted by classical poromechanics. If adsorption in nanopores induces instantaneous deformation at a higher scale, the matrix swelling may close the transport porosity, reducing the global permeability of the porous system. This is important for applications in petroleum oil and gas recovery, gas storage, separation, catalysis or drug delivery. This study aims at characterizing the influence of an adsorbed phase on the instantaneous deformation of micro-to-macro porous media presenting distinct and well-separated porosities. A new incremental poromechanical framework with varying porosity is proposed allowing the prediction of the swelling induced by adsorption without any fitting parameters. This model is validated by experimental comparison performed on a high micro and macro porous activated carbon. It is shown also that a single porosity model cannot predict the adsorption-induced strain evolution observed during the experiment. After validation, the double porosity model is used to discuss the evolution of the poromechanical properties under free and constraint swelling.

Natural and synthetic porous media generally encompass different and distinct porosities: a microporosity where the fluid is trapped as an adsorbed phase and a mesoporosity or a macroporosity required to ensure the transport of fluids to and from the smaller pores. Zeolites, activated carbon, tight rocks, coal rocks, source rocks, cement paste or construction materials are among these materials.

A new experimental setup is presented allowing the simultaneous measurement of adsorption isotherms and adsorption-induced deformations. It is composed of a manometric technique coupled with a digital image correlation setup for full-field displacement measurements. The manometric part is validated by comparing adsorption isotherms with those obtained by a gravimetric method. The principles and methods of both adsorption isotherm and induced deformation measurements are presented in detail. As a first application of this new apparatus, the coupling between adsorption and induced deforma- tion is characterised for a microporous media (activated carbon) saturated by pure CO2 (318.15 K, [0–60] bars) and pure CH4 (303.15 K, [0–130] bars). For this very homogeneous porous material, the induced deformation is characteristic of a pure volumetric swelling but the full-field setup may allow the characterisation of the localised pattern of deformation for heterogenous or cracked microporous media.

A poromechanical model is presented for estimating swelling of nano-porous media fully saturated with a fluid phase. From the Gibbs adsorption isotherm, the effective pore pressure and the volumetric strain are estimated incrementally taking into account the variations of porosity upon swelling and therefore the variations of the poromechanical properties (apparent modulus, Biot coefficient, Biot modulus). Moreover, the interaction between swelling and the adsorption isotherms are examined by proposing a correction to the Gibbs formalism by taking into account the pore volume variation upon swelling. First, comparisons with experimental data found in the literature are performed, and a fair agreement is observed.

The purpose of this work is to achieve a better understanding of the coupling between adsorption and swelling in microporous materials. This is typically of utmost importance in the enhancement of non-conventional reservoirs or in the valorization of CO 2 geological storage. We consider here the case of fully saturated porous solids with pores down to the nanometer size (≤ 2nm). Hardened cement paste, tight rocks, activated carbon or coal are among those materials. Experimentally, different authors tried to combine gas adsorption results and volumetric swelling data, especially for bituminous coal. However, most results in the literature are not complete in a sense that the adsorption experiments and the swelling experiments were not performed on the exact same coal sample. Other authors present simultaneous in-situ adsorption and swelling results but the volumetric strain is extrapolated from a local measurement on the surface sample or by monitoring the two-dimensional silhouette expansion. Only elastic and reversible swellings are reported in the literature. Theoretically, most continuum approaches to swelling upon adsorption of gas rely on a coupling between the adsorption isotherms and the mechanical deformation. A new poromechanical framework has been recently proposed to express the swelling increment as a function of the increment of bulk pressure with constant porosity. However, this framework has to be extended to take into account the porosity evolution upon swelling. This paper aims at presenting a new experimental setup where both adsorption and strain are measured in-situ and simultaneously and where the full-field swelling is monitored by digital image correlation. Permanent strain and damage are observed. On the other hand, we present an extended poromechanical framework where the porosity is variable upon swelling. A new incremental nonlinear scheme is proposed where the poromechanical properties are updated at each incremental pressure step, depending on the porosity changes. Interactions between swelling and the adsorption isotherms are examined and a correction to the classical Gibbs formalism is proposed. Predicted swellings are compared with results from the literature.