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Surface wettability is a critical factor in multi-phase flow within porous media, a processes essential in various applications e.g. in the energy sector. Traditional methods for assessing wettability of porous media by contact angle measurements, such as sessile droplet and micro-CT techniques, are limited by interface pinning, sample size or resolution impacting precision and accuracy. We hypothesized that using smaller and unconstrained probes, specifically gas molecules, to retrieve interactions along a representative sample size via inverse gas chromatography (IGC) could provide a more accurate determination of contact angles. We propose a procedure to relate IGC results with macro-scale wettability descriptions, such as the Young equation. To test the effectiveness of IGC method, glass bead samples with varying wettability, modified through a silanization process, were prepared. Contact angles for a distilled water-air-sample system were measured using the sessile droplet method and micro-CT for comparative analysis. IGC was employed to determine the surface energy components of these samples, which were then used in the extended Young-Dupré equation to calculate the contact angles. The contact angle ranges determined by IGC and micro-CT for untreated glass beads, the most hydrophilic samples, showed great alignment. This consistency is attributed to the chemical amorphous nature of the untreated beads reflected in the assumption that dispersive and specific energetic components of surface sites are uncorrelated, on which the proposed analysis is based. For treated samples, where the silanization process creates correlations between surface energetic components, the alignment between IGC and micro-CT results was less precise. This study successfully demonstrated that IGC, a molecular-scale probe-based technique, can effectively determine the contact angle range, a macroscopic property, for amorphous samples. Future work should incorporate correlations between energetic components of surface detected by IGC to extend this method's applicability to a wider material range.   • Novel IGC-based method introduced for determining contact angle ranges in porous media. • Validated IGC method by comparing contact angles with micro-CT and sessile droplet tests. • Assessed IGC's applicability across different wettability levels using silanized glass beads. • Remarkable alignment with micro-CT and sessile droplet data for unmodified glass beads. • IGC effectively detected wettability changes in silanized glass beads. [ABSTRACT FROM AUTHOR]

[Display omitted] • Lignin nanoparticles bridge hydrophilic nanocellulose and hydrophobic polycaprolactone. • Lignin nanoparticles mitigate nano-scaled phase separation in composite. • Interfacial interactions in aqueous and dry states tailor composite properties. • Broadband dielectric spectroscopy reveals details about molecular dynamics. • Surface analysis elucidates interactions during composite formation. Advancing nanocomposites requires a deep understanding and careful design of nanoscale interfaces, as interfacial interactions and adhesion significantly influence the physical and mechanical properties of these materials. This study demonstrates the effectiveness of lignin nanoparticles (LNPs) as interfacial compatibilizer between hydrophilic cellulose nanofibrils (CNF) and a hydrophobic polyester, polycaprolactone (PCL). In this context, we conducted a detailed analysis of surface-to-bulk interactions in both wet and dry conditions using advanced techniques such as quartz crystal microbalance with dissipation (QCM-D), atomic force microscopy (AFM), water contact angle (WCA) measurements, broadband dielectric spectroscopy (BDS), and inverse gas chromatography (IGC). QCM-D was employed to quantify the adsorption behavior of LNPs on CNF and PCL surfaces, demonstrating LNPs' capability to interact with both hydrophilic and hydrophobic phases, thereby enhancing composite material properties. LNPs showed extensive adsorption on a CNF model film (1186 ± 178 ng.cm−2) and a lower but still significant adsorption on a PCL model film (270 ± 64 ng.cm−2). In contrast, CNF adsorption on a PCL model film was the lowest, with a sensed mass of only 136 ± 35 ng.cm−2. These findings were further supported by comparing the morphology and wettability of the films before and after adsorption, using AFM and WCA analyses. Then, to gain insights into the molecular-level interactions and molecular mobility within the composite in dry state, BDS was employed. The BDS results showed that LNPs improved the dispersion of PCL within the CNF network. To further investigate the impact of LNPs on the composites' interfacial properties, IGC was employed. This analysis showed that the composite films containing LNPs exhibited lower surface energy compared to those composed of only CNF and PCL. The presence of LNPs likely reduced the availability of surface hydroxyl groups, thus modifying the physicochemical properties of the interface. These changes were particularly evident in the heterogeneity of the surface energy profile, indicating that LNPs significantly altered the interfacial characteristics of the composite materials. Overall, these findings emphasize the necessity to control the interfaces between components for next-generation nanocomposite materials across diverse applications. [ABSTRACT FROM AUTHOR]

A new methodology based on the Hamieh thermal model was applied for the determination of the surface properties of solid surfaces. The new approach consisted of the accurate quantification of the London dispersive surface energy of materials using the two-dimensional inverse gas chromatography technique at infinite dilution. This technique used the notion of the net retention volume of adsorbed molecules on the solid catalysts, allowing the determination of the free energy of adsorption. The Hamieh thermal model proving the temperature effect on the surface area of organic molecules adsorbed on H-β-zeolite/rhodium catalysts at different rhodium percentages was used to determine the accurate values of the London dispersive surface energy of solid surfaces at different temperatures. This new method also allowed a precise evaluation of the dispersive adhesion work, dispersive surface enthalpy, and entropy of adsorption of n-alkanes adsorbed on the catalysts. In this paper, the London dispersive surface energy and adhesion work of H-β-zeolite-supported rhodium catalysts were determined using the free energy of adsorbed molecules obtained from the two-dimensional inverse gas chromatography technique at infinite dilution. It was proved that the London dispersive surface energy strongly depended on the temperature and the rhodium percentage, while the dispersive adhesion work of n-alkanes adsorbed on H-β-zeolite/rhodium catalysts was proved to be a function of the temperature, rhodium percentage, and the carbon atom number of the n-alkanes. [ABSTRACT FROM AUTHOR]

The particulate properties of α-lactose monohydrate (αLMH), an excipient and carrier for pharmaceuticals, is important for the design, formulation and performance of a wide range of drug products. Here an integrated multi-scale workflow provides a detailed molecular and inter-molecular (synthonic) analysis of its crystal morphology, surface chemistry and surface energy. Predicted morphologies are validated in 3D through X-ray diffraction (XCT) contrast tomography. Interestingly, from aqueous solution the fastest growth is found to lie along the b-axis, i.e. the longest unit cell dimension of the αLMH crystal structure reflecting the greater opportunities for solvation on the prism compared to the capping faces leading to the former's slower relative growth rates. The tomahawk morphology reflects the presence of β-lactose which asymmetrically binds to the capping surfaces creating a polar morphology. The crystal lattice energy is dominated by van der Waals interactions (between lactose molecules) with electrostatic interactions contributing the remainder. Predicted total surface energies are in good agreement with those measured at high surface coverage by inverse gas chromatography, albeit their dispersive contributions are found to be higher than those measured. The calculated surface energies of crystal habit surfaces are not found to be significantly different between different crystal surfaces, consistent with αLMH's known homogeneous binding to drug molecules when formulated. Surface energies for different morphologies reveals that crystals with the elongated crystal morphologies have lower surface energies compared to those with a triangular or tomahawk morphologies, correlating well with literature data that the surface energies of the lactose carriers are inversely proportional to their aerosol dispersion performance. A predictive workflow for inhalation drug formulation highlighting the 4-stage pathway from the molecular state through solid-state and surface properties to the blended powder. [Display omitted] • Lattice energy dominated by van der Waals interactions with electrostatic interactions contributing about 13%. • Predicted 3D crystal morphology agrees with aqueous solution grown data as measured using X-ray Computed Tomography. • Polar "tomahawk" morphology reflects differential adsorption of β-lactose molecules between {010} and {0-10} surfaces. • Predicted surface energies agree with IGC data albeit with higher predicted dispersive energies compared to measurements. • Low variation between face-specific surface energies consistent with observed homogenous binding of crystals when blended. [ABSTRACT FROM AUTHOR]

The dispersive and polar properties of materials, and especially of polymers and copolymers, play an important role in several engineering applications implying their surfaces and interfaces. The surface energetic properties of poly(styrene-co-butadiene) have never been studied. We proposed in this study an accurate determination of such properties by using inverse gas chromatography (IGC) at infinite dilution. Background: The IGC surface technique led to the dispersive and polar properties of poly(styrene-co-butadiene) rubber (SBR) by adsorption of organic solvents at various temperatures. Methods: Our new methodology, based on the thermal Hamieh model and the London dispersion interaction energy, was used to determine the London dispersion surface energy, the polar acid–base surface energy, and the Lewis acid–base properties of the copolymer. Results: The different surface energy parameters of the SBR were obtained as a function of temperature from the chromatographic measurements. Conclusions: The dispersive and polar free energies of adsorption of the various n-alkanes and polar molecules on poly(styrene-co-butadiene) were determined at different temperatures. A decrease in the London dispersive surface energy and the polar Lewis acid–base surface energies of SBR was highlighted when the temperature increased. It showed a Lewis amphoteric character of poly(styrene-co-butadiene) with a highest basic constant 10 times larger than its acidic constant. This new and original method can better characterize the surface thermodynamic properties of poly(styrene-co-butadiene). [ABSTRACT FROM AUTHOR]

Copyright of Acta Materiae Compositae Sinica is the property of Acta Materiea Compositae Sinica Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The linear diblock copolymer polystyrene-b-poly(4-vinylpyridine) (PS-P4VP) is an important copolymer recently used in many applications such as optoelectronics, sensors, catalysis, membranes, energy conversion, energy storage devices, photolithography, and biomedical applications. (1) Background: The surface thermodynamic properties of PS-P4VP copolymers are of great importance in many chemical and industrial processes. (2) Methods: The inverse gas chromatography (IGC) at infinite dilution was used for the experimental determination of the retention volumes of organic solvents adsorbed on copolymer surfaces as a function of temperature. This led to the variations in the free energy of interaction necessary to the evaluation of the London dispersive and polar acid–base surface energies, the polar enthalpy and entropy, the Lewis acid–base constants, and the transition temperatures of the PS-P4VP copolymer. (3) Results: The application of the thermal Hamieh model led to an accurate determination of the London dispersive surface energy of the copolymer that showed non-linear variations versus the temperature, highlighting the presence of two transition temperatures. It was observed that the Lewis acid–base parameters of the copolymer strongly depend on the temperature, and the Lewis base constant of the solid surface was shown to be higher than its acid constant. (4) Conclusions: An important effect of the temperature on the surface thermodynamic properties of PS-P4VP was proven and new surface correlations were determined. [ABSTRACT FROM AUTHOR]

The surface thermodynamic properties of polymers and copolymers modified by supramolecular structures are used in several industrial processes, such as selective adsorption, paints, coatings, colloids, and adhesion applications. Background: Inverse gas chromatography at infinite dilution was proved to be the best technique to determine the surface properties of solid surfaces by studying the adsorption of some model polar and non-polar organic molecules adsorbed on solid surfaces at different temperatures. Methods: The retention volume of adsorbed solvents is a valuable parameter that was used to obtain the London dispersive and polar free energies and the London dispersive surface energy of styrene–divinylbenzene copolymer modified by supramolecular structure of melamine using both the Hamieh thermal model and our new methodology consisting of the separation of the two polar molecules and the dispersive free energy of their interaction. This led to the determination of the polar acid and base surface energy, and the Lewis acid–base constants of the various solid materials. Results: Following our new methodology, all surface energetic properties of styrene–divinylbenzene copolymer modified by melamine at different percentages were determined as a function of temperature. Conclusions: It was observed that the styrene–divinylbenzene copolymer exhibited the highest London dispersive surface energy, which decreased when the melamine percentage increased. All materials presented higher Lewis basicity and this Lewis basicity increased with the percentage of melamine. [ABSTRACT FROM AUTHOR]

Aspergillus niger is a species of fungus that is widely found in natural ecosystems and has an important role in various industrial fields and is readily available. To study the adhesion of microbial cells to solid substrates and to improve their properties, physicochemical characterization of microorganisms is extremely important. For this purpose, in this study, the surface properties of A. niger biomass were determined at low cost and with high accuracy by inverse gas chromatography (IGC), a physicochemical characterization technique. IGC experiments were conducted between 303.2 and 328.2 K at infinite dilution. Among these temperatures, various organic solvent vapors were passed over the A. niger biomass considered as stationary phase and their retention behavior was studied. Using the raw data, net retention volumes were calculated and retention diagrams were drawn. From the linear retention diagrams, the dispersive surface energy was calculated according to Dorris-Gray (48.73–46.09 mJ/m2), Donnet-Park (47.12–44.50 mJ/m2), Schultz (46.88–42.45 mJ/m2), and Hamieh (76.42–64.06 mJ/m2) methods. With the IGC method, the acidity-basicity parameters of A. niger biomass were determined and it was found that the surface was basic ( K D / K A = 4.871 ). In the second part of this study, the butyl acetate isomer series, which are difficult to be separated by conventional methods, were effectively separated by the IGC method using A. niger stationary phase. [ABSTRACT FROM AUTHOR]

Mass transport in porous systems is inherently complex, but at the same also of utmost importance for large‐scale industrial processes such as heterogeneous catalysis. For each of the different length scales of diffusive motion potentially involved or relevant, specific characterization techniques have been developed and successfully applied over the years – including, but not limited to pulsed field gradient nuclear magnetic resonance (PFG‐NMR) spectroscopy, zero length column (ZLC) measurements and inverse gas chromatography (iGC). While each of these methods can deliver detailed information on certain types of diffusion, none of them are capable of delivering a full picture of mass transport across multiple length scales alone. In this context, the goal of the present work was to evaluate the technical feasibility and characterization potential of the hyphenated combination of PFG‐NMR and iGC in a coupled experimental setup. Challenges, advantages, and limitations of this approach are discussed using the example of propane adsorption and diffusion in two different zeolite catalysts (Mg(H)‐ZSM‐5 and Silicalite‐1). It is shown that the simultaneous detection of self‐diffusion on short length scales (as probed by PFG‐NMR) and transport diffusion covering longer distances (detectable by iGC) cannot be realized under the used conditions, essentially due to the lack of kinetic control at higher reactant loadings. The key advantage of the developed coupled setup is the ability of the iGC instrument to provide defined and readily variable levels of catalyst loading, which enables advanced pore connectivity studies by PFG‐NMR and yields thermodynamic data on reactant adsorption at the same time. [ABSTRACT FROM AUTHOR]

Particle systems and their efficient and precise separation are becoming increasingly complex. Therefore, instead of focusing on a single separation feature, a multidimensional approach is needed where more than one particle property is considered. This, however, requires the precise characterization of the particle system, which is especially challenging for fine particles with sizes below 10 µm. This paper discusses the benefits and limitations of different characterization techniques, including optical contour analysis, inverse gas chromatography, flow cytometry, and SEM-based image analysis. The separation of ultrafine particles was investigated for a binary system using froth flotation, where a novel developed flotation apparatus is used. A special focus was placed on the multidimensional evaluation of the separation according to the particle properties of size, shape, and wettability, which was addressed via multivariate Tromp and entropy functions. The results emphasize the intricacy of the flotation process and the complex interaction of the individual particle properties and process parameters. The investigations contribute to the understanding of the characterization of particulate properties as well as the separation behavior of ultrafine particles via froth flotation, especially in the case of a multidimensional approach. [ABSTRACT FROM AUTHOR]

4-[(S)-2-Methyl-3-hydroxypropyloxy]-4'-formylazobenzene, 4-(3-hydroxypropyloxy)-4'-formylazobenzene and µ-oxodimer of iron 2,8,12,18-tetramethyl-3,7,13,17-tetra-n-amylporphine were synthesized using known methods. A mixture with a certain concentration of components was prepared from the synthesized compounds. The resulting mixture was used as an impregnation of the wide-porous adsorbent Chromaton N-AW. The degree of impregnation was 10%. The prepared adsorbent was used as a stationary phase for inverse gas-mesophase chromatography. In this work, the sorption redistribution of a number of volatile organic compounds—isomers of methyl and dimethylpyridines, weakly polar xylenes and enantiomers from the gas phase on the prepared adsorbent was studied using inverse gas chromatography. During the experiment, the specific retention volumes of sorbates, characterizing the sorption activity of the prepared stationary phase were calculated. For structural isomers, activity coefficients for the distribution of sorbates in the liquid layer of the liquid crystal were obtained. To confirm the data on the sorption activity of sorbates, the thermodynamic parameters of the dissolution of specific isomers were found. Conclusions were drawn about the influence of enthalpy and entropy factors on the retention ability of sorbates. The influence of structure, isomerism, intermolecular interactions, and the addition of a macrocycle on the sorption properties of sorbates is discussed. Data on the analytical features of sorption were obtained, namely, the maximum values of separation factors for structural and optical isomers and compounds of different structures, but with similar boiling points, were calculated. It was experimentally established that the prepared adsorbent exhibits a fairly high ability to separate close-boiling structural isomers and a moderate ability to separate enantiomers. Emphasis is placed on the maximum value of the separation factor of 3,4- and 3,5-lutidines, which is the highest in value among the previously developed stationary phases of similar structure. In conclusion, the use of the resulting adsorbent in a unified system of chemical analysis is justified. [ABSTRACT FROM AUTHOR]

The study presents experimental results on the adsorption of endosulfan in new natural zeolite deposits from Mexico. The adsorption of this herbicide was evaluated using inverse gas chromatography with a thermal conductivity detector and helium as the carrier gas. The experimental adsorption data were analyzed using the Langmuir and Freundlich equations in their linear form over a temperature range of 413–573 K. The study also estimated thermodynamic parameters such as the Free Energy of Gibbs (ΔG), isosteric enthalpy of adsorption (ΔH), and entropy change (ΔS) within this temperature range. The results indicated that the zeolites studied had a low adsorption capacity for this herbicide under the experimental conditions. The study also quantitatively determined the presence of starting minerals, with Na-Mordenite and Na-Clinoptilolite being the most prevalent, followed by Ca-Chabazite, Ca-Clinoptilolite, and Montmorillonite, with Quartz being present in low amounts. The NMOR zeolite underwent ion exchanges with AgNO3 to produce the Ag-MOR zeolite and assess its herbicide adsorption capacity. Another mineral, Ca-Stilbite, was present in higher quantities than Ca-Clinoptilolite and Quartz. [ABSTRACT FROM AUTHOR]

Crystalline active pharmaceutical ingredients with comparable size and surface area can demonstrate surface anisotropy induced during crystallization or downstream unit operations such as milling. To the extent that varying surface properties impacts bulk powder properties, the final drug product performance such as stability, dissolution rates, flowability, and dispersibility can be predicted by understanding surface properties such as surface chemistry, energetics, and wettability. Here, we investigate the surface properties of different batches of Odanacatib prepared through either jet milling or fast precipitation from various solvent systems, all of which meet the particle size specification established to ensure equivalent biopharmaceutical performance. This work highlights the use of orthogonal surface techniques such as Inverse Gas Chromatography (IGC), Brunauer–Emmett–Teller (BET) surface area, contact angle, and X-ray Photoelectron Spectroscopy (XPS) to demonstrate the effect of processing history on particle surface properties to explain differences in bulk powder properties. [ABSTRACT FROM AUTHOR]

Copyright of Archives of Environmental Protection is the property of Polish Academy of Sciences and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of China Rubber Industry is the property of Editorial Office of China Rubber Industry and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Prussian Blue Analogues (PBAs), which are characterized by their open structure, high stability, and non-toxic properties, have recently been the subject of research for various applications, including their use as electrode precursors for capacitive deionization, gas storage, and environmental purification. These materials can be readily tailored to enhance their affinity towards gases for integration with sensing devices. An improved understanding of PBA-gas interactions is expected to enhance material development and existing sensor deposition schemes greatly. The use of inverse gas chromatography (IGC) is a robust approach for examining the relationship between porous materials and gases. In this study, the adsorption properties of (functionalized) hydrocarbons, i.e., probe molecules, on the copper hexacyanoferrate (CuHCF) lattice were studied via IGC, demonstrating that alkylbenzenes have a higher affinity for this material than n-alkanes. This difference was rationalized by steric hindrance, π–π interactions, and vapour pressure effects. Along the same line, the five isomers of hexane showed decreasing selectivity upon increased steric hindrance. Enthalpy values for n-pentane, n-hexane and n-heptane were lower than that of toluene. The introduction of increased probe masses resulted in a surface coverage of 46% for toluene. For all n-alkane probe molecules this percentage was lower. However, the isotherms of these probes did not show saturation points and the observed linear regime proves beneficial for gas sensing. Our work demonstrates the versatility of CuHCF for gas sensing purposes and the potential of IGC to characterize the adsorption characteristics of such a porous nanomaterial. [ABSTRACT FROM AUTHOR]

The thermal surface properties of graphenes and carbon materials are of crucial importance in the chemistry of materials, chemical engineering, and many industrial processes. Background: The determination of these surface properties is carried out using inverse gas chromatography at infinite dilution, which leads to the retention volume of organic solvents adsorbed on solid surfaces. This experimental and fundamental parameter actually reflects the surface thermodynamic interactions between injected probes and solid substrates. Methods: The London dispersion equation and the Hamieh thermal model are used to quantify the London dispersive and polar surface energy of graphenes and carbon fibers as well their Lewis acid-base constants by introducing the coupling amphoteric constant of materials. Results: The London dispersive and polar acid-base surface energies, the free energy of adsorption, the polar enthalpy and entropy, and the Lewis acid-base constants of graphenes and carbon materials are determined. Conclusions: It is shown that graphene exhibited the highest values of London dispersive surface energy, polar surface energy, and Lewis acid-base constants. The highest characteristics of graphene justify its great potentiality and uses in many industrial applications. [ABSTRACT FROM AUTHOR]

Inverse gas chromatography at infinite dilution was used to determine the surface thermodynamic properties of silica particles and PMMA adsorbed on silica, and more particularly, to quantify the London dispersive energy γ s d , the Lewis acid γ s + , and base γ s − polar surface energies of PMMA/silica composites as a function of the temperature and the recovery fraction θ of PMMA. The polar acid-base surface energy γ s A B and the total surface energy of the different composites were then deduced as a function of the temperature. In this paper, the Hamieh thermal model was used to quantify the surface thermodynamic energy of polymethyl methacrylate (PMMA) adsorbed on silica particles at different recovery fractions. A comparison of the new results was carried out with those obtained by applying other molecular models of the surface areas of organic molecules adsorbed on the different solid substrates. An important deviation of these molecular models from the thermal model was proved. The determination of γ s d , γ s + , γ s − , and γ s A B of PMMA in both the bulk and adsorbed phases showed an important non-linearity variation of these surface parameters as a function of the temperature. The presence of maxima in the curves of γ s d (T) highlighted the second-order transition temperatures in PMMA showing beta-relaxation, glass transition, and liquid–liquid temperatures. These three transition temperatures depended on the adsorption rate of PMMA on silica. The proposed method gave a new relation between the recovery fraction of PMMA and its London dispersive energy, showing an important effect of the temperature on the surface energy parameters of the adsorption of PMMA on silica. A universal equation relating γ s d (T , θ) of the systems PMMA/silica to the recovery fraction and the temperature was proposed. [ABSTRACT FROM AUTHOR]

This research was devoted to study the effect of the tacticity on the surface physicochemical properties of PMMA. (1) Background: The determination of the surface free energy of polymers is generally carried out by inverse gas chromatography (IGC) at infinite dilution. The dispersive, polar and surface acid-base properties of PMMA at different tacticities were obtained via IGC technique with the help of the net retention time and volume of adsorbed. (2) Methods: The London dispersion equation was used to quantify the polar free energy of adsorption, while the London dispersive surface energy γ s d (T) of PMMAs was determined using the thermal model. (3) Results: The results showed non-linear variations of γ s d (T) of atactic, isotactic, and syndiotactic PMMAs with three maxima characterizing the three transition temperatures of PMMAs. The obtained values of the enthalpic and entropic Lewis's acid-base parameters showed that the basicity of the atactic PMMA was about four times larger than its acidity. (4) Conclusions: A large difference in the behavior of the various PMMAs was proven in the different values of the polar acid and base surface energies of the three PMMAs with an important effect of the tacticity of PMMA on its acid-base surface energies. [ABSTRACT FROM AUTHOR]

Samples of mesoporous silica gel doped with cerium and terbium and modified with silver were synthesized using the template method. The textural and morphological characteristics of the samples were studied using scanning electron microscopy, inductively coupled plasma mass spectrometry, X-ray diffraction analysis, Fourier-transform infrared (FT-IR) spectroscopy, and nitrogen adsorption-desorption analysis. Moreover, thermodynamic characteristics of adsorption (differential heats and entropies) of test organic compounds were obtained using the inverse gas chromatography method. It was established that the nature of the dopant leads to changes in the textural characteristics of the samples and the heat of adsorption for hydrocarbons and compounds prone to various types of specific interactions. [ABSTRACT FROM AUTHOR]

Review contents the extensive insight into the last 10 years in the history of inverse gas chromatography (IGC). Although this technique seems to be well-known. Every year brings new proposals concerning the procedures enabling the deeper insights in the properties of the surfaces as well as the bulk of various materials. Meetings organized by the universities and commercial groups indicate the growing society of users. Different versions of IGC are most often used in following the changes of materials properties undergoing technological modifications and/or changes caused by the environment in which such material is applied.The wide group of raw materials, minerals, pharmaceutical components, abrasive articles, cellulosic materials, bacteria biomass, ionic liquids, metal-organic frameworks (MOFs) as well as various hybrid materials were characterized by IGC. Here it is worth to indicate the properties of dentine and enamel during dental treatment or (on the other side) examination of the influence of various external parameters on the transport of gaseous compounds in different geologic materials. The advantages and challenges that arise during such experiments are presented and discussed.

Poly lactic acid (PLA) is one of the most commonly used bio-derived thermoplastic polymers in 3D and 4D printing applications. The determination of PLA surface properties is of capital importance in 3D/4D printing technology. The surface thermodynamic properties of PLA polymers were determined using the inverse gas chromatography (IGC) technique at infinite dilution. The determination of the retention volume of polar and non-polar molecules adsorbed on the PLA particles filling the column allowed us to obtain the dispersive, polar, and Lewis's acid–base surface properties at different temperatures from 40 °C to 100 °C. The applied surface method was based on our recent model that used the London dispersion equation, the new chromatographic parameter function of the deformation polarizability, and the harmonic mean of the ionization energies of the PLA polymer and organic molecules. The application of this new method led to the determination of the dispersive and polar free surface energy of the adsorption of molecules on the polymeric material, as well as the glass transition and the Lewis acid–base constants. Four interval temperatures were distinguished, showing four zones of variations in the surface properties of PLA as a function of the temperature before and after the glass transition. The acid–base parameters of PLA strongly depend on the temperature. The accurate determination of the dispersive and polar surface physicochemical properties of PLA led to the work of adhesion of the polar organic solvents adsorbed on PLA. These results can be very useful for achieving reliable and functional 3D and 4D printed components. [ABSTRACT FROM AUTHOR]

The adsorption of polymers on solid surfaces is common in many industrial applications, such as coatings, paints, catalysis, colloids, and adhesion processes. The properties of absorbed polymers commonly vary with temperature. In this paper, inverse gas chromatography at infinite dilution was used to determine the physicochemical characterization of PMMA adsorbed on silica. A new method based on the London dispersion equation was applied with a new parameter associating the deformation polarizability with the harmonic mean of the ionization energies of the solvent. More accurate values of the dispersive and polar interaction energies of the various organic solvents adsorbed on PMMA in bulk phase and PMMA/silica at different recovery fractions were obtained, as well as the Lewis acid–base parameters and the transition temperatures of the different composites. It was found that the temperature and the recovery fraction have important effects on the various physicochemical and thermodynamic properties. The variations in all the interaction parameters showed the presence of three transition temperatures for the different PMMA composites adsorbed on silica with various coverage rates, with a shift in these temperatures for a recovery fraction of 31%. An important variation in the polar enthalpy and entropy of adsorption, the Lewis acid–base parameters and the intermolecular separation distance was highlighted as a function of the temperature and the recovery fraction of PMMA on silica. [ABSTRACT FROM AUTHOR]

The surfaces of natural (NZ) and zeolite/iron oxyhydroxide composite (ZFe) samples were analysed by means of inverse gas chromatography (IGC) using the adsorption data of organic non-polar and polar probes, in the infinite and finite-dilution regimes, in the temperature range 483-513 K. The dispersive components of the free energy of adsorption, S, determined by the Gray method, decreased with increasing temperature for both zeolites. The specific interactions were characterised by the specific free adsorption energy change, Ga S, the specific enthalpy change of adsorption, Ha S, as well as the donor and acceptor interaction parameters (KA, KD) and the basic character of the NZ and ZFe was evidenced. The adsorption isotherms of n-hexane, benzene, chloroform and tetrahydrofuran (THF) were determined under finite surface coverage and used to estimate the specific surface area and the adsorption energy distribution. The adsorption capacity of the ZFe was higher than for NZ for all the investigated adsorbates. The specific surface areas and pore size distributions were also determined using nitrogen adsorption-desorption isotherms, i.e., the BET method. It was observed that the nature of the adsorbate and the properties of the solid surface of the initial and modified samples governed the uptake of adsorbates. [ABSTRACT FROM AUTHOR]

Research on the hygroscopic behavior of NC is essential because it affects the mechanical properties, combustion properties, and safe storage of NC‐based products. In this study, Fourier transform infrared spectroscopy (FTIR), X‐ray diffraction (XRD), and scanning electron microscopy (SEM) are used to characterize the chemical structure, crystal structure, and microscopic morphology of NC, respectively. The moisture adsorption isotherms of NC fibers with different nitrogen content are determined by dynamic vapor sorption (DVS) and fitted with Hailwood‐Horrobin (H−H) and Guggenheim‐Anderson‐de Boer (GAB) models. The specific surface area and surface energy of NC are also measured by inverse gas chromatography (IGC). The results show that as the nitrogen content of NC increases, the intensity of the −OH characteristic absorption peak is weakened, the crystallinity does not change much, the number of cracks and pores on the NC fiber surface increases, and the equilibrium moisture content (EMC) of the NC decreases in general. In addition, the fitting results based on the H−H and GAB models show that, under low humidity conditions, the EMC value of NC is determined by the adsorbed water content of the monolayer, which is mainly related to the −OH content in NC. However, with the increase of humidity, the EMC value of NC is gradually determined by the multilayer adsorbed water content, which is influenced by both the nitrogen content and the fiber cleavage structure. Meanwhile, the IGC results show that the surface energy of the NC consists mainly of the dispersive surface energy (values >46 mJ m−2), with the specific surface energy contributing approximately 25 mJ m−2. The total surface energy of NC and the bonding strength between NC molecules and water molecules decrease with increasing nitrogen content. [ABSTRACT FROM AUTHOR]

The adsorption properties of mesoporous silica gel synthesized by the template method, doped with terbium, dysprosium, lanthanum and modified with nickel (Tb-Ni/MS, Dy-Ni/MS, La-Ni/MS) were studied using gas chromatography. The textural characteristics of the obtained materials were studied by low-temperature nitrogen adsorption-desorption method, atomic emission spectroscopy (ICP), X-ray phase analysis (XPA), X-ray structural analysis (XRD), and scanning electron microscopy (SEM). Thermodynamic characteristics of adsorption (differential heats and entropies) of test organic compounds were obtained using the inverse gas chromatography method. It has been established that the nature of the dopant leads to changes in the heats of adsorption for compounds prone to various types of specific interactions. It has been shown that mesoporous silica gels doped with dysprosium, terbium and modified with nickel enhance dispersion interactions of linear hydrocarbons with the sorbent surface; the heat of adsorption of compounds prone to specific interactions is higher on mesoporous silica gel doped with lanthanum and modified with nickel. [ABSTRACT FROM AUTHOR]

Direct modification of surface properties is one of the methods that are used to prepare new nanomaterials. The surface of detonation nanodiamond can be modified, for example, by treatment with gaseous hydrogen. In the present work, the adsorption properties of nanodiamonds with a hydrogenated surface were examined by the method of inverse gas chromatography and compared with those of the initial detonation nanodiamond. Specific retention volumes V and differential molar isosteric heats of adsorption qst were measured for water and heptane. It was established that the values of V for both water and heptane on hydrogenated nanodiamonds were several times higher than those for the initial detonation nanodiamonds. This fact indicated that additional treatment of the surface led to an increase in the density (per unit area) of functional groups, which ensured adsorption interactions of the surface with water and heptane. In the case of water, the heat of adsorption at a maximum content of the adsorbate in a gaseous phase increased from 31.6 to 36.3 kJ/mol, whereas the heat of heptane adsorption remained constant at a level of 49.5 kJ/mol. It was found that the surface hydrogenation of nanodiamonds changed the nature of the adsorption sites that are responsible for water retention. [ABSTRACT FROM AUTHOR]

This paper is devoted to an accurate determination of the London dispersive, polar free energy of adsorption, Lewis acid γ s + and Lewis base γ s − components of the polar surface energy γ s A B of 2D single-crystalline and polycrystalline covalent organic frameworks such as TAPPy-TPA-COFs. The obtained results showed the highest values of polar and total surface energy of the polycrystalline COF relative to those of the single-crystalline COF. Inverse gas chromatography (IGC) at infinite dilution was used to quantify the various surface parameters of the different materials. The net retention times of the adsorption of n-alkanes and several polar solvents on single-crystalline and polycrystalline covalent organic frameworks were obtained from IGC measurements. The free surface Gibbs energy of adsorption was obtained for the various organic molecules at different temperatures from their net retention volume values. The separation between the London dispersive energy and the polar energy of adsorbed molecules was carried out by using a new thermodynamic parameter P S X chosen as new indicator variable and taking into account the deformation polarizability and the harmonic mean of the ionization energies of solvents and solid materials, derived from the London dispersion equation. The obtained results gave higher acidity ( K A = 0.22) for the 2D polycrystalline COF than that of the single-crystalline COF ( K A = 0.15) and an equivalent basicity of the two COFs. The obtained results are very promising for the accurate determination of the surface thermodynamic parameters of adsorption of organic solvents on solid surfaces. [ABSTRACT FROM AUTHOR]

The aim of this study is to examine the interactions of composite materials obtained by adding single-walled carbon nanotubes (SWCNT) to polyetherimide (ULTEM) in different weight ratios with various organic solvents, and to evaluate the solubility of composites in these organic solvents. The characterization of prepared composites was performed with SEM analysis. Thermodynamic properties of ULTEM/SWCNT composites were determined by the inverse gas chromatography (IGC) method at 260–285°C in infinite dilution. According to the IGC method, the retention behaviors were examined by passing different organic solvent vapors over the composites used as stationary phase, and retention diagrams were drawn using the obtained retention data. Thermodynamic parameters including Flory–Huggins interaction parameters (⁠|${\chi}_{12}^{\infty }$|⁠), equation of state interaction parameters (⁠|${\chi}_{12}^{\ast }$|⁠), weight fraction activity coefficients in infinite dilution (⁠|${\Omega}_1^{\infty }$|⁠), effective exchange energy parameters (⁠|${\chi}_{\mathrm{eff}}$|⁠), partial molar sorption enthalpies (⁠|$\Delta{\overline{H}}_1^S$|⁠), partial molar dissolution enthalpies in infinite dilution (⁠|$\Delta{\overline{H}}_1^{\infty }$|⁠) and molar evaporation enthalpies (⁠|$\Delta{\overline{H}}_v$|⁠) were calculated using the linear retention diagrams. According to |${\chi}_{12}^{\infty }$|⁠ , |${\chi}_{12}^{\ast }$|⁠ , |${\Omega}_1^{\infty }$| and |${\chi}_{\mathrm{eff}}$| values, organic solvents were found to be poor solvents for composites at all temperatures. Besides, the solubility parameters of composites were determined by IGC method at infinite dilution. [ABSTRACT FROM AUTHOR]

This paper constitutes an original and new methodology for the determination of the surface properties of carbon fibers in two forms, namely, oxidized and untreated, using the inverse gas chromatography technique at infinite dilution based on the effect of temperature on the surface area of various organic molecules adsorbed on the carbon fibers. The studied thermal effect showed a large deviation from the classical methods or models relative to the new determination of the surface properties of carbon fibers, such as the dispersive component of their surface energy, the free surface energy, the free specific energy, and the enthalpy and entropy of the adsorption of molecules on the carbon fibers. It was highlighted that the variations in the London dispersive surface energy of the carbon fibers as a function of the temperature satisfied excellent linear variations by showing large deviations between the values of γ s d   (T) , calculated using different models, which can reach 300% in the case of the spherical model. All models and chromatographic methods showed that the oxidized carbon fibers gave larger specific free enthalpy of adsorption whatever the adsorbed polar molecules. The obtained specific enthalpy and entropy of the adsorption of the polar solvents led to the determination of the Lewis acid–base constants of the carbon fibers. Different molecular models and chromatographic methods were used to quantify the surface thermodynamic properties of the carbon fibers, and the results were compared with those of the thermal model. The obtained results show that the oxidized carbon fibers gave more specific interaction energy and greater acid–base constants than the untreated carbon fibers, thus highlighting the important role of oxidization in the acid–base of fibers. The determination of the specific acid–base surface energy of the two carbon fibers showed greater values for the oxidized carbon fibers than for the untreated carbon fibers. An important basic character was highlighted for the two studied carbon fibers, which was larger than the acidic character. It was observed that the carbon fibers were 1.4 times more acidic and 2.4 times more basic. The amphoteric character of the oxidized fibers was determined, and it was 1.7 times more important than that of the untreated fibers This tendency was confirmed by all molecular models and chromatographic methods. The Lewis acid and base surface energies of the solid surface, γ s + and γ s − , as well as the specific acid–base surface energy γ s A B of the carbon fibers at different temperatures were determined. One showed that the specific surface energy γ s A B of the oxidized fibers was 1.5 times larger than that of the untreated fibers, confirming the above results obtained on the strong acid–base interactions of the oxidized carbon fibers with the various polar molecules. [ABSTRACT FROM AUTHOR]

The work is devoted to the study of the capacity for chiral recognition during the adsorption process of hippuric acid crystals obtained by the temperature gradient method under Viedma ripening conditions. This method is distinguished by the fact that the primary violation of chiral equilibrium between the nuclei formed during crystallization is not caused by the mechanical action of the stirrer but by crystallization at low temperatures. Limonenes and α-pinenes were used as test enantiomers. Adsorption isotherms were obtained using inverse gas chromatography, and their analysis made it possible to establish the chiral recognition ability of the surface. It was shown that both the enantioselectivity and adsorption capability of the synthesized hippuric acid crystals were significantly higher than those of crystals obtained under classical Viedma ripening conditions. High surface heterogeneity is probably the reason for this phenomenon. [ABSTRACT FROM AUTHOR]

In this study, Phenylbenzoate-based calamitic liquid crystals (LCs) were synthesized and characterized, and then the thermodynamic properties and phase transition temperatures were investigated by inverse gas chromatography (IGC) at infinite dilution. The phase transition temperatures of the LCs were determined in the range of 40–170°C by the IGC method. Finally, in the thermodynamic equilibrium region (the range of 160–200°C), Flory-Huggins theory and the equation of state theory with the LC-solvent interaction parameters, the effective exchange energy parameters, the weight fraction activity coefficient, and also the partial molar heat of mixing at infinite dilution of solvent, the molar heat of vaporization of solvent, and the partial molar heat of sorption of solvent were calculated. [ABSTRACT FROM AUTHOR]

The retention behavior of various organic probes on the 4-(Nonyloxy) benzoic acid liquid crystal, which is used as a stationary phase, was investigated using the inverse gas chromatography method at infinite dilution. The thermodynamic parameters including the Flory-Huggins parameter, equation-of-state interaction parameter, the mole fraction activity coefficient, the effective exchange energy parameter, and residual thermodynamic parameters were determined in the temperature range of 423.15-433.15 K by using the retention behavior of the probes on the liquid crystal. It was determined from the thermodynamic parameters that all probes were poor solvents for the liquid crystal. Besides, the results of the 4-(Nonyloxy) benzoic acid liquid crystal was compared with a liquid crystal in the literature, and the effect of the number of alkyl groups on the liquid crystals on the Flory-Huggins interaction parameter and isomer separation was evaluated. [ABSTRACT FROM AUTHOR]

The selection of appropriate solvents into which carbon blacks can be dispersed optimally is important for product manufacture and performance. Molecular-level interactions determine solvent suitability but are difficult to measure; existing experimental approaches require slow/expensive tests of dispersion stability. NMR solvent relaxation measurements are shown to be a fast indicator of solvent suitability, with sensitivity to the solvent-particle intermolecular forces making it a reliable proxy for determining optimum dispersibility. A structured approach to relaxation measurements with a selection of both good and poor solvents yields the Hansen solubility parameters (HSP) for the particle surface. Once obtained, suitable solvents (or solvent mixtures) can be selected from a database of HSP values to match the particle interface. The application of the NMR solvent relaxation approach for determining the HSP values is illustrated for a commercially available carbon black. Furthermore, individual solvent relaxation data for two solvents (e.g., hexane and IPA) with a variety of carbon blacks may be plotted against each other to highlight differences in surface chemistry. Using this approach, results are compared, for the first time, with data from inverse gas chromatography (IGC) with a relatively similar outcome. NMR solvent relaxation analysis provides a quick, facile, and cost-effective methodology to identify the replacement of both powder and solvent raw materials. [ABSTRACT FROM AUTHOR]

The chiral recognition ability of microporous MOF [{Cu12I(trz)8}·4 Cl·8 H2O]n in adsorption processes was studied. The MOF sample was obtained from achiral molecules in the absence of an external source of chirality. It has, in its structure, a right-handed single-stranded helix nanotube with a size of 14 Å and a left-handed single-stranded helix nanotube measuring 4.9 Å. The aim of this study was to use substances capable of adsorbing only in one type of nanotubes. This could lead to chiral recognition by racemic crystals. To test the recognition ability, the enantiomers of limonene were used. The limonene dimensions were too large to fit in the left-handed nanotube but small enough to get adsorbed by the right-handed nanotube. To analyze the enantioselectivity of [{Cu12I(trz)8}·4 Cl·8 H2O]n, inverse gas chromatography was used. The specific retention volumes were calculated and the adsorption isotherms were plotted. In addition, the MOF sample was characterized by XRD, IR spectrometry, and porosimetry analyses. It has been shown that the MOF-based stationary phase was capable of chiral recognition. The maximum selectivity coefficient was 1.43. The reliability of differences in enantiomer adsorption isotherms was confirmed by t-test. The data obtained proved the chiral recognition ability. During adsorption data collection, a decrease in enantioselectivity was observed. It was caused by the irreversible (under gas chromatography conditions) adsorption of the limonene enantiomers in the MOF pores. This fact was confirmed by eluting n-heptane through a MOF column after a gas chromatographic experiment. Furthermore, irreversible nitrogen adsorption was observed during the porosimetry experiment. [ABSTRACT FROM AUTHOR]

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Porous materials can be found in numerous essential applications. They are of particular interest when, in addition to their porosity, they have other advantageous properties such as thermal stability or chemical diversity. The main aim of this study was to synthesize the porous copolymers of 9,10-bis(methacryloyloxymethyl)anthracene (BMA) with three different co-monomers divinylbenzene (DVB), ethylene glycol dimethacrylate (EGDMA) and trimethylpropane trimethacrylate (TRIM). They were synthesized via suspension polymerization using chlorobenzene and toluene served as porogenic solvents. For the characterization of the synthesized copolymers ATR-FTIR spectroscopy, a low-temperature nitrogen adsorption–desorption method, thermogravimetry, scanning electron microscopy, inverse gas chromatography and size distribution analysis were successfully employed. It was found that depending on the used co-monomer and the type of porogen regular polymeric microspheres with a specific surface area in the range of 134–472 m2/g can be effectively synthesized. The presence of miscellaneous functional groups promotes divergent types of interactions Moreover, all of the copolymers show a good thermal stability up to 307 °C. What is important, thanks to application of anthracene derivatives as the functional monomer, the synthesized materials show fluorescence under UV radiation. The obtained microspheres can be used in various adsorption techniques as well as precursor for thermally resistant fluorescent sensors. [ABSTRACT FROM AUTHOR]

The applicability of clinoptilolite zeolites in controlling the emission of greenhouse gases (GHGs) such as CO2, the most significant GHG, is investigated herein. In this research, Mexican natural zeolites (ATN) originating from an Atzinco deposit in the state of Puebla were used. Samples of modified clinoptilolite (ATH4, ATH3, ATH2 and ATH1) were obtained from the starting material by acid treatment of various intensities. Inverse gas chromatography was used to evaluate CO2 adsorption in clinoptilolite, natural and chemically modified. Adsorption of CO2 was investigated in the temperature range of 433–573 K, using a TCD detector, and He as a carrier gas. The experimental CO2 adsorption data were processed by Freundlich and Langmuir equations. The degree of interaction between CO2 and the dealuminated clinoptilolite samples was examined through the evaluation of the isosteric enthalpy of adsorption. This calculation was made by using the Clausius–Clapeyron equation, which established the following sequence: ATH1 > ATH2 > ATH4 > ATN > ATH3. The nanoporosity of these clinoptolite zeolites from new deposit in sedimentary rocks was studied through HRADS adsorption of N2. Simultaneously, these zeolites were, respectively, characterized by XRD, EDS, and SEM. Micropores are described by the Dubinin–Asthakov distribution. Various adsorption mechanisms that occur in these nanoporous materials at different relative pressures can be visualized. The quantitative determination of starting mineral is described as: Ca-Clinoptilolite (88.76%) >> Montmorillonite (11.11%) >> quartz (0.13%). The Si/Al molar ratio after acid treatment is: ATH4 > ATH2 > ATN > ATH3 > ATH1. The Langmuir specific surface area (ASL) varies as follows: ATN > ATH2 > ATH4 > ATH3 > ATH1. At the same time, the VΣ values are as follows: ATN > ATH4 > ATH3 > ATH1 > ATH2. [ABSTRACT FROM AUTHOR]

Cellulose is one of the most abundant and sustainable biopolymers on earth. Various types of cellulosic materials such as natural fibres, regenerated cellulose fibres, cellulose derivatives and nanocellulose have increasingly been utilised in developing fibre-reinforced polymeric composites. Analysis of surface physicochemical properties of cellulose-based fillers is essential to maximise fibre-matrix interfacial adhesion to obtain excellent mechanical performance. Among different techniques which can be used to investigate the surface science of cellulose-based materials, inverse gas chromatography (IGC) has been proven as a successful technique for characterising the surface activity, evaluating the efficiency of surface modification methods, and predicting the behaviour of final products. IGC is a versatile approach to evaluate surface energy, acidic-basic characteristics, and surface heterogeneity. These key parameters are used in (i) evaluating the efficiency of different surface treatments for adding new functional groups, (ii) determining the compatibility of cellulosic materials with various polymer matrices to ensure optimal fibre-matrix interaction, and (iii) predicting the performance of cellulose-reinforced composites in actual applications. This article provides a concise review on recent progress in using IGC method for surface analysis of different forms of cellulosic materials in the context of fibre-reinforced composites. For future perspective, the IGC technique can be extensively applied in studying cellulosic materials with high application potential in a variety of fields. This review paper will shed light on understanding the surface characteristics of cellulose-based composites and pave the way for their real-world applications. [ABSTRACT FROM AUTHOR]

The potentialities of methylimidazolium-based ionic liquids (ILs) as solvents were evaluated for some relevant separation problems—terpene fractionation and fuel processing—studying selectivities, capacities, and solvent performance indices. The activity coefficients at infinite dilution of the solute (1) in the IL (3), γ 13 ∞ , of 52 organic solutes were measured by inverse gas chromatography over a temperature range of 333.2–453.2 K. The selected ILs are 1-butyl-3-methylimidazolium hexafluorophosphate, [C4mim][PF6], and the equimolar mixture of [C4mim][PF6] and 1-butyl-3-methylimidazolium chloride, [C4mim]Cl. Generally, low polar solutes follow γ 1 , C 4 mim Cl ∞ > γ 1 , C 4 mim PF 6 + C 4 mim Cl ∞ > γ 1 , C 4 mim PF 6 ∞ while the opposite behavior is observed for alcohols and water. For citrus essential oil deterpenation, the results suggest that cations with long alkyl chains, such as C 12 mim + , promote capacity, while selectivity depends on the solute polarity. Promising results were obtained for the separation of several model mixtures relevant to fuel industries using the equimolar mixture of [C4mim][PF6] and [C4mim]Cl. This work demonstrates the importance of tailoring the polarity of the solvents, suggesting the use of ILs with mixed anions as alternative solvents for the removal of aliphatic hydrocarbons and contaminants from fuels. [ABSTRACT FROM AUTHOR]

Activated carbon fibers (ACFs) as one of the most important porous carbon materials are widely used in many applications that involve rapid adsorption and low-pressure loss, including air purification, water treatment, and electrochemical applications. For designing such fibers for the adsorption bed in gas and aqueous phases, in-depth comprehension of the surface components is crucial. However, achieving reliable values remains a major challenge due to the high adsorption affinity of ACFs. To overcome this problem, we propose a novel approach to determine London dispersive components ( γ S L ) of the surface free energy of ACFs by inverse gas chromatography (IGC) technique at an infinite dilution. Our data reveal the γ S L values at 298 K for bare carbon fibers (CFs) and the ACFs to be 97 and 260–285 mJ·m−2, respectively, which lie in the regime of secondary bonding of physical adsorption. Our analysis indicates that these are impacted by micropores and defects on the carbon surfaces. Comparing the γ S L obtained by the traditional Gray's method, our method is concluded as the most accurate and reliable value for the hydrophobic dispersive surface component of porous carbonaceous materials. As such, it could serve as a valuable tool in designing interface engineering in adsorption-related applications. [ABSTRACT FROM AUTHOR]

Carbon fiber (CF) reinforced polyphenylene sulfide (PPS) composite shows extraordinary thermal stability, chemical resistance, and processability. The interface between CF and PPS transfers the load, and its properties are crucial to determine composite properties such as mechanical performance, reliability, and so forth. This work explores the relationship between surface properties of CFs (with/without sizing layer) and the interfacial properties of CF/PPS composite. X‐ray photoelectron spectroscopy, scanning electron microscopy, atomic force microscope were employed to evaluate surface physicochemical properties of CFs, and reveal the increasing roughness and decreasing content of functional groups on the CF surface after desizing. Inverse gas chromatography and dynamic contact angle tests were adopted to characterize the surface energy of CFs, and present that the dispersive component of surface energy increases, while the polar component decreases, and the total surface energy is barely changed after desizing. Differential scanning calorimetry measurement reveals the increasing crystallinity of CF/PPS after CF desizing. Microbond test was performed to analyze interfacial shear strength (IFSS) of CF/PPS, displays that IFSS keeps almost constant after CF desizing. The results demonstrate that the surface energy of CF is important to the interfacial crystallinity, but not the critical factor for interfacial strength of CF/PPS composite. [ABSTRACT FROM AUTHOR]

• Temperature effect on the flotation of galena, sphalerite and pyrite were investigated. • The microflotation yields corresponded well with the inverse gas chromatography surface energy results. • Adsorption kinetics of sodium isopropyl xanthate was heavily controlled by pH, temperature, and copper sulfate concentration. • Lower recovery of sphalerite at higher temperatures may be explained by the formation of calcium carbonate precipitates. • Lower recoveries at lower temperatures may be explained by a shift in the xanthate – oxy-complexes equilibrium. Selective flotation of lead–zinc ores is a process with many variables and a delicate balance of external (such as temperature) and internal factors (reagent concentrations, surface alterations). The purpose of this study is to explore flotation selectivity issues arising from changes in flotation pulp temperature. A deeper understanding of these issues can help to clarify industrial scale flotation discrepancies observed at different temperatures. Therefore, this paper provides insight into potential theoretical contributors to this balance, as well as assesses their affinity to temperature changes. These theoretical calculations assist in explaining observed variations in adsorption and microflotation results with temperature. Other statistically significant parameters influencing adsorption performance included xanthate concentration, copper sulfate dosage, and pH. Adsorption selectivity calculations were performed on individual mineral responses, which give insights into potential trends in the separation of galena, sphalerite, and pyrite. Adsorption results also confirmed current perceptions of the adsorption mechanism of dextrin. It has been shown that xanthate adsorption had the highest performance for galena among the three tested minerals. Scanning electron microscopy and EDS results allowed the extrapolation of a potential mechanism contributing to sphalerite depression at 45 °C. Inverse gas chromatography provided surface energy heterogeneity maps of the minerals. Surface energy values were generally in line with microflotation performance. The highest surface energy heterogeneity was observed for galena at 5 °C and for sphalerite at 45 °C. The role and variations in dissolved oxygen and lime dosages with temperature were also discussed with regard to flotation performance. [ABSTRACT FROM AUTHOR]

Molecular-scale modelling for predicting surface energies on a face-specific and whole particle basis is applied to all the crystallographically-independent surfaces of L-glutamic acid forms. The predicted data is found to be in good general agreement with measured surface energies using inverse gas chromatography and Washburn capillary rise techniques with the former revealing higher values compared to the prediction, perhaps consistent with the polar (zwitterionic) nature of this material. This fusion of experimental and computational data provides a high-fidelity definition of the face-by-face breakdown of the energetic anisotropy of the crystals. There is increasing industrial interest in defining the potential impact of whole particle properties on the performance of formulated drug product and their manufacturability especially as the community accelerates the molecule to medicine journey. The overall molecular modelling approach highlights its application in designing ingredients for optimising face-specific particle surface energies for product formulatability particularly in early phase process development. A route map from molecular and crystallographic structure to surface energy calculation with combined experimental workflow. [Display omitted] • A methodology fusing experimental and computational workflows for the investigation of crystal surface energy has been presented. • Molecular-scale (synthonic) modelling used to predict the surface energies of α and β forms of L-glutamic acid on a face-specific and whole particle basis. • Predicted surface energies are in good general agreement with measurements using IGC and Washburn capillary rise techniques. • Calculated surface energies have the same trend as those from experiments though they are higher than the experimental values, which are consistent with literature findings. • The overall molecular modelling approach demonstrates its application in designing crystal habit for optimising particle surface energies for product formulatability particularly in early phase process development. [ABSTRACT FROM AUTHOR]

Surface-modified porous silica is a well-established composite material. To improve its embedding and application behavior, adsorption studies of various probe molecules have been performed using the technique of inverse gas chromatography (IGC). For this purpose, IGC experiments were carried out in the infinite dilution mode on macro-porous micro glass spheres before and after surface modification with (3-mercaptopropyl)trimethoxysilane. To provide information about the polar interactions between probe molecules and the silica surface, in particular, eleven polar molecules have been injected. In summary, the free surface energy for pristine silica (γStotal = 229 mJ/m2) and for (3-mercaptopropyl)trimethoxysilane-modified silica (γStotal = 135 mJ/m2) indicates a reduced wettability after surface modification. This is due to the reduction of the polar component of the free surface energy (γSSP) from 191 mJ/m2 to 105 mJ/m2. Simultaneously, with the reduction of surface silanol groups caused by surface modification of silica and, therefore, the decrease in polar interactions, a substantial loss of Lewis acidity was observed by various IGC approaches. Experiments with all silica materials have been conducted at temperatures in the range from 90°C to 120°C to determine the thermodynamic parameters, such as adsorption enthalpy (ΔHads) and adsorption entropy (ΔSads), using the Arrhenius regression procedure evaluating the IGC data. With the help of the enthalpy–entropy compensation, two types of adsorption complexes are assumed between polar probe molecules and the silica surface because of different isokinetic temperatures. Identical adsorption complexes with an isokinetic temperature of 370°C have been assigned to alkanes and weakly interacting polar probes such as benzene, toluene, dichloromethane, and chloroform. Polar probe molecules with typical functional groups such as OH, CO, and CN, having the ability to form hydrogen bonds to the silica surface, exhibit a lower isokinetic temperature of 60°C. Quantum chemical calculations of the probe molecules on a non-hydroxylated and hydroxylated silica cluster supported the formation of hydrogen bonds in the case of a strong polar adsorption complex with a bonding distance of 1.7 nm–1.9 nm to the silica surface.