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Heavy metal pollution in water is a critical environmental concern, demanding effective remediation techniques. Traditional methods, including ion exchange and adsorption, often rely on inductively coupled plasma (ICP) atomic emission spectroscopy/mass spectrometry (AES/MS) for the indirect and time-consuming measurement of residual metal concentrations. In contrast, this study employs innovative direct monitoring of nickel removal by benchtop NMR relaxometry using the paramagnetic properties of Ni2+. To prove the feasibility of the NMR follow-up of Ni2+ uptake, batch experiments were performed with Amberlite IR120, Amberlite IRC748, Dowex Marathon MSC, and activated carbon (AC), which were previously characterized by various techniques. The effect of contact time, pH, and Ni2+ concentration on removal efficiency were studied. Pseudo-first and pseudo-second order kinetic models were used. The Langmuir model effectively described the equilibrium isotherms. The longitudinal and transverse relaxation curves of the loaded resins were biexponential. For sulfonic resins, a strong correlation was observed between the relaxation rates of the fast-relaxing fraction and the Ni2+ content determined by ICP-AES/MS. For IRC748, the effect of Ni2+ loading on the relaxation rates was weaker because of Ni2+ complexation. The relaxation curves of loaded AC revealed multiple fractions. Centrifugation was employed to eliminate the contribution of intergranular water. The remaining intragranular water contribution was biexponential. For high Ni2+ loadings, the relaxation rates of the slow relaxing fraction increased with the AC Ni2+ content. These results mark the initial stage in developing a column experiment to monitor, in real-time, adsorbent loading by NMR relaxometry. [ABSTRACT FROM AUTHOR]

Theoretical description of single gas and gas mixture adsorption equilibria can be achieved in many different ways depending on the kind of approach (microscopic or macroscopic). In this paper, we present a statistical thermodynamics approach for the calculation of mixed gas adsorption equilibrium data on uniform surfaces. The non-ideality of both the mixed gas phase and the adsorbed phase is considered by using the Redlich–Kwong EOS associated to the classic Lorentz–Berthelot mixing rules. This is an interesting way to extend the model presented in Part I and to predict multicomponent gas adsorption equilibria for highly non-ideal systems from parameters deduced from pure gas data. We present mixture adsorption isotherms and selectivity curves calculated using our model. [ABSTRACT FROM AUTHOR]

Conventional SO2 scrubbing agents, namely calcium oxide and zeolites, are often used to remove SO2 using a strong or irreversible adsorption-based process. However, adsorbents capable of sensing and selectively capturing this toxic molecule in a reversible manner, with in-depth understanding of structure-property relationships, have been rarely explored. Here we report the selective removal and sensing of SO2 using recently unveiled fluorinated metal-organic frameworks (MOFs). Mixed gas adsorption experiments were performed at low concentrations ranging from 250 p.p.m. to 7% of SO2. Direct mixed gas column breakthrough and/or column desorption experiments revealed an unprecedented SO2 affinity for KAUST-7 (NbOFFIVE-1-Ni) and KAUST-8 (AlFFIVE-1-Ni) MOFs. Furthermore, MOF-coated quartz crystal microbalance transducers were used to develop sensors with the ability to detect SO2 at low concentrations ranging from 25 to 500 p.p.m. Removal of SO2 from flue gas is of prime importance to avoid its poisoning of CO2-seperating agents. Here, the authors demonstrate that two fluorinated metal-organic frameworks selectively remove SO2 from synthetic flue gas and can sense SO2 with p.p.m.-level detection using quartz crystal microbalance transducers. [ABSTRACT FROM AUTHOR]

Highlights: [•] Synthesis of hierarchically porous Nb doped TiO2 catalyst support. [•] Preservation of multi-modal porosity on calcination to crystalline anatase phase. [•] Metal oxide–catalyst interaction influenced by chemical composition of support. [•] Nb promotes catalytic destruction of pollutants by noble metal nanoparticles. [•] Increase in activity and CO2 selectivity for Pt/Nb–TiO2 compared to Pt/TiO2. [ABSTRACT FROM AUTHOR]

Abstract: The process design for air separation based on adsorption requires knowledge of the following data: pure adsorption isotherms at different temperatures, multicomponent adsorption equilibrium data and kinetic data. In this paper, we present a complete study of oxygen and nitrogen adsorption at three temperatures on a set of Li exchanged NaKLSX zeolites. Pure gas isotherms were obtained for five different zeolites up to 2500kPa at 303K and for three of the five also at 288 and 318K. Co-adsorption equilibria were analyzed for different compositions at 400kPa and 303K on the two zeolites which present the best adsorption capacities. Data were obtained with two volumetric apparatus constructed in lab. Furthermore, predictive binary equilibria obtained by Ideal Adsorbed Solution Theory (IAST) from pure component isotherms were compared with experimental mixture data. Finally, the zeolite which has the best adsorption capacities was formed with two different binders and their thermodynamic adsorption properties were compared to the original zeolite. [Copyright &y& Elsevier]

Abstract: In order to assess and improve the quality of high-pressure sorption isotherms of carbon dioxide (CO2) on coals, an inter-laboratory study (Round Robin) has been conducted among three European research laboratories. Excess sorption isotherms, determined in a first round of measurements, on Filtrasorb 400 (F400) activated carbon showed excellent agreement. In the second round of this study, excess sorption isotherms were determined on three coals at 318K using the manometric (TU Delft, Netherlands and RWTH Aachen University, Germany) and the gravimetric (University Mons, Belgium) methods up to 16MPa. The CO2 excess sorption isotherms for the three coal samples, a lignite, a bituminous coal and a semi-anthracite, exhibited maximum values of 1.77±0.07, 1.37±0.01 and 1.37±0.05molkg−1 respectively. The pressure ranges for the observed maximum excess sorption capacities decreased with increasing maturities from 6.89±0.5MPa for the lignite, to 6.68±0.4MPa for the bituminous coal and to 5.89±0.6MPa for the semi-anthracite. The results show that high-pressure CO2 excess sorption isotherms on natural coals in the supercritical range can be determined accurately with both gravimetric and manometric equipment. [ABSTRACT FROM AUTHOR]

Abstract: In order to assess and improve the quality of high-pressure sorption isotherms of carbon dioxide (CO2) on coals, an inter-laboratory study (“Round Robin”) has been conducted among four European research laboratories. In a first round of measurements, excess sorption isotherms were determined on Filtrasorb 400 (F400) activated carbon at 318K using the manometric (TU Delft and RWTH Aachen University) and the gravimetric (FP Mons and INERIS) method up to 16MPa. The study shows that CO2 sorption in the supercritical range can be determined accurately with both gravimetric and manometric equipment but requires thorough optimization of instrumentation and measuring as well as proper sample preparation procedures. For the characterization of the activated carbon F400, which we used as benchmark, we have determined a surface area of 1063m2 g−1, and Dubinin-Radushkevich (DR) micropore volume of 0.51cm3 g−1. Additionally, we analysed the elementary near-surface composition by energy dispersive X-ray spectroscopy (EDX). To characterise the bulk composition of the F400 activated carbon, a proximate and ultimate analysis was performed. The observed excess sorption maxima around 5MPa have values around 8.0molkg−1, which are consistently higher (by upto 0.8molkg−1) than literature data. [Copyright &y& Elsevier]

Abstract: Macro-mesoporous ZrO2, TiO2 and ZrO2-TiO2 have been synthesized and used as catalytic supports for volatile organic compounds (VOCs) oxidation. These supports present high surface areas. Stability of the porous structure is observed after calcination at 400°C for ZrO2-TiO2 and TiO2 but partial breakdown of the structure occurs for ZrO2 by the crystallization into tetragonal phase. All these Pd impregnated catalysts are found to be powerful catalysts for total oxidation of toluene and chlorobenzene. Pd/TiO2 presents the highest catalytic potential. The lowest toluene adsorption enthalpy, the low coke content observed after the catalytic test, PdO particles easily reducible should explain the interesting catalytic behaviour of Pd/TiO2. However, production of polychlorinated compounds PhCl x (with x =2–6) occurs at low temperature during the chlorobenzene oxidation and this amount is lower over Pd/TiO2-ZrO2 compared to Pd/TiO2. But chlorobenzene is readily converted into HCl, CO2 and H2O at a temperature of 530°C. [Copyright &y& Elsevier]

Herein, a robust microporous aluminum tetracarboxylate framework, MIL-120(Al)-AP, (MIL, AP: Institute Lavoisier and Ambient Pressure synthesis, respectively) is reported, which exhibits high CO 2 uptake (1.9 mmol g -1 at 0.1 bar, 298 K). In situ Synchrotron X-ray diffraction measurements together with Monte Carlo simulations reveal that this structure offers a favorable CO 2 capture configuration with the pores being decorated with a high density of µ 2 -OH groups and accessible aromatic rings. Meanwhile, based on calculations and experimental evidence, moderate host-guest interactions Q st (CO 2 ) value of MIL-120(Al)-AP (-40 kJ mol -1 ) is deduced, suggesting a relatively low energy penalty for full regeneration. Moreover, an environmentally friendly ambient pressure green route, relying on inexpensive raw materials, is developed to prepare MIL-120(Al)-AP at the kilogram scale with a high yield while the Metal- Organic Framework (MOF) is further shaped with inorganic binders as millimeter-sized mechanically stable beads. First evidences of its efficient CO 2 /N 2 separation ability are validated by breakthrough experiments while operando IR experiments indicate a kinetically favorable CO 2 adsorption over water. Finally, a techno-economic analysis gives an estimated production cost of ≈ 13 $ kg -1 , significantly lower than for other benchmark MOFs. These advancements make MIL-120(Al)-AP an excellent candidate as an adsorbent for industrial-scale CO 2 capture processes., (© 2024 The Authors. Advanced Science published by Wiley‐VCH GmbH.)

Fructo-oligosaccharide (FOS) mixtures produced by fermentation contain large amounts of non-prebiotic sugars. Here we propose a mixed culture of Aureobasidium pullulans and Saccharomyces cerevisiae cells to produce FOS and consume the small saccharides simultaneously, thereby increasing FOS purity in the mixture. The use of immobilised A. pullulans in co-culture with encapsulated S. cerevisiae, inoculated after 10 h fermentation, enhanced FOS production in a 5 L bioreactor. Using this strategy, a maximal FOS concentration of 119 g L -1 , and yield of 0.59 g FOS g sucrose , were obtained after 20 h fermentation, increasing FOS productivity from about 4.9 to 5.9 g -1 , were obtained after 20 h fermentation, increasing FOS productivity from about 4.9 to 5.9 g FOS L -1 compared to a control fermentation of immobilized A. pullulans in monoculture. In addition, the encapsulated S. cerevisiae cells were able to decrease the glucose in the medium to about 7.6% (w/w) after 63 h fermentation. This provided a final fermentation mixture with 2.0% (w/w) sucrose and a FOS purity of over 67.0% (w/w). Moreover, a concentration of up to 58.0 g L -1 compared to a control fermentation of immobilized A. pullulans in monoculture. In addition, the encapsulated S. cerevisiae cells were able to decrease the glucose in the medium to about 7.6% (w/w) after 63 h fermentation. This provided a final fermentation mixture with 2.0% (w/w) sucrose and a FOS purity of over 67.0% (w/w). Moreover, a concentration of up to 58.0 g L -1 of ethanol was obtained through the enzymatic transformation of glucose. The resulting pre-purified FOS mixture could improve the separation and purification of FOS in downstream treatments, such as simulated moving bed chromatography., (Copyright © 2019. Published by Elsevier B.V.)

The energy-storage capacities of a series of water-stable porous metal-organic frameworks, based on high-valence metal cations (Al 3+ , Fe 3+ , Cr 3+ , Ti 4+ , Zr 4+ ) and polycarboxylate linkers, were evaluated under the typical conditions of seasonal energy-storage devices. The results showed that the microporous hydrophilic Al-dicarboxylate MIL-160(Al) exhibited one of the best performances. To assess the properties of this material for space-heating applications on a laboratory pilot scale with an open reactor, a new synthetic route involving safer, greener conditions was developed. This led to the production of MIL-160(Al) on a 400 g scale, before the material was shaped into pellets through a wet-granulation method. The material exhibited a very high energy-storage capacity for a physical-sorption material (343 Wh kg -1 ), which is in full agreement with the predicted value., (© 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

A combination of adsorption, microcalorimetry, infra-red spectroscopy and modeling has been implemented to reveal the potential of the H2S resistant amino-functionalized Ti MOF MIL-125 porous solid for the concomitant elimination of CO2 and H2S from biogas and natural gas.

The adsorption of carbon dioxide, methane, and their mixtures in nanoporous carbons in the presence of water is studied using experiments and molecular simulations. Both the experimental and numerical samples contain polar groups that account for their partially hydrophilicity. For small amounts of adsorbed water, although the shape of the adsorption isotherms remain similar, both the molecular simulations and experiments show a slight decrease in the CO2 and CH4 adsorption amounts. For large amounts of adsorbed water, the experimental data suggest the formation of methane or carbon dioxide clathrates in agreement with previous work. In contrast, the molecular simulations do not account for the formation of such clathrates. Another important difference between the simulated and experimental data concerns the number of water molecules that desorb upon increasing the pressure of carbon dioxide and methane. Although the experimental data indicate that water remains adsorbed upon carbon dioxide and methane adsorption, the molecular simulations suggest that 40 to 75% of the initial amount of adsorbed water desorbs with carbon dioxide or methane pressure. Such discrepancies show that differences between the simulated and experimental samples are crucial to account for the rich phase behavior of confined water-gas systems. Our simulations for carbon dioxide-methane coadsorption in the presence of water suggest that the pore filling is not affected by the presence of water and that adsorbed solution theory can be applied for pressures as high as 15 MPa.

Hydrogen sulfide is an extremely toxic gas that is also of great interest for biological applications when delivered in the correct amount and at the desired rate. Here we show that the highly porous metal-organic frameworks with the CPO-27 structure can bind the hydrogen sulfide relatively strongly, allowing the storage of the gas for at least several months. Delivered gas is biologically active in preliminary vasodilation studies of porcine arteries, and the structure of the hydrogen sulfide molecules inside the framework has been elucidated using a combination of powder X-ray diffraction and pair distribution function analysis.

Carbon dioxide is the main undesirable compound present in raw natural gas and biogas. Physisorption based adsorption processes such as pressure swing adsorption (PSA) are one of the solutions to selectively adsorb CO(2) from CH(4). Some hybrid crystalline porous materials that belong to the family of metal-organic frameworks (MOFs) show larger CO(2) adsorption capacity compared to the usual industrial adsorbents, such as zeolites and most activated carbons, which makes them potentially promising for such applications. However, their selectivity values have been most often determined using only single gas adsorption measurements combined with simple macroscopic thermodynamic models or by means of molecular simulations based on generic forcefields. The transfer of this systematic approach to all MOFs, whatever their complex physico-chemical features, needs to be considered with caution. In contrast, direct co-adsorption measurements collected on these new materials are still scarce. The aim of this study is to perform a complete analysis of the CO(2)-CH(4) co-adsorption in the mesoporous MIL-100(Cr) MOF (MIL stands for Materials from Institut Lavoisier) by means of a synergic combination of outstanding experimental and modelling tools. This solid has been chosen both for its fundamental interests, given its very large CO(2) adsorption capacities and its complexity with a combination of micropores and mesopores and the existence of unsaturated accessible metal sites. The predictions obtained by means of Grand Canonical Monte Carlo simulations based on generic forcefields as well as macroscopic thermodynamic (IAST, RAST) models will be compared to direct the co-adsorption experimental data (breakthrough curve and volumetric measurements).

The use of porous materials to eliminate volatile organic compounds (VOCs) has proven very effective towards achieving sustainability and environmental protection goals. The activity of zeolites and macro-mesoporous metal-oxide supports in the total oxidation of VOCs has been investigated, with and without noble-metal deposition, to develop highly active catalyst systems where the formation of by-products was minimal. The first catalysts employed were zeolites, which offered a good activity in the oxidation of VOCs, but were rapidly deactivated by coke deposition. The effects of the acido-basicity and ionic exchange of these zeolites showed that a higher basicity was related to exchanged ions with lower electronegativities, resulting in better catalytic performances in the elimination of VOCs. Following on from this work, noble metals were deposited onto macro-mesoporous metal-oxide supports to form mono and bimetallic catalysts. These were then tested in the oxidation of toluene to study their catalytic performance and their deactivation process. PdAu/TiO(2) and PdAu/TiO(2) -ZrO(2) 80/20 catalysts demonstrated the best activity and life span in the oxidation of toluene and propene and offered the lowest temperatures for a 50 % conversion of VOCs and the lowest coke content after catalytic testing. Different characterization techniques were employed to explain the changes occurring in catalyst structure during the oxidation of toluene and propene., (Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The adsorption of carbon dioxide and methane in nanoporous carbons in the presence of water is studied using experiments and molecular simulations. For all amounts of adsorbed water molecules, the adsorption isotherms for carbon dioxide and methane resemble those obtained for pure fluids. The pore filling mechanism does not seem to be affected by the presence of the water molecules. Moreover, the pressure at which the maximum adsorbed amount of methane or carbon dioxide is reached is nearly insensitive to the loading of preadsorbed water molecules. In contrast, the adsorbed amount of methane or carbon dioxide decreases linearly with the number of guest water molecules. Typical molecular configurations obtained using molecular simulation indicate that the water molecules form isolated clusters within the host porous carbon due to the nonfavorable interaction between carbon dioxide or methane and water.

Hybrid porous solids, with their tunable structures, their multifunctional properties and their numerous applications, are currently topical, particularly in the domain of adsorption and storage of greenhouse gases. Most of the data reported so far concern the performances of these solids in this domain, particularly in terms of adsorbed amounts of gas but do not explain at the atomic level why and how adsorption and storage occur. From a combination of structural, spectroscopic, thermodynamic experiments and of molecular simulations, this tutorial review proposes answers to these open questions with a special emphasis on CO(2) and CH(4) storage by some rigid and flexible hybrid porous materials.

Triamine-grafted pore-expanded mesoporous silica (TRI-PE-MCM-41) exhibited high CO(2) and H(2)S adsorption capacity as well as high selectivity toward acid gases versus CH(4). Unlike physical adsorbents such as zeolites and activated carbons, the presence of moisture in the feed enhanced the CO(2) removal capability of TRI-PE-MCM-41 without altering its H(2)S adsorption capacity. Thus, depending on the feed composition, CO(2) and H(2)S may be removed over TRI-PE-MCM-41 simultaneously or sequentially. These findings are suitable for acid gas separation from CH(4)-containing mixtures such as natural gas and biogas.

Hydrogen sulfide gravimetric isotherm adsorption measurements were carried out on MIL-53(Al, Cr, Fe), MIL-47(V), MIL-100(Cr), and MIL-101(Cr) metal-organic frameworks (MOFs). A two-step adsorption mechanism related to a breathing effect was observed for MIL-53 terephthalate-based MOFs. Methane adsorption measurements highlighted the regenerability of MIL-53(Al, Cr) and MIL-47(V) MOFs after H(2)S treatment, whereas MIL-100 and MIL-101 CH(4) adsorption capacities were significantly decreased.