Reaching Quantum Accuracy in Predicting Adsorption Properties for Ethane/Ethene in Zeolitic Imidazolate Framework-8 at Low Pressure Regime.

Nanoporous materials in the form of metal-organic frameworks such as zeolitic imidazolate framework-8 (ZIF-8) are promising membrane materials for the separation of hydrocarbon mixtures. To compute the adsorption isotherms in such adsorbents, grand canonical Monte Carlo simulations have proven to be very useful. The quality of these isotherms depends on the accuracy of adsorbate-adsorbent interactions, which are mostly described using force fields owing to their low computational cost. However, force field predictions of adsorption uptake often show discrepancies from experiments at low pressures, providing the need for methods that are more accurate. Hence, in this work, we propose and validate two novel methodologies for the ZIF-8/ethane and ethene systems; a benchmarking methodology to evaluate the performance of any given force field in describing adsorption in the low-pressure regime and a refinement procedure to rescale the parameters of a force field to better describe the host-guest interactions and provide for simulation isotherms with close agreement to experimental isotherms. Both methodologies were developed based on a reference Henry coefficient, computed with the PBE-MBD functional using the importance sampling technique. The force field rankings predicted by the benchmarking methodology involve the comparison of force field derived Henry coefficients with the reference Henry coefficients and ranking the force fields based on the disparities between these Henry coefficients. The ranking from this methodology matches the rankings made based on uptake disparities by comparing force field derived simulation isotherms to experimental isotherms in the low-pressure regime. The force field rescaling methodology was proven to refine even the worst performing force field in UFF/TraPPE. The uptake disparities of UFF/TraPPE improved from 197% and 194% to 11% and 21% for ethane and ethene, respectively. The proposed methodology is applicable to predict adsorption across nanoporous materials and allows for rescaled force fields to reach quantum accuracy without the need for experimental input.

Performance of ferrite nanoparticles in inductive heating swing adsorption (IHSA): how tailoring material properties can circumvent the design limitations of a system.

Inductive heating swing adsorption (IHSA) using hybrid adsorbents incorporating a porous material and ferrite nanoparticles holds promise to be a performant, electrified alternative for conventional gas separation. Successful implementation of hybrid adsorbents in IHSA depends on achieving a maximal specific absorption rate (SAR) in the conditions and at the frequency of the induction setup. This paper outlines and demonstrates successful strategies for optimization of the particle composition, tailoring the coercivity and susceptibility of the ferrite particles to optimal performance in a given alternating magnetic field.

Starch biocomposites preparation by incorporating organosolv lignins from potato crop residues.

Plastic wastes accumulated due to food packaging pose environmental threats. This study proposes biopolymeric films containing lignins extracted from potato crop residues (PCR) through organosolv treatment as a green alternative to non-degradable food packaging. The isolation process yielded 43.9 wt% lignins with a recovery rate of 73.5 wt% achieved under optimum conditions at 180 °C with 50 % v/v ethanol. The extracted lignins were then incorporated into a starch matrix to create biocomposite films. ATR-FTIR analysis confirmed interactions between the starch matrix and extracted lignins, and XRD analysis showed the amorphous structure of lignins, reducing film crystallinity. The addition of 1 wt% of extracted lignins resulted in a 87 % reduction in oxygen permeability, a 25 % increase in the thermal stability of the film, and a 78 % enhancement in antioxidant. Furthermore, introducing 3 wt% lignins led to the lowest water vapor transmission rate, measuring 9.3 × 10-7 kg/s·m2. Morphological studies of the films demonstrated a homogeneous and continuous structure on both the surface and cross-sectional areas when the lignins content was below 7 wt%. These findings highlight the potential of using organosolv lignins derived from potato crop residues as a promising additive for developing eco-friendly films designed for sustainable food packaging.

Enabling hydrate-based methane storage under mild operating conditions by periodic mesoporous organosilica nanotubes.

Biomethane is a renewable natural gas substitute produced from biogas. Storage of this sustainable energy vector in confined clathrate hydrates, encapsulated in the pores of a host material, is a highly promising avenue to improve storage capacity and energy efficiency. Herein, a new type of periodic mesoporous organosilica (PMO) nanotubes, referred to as hollow ring PMO (HR-PMO), capable of promoting methane clathrate hydrate formation under mild working conditions (273 K, 3.5 MPa) and at high water loading (5.1 g water/g HR-PMO) is reported. Gravimetric uptake measurements reveal a steep single-stepped isotherm and a noticeably high methane storage capacity (0.55 g methane/g HR-PMO; 0.11 g methane/g water at 3.5 MPa). The large working capacity throughout consecutive pressure-induced clathrate hydrate formation-dissociation cycles demonstrates the material's excellent recyclability (97% preservation of capacity). Supported by ex situ cryo-electron tomography and x-ray diffraction, HR-PMO nanotubes are hypothesized to promote clathrate hydrate nucleation and growth by distribution and confinement of water in the mesopores of their outer wall, along the central channels of the nanotubes and on the external nanotube surface. These findings showcase the potential for application of organosilica materials with hierarchical and interconnected pore systems for pressure-based storage of biomethane in confined clathrate hydrates.

Development of a 3D-Printable, Porous, and Chemically Active Material Filled with Silica Particles and its Application to the Fabrication of a Microextraction Device.

We report on the first successful attempt to produce a silica/polymer composite with retained C18 silica sorptive properties that can be reliably printed using three-dimensional (3D) FDM printing. A 3D printer provides an exceptional tool for producing complex objects in an easy and inexpensive manner and satisfying the current custom demand of research. Fused deposition modeling (FDM) is the most popular 3D-printing technique based on the extrusion of a thermoplastic material. The lack of appropriate materials limits the development of advanced applications involving directly 3D-printed devices with intrinsic chemical activity. Progress in sample preparation, especially for complex sample matrices and when mass spectrometry is favorable, remains a vital research field. Silica particles, for example, which are commonly used for extraction, cannot be directly extruded and are not readily workable in a powder form. The availability of composite materials containing a thermoplastic polymer matrix and dispersed silica particles would accelerate research in this area. This paper describes how to prepare a polypropylene (PP)/acrylonitrile-butadiene-styrene (ABS)/C18-functionalized silica composite that can be processed by FDM 3D printing. We present a method for producing the filament as well as a procedure to remove ABS by acetone rinsing (to activate the material). The result is an activated 3D-printed object with a porous structure that allows access to silica particles while maintaining macroscopic size and shape. The 3D-printed device is intended for use in a solid-phase microextraction (SPME) procedure. The proposed composite's effectiveness is demonstrated for the microextraction of glimepiride, imipramine, and carbamazepine. The complex honeycomb geometry of the sorbent has shown to be superior to the simple tubular sorbent, which proves the benefits of 3D printing. The 3D-printed sorbent's shape and microextraction parameters were fine-tuned to provide satisfactory recoveries (33-47%) and high precision (2-6%), especially for carbamazepine microextraction.

A critical review on biodegradable food packaging for meat: Materials, sustainability, regulations, and perspectives in the EU.

The development of biodegradable packaging is a challenge, as conventional plastics have many advantages in terms of high flexibility, transparency, low cost, strong mechanical characteristics, and high resistance to heat compared with most biodegradable plastics. The quality of biodegradable materials and the research needed for their improvement for meat packaging were critically evaluated in this study. In terms of sustainability, biodegradable packagings are more sustainable than conventional plastics; however, most of them contain unsustainable chemical additives. Cellulose showed a high potential for meat preservation due to high moisture control. Polyhydroxyalkanoates and polylactic acid (PLA) are renewable materials that have been recently introduced to the market, but their application in meat products is still limited. To be classified as an edible film, the mechanical properties and acceptable control over gas and moisture exchange need to be improved. PLA and cellulose-based films possess the advantage of protection against oxygen and water permeation; however, the addition of functional substances plays an important role in their effects on the foods. Furthermore, the use of packaging materials is increasing due to consumer demand for natural high-quality food packaging that serves functions such as extended shelf-life and contamination protection. To support the importance moving toward biodegradable packaging for meat, this review presented novel perspectives regarding ecological impacts, commercial status, and consumer perspectives. Those aspects are then evaluated with the specific consideration of regulations and perspective in the European Union (EU) for employing renewable and ecological meat packaging materials. This review also helps to highlight the situation regarding biodegradable food packaging for meat in the EU specifically.

Strategic Fast Induction Heating to Combat Hysteresis Barriers in a Flexible MOF for Rapid CO2 Desorption in Biogas Upgrading.

A major challenge in Cyclic Swing Separation using flexible adsorbents that have high equilibrium CO2  adsorption capacity is their very low-pressure hysteresis that hinders efficient desorption. Mg-Gallate MOF is such a flexible adsorbent that only begins to release CO2 at its pore closing pressure at 0.08 bar and 30 °C, showing very slow and inefficient desorption in pressure or temperature swing. Therefore, a novel strategy is presented that combines state of art technique Magnetic Induction Heating with a vacuum swing for fast and efficient CO2 desorption from flexible adsorbents at a moderately elevated temperature (70 °C).

Potassium Silicate as Low-Temperature Binder in 3D-Printed Porous Structures for CO2 Separation.

Activated carbon sorbents were directly 3D-printed into highly adaptable monolithic/multi-channel systems by using potassium silicate as a low-temperature binder. By employing emerging 3D-printing technologies, monolithic structured sorbents were printed and fully characterized using N2, Ar, and CO2-sorption and Hg-intrusion porosimetry. The CO2-capture performance and the required temperature for active-site regeneration were evaluated by thermogravimetric analysis-looping experiments. A mechanically stable activated carbon sorbent was developed with an increased carbon capture performance, even when a room-temperature regeneration by N2 purging was applied. Although the CO2 uptake slightly dropped after several cycles due to incomplete recovery at room temperature, a capacity increase of 25% was observed in comparison with the original activated carbon powder. To improve the recovery of the active sorbent, an optimization of the desorption step was performed by increasing the regeneration temperature up to 150 °C. This resulted in a CO2 uptake of the composite material of 0.76 mmol/g, almost tripling the working capacity of the original activated carbon powder (0.28 mmol/g). An in situ X-ray diffraction study was carried out to confirm the proposed sorption mechanism, indicating the presence of potassium bicarbonates and confirming the combination of physisorption and chemisorption in our composites. Finally, the structured adsorbent was heated homogeneously by applying a current through the monolith. These results describe the development of a new type of 3D-printed regenerable CO2 sorbents by using potassium silicate as a low-temperature binder, providing high mechanical strength, good chemical and thermal stability, and improving the total CO2 capacity. Moreover, the developed monolith is showing a homogeneous resistivity, leading to uniform Joule heating of the CO2 adsorbent.

Removal of Low Trace ppb-Level Perfluorooctanesulfonic Acid (PFOS) with ZIF-8 Coatings Involving Adsorbent Degradation.

For the first time, low trace-level removal of perfluorooctanesulfonic acid (PFOS), i.e., 20-500 µg/L (ppb), from aqueous solutions using zeolitic imidazolate framework-8 (ZIF-8)-coated copper sheet (ZIF-8@Cu) composite is reported here. In comparison with different commercial activated carbon (AC) and all-silica zeolites, the composite showed the highest removal rate of 98%, which remained consistent over a wide range of concentrations. Additionally, no adsorbent leaching from the composite was noticed, which eradicated pre-analysis steps such as filtration and centrifugation, unless needed for other adsorbents studied here. The composite displayed fast uptake with saturation reaching within 4 h, irrespective of the initial concentration. However, the morphological and structural characterization revealed surface degradation of ZIF-8 crystals, along with a decline in the crystal size. The adsorption of PFOS on ZIF-8 crystals was linked to chemisorption, as the surface degradation surges with an increase in PFOS concentration or with cyclic exposure at low concentrations. Methanol seemingly removed surface debris (partially), thus providing access to ZIF-8 beneath the surface debris. Overall, the findings demonstrate that at low trace ppb-level PFOS concentrations ZIF-8 can be considered as a possible candidate for PFOS removal, even though it suffers slow surface degradation, it also removes efficiently PFOS molecules from aqueous solutions.

A critical review on pretreatment and detoxification techniques required for biofuel production from the organic fraction of municipal solid waste.

The organic fraction of municipal solid waste (OFMSW) is a widely-available promising feedstock for biofuel production. However, the presence of different inhibitors originating from fruit and food/beverage wastes as well as recalcitrant lignocellulosic fractions hampers its bioconversion. This necessitates a pretreatment to augment the biodigestibility and fermentability of OFMSW. Hence, this review aims to provide the in-vogue inhibitory compound removal and pretreatment techniques that have been employed for efficient OFMSW conversion into biofuels, i.e., hydrogen, biogas, ethanol, and butanol. The techniques are compared concerning their mode of action, chemical and energy consumption, inhibitor formation and removal, economic feasibility, and environmental sustainability. This critique also reviews the existing knowledge gap and future perspectives for efficient OFMSW valorization. The insights provided pave the way toward developing energy-resilient cities while addressing environmental crises related to generating OFMSW.

Potato peel waste biorefinery for the sustainable production of biofuels, bioplastics, and biosorbents.

Potato is the fourth most abundant crop harvested annually worldwide. Potato peel waste (PPW) is the main waste stream of potato-processing industries which is generated in large quantities and is a threat to the environment globally. However, owing to its compositional characteristics, availability, and zero cost, PPW is a renewable resource for the production of high-value bioproducts. Hence, this study provides a state-of-the-art overview of advancements in PPW valorization through biological and thermochemical conversions. PPW has a high potential for biofuel and biochemical generation through detoxification, pretreatment, hydrolysis, and fermentation. Moreover, many other valuable chemicals, including bio-oil, biochar, and biosorbents, can be produced via thermochemical conversions. However, several challenges are associated with the biological and thermochemical processing of PPW. The insights provided in this review pave the way toward a PPW-based biorefinery development, providing sustainable alternatives to fossil-based products and mitigating environmental concerns.

Hydrothermal pretreatment: An efficient process for improvement of biobutanol, biohydrogen, and biogas production from orange waste via a biorefinery approach.

Orange waste (OW), an abundant and severe globally environmental treat, was used for biobutanol and biohydrogen production emploing acetone-butanol-ethanol (ABE) fermentation through a biorefinery process. The solvent yield from untreated OW was insufficient; thus, the substrate was subjected to hydrothermal pretreatment before hydrolysis. The pretreatment at 140 ℃ for 30 min resulted in the solid with the highest yield of hydrolysis and fermentation. Moreover, the anaerobic digestion of hydrolysis residue produced appreciable amounts of biomethane. However, the pretreatment liquor was not fermentable; thus, it was detoxified by overliming for 24 h at 30 ℃ and then fermented. Overall, this sustainable biorefinery, based on pretreatment without any additional chemical agent, hydrolysis of pretreated solids, detoxification of pretreatment liquor, ABE fermentation, and anaerobic digestion of residues, produced 42.3 g biobutanol, 33.1 g acetone, 13.4 g ethanol, 104.5 L biohydrogen, and 28.3 L biomethane per kg of OW that contained 4560 kJ energy.

Macroscopic and Microscopic View of Competitive and Cooperative Adsorption of Alcohol Mixtures on ZIF-8.

While in most adsorptive separations different mixture components tend to compete for different adsorption sites, we report the existence of cooperative effects in the adsorption of alcohols (ethanol and 1-butanol) from the vapor phase on ZIF-8. The presence of these molecules in binary mixtures leads to an increase in their equilibrium capacities, compared to the pure component isotherms. These effects were first observed when predicting the mixture equilibrium capacities using the ideal adsorbed solution theory (IAST) and were also observed via grand canonical Monte Carlo (GC MC) simulations. GC MC simulations showed that the interaction between adsorbate molecules leads to the cooperative effect predicted by IAST. The predicted cooperative adsorption could be confirmed via breakthrough experiments. In these experiments, a "roll-up" of 1-butanol was observed during the regeneration of a ZIF-8 packed column. A dynamic breakthrough model employing IAST was developed and used to explain the effect of the adsorption equilibrium on the dynamic breakthrough profiles.

Unravelling the influence of carbon dioxide on the adsorptive recovery of butanol from fermentation broth using ITQ-29 and ZIF-8.

The vapor phase adsorption of butanol from ABE fermentation at the head space of the fermenter is an interesting route for the efficient recovery of biobutanol. The presence of gases such as carbon dioxide that are produced during the fermentation process causes a stripping of valuable compounds from the aqueous into the vapor phase. This work studies the effect of the presence of carbon dioxide on the adsorption of butanol at a molecular level. With this aim in mind Monte Carlo simulations were employed to study the adsorption of mixtures containing carbon dioxide, butanol and ethanol. Molecular models for butanol and ethanol that reproduce experimental properties of the molecules such as polarity, vapor-liquid coexistence or liquid density have been developed. Pure component isotherms and heats of adsorption have been computed and compared to experimental data to check the accuracy of the interacting parameters. Adsorption of butanol/ethanol mixtures has been studied in absence and presence of CO2 on two representative materials, a pure silica LTA zeolite and a hydrophobic metal-organic framework ZIF-8. To get a better understanding of the molecular mechanism that governs the adsorption of the targeted mixture in the selected materials, the distribution of the molecules inside the structures was analyzed. The combination of these features allows obtaining a deeper understanding of the process and to identify the role of carbon dioxide in the butanol purification process.

Intensified Biobutanol Recovery by using Zeolites with Complementary Selectivity.

A vapor-phase adsorptive recovery process is proposed as an alternative way to isolate biobutanol from acetone-butanol-ethanol (ABE) fermentation media, offering several advantages compared to liquid phase separation. The effect of water, which is still present in large quantities in the vapor phase, on the adsorption of the organics could be minimized by using hydrophobic zeolites. Shape-selective all-silica zeolites CHA and LTA were prepared and evaluated with single-component isotherms and breakthrough experiments. These zeolites show opposite selectivities; adsorption of ethanol is favorable on all-silica CHA, whereas the LTA topology has a clear preference for butanol. The molecular sieving properties of both zeolites allow easy elimination of acetone from the mixture. The molecular interaction mechanisms are studied by density functional theory (DFT) simulations. The effects of mixture composition, humidity and total pressure of the vapor stream on the selectivity and separation behavior are investigated. Desorption profiles are studied to maximize butanol purity and recovery. The combination of LTA with CHA-type zeolites (Si-CHA or SAPO-34) in sequential adsorption columns with alternating adsorption and desorption steps allows butanol to be recovered in unpreceded purity and yield. A butanol purity of 99.7 mol % could be obtained at nearly complete butanol recovery, demonstrating the effectiveness of this technique for biobutanol separation processes.

Gel-based morphological design of zirconium metal-organic frameworks.

The ability of metal-organic frameworks (MOFs) to gelate under specific synthetic conditions opens up new opportunities in the preparation and shaping of hierarchically porous MOF monoliths, which could be directly implemented for catalytic and adsorptive applications. In this work, we present the first examples of xero- or aerogel monoliths consisting solely of nanoparticles of several prototypical Zr4+-based MOFs: UiO-66-X (X = H, NH2, NO2, (OH)2), UiO-67, MOF-801, MOF-808 and NU-1000. High reactant and water concentrations during synthesis were observed to induce the formation of gels, which were converted to monolithic materials by drying in air or supercritical CO2. Electron microscopy, combined with N2 physisorption experiments, was used to show that irregular nanoparticle packing leads to pure MOF monoliths with hierarchical pore systems, featuring both intraparticle micropores and interparticle mesopores. Finally, UiO-66 gels were shaped into monolithic spheres of 600 µm diameter using an oil-drop method, creating promising candidates for packed-bed catalytic or adsorptive applications, where hierarchical pore systems can greatly mitigate mass transfer limitations.

Separation properties of the MIL-125(Ti) Metal-Organic Framework in high-performance liquid chromatography revealing cis/trans selectivity.

Monodisperse MIL-125(Ti) Metal-Organic Framework crystals were synthesized and studied as stationary phase in high performance liquid chromatography (HPLC). Different pure compounds and model mixtures (including stereoisomer mixtures) were injected from which chromatographic parameters, including selectivities and resolution factors, were determined to evaluate the adsorption properties and separation performance of MIL-125(Ti) in liquid phase. The MIL-125(Ti) framework displayed a trans selectivity for cis/trans difunctionalized cyclohexane molecules with high selectivity and resolution for 1,3-dimethylcyclohexane and 4-ethylcyclohexanol. The slurry-packed column was further characterized via van Deemter analysis. Fitting of the van Deemter equation through the experimental points allowed to define the contributions of the different processes to plate height with a significant proportion of the A-term, reflecting the importance of a good crystal packing. Although high in comparison to commercial HPLC stationary phases, a very good plate height of around 50µm was found.

Enhanced gas sorption and breathing properties of the new sulfone functionalized COMOC-2 metal organic framework.

A new sulfone functionalized vanadium metal-organic framework (MOF), denoted as SO2-COMOC-2, has been synthesized solvothermally. Its structural and gas sorption properties towards CO2 and CH4 have been evaluated and compared to those of the pristine COMOC-2 material. The SO2-COMOC-2 shows a remarkable increase in CO2 capacity at ambient pressure (2.13 mmol g(-1) at 273 K vs. 1.23 mmol g(-1) for the pristine COMOC-2). Additionally, the high pressure CO2 sorption isotherm shows a distinctive two-step sorption behavior with a final capacity of 12.45 mmol g(-1) for SO2-COMOC-2 at 303 K, while for CH4 a typical Type I isotherm was obtained with a capacity of 4.13 mmol g(-1). In situ synchrotron X-ray powder diffraction measurements have been carried out to characterize the structural flexibility of the materials, showing both the presence of large pore and narrow pore form. Furthermore, synchrotron XANES and a variety of spectroscopic techniques have been utilized to verify the presence of hydroxyl groups and the existence of the mixed vanadium oxidation states in the titled MOF structure.

Molecular separations with breathing metal-organic frameworks: modelling packed bed adsorbers.

Various metal-organic framework (MOFs) adsorbents show peculiar adsorption behaviour as they can adopt different crystal phases, each phase with its own adsorption characteristics. Besides external stimuli such as temperature or light, different species of guest adsorbate can trigger a transition (breathing) of the host structure at a different pressure. Such phase transitions also occur during dynamic separations on a packed bed of adsorbent, where the concentrations of the adsorbates vary throughout axial column distance and time. This work presents a general strategy to model the adsorption behavior of such phase changing adsorbents during column separations and focuses on remarkable model predictions for pure components and binary mixtures in diluted and non-diluted conditions. During binary breakthrough experiments, the behaviour of flexible adsorbents is quite complex. A succession of complete or even partial phase transformations (resulting in phase coexistence) can occur during the adsorption process. A variety of unusual breakthrough profiles is observed for diluted binary mixtures. Simulations reveal at least five types of breakthrough profiles to emerge. The occurrence of these cases can be rationalized by the hodograph technique, combined with the phase diagram of the adsorbent. The remarkable experimental breakthrough profiles observed for ortho-xylene/ethylbenzene (diluted) and CO2/CH4 (non-diluted) separation on the flexible MIL-53 framework can be rationalized by application of the proposed model strategy.

Shape selective properties of the Al-fumarate metal-organic framework in the adsorption and separation of n-alkanes, iso-alkanes, cyclo-alkanes and aromatic hydrocarbons.

The primary goal of this work is to study the adsorption of a wide range of hydrocarbon adsorbates in the Al-fumarate metal-organic framework in order to identify and explore trends in adsorption behaviour that can be related to the sorbate's molecular properties and as well as the properties of this MOF. The pulse chromatographic technique was used to study the adsorption properties of C5-C8 linear, branched, cyclic and aromatic hydrocarbons in vapour phase at low coverage and at high temperatures (150-250 °C). Chromatograms of alkanes having the same number of carbon atoms (C5-C8) clearly show that the linear alkane is retained the longest over its branched and cyclic isomers. Moreover, xylene isomers are also clearly separated by Al-fumarate, with retention times increasing in the order: ortho-xylene < meta-xylene < para-xylene. Differences in adsorption enthalpy of more than 10 kJ mol(-1) between linear alkanes and their di/tri-branched or cyclo-alkane isomers were observed, clearly showing that steric effects imposed by the pore structure of the adsorbent cause the difference in adsorption between linear alkanes and their isomers. In conclusion, Al-fumarate behaves as a shape selective material with respect to structural isomers of linear alkanes, with properties resembling those of medium pore size zeolites.