Novel CO₂‑Selective Cross-Linked Poly(vinyl alcohol)/Poly­vinyl­pyrrolidone Blend Membrane Containing Amine Carrier for CO₂–N₂ Separation: Synthesis, Characterization, and Gas Permeation Study

This article reports structural characterizations and gas permeation properties of novel CO₂-selective cross-linked thin-film composite poly­(vinyl alcohol) (PVA)/polyvinylpyrrolidone (PVP) blend membranes doped with suitable amine carriers. The characterization of the active layer was carried out by thermogravimetric analysis, differential scanning calorimetry, Fourier transform infrared spectroscopy, and X-ray diffraction. Gas streams containing 20% CO₂ and 80% N₂ by volume were used to study the transport properties of CO₂ (CO₂ and N₂ flux, CO₂ permeability, and CO₂/N₂ selectivity) across the membrane. The effects of active layer thickness (34–87 μm), feed absolute pressure (1.7–6.2 atm), temperature (90–125 °C), and sweep side water flow rate (0.02–0.075 cm³/min) on CO₂ transport properties across the membrane were analyzed. The maximum CO₂/N₂ selectivity of 370 and a CO₂ permeability of 1396 barrer were obtained for the composite membrane with 40 μm active layer thickness at 2.8 atm feed side absolute pressure and 100 °C

Fabrication, characterization and optimization of industrial alpha alumina powders based ceramic membrane supports and its applicative potential for CO2/N-2 separation

In this investigation, an economically feasible strategy has been proposed for the fabrication of good quality membrane support by utilizing low-cost industrial-grade alumina powders, coded as A-16SG and CT-1200SG with an average particle size of 0.44 and 1.41 mu m, respectively. Herein, the meticulous alteration of the processing parameters and the targeted utilization of industrial grade powders with distinctive particle morphologies have shown promising aspect towards governing the overall sintering and densification behavior, pore morphology and the microstructural facets of the sintered alumina compacts. More precisely, while connecting the structure-property relationship aspect, the broader particle size distribution and the higher quartile ratio of CT-1200SG powders lends to originate relatively higher average pore size and wider pore size distribution in the as-optimized sintered membrane support system in comparison to the narrow particle sized and low quartile ratio comprising A-16SG powder. Additionally, the near surface morphology of the intermediate layers deposited over the two distinctive membrane support systems via implementing differential colloidal chemistry of the respective sols have also been demonstrated for the precise understanding of the role of particle morphology on the progressive perseverance of pore characteristics of the overall asymmetric graded membrane substrate. Finally, the performance evaluation of the alumino-silicate membrane layer assembled on the tailor-made multilayered graded cost-competent alumina support system has been executed which revealed comparable CO2/N2 gas permeance of 46.44GPU and 534.25GPU along with the selectivity of 12.5 and 1.9 for the respective A-16SG and CT-1200SG powders based individual support systems under nearly identical flue gas separation conditions

Measurement and Correlation of the Physicochemical Properties of Novel Aqueous Bis(3-aminopropyl)amine and Its Blend with <i>N</i>‑Methyldiethanolamine for CO₂ Capture

Physicochemical properties such as density and viscosity of aqueous novel bis­(3-aminopropyl)­amine (APA) and an aqueous novel blend of <i>N</i>-methyldiethanolamine (MDEA) and APA solutions as well as solubility and diffusivity of N₂O into these binary and ternary solutions were measured from temperature <i>T</i> = 298 to 323 K at atmospheric pressure. In this study, experiments cover the molality range for APA = 0–1.291 mol·kg^–1 and MDEA = 2.915–4.416 mol·kg^–1. The diffusivity and solubility experiments were conducted with a wetted wall column absorber and Corning glass equilibrium cell, respectively. The experimental binary and ternary density data as well as binary viscosity data were correlated by Redlich–Kister equation whereas ternary viscosity data were correlated by the Grunberg and Nissan model. On the other hand, solubility and diffusivity were correlated with different models. All of the correlations based on the different model performed are capable of adequately predicting experimental physicochemical data

Adsorption Characteristics of Metal–Organic Frameworks Containing Coordinatively Unsaturated Metal Sites: Effect of Metal Cations and Adsorbate Properties

Metal–organic frameworks in the M/DOBDC series are known to contain a large number of coordinatively unsaturated metal (M) sites. In this work, we study the influence of various metal cations (M = Mg, Mn, Co, and Ni) in the framework on its gas adsorption characteristics. The probe gases (viz. CO₂, CO, CH₄, C₂H₆, N₂, and Ar) were carefully chosen to cover a wider range of polarity and polarizability. While a significant impact of metal atom in the framework is observed on adsorption of polar gases such as CO₂ and CO, it has a negligible effect on adsorption of other relatively nonpolar gases. On one hand, Henry’s constant of CO₂ for Mg/DOBDC is about 4–10 times higher than that for other frameworks; on the other, Henry’s constant for CO on Ni/DOBDC is about 100 times larger than that on Mn/DOBDC. The pore volume of the framework governs adsorption capacity at higher pressures. Each of the frameworks exhibits widely different adsorption enthalpies for polar gases such as CO₂ and CO. At pressures below 15 bar, the Ideal Adsorbed Solution Theory predicts very good selectivity for CO over all other studied gases on Ni and Co/DOBDC frameworks, while Mg and Mn/DOBDC frameworks exhibit preferential selectivity for CO₂

Structural and electronic phase transitions in Zr1.03_{1.03}Se2_{2} at high pressure

A detailed high pressure investigation is carried out using x-ray diffraction, Raman spectroscopy and low temperature resistivity measurements on hexagonal ZrSe$_{2}$ having an excess of 3 at.\% Zr. Structural studies show that the sample goes through a gradual structural transition from hexagonal to monoclinic phase, with a mixed phase in the pressure range 5.9 GPa to 14.8 GPa. Presence of a minimum in the $c/a$ ratio in the hexagonal phase and a minimum in the full width half maximum of the $A_{1g}$ mode at about the same pressure indicates an electronic phase transition. The sample shows a metallic characteristic in its low temperature resistivity data at ambient pressure, which persist till about 5.1 GPa and can be related the presence of slight excess Zr. At and above 7.3 GPa, the sample shows a metal to semiconductor transition with the opening of a very small band gap, which increases with pressure. The low temperature resistivity data show an upturn, which flattens with an increase in pressure. The phenomenological analysis of the low temperature resistivity data indicates the presence of Kondo effect in the sample, which may be due to the excess Zr

Composite scaffolds based on bacterial cellulose for wound dressing application

Wound dressing materials fabricated using biocompatible polymers have become quite relevant in medical applications, and one such material is bacterial cellulose (BC) with exceptional properties in terms of biocompatibility, high purity, crystallinity (∼88%), and high water holding capacity. However, the lack of antibacterial activity slightly restricts its application as a wound dressing material. In this work, polycaprolactone (PCL) was first impregnated into the BC matrix to fabricate flexible bacterial cellulose-based PCL membranes (BCP), which was further functionalized with antibiotics gentamicin (GEN) and streptomycin (SM) separately, to form wound dressing composite scaffolds to aid infectious wound healing. Fourier transform infrared spectroscopy (FT-IR) results confirmed the presence of characteristic PCL and cellulose peaks in the composite scaffolds at 1720 cm-1, 3400 cm-1, and 2895 cm-1, respectively, explaining the successful interaction of PCL with the BC matrix, which is further corroborated by scanning electron microscopy (SEM) images. X-ray diffraction (XRD) studies revealed the formation of highly crystalline BCP films (∼86%). In vitro studies of the BC and BCP scaffolds against baby hamster kidney (BHK-21) cells revealed their cytocompatible nature; also the wettability studies indicated the hydrophilicity of the developed scaffolds, qualifying the main criterion in wound dressing applications. Energy dispersive X-ray analysis (EDX) of the drug loaded scaffolds showed the presence of sulfur in the composites. The prepared scaffolds also exhibited excellent antimicrobial activity against Escherichia coli and Staphylococcus aureus. The release profiles initially indicated a burst release (6 h) followed by controlled release of GEN (∼42%) and SM (∼58%) from the prepared scaffolds within 48 h. Hence, these results interpret that the prepared drug-functionalized cellulosic scaffolds have great potential as a wound dressing material in biomedical applications. © 2022 American Chemical Society.Tomas Bata University in Zlin, TB

Adsorption and Separation of Carbon Dioxide Using MIL-53(Al) Metal-Organic Framework

In this work, we report adsorption isotherms of various industrially important gases, viz. CO₂, CO, CH₄, and N₂ on MIL-53­(Al) metal organic framework (MOF). The isotherms were measured in the range of 0–25 bar over a wide temperature range (294–350 K). The structural transformation of the adsorbent and the resulting breathing phenomenon were observed only in the case of CO₂ adsorption at 294 and 314 K. Adsorption of CO (another polar gas), N₂ and CH₄ did not induce any structural transformation in this adsorbent for the experimental conditions considered in this work. Since the CO₂ isotherms at 294 and 314 K involve structural transformation and show a distinct step, a conventional isotherm model cannot be used to describe such behavior. In order to model these isotherms, a dual-site Langmuir-type equation (one site each for the two structural forms, i.e., large pore phase and narrow pore phase) that includes a normal distribution function to account for structural transformation is proposed. This model successfully mimics the Type-IV isotherm behavior of CO₂ on MIL-53­(Al). Henry’s constants and adsorption enthalpies of CO₂ on the two structural forms were calculated using this model. The Ideal Adsorbed Solution Theory (IAST) was used to predict the selectivity of CO₂ at 350 K over other gases studied in this work