18 research outputs found
Novel CO<sub>2</sub>‑Selective Cross-Linked Poly(vinyl alcohol)/PolyÂvinylÂpyrrolidone Blend Membrane Containing Amine Carrier for CO<sub>2</sub>–N<sub>2</sub> Separation: Synthesis, Characterization, and Gas Permeation Study
This article reports structural characterizations
and gas permeation
properties of novel CO<sub>2</sub>-selective cross-linked thin-film
composite polyÂ(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% CO<sub>2</sub> and
80% N<sub>2</sub> by volume were used to study the transport properties
of CO<sub>2</sub> (CO<sub>2</sub> and N<sub>2</sub> flux, CO<sub>2</sub> permeability, and CO<sub>2</sub>/N<sub>2</sub> 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
cm<sup>3</sup>/min) on CO<sub>2</sub> transport properties across
the membrane were analyzed. The maximum CO<sub>2</sub>/N<sub>2</sub> selectivity of 370 and a CO<sub>2</sub> 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
Absorption of Carbon Dioxide into Aqueous Solutions of 2-Piperidineethanol: Kinetics Analysis
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 CO<sub>2</sub> Capture
Physicochemical properties
such as density and viscosity of aqueous
novel bisÂ(3-aminopropyl)Âamine (APA) and an aqueous novel blend of <i>N</i>-methyldiethanolamine (MDEA) and APA solutions as well
as solubility and diffusivity of N<sub>2</sub>O 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<sup>–1</sup> and MDEA = 2.915–4.416 mol·kg<sup>–1</sup>. 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. CO<sub>2</sub>, CO, CH<sub>4</sub>, C<sub>2</sub>H<sub>6</sub>, N<sub>2</sub>, 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 CO<sub>2</sub> and CO, it has a negligible effect on adsorption of other
relatively nonpolar gases. On one hand, Henry’s constant of
CO<sub>2</sub> 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 CO<sub>2</sub> 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 CO<sub>2</sub>
Structural and electronic phase transitions in ZrSe 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 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 ratio in the hexagonal phase and a minimum
in the full width half maximum of the 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. CO<sub>2</sub>, CO, CH<sub>4</sub>, and N<sub>2</sub> on MIL-53Â(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 CO<sub>2</sub> adsorption at 294 and 314 K. Adsorption of CO (another
polar gas), N<sub>2</sub> and CH<sub>4</sub> did not induce any structural
transformation in this adsorbent for the experimental conditions considered
in this work. Since the CO<sub>2</sub> 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 CO<sub>2</sub> on MIL-53Â(Al).
Henry’s constants and adsorption enthalpies of CO<sub>2</sub> on the two structural forms were calculated using this model. The
Ideal Adsorbed Solution Theory (IAST) was used to predict the selectivity
of CO<sub>2</sub> at 350 K over other gases studied in this work