12 research outputs found
Facile and Efficient Synthesis of Silver Nanoparticles Based on Biorefinery Wood Lignin and Its Application as the Optical Sensor
Fabricating
silver nanoparticles (AgNPs) based on renewable energy
sources is wildly exploited because of the sustainable synthetic strategy
and versatile applications of AgNPs. Alkali lignin (AL), as the byproduct
from pulp mills, is a potential natural reducing agent. However, the
synthetic methods of AL-based AgNPs (AL@Ag) still have drawbacks,
such as unusual conditions and extra and high-cost purification processes.
Here, a facile and efficient approach to synthesize and purify good-dispersing
AL@Ag (17–27 nm) was presented, using Ag<sub>2</sub>O as the
silver precursor and AL as both reducing agents and stabilizers in
dimethyl sulfoxide (DMSO) solvent. The maximum reduction capacity
of AL to Ag<sup>+</sup> was increased to 8 mM/g at room temperature
because of the activation of both Ag<sub>2</sub>O and DMSO. Most conveniently,
the product was effectively purified by easy centrifugation. The reducing
mechanism and reaction behavior were also systematically studied.
Meanwhile, AL@Ag maintained versatile applications of AgNPs and exhibited
great potential as the colorimetric sensor and plasmonic resonance
energy acceptor for Hg<sup>2+</sup> and rhodamine B, respectively.
Our work displayed a general and efficient method to prepare AL@Ag,
which might provide a realizable perspective to the high-value utilization
of lignin
Liquid-Assisted Mechanochemical Synthesis of Copper Based MOF-505 for the Separation of CO<sub>2</sub> over CH<sub>4</sub> or N<sub>2</sub>
Mechanochemical
synthesis, driven the chemical transformation by mechanical force,
has been a rapid and efficient strategy to prepare metal–organic
frameworks (MOFs). In this work, a liquid-assisted mechanochemical
method has been successfully applied to the synthesis of copper based
MOF-505. The crystallinity and porosity of MOF-505 were investigated
by adjusting the synthesis parameters, such as added solvent (type
and amount) and grinding time. Results showed that the type and amount
of added solvent were crucial parameters for the mechanochemical synthesis
of MOF-505. Furthermore, the optimizations of MOF-505 synthesis were
carried out: grinding CuÂ(OAc)<sub>2</sub>·H<sub>2</sub>O and
H<sub>4</sub>bptc as starting materials for 80 min with 0.4 mL of
DMF assisted, giving MOF-505-K with Brunauer–Emmett–Teller
(BET) surface area of 977 m<sup>2</sup>/g. Meanwhile, MOF-505-K had
moderate CO<sub>2</sub> adsorption capacity of 2.01 mmol/g at 298
K and 100 kPa. The adsorptive selectivity determined from ideal adsorbed
solution theory (IAST) indicated that MOF-505-K had high CO<sub>2</sub>/N<sub>2</sub> and CO<sub>2</sub>/CH<sub>4</sub> selectivities (26.6
and 5.5) at 298 K. Highly efficient mechanochemical synthesis of MOF-505
provides the promise to facilitate the industrial application of CO<sub>2</sub> capture
Adsorptive Separation of Methanol–Acetone on Isostructural Series of Metal–Organic Frameworks M‑BTC (M = Ti, Fe, Cu, Co, Ru, Mo): A Computational Study of Adsorption Mechanisms and Metal-Substitution Impacts
The adsorptive separation properties
of M-BTC isostructural series (M = Ti, Fe, Cu, Co, Ru, Mo) for methanol–acetone
mixtures were investigated by using various computational procedures
of grand canonical Monte Carlo simulations (GCMC), density functional
theory (DFT), and ideal adsorbed solution theory (IAST), following
with comprehensive understanding of adsorbate–metal interactions
on the adsorptive separation behaviors. The obtained results showed
that the single component adsorptions were driven by adsorbate–framework
interactions at low pressures and by framework structures at high
pressures, among which the mass effects, electrostatics, and geometric
accessibility of the metal sites also played roles. In the case of
methanol-acetone separation, the selectivity of methanol on M-BTCs
decreased with rising pressures due to the pressure-dependent separation
mechanisms: the cooperative effects between methanol and acetone hindered
the separation at low pressures, whereas the competitive effects of
acetone further resulted in the lower selectivity at high pressures.
Among these M-BTCs, Ti and Fe analogues exhibited the highest thermodynamic
methanol/acetone selectivity, making them promising for adsorptive
methanol/acetone separation processes. The investigation provides
mechanistic insights on how the nature of metal centers affects the
adsorption properties of MOFs, and will further promote the rational
design of new MOF materials for effective gas mixture separation
In Situ Assembly of Nanoparticles into Hierarchical Beta Zeolite with Tailored Simple Organic Molecule
A hierarchically
structured beta zeolite with intercrystalline
mesopores was successfully synthesized via in situ assembly of nanoparticles
by employing a simple organic molecule N<sub>2</sub>-<i>p</i>-N<sub>2</sub>, tailored from polyquaternium surfactant, with no
hydrophobic long chain. The generated samples were studied by using
powder X-ray diffraction (XRD) and nitrogen adsorption/desorption
isotherms. Computer simulation, scanning electron microscopy (SEM),
and transmission electron microscopy (TEM) technologies were also
used. The characterized results show that the tailored template molecule
N<sub>2</sub>-<i>p</i>-N<sub>2</sub> without hydrophobic
long-chain tail still can direct the zeolite crystallization, while
the hydrophobic long-chain tail is not necessary during the mesoporous
Beta zeolite formation. The catalytic performances of the sample were
studied using alkylation of benzene with propene reaction to evaluate
the relationship between the structure and property. The results apparently
suggested an overall improved resistance against deactivation as compared
to conventional beta zeolite in reactions. Furthermore, this tailored
simple organic molecule strategy from dual-functional surfactant for
making mesoporous zeolite would offer a new method of synthesizing
other hierarchically structured zeolites
Construction of Novel <i>Saccharomyces cerevisiae</i> Strains for Bioethanol Active Dry Yeast (ADY) Production
<div><p>The application of active dry yeast (ADY) in bioethanol production simplifies operation processes and reduces the risk of bacterial contamination. In the present study, we constructed a novel ADY strain with improved stress tolerance and ethanol fermentation performances under stressful conditions. The industrial <i>Saccharomyces cerevisiae</i> strain ZTW1 showed excellent properties and thus subjected to a modified whole-genome shuffling (WGS) process to improve its ethanol titer, proliferation capability, and multiple stress tolerance for ADY production. The best-performing mutant, Z3-86, was obtained after three rounds of WGS, producing 4.4% more ethanol and retaining 2.15-fold higher viability than ZTW1 after drying. Proteomics and physiological analyses indicated that the altered expression patterns of genes involved in protein metabolism, plasma membrane composition, trehalose metabolism, and oxidative responses contribute to the trait improvement of Z3-86. This work not only successfully developed a novel <i>S. cerevisiae</i> mutant for application in commercial bioethanol production, but also enriched the current understanding of how WGS improves the complex traits of microbes.</p> </div
Iron-Based Metal–Organic Framework with Hydrophobic Quadrilateral Channels for Highly Selective Separation of Hexane Isomers
A novel iron-based
microporous metal–organic framework built of trinuclear iron
clusters [Fe<sub>3</sub>(ÎĽ<sub>3</sub>-O)Â(COO)<sub>6</sub>]
and 2,2-bisÂ(4-carboxyphenyl)-hexafluoropropane (6FDCA) has been prepared
by solvothermal synthesis. It exhibits excellent chemical stability
and strong hydrophobic character. More importantly, this material
is capable of separating hexane isomers with good separation performance
on the basis of a kinetically controlled process, making it a promising
candidate for improving the research octane number of gasoline
Malondialdehyde (MDA) formation and tolerance to H<sub>2</sub>O<sub>2</sub> of ZTW1 and Z3-86.
<p>MDA content determination of fresh and dried ZTW1 and Z3-86 cells (a). “*” indicates significant difference between samples at the P < 0.05 level, using <i>t</i> test. Growth of ZTW1 and Z3-86 on YPD plates containing H<sub>2</sub>O<sub>2</sub> (b). Cells were pre-cultured in YPD liquid medium for 18 h, and 5 μL of 10-fold serial dilutions were spotted onto plates.</p
Viabilities of strains A1, ZTW1, and Z3-86 after drying and application of certain stressors.
<p>Ratios of viable cells of the three strains after dehydration described in the Material and methods section (a). The dired cells were then diluted serially and the appropriate dilutions were plated onto solid YPD medium to count the colony-forming. The sample without drying was used as the control. Comparison of the tolerance of A1, ZTW1, and Z3-86 to ethanol treatment [20% (v/v) for 2 h], osmotic pressure (4 M NaCl for 2 h), heat (55 °C for 5 min), and H<sub>2</sub>O<sub>2</sub> (20 mM for 1 h) (b). Yeast cells were pre-cultured in YPD at 30 °C for 18 h with the initial OD(A600) of 0.05. The cells (~3×10<sup>7</sup>) were collected and transferred into 2 mL YPD (for heat tolerance test) or YPD with indicated stressors. The treated cells were diluted and plated onto solid YPD medium for viability calculation. “a” indicates significant difference between Z3-86 and ZTW1 at <i>P</i> < 0.01; “b” indicates significant difference between Z3-86 and A1 at the P < 0.05 level, using <i>t</i> test. The bars indicated the standard deviation here and other figures.</p
Differences in the trehalose metabolism of ZTW1 and Z3-86.
<p>Genes involved in trehalose metabolism were upregulated in Z3-86 (a). Osmotic pressure induced intracellular trehalose accumulation in ZTW1 and Z3-86 (b). Trehalose contents of ZTW1 and Z3-86 when cultured in YPD or YPD with 50 mM trehalose for 18 h (c). Exogenous trehalose enhanced the viability of ZTW1 and Z3-86 (d). “*” indicates significant difference between samples at the P < 0.05 level, using <i>t</i> test.</p
Growth curves of A1, ZTW1, and Z3-86.
<p>Cells were cultured in 25 mL of YPD at 30 °C with an initial OD (A600) of 0.05. 20 μL of yeast cells were aspirated at certain time points and the colony forming unites (CFU) were determined. The data was represented as the mean±SD of three independent experiments.</p