| 1. |
- Alves, L., et al.
(författare)
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Unusual extraction and characterization of nanocrystalline cellulose from cellulose derivatives
- 2015
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Ingår i: Journal of Molecular Liquids. - : Elsevier BV. - 0167-7322 .- 1873-3166. ; 210, s. 106-112
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Tidskriftsartikel (refereegranskat)abstract
- Unlike many nanomaterials, nanocrystalline cellulose (CNC) is not synthesized from molecular or atomic components but rather extracted from naturally occurring cellulose. Undoubtedly, the exploitation of CNCs will become a bridge between nanoscience and natural resource products, which could play a major role in reviving the forest industry. In this work, CNC was successfully extracted from unusual sources, hydroxypropyl methylcellulose (HPMC) and carboxymethylcellulose (CMC). The extracted crystallites were purified and further characterized by Fourier transform infrared (FTIR), scanning electron microscopy (SEM), X-ray powder diffraction (XRD) and dynamic light scattering (DLS). The average size of the CNCs extracted from HPMC and CMC was found to be less (and with lower zeta potential) than the ones extracted from microcrystalline cellulose (MCC). On the other hand, FTIR and XRD revealed that native HPMC and CMC are unexpectedly highly crystalline and hence can be used as a source for CNCs. © 2014 Elsevier B.V.All rights reserved.
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| 2. |
- Arkhipov, Victor P., et al.
(författare)
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Abnormal diffusion behavior and aggregation of oxyethylated alkylphenols in aqueous solutions near their cloud point
- 2022
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Ingår i: Journal of Molecular Liquids. - : Elsevier. - 0167-7322 .- 1873-3166. ; 358
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Tidskriftsartikel (refereegranskat)abstract
- We have investigated solutions of oxyethylated alkylphenols (neonols) in a mixture of ordinary and heavy water with equal densities of the neonols and the aqueous mixture. The equal densities allow exclusion of sedimentation effects and study of the evolution of micelles and neonol aggregates in the range from room temperature to above the cloud point. The self-diffusion coefficients of neonols were measured by NMR and the effective hydrodynamic radii of micelles and neonol aggregates were calculated using the Stokes-Einstein relation. An abnormal decrease in neonols diffusion coefficients occurred when the system approached the cloud point, while an abnormal increase in the diffusion coefficients occurred at temperatures above the cloud point. We explained the abnormal temperature behavior of the diffusion coefficients of neonols by changes in the size of the diffusing objects from the spherical and spherocylindrical micelles to dehydrated aggregates and the destruction of micelles by thermal motion and by formation of aggregates with sizes of the order 102 nm at temperatures above the cloud point. Conclusions about the increase in the hydrodynamic radii of the micelles with increasing temperature up to the cloud point and about the formation of dehydrated aggregates above the cloud point are confirmed by the results of DLS studies.
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| 3. |
- Babucci, Melike, et al.
(författare)
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Effects of interionic interactions in 1,3-dialkylimidazolium ionic liquids on the electronic structure of metal sites in solid catalysts with ionic liquid layer (SCILL)
- 2016
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Ingår i: Journal of Molecular Liquids. - : Elsevier BV. - 0167-7322 .- 1873-3166. ; 216, s. 293-297
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Tidskriftsartikel (refereegranskat)abstract
- Well-defined gamma-Al2O3-supported Ir(CO)(2) complexes were coated with various 1,3-dialkylimidazolium ionic liquids (ILs) to elucidate the ligand effect of ILs. Variations in electron density of iridium sites when coated with ILs were probed by the infrared (IR) fingerprints of carbonyl ligands. Results presented here illustrate that IL layer strongly controls the electron density of metal sites; and there is a strong correlation between the interionic interactions in ILs and the degree of electron donation to the metal. These results create opportunities to tune the electronic structure of active metal sites by tailoring the structure of IL for optimum catalytic performance.
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| 4. |
- Bako, Imre, et al.
(författare)
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Effects of H-bond asymmetry on the electronic properties of liquid water : An AIMD analysis
- 2019
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Ingår i: Journal of Molecular Liquids. - : Elsevier BV. - 0167-7322 .- 1873-3166. ; 293
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Tidskriftsartikel (refereegranskat)abstract
- The effects of an asymmetric environment on the electronic properties of a water molecule in liquid water are in focus in this paper and were analysed from ab initio molecular dynamics simulations of liquid water at 300 and 350 K with the BLYP-D3 functional. We make the following observations. (1) The electronic DOS and the net molecular charge are more affected by the asymmetry of the water molecule's H-bond surroundings than by the number of H-bonded neighbours. The reverse is true for the dipole moment. (2) For all three properties, a 3-coordinated water molecule is more perturbed by accepting two H-bonds and donating one than by donating two and accepting one. (3) This order is not maintained in the calculated XES spectrum, which is less straightforward to interpret in terms of structure-property relationships than the DOS spectrum.
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| 5. |
- Bakó, Imre, et al.
(författare)
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How can we detect hydrogen bond local cooperativity in liquid water : A simulation study
- 2017
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Ingår i: Journal of Molecular Liquids. - : Elsevier BV. - 0167-7322 .- 1873-3166. ; 245, s. 140-146
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Tidskriftsartikel (refereegranskat)abstract
- The significant cooperative effect between water molecules substantially affects the properties of liquid water. The cooperativity of hydrogen bonds means that the hydrogen bond strength is influenced by the neighboring water molecules. Another descriptor related to cooperativity is degree correlation (or static correlation) describing the probability of hydrogen-bonded molecule pairs participating in additional hydrogen-bonds. Herein we analyze the latter one in liquid water at various temperatures and densities in a series of molecular dynamics simulations with the help of knowledge from network science. We investigated how the applied hydrogen bond criteria (energetic or geometric) influence the obtained results, and showed that the energetic criterion is much more rigorous and reliable, therefore should be used for similar studies. We found that the structure of the subsystems of water molecules with 3 and 4 hydrogen-bonds is distinctly different at low temperature, 3‑hydrogen-bonded water molecules form branched chain structures at all temperature. Deconvolution of the descriptors of the mixing pattern of water molecules according to their donor and acceptor numbers showed that species with complementary hydrogen bonding properties are likely to correlate and form H-bonds with each other, while species with similar H-bond pattern tend to avoid each other. Pearson's coefficient (global descriptor of the local cooperativity) of the studied networks suggests that at normal density the H-bonded network in liquid water can be described by an uncorrelated network.
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| 6. |
- Bhattacharyya, Shubhankar, et al.
(författare)
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Thermal stability of choline based amino acid ionic liquids
- 2018
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Ingår i: Journal of Molecular Liquids. - : Elsevier. - 0167-7322 .- 1873-3166. ; 266, s. 597-602
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Tidskriftsartikel (refereegranskat)abstract
- Thermal stability of different choline based amino acid ionic liquids were studied. Both short term as well as long term thermal studies were carried out. Long term thermal studies of all ILs were carried out by isothermal TGA and short term thermal studies were measured by temperature ramped TGA. Isothermal TGA were studied at two different temperatures 100 °C and 150 °C for 500 min. Whereas, short term thermal stability represents as T2%, T5% and T10% which are the temperature at which 2%, 5% and 10% mass loss of ILs were observed. The effect of alkyl side chain on the cation, etherification of the cation as well structural variation of anion on the thermal stability of choline based ILs were investigated. It was observed that thermal characteristics of ILs towards temperature ramped TGA were different compared to isothermal TGA.
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| 7. |
- Bundschuh, Mirco
(författare)
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Doping zinc oxide (ZnO) nanoparticles with molybdenum boosts photocatalytic degradation of Rhodamine b (RhB): Particle characterization, degradation kinetics and aquatic toxicity testing
- 2023
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Ingår i: Journal of Molecular Liquids. - 0167-7322 .- 1873-3166. ; 385
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Tidskriftsartikel (refereegranskat)abstract
- Undoped and Mo-doped ZnO photocatalysts were synthesized by hydrothermal method and characterized by field emission scanning electron microscopy coupled to energy dispersive- X ray spectroscopy (FESEM- EDAX), Xray diffraction (XRD), fourier transform infrared spectroscopy (FTIR), Brunauer-Emmett-Teller (BET) and thermogravimetric analysis (TGA) analyses. The photocatalytic activity of the photocatalysts and the kinetic of the reaction was assessed by degrading Rhodamine B under UV and sun light irradiation under variable conditions. Eventually the acute toxicity of undoped and doped nanophotocatalysts, RhB and the consequences of photocatalytic treatment were assessed using zebrafish (Danio rerio). The analytical results showed that Mo doping increased catalysts specific surface area and thermal stability. The results of photocatalytic degradation demonstrated that Mo doping has increased the photocatalytic activity under both UV and sunlight irradiation with 95 % RhB degradation efficiency and 41 % TOC removal efficiency over 30 min. The reusability of photocatalysts showed constant degradation efficiency over multiple cycles. The 96 h LC50 of undoped ZnO, Mo doped ZnO and RhB were 482.71 and 459.05 and 20.38 mg/L, respectively. Moreover, a lower toxicity was observed for the treated compared to untreated dye solution. This study indicates a promising potential of Modoped ZnO nanophotocatalysts for wastewater treatment and warrants further studies in this direction.
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| 8. |
- Camisasca, Gaia, et al.
(författare)
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Structure and slow dynamics of protein hydration water
- 2018
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Ingår i: Journal of Molecular Liquids. - : Elsevier BV. - 0167-7322 .- 1873-3166. ; 268, s. 903-910
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Tidskriftsartikel (refereegranskat)abstract
- We report results on the structure, local order and dynamics of water surrounding a lysozyme protein. The local order of water molecules is as much tetrahedral as in bulk water already at close vicinity of the protein but the number of hydrogen bonds depends more on the distance from the protein and gradually recovers bulk value upon moving outer. The dynamics of water seems in general to be more affected than its structure by the presence of the protein. An extremely long-relaxation detected in hydration water appears in the first monolayer around the protein, and the slow down is enhanced at low temperature. The dynamics of water within a layer of thickness 6 A is sub-diffusive up to about similar to 1 ns, above 1 ns we observe a crossover toward a hopping regime over a length-scale larger than that of nearest neighbors molecules. This hopping seems connected to transient trapping of water molecules on some specific protein domains.
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| 9. |
- Cao, Yingying, et al.
(författare)
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Screening of Alternative Solvent Ionic Liquids for Artemisinin : COSMO-RS Prediction and Experimental Verification
- 2021
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Ingår i: Journal of Molecular Liquids. - : Elsevier. - 0167-7322 .- 1873-3166. ; 338
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Tidskriftsartikel (refereegranskat)abstract
- Organic solvents are usually used to extract artemisinin from Artemisia annua L., and they can also be the solvents for the subsequent purification or derivatization to produce compounds with more efficient antimalarial effect. However, these solvents are volatile, explosive and toxic. The designable material ionic liquids (ILs) are alternative solvents to replace traditional ones. In this work, a reliable method for screening ILs with high solvation capability for artemisinin was developed. The infinite dilution activity coefficients of artemisinin in 903 ILs, composed by 43 cations and 21 anions, were calculated by COSMO-RS, and the results implied that the solubility of artemisinin in ILs mainly depends on the anions. Solubilities of artemisinin in 14 representative ILs were tested, and the results were in good accordance with those obtained in COSMO-RS calculation. The stability of artemisinin in some typical ILs was also studied, which indicated that this drug was stable in [EMIM][BF4], [EMIM][CF3Ac], [EMIM][NTF2], [BPY][NTF2], [EMIM][SCN], and [EMIM][Ac]. The excess enthalpy analysis demonstrated that artemisinin interacted with ILs mainly through hydrogen bond. Extraction of artemisinin using the optimal IL indicated that more artemisinin could be extracted from the leaves when compared with petroleum ether (254.73 mg/mol vs. 14.16 mg/mol), further verifying accuracy of the simulation results. Therefore, structures of ILs with high solvation capacity for artemisinin can be obtained by the COSMO-RS method.
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| 10. |
- Chen, Yifeng, et al.
(författare)
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Mass-transfer kinetics of CO2 in a hybrid choline-2-pyrrolidine-carboxylic acid/polyethylene glycol/water absorbent
- 2021
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Ingår i: Journal of Molecular Liquids. - : Elsevier. - 0167-7322 .- 1873-3166. ; 336
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Tidskriftsartikel (refereegranskat)abstract
- Understanding the mass-transfer kinetics of CO2 in novel hybrid absorbents with physical and chemical contributions is essential for process design and evaluation. In this study, the liquid-side mass-transfer coefficients (kL) and second-order reaction rate constants (k2) of CO2 in hybrid absorbents (namely, choline-2-pyrrolidine-carboxylic acid salt/polyethylene glycol/water ([Cho][Pro]/PEG200/H2O)) were determined. The kL values for the hybrid absorbents were obtained from the CO2 diffusion coefficients (DCO2) and the kL values in PEG200/H2O. The DCO2 value was calculated from the density and viscosity of the hybrid absorbents, whereas the kL values in PEG200/H2O were measured experimentally. The k2 values of CO2 in the hybrid absorbents were estimated according to the reaction mechanism, the enhancement factor, and the kL values, and compared with those of other commercialized absorbents. The results showed that 30 wt% [Cho][Pro]+70 wt% H2O had the highest kL and k2 values at atmospheric pressure, whereas the values of kL and k2 of CO2 in 30 wt% [Cho][Pro]/H2O+PEG200 were comparable to those in diethanolamine aqueous and amino-functionalized ILs. The hybrid absorbent of [Cho][Pro]/PEG200/H2O could be promising for CO2 separation considering its thermodynamic and kinetic properties.
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