Simulating infrared spectra and hydrogen bonding in cellulose Iβ at elevated temperatures

Agarwal, Vishal; Huber, George W.; Conner, W. Curtis; Auerbach, Scott M.

doi:10.1063/1.3646306

Cited by 104 publications

(84 citation statements)

References 77 publications

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“…In general, the monomeric and dimeric species show that the β-forms are the most stable in both media with higher dipole moment and population values, presenting the β-dimeric species the higher populations in both media, as obviously it is expected because the real cellulose structure is polymeric and, as a consequence the structures with four units are most stable than those with two units. The dipole moment value for the β-form in gas phase (3.67 D) is in good agreement with the value of 4.4 D reported by Agarwal et al [63] for this form from atomistic molecular dynamics (MD) simulations. Besides, the magnitude, orientation and directions of both vector dipole moments are different from both monomeric structures, as can be seen in Figure S3.…”

Section: Structural Analysissupporting

confidence: 77%

“…Besides, the magnitude, orientation and directions of both vector dipole moments are different from both monomeric structures, as can be seen in Figure S3. The α-form shows the vector located in a direction forming angles on the xz and yz planes while in the β-form the vector is directly on the y-axis, as observed in Figure S3 and, as reported by Agarwal et al [63] because the cellulose polymer consists of alternating glucose units with 180• flips along the y-axis. Here, it is very important to clarify that the OH and CH 2 OH groups belonging to the R2 rings in both forms remain without change while the CH 2 OH groups belonging to the R1 rings change their positions in the α and β-forms.…”

Section: Structural Analysissupporting

confidence: 50%

“…The same signs observed for both forms in the two media are different from those experimental ones which could indicate that these changes can be dependent of the used method, as verified by us by using the wb97xd/6-31G* method. In general, the parameters for both forms show that in aqueous solution the structures practically no change and that the two forms could exist in this media, as the cellulose I structure that is a mixture of both forms with major proportion of the β-form [17,63]. But, analyzing the glycosidic C1-O33 and C24-O33 bonds in solution, it is observed that the increasing in the former bond is of 0.014 Å in α and of 0.01 Å in β while in the other one the increasing is of 0.005 Å in α and of 0.009 Å in β.…”

Section: Structural Analysismentioning

confidence: 99%

“…Therefore, both forms can be seen in solution and, also, probably in the solid state, showing the β-form the major stability in both media [17,63]. Table S5 shows the analysis of the bond cr itical points (BCP) for the two cellulose for ms in gas and in aqueous solution phases computed by using the B3LYP/6-31G* Method.…”

Section: Donor-acceptor Interaction Bond Order (Bo) and Aim Studymentioning

confidence: 99%

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Vibrational characterization of monomers and dimers of cellulose by using DFT calculations and the SQM methodology

Brandán¹,

Desk²

2017

SDRP-JCCMM

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In this work, monomeric and dimeric species of α-and β-cellulose were vibrationally characterized by using theoretical calculations derived from the density functional theory (DFT) and the scaled quantum mechanical force field (SQMFF) methodology. Here, the experimental available FT-IR and Raman spectra and the experimental available structure for the β-form were used in order to perform the assignments of the 129 normal vibration modes for both α-and β-cellulose forms. Raman bands and shoulders at 1258, 1153, 1123, 918, 907, 897, 864, 744, 727, 721, 483 and 281 cm -1 could probably support the presence of two proposed dimeric species of cellulose in the solid state. The structural properties reveal differences between both monomeric α-and β-cellulose species mainly evidenced by their molecular electrostatic potentials. The high dipole moment values and the higher populations for the β-form could support the major proportion found experimentally for this form. The volume contraction observed for the β-dimer could be related to their lower dipole moment in solution in relation to that observed in the gas phase. The reduction of the glycosidic angles for both forms in solution support their rigid structures, as was experimentally observed. The atomic charges on the O atoms belonging to the glucopyranose rings and to the glycosidic bonds (O33) present the lower values. The NBO and AIM studies suggest the presence of α-and β-cellulose in the two media but the major quantity of H bonds predicted for the β-form and their high donor-acceptor interaction values could support their most important proportion existent of this form in the earth. Similar reactivities were found in gas phase but the α-form is more reactive in solution than the other one probably because the electrophilicity and nucleophilicity for the β-form show lower values than the α ones.

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Section: Structural Analysissupporting

confidence: 77%

Section: Structural Analysissupporting

confidence: 50%

Section: Structural Analysismentioning

confidence: 99%

Section: Donor-acceptor Interaction Bond Order (Bo) and Aim Studymentioning

confidence: 99%

See 2 more Smart Citations

Vibrational characterization of monomers and dimers of cellulose by using DFT calculations and the SQM methodology

Brandán¹,

Desk²

2017

SDRP-JCCMM

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“…As shown in Fig. 1 with the assignments of the FT-IR absorption band, the main bands observed for bagasse are as follows : O-H stretching at 3406 cm -1 , C-H stretching at 2907 cm -1 , and O-H bending of absorbed water at 1639 cm -1 [26]. After condensation reaction, the broader band with less intensity of O-H stretching is observed at 3442 cm -1 .…”

Section: A Characterization Of Modified Biosorbentmentioning

confidence: 89%

Adsorptive Recovery of Au(III) from Aqueous Solution Using Modified Bagasse Biosorbent

Rubcumintara¹

2015

IJCEA

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Abstract-The recovery of Au(III) from aqueous chloride solutions onto modified bagasse biosorbent was investigated. The parameters for biosorbent preparation as well as gold recovery were studied in detail. It was found that 99.8 % of sugarcane bagasse could be modified as biosorbent having better physical properties for adsorption. The solution pH, sorbent dosage, initial Au(III) concentration and temperature were the studied variables that affect the efficiency of gold recovery as well as adsorption behavior. The efficiency of 99% for Au(III) recovery was obtained under the following conditions: 25 mg sorbent, 25 mL of 25-500 mg/L Au(III), pH 2, 150 rpm, 4 h and 25 o C. The 99% of gold recovery still obtained in only 1 h or less with the increasing of dosage or temperature. The gold adsorption in this study was best fitted with Langmuir isotherm model and the maximum capacity for gold loading was determined to be 1497.5 mg/g or 7.6 mmol/g. The adsorption kinetics was also evaluated in terms of the pseudo first-order and pseudo second-order kinetic models. The high activation energy of 45.8 kJ/mol was estimated which represents a chemisorption process. The adsorption mechanism in this study is clarified to be the oxidation of hydroxyl to carbonyl in biosorbent and reduction of trivalent gold ions to metallic gold simultaneously on biosorbent surface. The results from ORP measurement, FT-IR and EDS spectra including SEM images were the supported evidence for this adsorption mechanism. The modified bagasse biosorbent therefore has potential in gold recovery process.Index Terms-Au(III) recovery, modified bagasse, biosorbent.

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Fast Pyrolysis of Wood for Biofuels: Spatiotemporally Resolved Diffuse Reflectance In situ Spectroscopy of Particles

et al. 2014

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Fast pyrolysis of woody biomass is a promising process capable of producing renewable transportation fuels to replace gasoline, diesel, and chemicals currently derived from nonrenewable sources. However, biomass pyrolysis is not yet economically viable and requires significant optimization before it can contribute to the existing oil-based transportation system. One method of optimization uses detailed kinetic models for predicting the products of biomass fast pyrolysis, which serve as the basis for the design of pyrolysis reactors capable of producing the highest value products. The goal of this work is to improve upon current pyrolysis models, usually derived from experiments with low heating rates and temperatures, by developing models that account for both transport and pyrolysis decomposition kinetics at high heating rates and high temperatures (>400 °C). A new experimental technique is proposed herein: spatiotemporally resolved diffuse reflectance in situ spectroscopy of particles (STR-DRiSP), which is capable of measuring biomass composition during fast pyrolysis with high spatial (10 μm) and temporal (1 ms) resolution. Compositional data were compared with a comprehensive 2D single-particle model, which incorporated a multistep, semiglobal reaction mechanism, prescribed particle shrinkage, and thermophysical properties that varied with temperature, composition, and orientation. The STR-DRiSP technique can be used to determine the transport-limited kinetic parameters of biomass decomposition for a wide variety of biomass feedstocks.

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Simulating infrared spectra and hydrogen bonding in cellulose Iβ at elevated temperatures

Cited by 104 publications

References 77 publications

Vibrational characterization of monomers and dimers of cellulose by using DFT calculations and the SQM methodology

Vibrational characterization of monomers and dimers of cellulose by using DFT calculations and the SQM methodology

Adsorptive Recovery of Au(III) from Aqueous Solution Using Modified Bagasse Biosorbent

Fast Pyrolysis of Wood for Biofuels: Spatiotemporally Resolved Diffuse Reflectance In situ Spectroscopy of Particles

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