Enthalpy of Combustion of Microcrystalline Cellulose

Colbert, J. C.; Xiheng, He; Kirklin, Duane R.

doi:10.6028/jres.086.030

Cited by 9 publications

(15 citation statements)

References 9 publications

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“…[91], and by Blokhin et al [92] lead, respectively, to D c H Ã w = À17337 JÁg À1 , D c H Ã w = À17458 JÁg À1 , and D c H Ã w = À17165 JÁg À1 for cellulose I(cr). The earlier, very carefully done measurements of Jessup and Prosen [83] and Colbert et al [87] did not include a measurement of CI but the samples that they used probably had high CI values. We use the value D r H w = À113 JÁg À1 for reaction (26) {this is the average of the values of D r H w for reaction (26) at w = 0; see table 18} and assume that the cellulose samples used by Jessup and Prosen [83] and by Colbert et al [87] had CI values of %75.…”

Section: Mid T Fitsmentioning

confidence: 97%

“…The earlier, very carefully done measurements of Jessup and Prosen [83] and Colbert et al [87] did not include a measurement of CI but the samples that they used probably had high CI values. We use the value D r H w = À113 JÁg À1 for reaction (26) {this is the average of the values of D r H w for reaction (26) at w = 0; see table 18} and assume that the cellulose samples used by Jessup and Prosen [83] and by Colbert et al [87] had CI values of %75. This assumption gives an adjustment of À(0.25ÁÀ113 JÁg À1 ) = 28 JÁg À1 to be applied to the values of D c H w obtained by Jessup and Prosen [83] and by Colbert et al [87].…”

Section: Mid T Fitsmentioning

confidence: 97%

“…We use the value D r H w = À113 JÁg À1 for reaction (26) {this is the average of the values of D r H w for reaction (26) at w = 0; see table 18} and assume that the cellulose samples used by Jessup and Prosen [83] and by Colbert et al [87] had CI values of %75. This assumption gives an adjustment of À(0.25ÁÀ113 JÁg À1 ) = 28 JÁg À1 to be applied to the values of D c H w obtained by Jessup and Prosen [83] and by Colbert et al [87]. Note that D c H Ã w for cellulose(am) is more exothermic than D c H Ã w for cellulose I (cr).…”

Section: Mid T Fitsmentioning

confidence: 99%

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A thermodynamic investigation of the cellulose allomorphs: Cellulose(am), cellulose Iβ(cr), cellulose II(cr), and cellulose III(cr)

Goldberg

Schliesser

Mittal

et al. 2015

The Journal of Chemical Thermodynamics

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a b s t r a c tThe thermochemistry of samples of amorphous cellulose, cellulose I, cellulose II, and cellulose III was studied by using oxygen bomb calorimetry, solution calorimetry in which the solvent was cadoxen (a cadmium ethylenediamine solvent), and with a Physical Property Measurement System (PPMS) in zero magnetic field to measure standard massic heat capacities C p;w over the temperature range T = (2 to 302) K. The samples used in this study were prepared so as to have different values of crystallinity indexes CI and were characterized by X-ray diffraction, by Karl Fischer moisture determination, and by using gel permeation chromatography to determine the weight average degree of polymerization DP w . NMR measurements on solutions containing the samples dissolved in cadoxen were also performed in an attempt to resolve the issue of the equivalency or non-equivalency of the nuclei in the different forms of cellulose that were dissolved in cadoxen. While large differences in the NMR spectra for the various cellulose samples in cadoxen were not observed, one cannot be absolutely certain that these cellulose samples are chemically equivalent in cadoxen. Equations were derived which allow one to adjust measured property values of cellulose samples having a mass fraction of water w H 2 O to a reference value of the mass fraction of water w ref . The measured thermodynamic properties (standard massic enthalpy of combustion D c H w , standard massic enthalpy of solution D sol H w , and C p;w ) were used in conjunction with the measured CI values to calculate values of the changes in the standard massic enthalpies of reactionD r H Ã w , the standard massic entropies of reaction D r S Ã w , the standard massic Gibbs free energies of reaction D r G Ã w , and the standard massic heat capacity D r C p;w , for the interconversion reactions of the pure (CI = 100) cellulose allomorphs, i.e., cellulose(am), cellulose I(cr), cellulose II(cr), and cellulose II(cr), at the temperature T = 298.15 K, the pressure p = 0.1 MPa, and w H 2 O = 0.073. The '' ⁄ '' denotes that the thermodynamic property pertains to pure cellulose allomorphs. Values of standard massic enthalpy differences D T 0 H w , standard massic entropy differences D T 0 S w , and the standard massic thermal functionwere calculated from the measured heat capacities for the cellulose samples and for the pure cellulose allomorphs. The extensive literature pertinent to the thermodynamic properties of cellulose has been summarized and, in many cases, property values have been calculated or recalculated from previously reported data. The thermodynamic property data show that cellulose(am) is the least stable of the cellulose allomorphs considered in this study. However, due to the uncertainties in the measured property values, it is not possible to use these values to order the relative stabilities of the cellulose (I, II, and III) crystalline allomorphs with a reasonable degree of certainty. Nevertheless, http://dx.

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Section: Mid T Fitsmentioning

confidence: 97%

Section: Mid T Fitsmentioning

confidence: 97%

Section: Mid T Fitsmentioning

confidence: 99%

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A thermodynamic investigation of the cellulose allomorphs: Cellulose(am), cellulose Iβ(cr), cellulose II(cr), and cellulose III(cr)

Goldberg

Schliesser

Mittal

et al. 2015

The Journal of Chemical Thermodynamics

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“…The pairs of samples designated as E and E' followed by the same number were prepared in such a way that each sample is "identical" (see reference [5]. p. [19][20][21][22]). The energy equivalent, E in column 3 is the average value of E, taken from table 3 plus a correction for the variation in ftIling temperature from 21 'c and for the difference between the amount of water retruned in the collector and ash in the combustor in these experi- …”

Section: Typical Resultsmentioning

confidence: 99%

“…The mean difference in the moisture contents of the unprocessed MSW minus that of the corresponding "identical" processed increments is -0.07%. Using the data analysis given in reference [19] and assuming the combustible components are given cellulose the -0.07% moisture difference, for example, corresponds to an estimated systematic error of -0.002% to be added to the average difference of -0.5% (see section 2).…”

Section: Uncertainty Estimatesmentioning

confidence: 99%

A Multi-Kilogram Capacity Calorimeter for Heterogenous Materials

Churney

Ledford

Reilly

et al. 1986

J. RES. NAT. BUR. STAN.

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A large capacity calorimeter was designed and constructed in order to determine the enthalpies of combustion of kilogram-size samples of municipal solid waste (MSW) in flowing oxygen near atmospheric pressure. The combustion of the organic fraction of the samples was complete to greater than 99.9+%. The percent coefficient of variation (100 X standard deviation/average), % ev.of calibration measurements using microcrystalline cellulose was 0.2%. The % CV of the measurements of the enthalpy of combm.tion of a processed MSW s.ample was 0.4%. The combined systematic errors due to departure from usual design standards and conventional operating procedures is estimated to be less than 0.4% of the calorific value.

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