Quantification of Hydrofluoric Acid Species by Chemical-Modeling Regression of Near-Infrared Spectra

Thompson, Christopher J.; Danielson, and J. D. Sheldon; Callis, James B.

doi:10.1021/ac9604550

Cited by 19 publications

(8 citation statements)

References 43 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…CMR is a multivariate analysis technique in which a set of orthogonal eigenvectors, computed from absorbance spectra, is iteratively fit to a chemical model by adjusting the model parameters. Thompson and colleagues demonstrated the utility of CMR for estimating the equilibrium constants and species concentrations for the hydrofluoric acid system (Thompson et al 1997). In the case of pH measurements using an indicating dye, the calibration spectra would consist of constant-concentration dye solutions buffered to span a desired pH range, and the chemical model is derived from the HendersonHasselbalch and mass-balance equations for the system: 6) where is the total concentration of the dye in solution.…”

Section: Discussionmentioning

confidence: 99%

FY12 ARRA-NRAP Report ? Studies to Support Risk Assessment of Geologic Carbon Sequestration

Cantrell¹,

Shao²,

Thompson³

et al. 2011

View full text Add to dashboard Cite

SummaryThis report summarizes results of research conducted during FY 2012 to support the assessment of environmental risks associated with geologic carbon dioxide (CO 2 ) sequestration and storage. Several research focus areas are ongoing as part of this project. This includes the quantification of the leachability of metals and organic compounds from representative CO 2 storage reservoir and caprock materials, the fate of metals and organic compounds after release, and the development of a method to measure pH in situ under supercritical CO 2 (scCO 2 ) conditions.Metal leachability experiments were completed on six different rock samples in brine in equilibrium with scCO 2 at representative geologic reservoir conditions. In general, the leaching of Resource Conservation and Recovery Act of 1976 metals and other metals of concern was found to be limited and not likely to be a significant issue (at least, for the rocks tested). Metals leaching experiments were also completed on one rock sample with scCO 2 containing oxygen at concentrations of 0%, 1%, 4%, and 8% to simulate injection of CO 2 originating from the oxy-fuel combustion process. Significant differences in the leaching behavior of certain metals were observed when oxygen is present in the CO 2 . These differences resulted from oxidation of sulfides, release of sulfate, ferric iron and other metals, and subsequent precipitation of iron oxides and some sulfates such as barite.Experiments to evaluate the potential for mobilization of organic compounds from representative reservoir materials and cap rock and their fate in porous media (quartz sand) have been conducted. Results with Fruitland coal and Gothic shale indicate that lighter organic compounds were more susceptible to mobilization by scCO 2 compared to heavier compounds. Alkanes demonstrated very low extractability by scCO 2 . No significant differences were observed between the extractability of organic compounds by dry or water saturated scCO 2 . Reaction equilibrium appears to have been reached by 96 hours.When the scCO 2 was released from the reactor, less than 60% of the injected lighter compounds (benzene, toluene) were transported through the dry sand column by the CO 2 , while more than 90% of the heavier organics were trapped in the sand column. For wet sand columns, most (80% to 100%) of the organic compounds injected into the sand column passed through, except for naphthalene which was substantially removed from the CO 2 within the column.A spectrophotometric method was developed to measure pH in brines in contact with scCO 2 . This method provides an alternative to fragile glass pH electrodes and thermodynamic modeling approaches for estimating pH. The method was tested in simulated reservoir fluids (CO 2 -NaCl-H 2 O) at different temperatures, pressures, and ionic strengths, and the results were compared with other experimental studies and geochemical models. Measured pH values were generally in agreement with the models, but inconsistencies were present between some of the models.v

show abstract

Section: Discussionmentioning

confidence: 99%

FY12 ARRA-NRAP Report ? Studies to Support Risk Assessment of Geologic Carbon Sequestration

Cantrell¹,

Shao²,

Thompson³

et al. 2011

View full text Add to dashboard Cite

show abstract

“…At this point we are able to point out the distinctive nature of the NaF solution. Previous ab initio simulation study of fluorine hydration, [27] as well as mid-infrared [28] and NIR [29] studies of hydrofluoric acid, showed uncertainties in the hydration structure and dissociation configuration of F and HF, as they are accompanied by the formation of various hydrogenbonded complexes (HF, HF 2 À , [H 3 O·F] À ) with exceptionally strong OÀH···F hydrogen bonding. Our measurement of pH ( % 7.98 at the 1.2 m level) suggested that significant ionization does take place and that we do not observe freely hydrated F À ions in the solution.…”

Section: Pure-water-subtracted Spectramentioning

confidence: 99%

Water Confined in the Local Field of Ions

et al. 2014

View full text Add to dashboard Cite

Interionic distances are shorter in concentrated ionic solutions, thus instigating the interaction and overlap of hydration shells, as ions become separated by only one or two layers of water molecules. The simultaneous interaction of water with two oppositely charged ions has, so far, only been investigated by computer simulation studies, because the isolated vibrational spectroscopic signature of these molecules remains undetected. Our combined near-infrared spectroscopic and molecular dynamics simulation studies of alkali halide solutions present a distinct spectral feature, which is highly responsive to depletion of bulk water and merging of hydration shells. The analysis of this spectral feature demonstrates that absorption trends are in good agreement with the law of matching affinities, thus providing the first successful vibrational spectroscopic treatment of this topic. Combined with commonly observed near-infrared bands, this feature provides a spectral pattern that describes some relevant aspects of ionic hydration.

show abstract

“…Besides the advantages of NIR spectroscopy, there are drawbacks to it, including its low sensitivity and the characteristic broadness of absorption bands, which often results in overlapped spectra (Thompson et al, 1997). For such spectra, multivariate calibration methods, such as principal component analysis (PCA), discriminant analysis (DA), soft independent modeling of class analogy (SIMCA), artificial neural networks (ANN), discriminant partial least-squares (DPLS), and so on, open the possibility to unravel and interpret the optical properties of the sample and allow a classification without the use of chemical information (Liu et al, 2006).…”

Section: Introductionmentioning

confidence: 99%

Use of near-infrared spectroscopy and least-squares support vector machine to determine quality change of tomato juice

Xie

2009

J. Zhejiang Univ. Sci. B

View full text Add to dashboard Cite

Near-infrared (NIR) transmittance spectroscopy combined with least-squares support vector machine (LS-SVM) was investigated to study the quality change of tomato juice during the storage. A total of 100 tomato juice samples were used. The spectrum of each tomato juice was collected twice: the first measurement was taken when the tomato juice was fresh and had not undergone any changes, and the second measurement was taken after a month. Principal component analysis (PCA) was used to examine a potential capability of separating juice before and after the storage. The soluble solid content (SSC) and pH of the juice samples were determined. The results show that changes in certain compounds between tomato juice before and after the storage period were obvious. An excellent precision was achieved by LS-SVM model compared with discriminant partial least-squares (DPLS), soft independent modeling of class analogy (SIMCA), and discriminant analysis (DA) models, with 100% of a total accuracy. It can be found that NIR spectroscopy coupled with LS-SVM, DPLS, SIMCA, and DA can be used to control the quality change of tomato juice during the storage.

show abstract

Quantification of Hydrofluoric Acid Species by Chemical-Modeling Regression of Near-Infrared Spectra

Cited by 19 publications

References 43 publications

FY12 ARRA-NRAP Report ? Studies to Support Risk Assessment of Geologic Carbon Sequestration

FY12 ARRA-NRAP Report ? Studies to Support Risk Assessment of Geologic Carbon Sequestration

Water Confined in the Local Field of Ions

Use of near-infrared spectroscopy and least-squares support vector machine to determine quality change of tomato juice

Contact Info

Product

Resources

About