IR Spectroscopy of aqueous alkali halides. Factor analysis

2001 ◽  
Vol 79 (1) ◽  
pp. 13-21 ◽  
Author(s):  
Jean-Joseph Max ◽  
Serge de Blois ◽  
Alain Veilleux ◽  
Camille Chapados
Keyword(s):  
Factor Analysis ◽  
Ir Spectroscopy ◽  
Aqueous Solutions ◽  
Pure Water ◽  
Alkali Halides ◽  
Attenuated Total Reflection ◽  
Order Effects ◽  
Solubility Range ◽  
Anions And Cations ◽  
Principal Species

The infrared spectra of ten salts in aqueous solutions were obtained in their solubility range using attenuated total reflection (ATR). The salts are: LiCl, NaCl, KCl, CsCl, MgCl2, NaBr, KBr, NaI, KI, and CsI. The salts, which are completely ionized in water, do not absorb in the IR. Only their interactions with water are observed and analyzed. Factor analysis (FA) applied to the spectra showed that two principal species are present in the solutions: pure water and salt-solvated water. The modifications of the water spectrum are dependent on the nature of the salts, their concentrations and are mainly of first-order. Second-order effects were observed but, being weak, were not investigated. The modifications of the IR-ATR spectrum from pure water to a salt solution are proportional to the modifications of the imaginary part of the refractive index spectrum (k(v)). This indicates that the anomalous dispersion effects do not interfere with the chemical analysis of the IR-ATR spectra. In every salt studied, the two main species present in the solutions remained stable throughout the salt solubility ranges. Comparison between the IR spectra of the different salts solutions indicates that both anions and cations are in strong interaction with water molecules and are solvated together in stable clusters.Key words: IR spectroscopy, ATR, liquid, aqueous solutions, factor analysis, principal spectra, LiCl, NaCl, KCl, CsCl, NaBr, KBr, NaI, KI, CsI, MgCl2.

1-Propanol hydrate by IR spectroscopy

2002 ◽  
Vol 80 (1) ◽  
pp. 113-123 ◽  
Author(s):  
Jean-Joseph Max ◽  
Stéphane Daneault ◽  
Camille Chapados
Keyword(s):  
Factor Analysis ◽  
Ir Spectroscopy ◽  
Hydrophobic Interactions ◽  
Pure Water ◽  
Attenuated Total Reflectance ◽  
Freely Moving ◽  
The One ◽  
Atr Spectroscopy ◽  
Ir Bands ◽  
Principal Species

The mid-IR attenuated total reflectance (mid-IR–ATR) spectra of a series of 1-propanol and water mixtures were obtained. Factor analysis (FA) applied to spectra gave the spectra of three principal species and their abundance: pure water, pure propanol, and a 1-propanol hydrate (1:1). When compared to the pure solvents, the hydrate propanol bands were modified which indicated that the valence bonds were perturbed. The assignment of the hydrate IR bands was made by comparing them with those of pure 1-propanol and pure water. No monomer was observed which indicated that all species were associated. The simplest representation of the different associations is by groups of two on which an intermolecular bond (H-bond) can be placed. The exchange between the molecules can be represented by the following equation: (H2O···H2O) + (CH3CH2CH2OH···OHCH2CH2CH3) [Formula: see text] 2(CH3CH2CH2OH···OH2). The hydrate's formation constant (Kf) is 1.2 (±0.2). This value is less than the one expected from the association of freely moving molecules, indicating that the hydrophobic interactions of the 1-propanol aliphatic chains decrease the strength of the hydrogen bond between water and alcohol in the hydrate.Key words: IR spectroscopy, ATR spectroscopy, 1-propanol, liquid, aqueous solutions, eigenspectra, hydrate, factor analysis.

Coefficient d'activité de l'acide sulfurique déterminé par titrage infrarouge

2000 ◽  
Vol 78 (8) ◽  
pp. 1128-1142 ◽  
Author(s):  
Christophe Ménichelli ◽  
Jean-Joseph Max ◽  
Camille Chapados
Keyword(s):  
Factor Analysis ◽  
Ir Spectroscopy ◽  
Aqueous Solutions ◽  
Activity Coefficients ◽  
Total Concentration ◽  
Relative Concentration ◽  
Ionic Species ◽  
Attenuated Total Reflection ◽  
Equilibrium Equations ◽  
Ph Range

The titration of sulphuric acid by infrared spectroscopy using the attenuated total reflection (ATR) technique was made in the 0 to 14 pH range for solutions ranging from 1.89 to 0.01 M. The subtraction of the water spectrum was made using acidic, neutral, and basic waters which exhibit different spectra. The results gave the spectra of mixtures of the HSO–4 and SO2–4 ionic species in solutions. For each concentration, factor analysis (FA) sorted the spectra of the pure ionic species and gave through the multiplying factors (MF) the distribution of the species as a function of pH. This distribution is the same as that obtained from the equilibrium equations. The IR measurements gave directly the ratios of the activity coefficients of HSO–4 and SO2–4 ions. This ratio varies with the total concentration of both ions but is independent of the relative concentration. The fitting of the experimental and theoretical volumetric titration curves in the high and low pH regions gave the mean activity coefficients of the other species present in the solutions. The values obtained are comparable to those obtained by electrochemical measurements. These results show that it is possible to use IR spectroscopy to study aqueous solutions of inorganic acids from low to high concentrations.Key words : IR spectroscopy, sulfuric acid, aqueous solutions, factor analysis, ATR, principal spectra, solvation, activity coefficients, IR titration.

IR Spectroscopy of aqueous alkali halides. Factor analysis

2001 ◽  
Vol 79 (1) ◽  
pp. 13-21 ◽  
Author(s):  
Jean-Joseph Ma× ◽  
Serge de Blois ◽  
Alain Veilleu× ◽  
Camille Chapados
Keyword(s):  
Factor Analysis ◽  
Ir Spectroscopy ◽  
Alkali Halides ◽  
Aqueous Alkali

scholarly journals Valorization of Spent Coffee by Caffeine Extraction Using Aqueous Solutions of Cholinium-Based Ionic Liquids

2021 ◽  
Vol 13 (13) ◽  
pp. 7509
Author(s):  
Ana M. Ferreira ◽  
Hugo M. D. Gomes ◽  
João A. P. Coutinho ◽  
Mara G. Freire
Keyword(s):  
Ionic Liquids ◽  
Aqueous Solutions ◽  
Pure Water ◽  
Waste Product ◽  
Weight Ratio ◽  
Extraction Yield ◽  
Operational Conditions ◽  
Coffee Grounds ◽  
Extractable Compounds ◽  
Nutraceutical Products

Spent coffee grounds (SCGs) are a waste product with no relevant commercial value. However, SCGs are rich in extractable compounds with biological activity. To add value to this coffee byproduct, water and aqueous solutions of cholinium-based ionic liquids (ILs) were studied to extract caffeine from SCGs. In general, all IL aqueous solutions lead to higher extraction efficiencies of caffeine than pure water, with aqueous solutions of cholinium bicarbonate being the most efficient. A factorial planning was applied to optimize operational conditions. Aqueous solutions of cholinium bicarbonate, at a temperature of 80 °C for 30 min of extraction, a biomass–solvent weight ratio of 0.05 and at an IL concentration of 1.5 M, made it possible to extract 3.29 wt% of caffeine (against 1.50 wt% obtained at the best conditions obtained with pure water). Furthermore, to improve the sustainability of the process, the same IL aqueous solution was consecutively applied to extract caffeine from six samples of fresh biomass, where an increase in the extraction yield from 3.29 to 13.10 wt% was achieved. Finally, the cholinium bicarbonate was converted to cholinium chloride by titration with hydrochloric acid envisioning the direct application of the IL-caffeine extract in food, cosmetic and nutraceutical products. The results obtained prove that aqueous solutions of cholinium-based ILs are improved solvents for the extraction of caffeine from SCGs, paving the way for their use in the valorization of other waste rich in high-value compounds.

scholarly journals Photo-transformation of aqueous nitroguanidine and 3-nitro-1,2,4-triazol-5-one : emerging munitions compounds

2021 ◽  
Author(s):  
Julie Becher ◽  
Samuel Beal ◽  
Susan Taylor ◽  
Katerina Dontsova ◽  
Dean Wilcox
Keyword(s):  
Aqueous Solutions ◽  
Degradation Products ◽  
Pure Water ◽  
Transformation Products ◽  
Water Soluble ◽  
Uv Exposure ◽  
Degradation Pathways ◽  
Solution Ph ◽  
Photo Degradation ◽  
Degradation Rates

Two major components of insensitive munition formulations, nitroguanidine (NQ) and 3-nitro-1,2,4-triazol-5-one (NTO), are highly water soluble and therefore likely to photo-transform while in solution in the environment. The ecotoxicities of NQ and NTO solutions are known to increase with UV exposure, but a detailed accounting of aqueous degradation rates, products, and pathways under different exposure wavelengths is currently lacking. We irradiated aqueous solutions of NQ and NTO over a 32-h period at three ultraviolet wavelengths and analyzed their degradation rates and transformation products. NQ was completely degraded by 30 min at 254 nm and by 4 h at 300 nm, but it was only 10% degraded after 32 h at 350 nm. Mass recoveries of NQ and its transformation products were >80% for all three wavelengths. NTO degradation was greatest at 300 nm with 3% remaining after 32 h, followed by 254 nm (7% remaining) and 350 nm (20% remaining). Mass recoveries of NTO and its transformation products were high for the first 8 h but decreased to 22–48% by 32 h. Environmental half-lives of NQ and NTO in pure water were estimated as 4 and 6 days, respectively. We propose photo-degradation pathways for NQ and NTO supported by observed and quantified degradation products and changes in solution pH.

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