Characterization of clathrate hydrate formed in H2 + CO2 + tetrahydropyran + water system as carbon capture materials

The preparation conditions in the water system of phenylalanine chelated calcium complex have been evaluated though single-factor tests and optimized by uniform design. Then the optimal parameters were obtained as follows: reaction temperature is 40 °C, reaction time is 182 min, the molar ratio of phenylalanine to calcium is 4.3 and pH = 9.0. Under the best conditions, the experimental result gives chelating rate = 87.40% that is 17.12% lower than the prediction = 104.52%.The infrared spectrum characterization has confirmed the formation of phenylalanine-Ca2+ chelates and the existence of chelate ring.

Download Full-text

Clathrate and other solid phases in the tetrahydrofuran–water system: thermal conductivity and heat capacity under pressure

Canadian Journal of Chemistry ◽

10.1139/v82-132 ◽

1982 ◽

Vol 60 (7) ◽

pp. 881-892 ◽

Cited By ~ 84

Author(s):

Russell G. Ross ◽

Per Andersson

Keyword(s):

Thermal Conductivity ◽

Heat Capacity ◽

Water System ◽

Clathrate Hydrate ◽

Transient Hot Wire ◽

Guest Molecules ◽

Hydrate Phase ◽

Wire Method ◽

Solid Phases ◽

Thermal Conductivity Λ

Solid phases in the tetrahydrofuran–water (THF–H2O) system were investigated in the temperature range 100–260 K and at pressures up to 1.5 GPa. Thermal conductivity, λ, and heat capacity per unit volume, ρcp, were measured, using the transient hot-wire method. We made measurements on solid phases having nominal compositions THF•17H2O, THF•7•1H2O, and THF•4•6H2O, which we refer to as phases α, β, and γ, respectively. Phase α is known to be a structure II clathrate hydrate, and λ for this phase was found to be similar to other crystalline solids which are glass-like in relation to their thermal properties. Low-energy excitations are known to be relevant to the properties of glass-like solids, and, in the case of phase α, were probably rotational vibrations of the THF guest molecules. Phase β was similar, and we inferred that it was probably a structure I clathrate hydrate. Phase γ behaved nearly like a normal crystal phase at low temperatures, but λ became almost independent of temperature near melting. At 1.1 GPa and 130 K, we found evidence that phase α transformed, on pressurization, to a metastable modification which may be a new high-density form of clathrate hydrate. The astrophysical implications of our results were mentioned briefly.

Download Full-text

The hydrological response of baseflow in fractured mountain areas

Hydrology and Earth System Sciences Discussions ◽

10.5194/hessd-6-3359-2009 ◽

2009 ◽

Vol 6 (2) ◽

pp. 3359-3384 ◽

Cited By ~ 5

Author(s):

A. Millares ◽

M. J. Polo ◽

M. A. Losada

Keyword(s):

Hydrological Model ◽

Water System ◽

Essential Element ◽

Mediterranean Area ◽

Mountainous Areas ◽

Mountain Areas ◽

Linear Behavior ◽

Time Period ◽

Recession Curves

Abstract. The study of baseflow in mountainous areas of basin headwaters, where the characteristics of the often fractured materials are very different to the standard issues concerning porous material applied in conventional hydrogeology, is an essential element in the characterization and quantification of water system resources. Their analysis through recession fragments provides information on the type of response of the sub-surface and subterranean systems and on the average relation between the storage and discharge of aquifers, starting from the joining of these fragments into a single curve, the Master Recession Curve (MRC). This paper presents the generation of the downward MRC over fragments selected after a preliminary analysis of the recession curves, using a hydrological model as the methodology for the identification and the characterization of quick sub-surface flows flowing through fractured materials. The hydrological calculation has identified recession fragments through surface runoff or snowmelt and those periods of intense evapotranspiration. The proposed methodology has been applied to three sub-basins belonging to a high altitude mountain basin in the Mediterranean area, with snow present every year, and their results were compared with those for the upward concatenation of the recession fragments. The results show the existence of two different responses, one quick (at the sub-surface, through the fractured material) and the other slow, with linear behavior which takes place in periods of 10 and 17 days, respectively and which is linked to the dimensions of the sub-basin. In addition, recesses belonging to the dry season have been selected in order to compare and validate the results corresponding to the study of recession fragments. The comparison, using these two methodologies, which differ in the time period selected, has allowed us to validate the results obtained for the slow flow.

Download Full-text

Worth a Closer Look: Raman Spectra of Lead-Pipe Scale

Minerals ◽

10.3390/min11101047 ◽

2021 ◽

Vol 11 (10) ◽

pp. 1047

Author(s):

Jill Dill Pasteris ◽

Yeunook Bae ◽

Daniel E. Giammar ◽

Sydney N. Dybing ◽

Claude H. Yoder ◽

...

Keyword(s):

Cross Sections ◽

Water System ◽

Analytical Techniques ◽

Real Time Analysis ◽

Fiber Optic Probes ◽

Lead Pipe ◽

Lead Pipes ◽

Non Destructive

The identification and characterization of lead-bearing and associated minerals in scales on lead pipes are essential to understanding and predicting the mobilization of lead into drinking water. Despite its long-recognized usefulness in the unambiguous identification of crystalline and amorphous solids, distinguishing between polymorphic phases, and rapid and non-destructive analysis on the micrometer spatial scale, the Raman spectroscopy (RS) technique has been applied only occasionally in the analysis of scales in lead service lines (LSLs). This article illustrates multiple applications of RS not just for the identification of phases, but also compositional and structural characterization of scale materials in harvested lead pipes and experimental pipe-loop/recirculation systems. RS is shown to be a sensitive monitor of these characteristics through analyses on cross-sections of lead pipes, raw interior pipe walls, particulates captured in filters, and scrapings from pipes. RS proves to be especially sensitive to the state of crystallinity of scale phases (important to their solubility) and to the specific chemistry of phases precipitated upon the introduction of orthophosphate to the water system. It can be used effectively alone as well as in conjunction with more standard analytical techniques. By means of fiber-optic probes, RS has potential for in situ, real-time analysis within water-filled pipes.

Download Full-text