Effect of Inhibitor Methanol on the Microscopic Structure of Aqueous Solution

Yamamoto, Yoshitaka; Nagashima, Katsuya; Kornai, Takeshi; Wakisaka, Akihiro

doi:10.1111/j.1749-6632.2000.tb06834.x

Cited by 9 publications

(11 citation statements)

References 13 publications

(36 reference statements)

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“…Indeed, it is well-known that methanol and water form complexes of variable compositions in solutions . Moreover, the water–methanol complexes are found in clathrates . The latter is of particular importance in our discussion because the clathrates provide a basic model for the development of the modern concepts on hydrophobic hydration .…”

Section: Resultsmentioning

confidence: 91%

“…35 Moreover, the water−methanol complexes are found in clathrates. 36 The latter is of particular importance in our discussion because the clathrates provide a basic model for the development of the modern concepts on hydrophobic hydration. 37 These features allow us to consider the hydro-solvation shell of a polymer, PNIPAM in particular, in water−methanol solutions as a single integrated structure, similar to that proposed first by Zhang and Wu.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

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Energetics and Mechanisms of poly(N-isopropylacrylamide) Phase Transitions in Water–Methanol Solutions

et al. 2020

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The phase transitions of poly(N-isopropylacrylamide) (PNIPAM) in water−methanol mixed solutions were studied in detail by high-sensitivity differential scanning calorimetry. From this study, the dependences of the transition temperature, enthalpy, heat capacity increment, and width on the methanol molar fraction (x MeOH ) were obtained. The transition temperature passed through a minimum at the methanol molar fraction x MeOH * ∼ 0.35. At x MeOH < x MeOH *, the transition enthalpy decreased quickly with the methanol content and became so small that it could not be measured, even with an increase in the polymer concentration by a hundred times (up to 150 mg mL −1 ). Furthermore, over this x MeOH range, the transition heat capacity increment being negative remained practically constant, but the transition width sharply increased. The transition thermograms were quantitatively described by the Okada−Tanaka theory, which takes into account the role of the polymer−solvent interaction cooperativity in the polymer thermoresponsivity. In terms of this approach, it is assumed that over the defined range of methanol content, PNIPAM possesses the cooperative hydro-solvation structure in the form of water−methanol complexes. The energetics of this structure smoothly decreases with the increase in the methanol content up to a complete disappearance of the structure at x MeOH > x MeOH *. In this range of the methanol content, the phase behavior of PNIPAM seems to be dictated by regularities typical of polymer solutions in organic solvents, that is, how the Flory−Huggins parameter depends on temperature.

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Section: Resultsmentioning

confidence: 91%

Section: ■ Results and Discussionmentioning

confidence: 99%

Energetics and Mechanisms of poly(N-isopropylacrylamide) Phase Transitions in Water–Methanol Solutions

et al. 2020

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“…[8,184] MS Molecular clustering structure; mass spectra of the clusters of water-methanol and water-propanol solutions. [46] LI Rapid formation and dissociation processes in slow motion. [51] QCM Screening low-dosage hydrate inhibitors (LDHIs); structural changes of macromolecules upon adsorption to the surface; dissociation temperatures.…”

Section: Interfacial Tension and Intermolecular Particle Forcesmentioning

confidence: 99%

“…[44] Differential scanning calorimetry (DSC) is one of the most commonly used thermal analysis methods, which has been utilised to obtain detailed equilibrium property data of gas hydrates during their solid-liquid phase transitions at a high pressure. [45,46] DSC determines the difference in the amount of heat required to increase the temperature of a sample and a reference when both materials are subjected to identical temperature regimes in an environment cooled or heated at a controlled rate. It can be used to investigate the hydrate dissociation in various aqueous media including highly concentrated salt solutions, water/oil emulsions, and actual drilling fluids, at a high pressure ranging between 5 and 12 MPa.…”

Section: Instrumental Analysis Of Gas Hydrates Thermal Analysis Of Gamentioning

confidence: 99%

“…[83] The same analysis has also been employed to study solid-liquid phasetransition properties under high pressure. [46] X-ray computerised tomography (CT) This method is used for projecting and photographing an image of crystals or the defect of crystals on a real space unit. It has been proved useful for determining the location of methane hydrates in sediments and the relationship of the gas hydrate to the host sediments, without significantly disturbing the samples at the grain scale.…”

Section: Powder X-ray Diffraction (Pxrd)mentioning

confidence: 99%

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Instrumental analysis of gas hydrates properties

Rojas

Lou

2009

Asia-Pacific J Chem Eng

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Gas hydrates attracted intense research interest when it was first recognised some 70 years ago that they were responsible for the blockage of flow lines, valves and well heads, thereby causing great loss of production and other severe safety hazards to the oil and gas industry. After many decades, these compounds are still the topic of research activities in various multi-disciplinary fields, including chemical and petroleum engineering, earth and geophysics, chemistry and environmental sciences. This is not only due to the great impact that these compounds have on the oil and gas industry, but also to the potential applications they have in many evolving areas, including, but not only, natural gas storage and transportation, carbon dioxide sequestration, and sea-water desalination. It is generally accepted that gas hydrates represent the largest source of hydrocarbons on earth, something which has not been appreciated until only recently.Management, either prevention or application or both, of gas hydrates requires a complete knowledge and understanding of the formation, decomposition and inhibition mechanisms of gas hydrates, which in turn demands advanced experimental methods and instrumental techniques for gas hydrate characterisation. This paper reviews a broad range of techniques that have been used for natural gas hydrate characterisation. It includes the basic physical science principles of each method and the gas hydrate properties that each method is capable of detecting, including some modern instrumental analyses that enable direct determination of gas hydrate phases and possible measurement of molecular interactions within the fluid phases. 

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Antifreezes Act as Catalysts for Methane Hydrate Formation from Ice

et al. 2014

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Contrary to the thermodynamic inhibiting effect of methanol on methane hydrate formation from aqueous phases, hydrate forms quickly at high yield by exposing frozen watermethanol mixtures with methanol concentrations ranging from 0.6-10 wt % to methane gas at pressures from 125 bars at 253 K. Formation rates are some two orders of magnitude greater than those obtained for samples without methanol and conversion of ice is essentially complete. Ammonia has a similar catalytic effect when used in concentrations of 0.3-2.7 wt %. The structure I methane hydrate formed in this manner was characterized by powder X-ray diffraction and Raman spectroscopy. Steps in the possible mechanism of action of methanol were studied with molecular dynamics simulations of the Ih (0001) basal plane exposed to methanol and methane gas. Simulations show that methanol from a surface aqueous layer slowly migrates into the ice lattice. Methane gas is preferentially adsorbed into the aqueous methanol surface layer. Possible consequences of the catalytic methane hydrate formation on hydrate plug formation in gas pipelines, on large scale energy-efficient gas hydrate formation, and in planetary science are discussed.

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Effect of Inhibitor Methanol on the Microscopic Structure of Aqueous Solution

Cited by 9 publications

References 13 publications

Energetics and Mechanisms of poly(N-isopropylacrylamide) Phase Transitions in Water–Methanol Solutions

Energetics and Mechanisms of poly(N-isopropylacrylamide) Phase Transitions in Water–Methanol Solutions

Instrumental analysis of gas hydrates properties

Antifreezes Act as Catalysts for Methane Hydrate Formation from Ice

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