The Widom line and dynamical crossover in supercritical water: Popular water models versus experiments

2015 ◽  
Vol 143 (11) ◽  
pp. 114502 ◽  
Author(s):  
D. Corradini ◽  
M. Rovere ◽  
P. Gallo
Keyword(s):  
Supercritical Water ◽  
Widom Line ◽  
Water Models ◽  
Dynamical Crossover

Dynamical crossover and its connection to the Widom line in supercooled TIP4P/Ice water

2021 ◽  
Vol 155 (5) ◽  
pp. 054502
Author(s):  
Laura Lupi ◽  
Benjamín Vázquez Ramírez ◽  
Paola Gallo
Keyword(s):  
Widom Line ◽  
Ice Water ◽  
Dynamical Crossover

scholarly journals Origin of the emergent fragile-to-strong transition in supercooled water

2018 ◽  
Vol 115 (38) ◽  
pp. 9444-9449 ◽  
Author(s):  
Rui Shi ◽  
John Russo ◽  
Hajime Tanaka
Keyword(s):  
Experimental Data ◽  
Glass Transition ◽  
Supercooled Water ◽  
Arrhenius Law ◽  
Widom Line ◽  
Slowing Down ◽  
Strong Transition ◽  
Dynamical Properties ◽  
Water Models ◽  
Insight Into

Liquids can be broadly classified into two categories, fragile and strong ones, depending on how their dynamical properties change with temperature. The dynamics of a strong liquid obey the Arrhenius law, whereas the fragile one displays a super-Arrhenius law, with a much steeper slowing down upon cooling. Recently, however, it was discovered that many materials such as water, oxides, and metals do not obey this simple classification, apparently exhibiting a fragile-to-strong transition far above Tg. Such a transition is particularly well known for water, and it is now regarded as one of water’s most important anomalies. This phenomenon has been attributed to either an unusual glass transition behavior or the crossing of a Widom line emanating from a liquid–liquid critical point. Here by computer simulations of two popular water models and through analyses of experimental data, we show that the emergent fragile-to-strong transition is actually a crossover between two Arrhenius regimes with different activation energies, which can be naturally explained by a two-state description of the dynamics. Our finding provides insight into the fragile-to-strong transition observed in a wide class of materials.

scholarly journals Dynamical crossover line in supercritical water

2015 ◽  
Vol 5 (1) ◽  
Author(s):  
Yu. D. Fomin ◽  
V. N. Ryzhov ◽  
E. N. Tsiok ◽  
V. V. Brazhkin
Keyword(s):  
Supercritical Water ◽  
Dynamical Crossover

scholarly journals Visualization of supercritical water pseudo-boiling at Widom line crossover

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Florentina Maxim ◽  
Cristian Contescu ◽  
Pierre Boillat ◽  
Bojan Niceno ◽  
Konstantinos Karalis ◽  
...  
Keyword(s):  
Supercritical Water ◽  
New Technologies ◽  
Waste Treatment ◽  
Imaging Techniques ◽  
Current Theory ◽  
Density Fluctuations ◽  
Neutron Imaging ◽  
Materials Synthesis ◽  
Natural Systems ◽  
Widom Line

Abstract Supercritical water is a green solvent used in many technological applications including materials synthesis, nuclear engineering, bioenergy, or waste treatment and it occurs in nature. Despite its relevance in natural systems and technical applications, the supercritical state of water is still not well understood. Recent theories predict that liquid-like (LL) and gas-like (GL) supercritical water are metastable phases, and that the so-called Widom line zone is marking the crossover between LL and GL behavior of water. With neutron imaging techniques, we succeed to monitor density fluctuations of supercritical water while the system evolves rapidly from LL to GL as the Widom line is crossed during isobaric heating. Our observations show that the Widom line of water can be identified experimentally and they are in agreement with the current theory of supercritical fluid pseudo-boiling. This fundamental understanding allows optimizing and developing new technologies using supercritical water as a solvent.

scholarly journals Supercritical water anomalies in the vicinity of the Widom line

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Konstantinos Karalis ◽  
Christian Ludwig ◽  
Bojan Niceno
Keyword(s):  
Supercritical Water ◽  
Industrial Applications ◽  
Density Fluctuations ◽  
Anomalous Behaviour ◽  
Detailed Knowledge ◽  
Interatomic Potentials ◽  
Homogeneous Fluid ◽  
Widom Line ◽  
Scale Inhomogeneity ◽  
Dynamics Simulations

Abstract Supercritical water is used in a variety of chemical and industrial applications. As a consequence, a detailed knowledge of the structure-properties correlations is of uttermost importance. Although supercritical water was considered as a homogeneous fluid, recent studies revealed an anomalous behaviour due to nanoscale density fluctuations (inhomogeneity). The inhomogeneity is clearly demarked through the Widom line (maxima in response factions) and drastically affect the properties. In the current study the physical properties of supercritical water have been determined by classical molecular dynamics simulations using a variety of polarized and polarizable interatomic potentials. Their validity which was not available at supercritical conditions has been assessed based on the ability to reproduce experimental data. Overall, the polarized TIP4P/2005 model accurately predicted the properties of water in both liquid-like and gas-like regions. All interatomic potentials captured the anomalous behaviour providing a direct evidence of molecular-scale inhomogeneity.

PENGGUNAAN AIR SUPER KRITIS PADA DEPOLIMERISASI NYLON-12 (BATCH PROCESS)

2018 ◽  
Vol 5 (3) ◽  
Author(s):  
Mohamad Yusman
Keyword(s):  
Supercritical Water ◽  
Scale Up ◽  
Experimental Studies ◽  
Reaction System ◽  
Batch Process ◽  
Chemical Recycling ◽  
Water Decomposition ◽  
Product Distributions ◽  
New Process ◽  
Nylon 12

Water at the supercritical state is a new process for the chemical recycling. At this thermodynamic state i.e. Pc = 218 atmospheres and Tc = 374oC , water behaves very differently from its everyday temperament and it is a very good solvent for organic components. Experimental studies show that supercritical water can decompose hydrocarbons/polymers and produce useful products like 2-Azacyclotridecanone /lactam-1 from Nylon-12 (batch process). The decomposition process itself was carried out in batch reaction system in order to get more information about product distributions, time dependence, and scale-up possibilities.Keywords: supercritical water, decomposition, batch, polymer, hydrocarbon

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