scholarly journals Induced polarization response of porous media with metallic particles — Part 8: Influence of temperature and salinity

Geophysics ◽  
2018 ◽  
Vol 83 (6) ◽  
pp. E435-E456 ◽  
Author(s):  
André Revil ◽  
Antoine Coperey ◽  
Deqiang Mao ◽  
Feras Abdulsamad ◽  
Ahmad Ghorbani ◽  
...  
Keyword(s):  
Activation Energy ◽  
Background Electrolyte ◽  
Element Model ◽  
Induced Polarization ◽  
Arrhenius Law ◽  
Water Conductivity ◽  
Dc Conductivities ◽  
Influence Of Temperature ◽  
Metallic Particles ◽  
C 50

We have investigated the influence of temperature and salinity upon the spectral induced polarization of 10 samples including rocks with their mineralization (galena, chalcopyrite) plus sand mixed with semiconductors such as magnetite grains, graphite, and pyrite cubes of two different sizes. Measurements are made in a temperature-controlled bath with a high-precision impedance meter and using NaCl solutions. We cover the temperature range 5°C−50°C and the frequency range [Formula: see text] to 45 kHz. For one large pyrite cube, we also investigated six salinities from 0.1 to [Formula: see text] (at 25°C, NaCl) and three salinities for graphite. The spectra are fitted with a Cole-Cole complex parametric conductivity model for which we provide a physical meaning to the four Cole-Cole parameters. As expected, the Cole-Cole exponent and the chargeability are independent of the temperature and salinity. The instantaneous and steady state (direct current [DC]) conductivities depend on the salinity and temperature. This temperature dependence can be fitted with an Arrhenius law (combining the Stokes-Einstein and Vogel-Fulcher-Tammann equations) with an activation energy in the range of [Formula: see text]. This activation energy is the same as for the bulk pore-water conductivity demonstrating the control by the background electrolyte of these quantities, as expected. The instantaneous and DC conductivities depend on the salinity in a predictable way. The Cole-Cole relaxation time decreases with the temperature and decreases with the salinity. This behavior can be modeled with an Arrhenius law with an apparent activation energy of [Formula: see text]. A finite-element model is used further to analyze the mechanisms of polarization, and it can reproduce the temperature and salinity dependencies observed in the laboratory.

Induced polarization response of porous media with metallic particles — Part 6: The case of metals and semimetals

Geophysics ◽  
2017 ◽  
Vol 82 (2) ◽  
pp. E97-E110 ◽  
Author(s):  
André Revil ◽  
Deqiang Mao ◽  
Zhenlu Shao ◽  
Michael F. Sleevi ◽  
Deming Wang
Keyword(s):  
Relaxation Time ◽  
Tap Water ◽  
Core Sample ◽  
Induced Polarization ◽  
Copper Plate ◽  
Secondary Source ◽  
Water Conductivity ◽  
Metallic Particles ◽  
Two Parameters ◽  
Polarization Spectra

We collected spectral induced polarization spectra with clean sand mixed with metallic particles (either silver, graphite, copper, steel, magnetite, or pyrite particles). The initial pore water conductivity was either 1500 or [Formula: see text] depending on the experiments (25°C, NaCl). For each of the 15 experiments, we used a narrow and unimodal grain size distribution for the metallic particles. The resulting polarization spectra display clear polarization peaks in the phase and can be fitted with a Cole-Cole complex conductivity model. In addition to this, the chargeability scales with the volume content of the metallic particles in a way that is consistent with the theory of disseminated metallic particles in a weakly polarizable background. Similarly, the phase scales with the content of the metallic particles in a predictable way. The Cole-Cole relaxation time shows a rough dependence with the mean particle size. The trend between these two parameters can be used to determine an apparent diffusion coefficient for the charge carriers responsible for the polarization. Finally, we conducted a laboratory sandbox experiment in which we put a copper plate in tap water-saturated sand. We use an approach based on self-potential tomography and compactness to invert the secondary source current density from the secondary voltages associated with time-domain induced polarization. With this approach, we localized the copper plate and determined a value for the relaxation time that is consistent with the laboratory core sample experiments.

Lithium tracer diffusion in LiNi0.33Mn0.33Co0.33O2 cathode material for lithium-ion batteries

2021 ◽  
Vol 23 (10) ◽  
pp. 5992-5998
Author(s):  
Daniel Uxa ◽  
Helen J. Holmes ◽  
Kevin Meyer ◽  
Lars Dörrer ◽  
Harald Schmidt
Keyword(s):  
Activation Energy ◽  
Cathode Material ◽  
Lithium Ion Batteries ◽  
Lithium Ion ◽  
Tracer Diffusion ◽  
Arrhenius Law

Lithium tracer diffusivities in LiNi0.33Mn0.33Co0.33O2 cathode material for lithium-ion batteries follows the Arrhenius law with an activation energy of 0.85 eV.

scholarly journals Induced polarization response of porous media with metallic particles — Part 7: Detection and quantification of buried slag heaps

Geophysics ◽  
2018 ◽  
Vol 83 (5) ◽  
pp. E277-E291 ◽  
Author(s):  
Youzheng Qi ◽  
Abdellahi Soueid Ahmed ◽  
André Revil ◽  
Ahmad Ghorbani ◽  
Feras Abdulsamad ◽  
...  
Keyword(s):  
Metal Content ◽  
Induced Polarization ◽  
Ore Deposits ◽  
Magnetic Method ◽  
Complex Conductivity ◽  
Metallic Particles ◽  
Polarization Response ◽  
Slag Heap ◽  
Detection And Quantification ◽  
Metallurgical Activities

With the progress of metallurgical activities, more and more dumped slag heaps emerge as valuable deposits to feed the growing need for metal resources. Detecting, quantifying, and reextracting metals from these slags may complement the prospection of new ore deposits. However, the spatial delineation of the slag heap cannot easily be obtained from the resistivity distribution alone (determined either with galvanometric or with induction-based methods). Although the magnetic method can detect slag heaps, it fails to make an estimation of the quantity of metal present in the slag. Alternatively, the induced polarization (IP) method can be used to fulfill this goal. The complex conductivity responses of slag samples from a slag heap in France are obtained in the laboratory. These data are used to assess the grade of the slag, which is close to 8%. Then, a least-squares 3D IP inversion is used to get the subsurface chargeability distribution delimiting the slag heap in the ground. From the linear relationship determined between the chargeability and the volumetric metal content or the volumetric slag content, the metallic volume of the slag heaps can be directly determined. This approach is used at the site of Saint-Vincent sur L'Isle, Dordogne (France), where it allows characterizing the shape of a slag heap and quantifying the total cumulative metal content of the investigated area.

scholarly journals The Application of Equivalent Age Concept to Sand Concrete Compared to Ordinary Concrete

2016 ◽  
Vol 2016 ◽  
pp. 1-7 ◽  
Author(s):  
Nabil Bella ◽  
Ilham Aguida Bella ◽  
Aissa Asroun
Keyword(s):  
Activation Energy ◽  
Coarse Aggregate ◽  
Strength Development ◽  
Arrhenius Law ◽  
Ordinary Concrete ◽  
Equivalent Age ◽  
Heat Treated ◽  
Sand Filler ◽  
Energy Activation ◽  
Prestressed Beams

In this research the equivalent age concept was used, in order to simulate strength development of heat treated sand concrete compared with ordinary concrete at different temperature, 35, 55, and 70°C, and validate the simulation results with our experimental results. Sand concrete is a concrete with a lower or without coarse aggregate dosage; it is used to realize thin element as small precast prestressed beams, in injected concrete or in regions where sand is in extra quantity and the coarse aggregate in penury. This concrete is composed by principally sand, filler, superplasticizer, water, and cement. The results show that the simulation of ordinary concrete was acceptable with an error lower than 20%. But the error was considerable for the sand concrete. The error was due to large superplasticizer dosage, which modified the hardening of sand concrete; the most influent parameter in Arrhenius law is apparent energy activation, to search for the value of the activation energy which gives the best simulation; a superposition is used of two curves of different temperature and with superplasticizer dosage 4% and several values of activation energy, 15, 20, 25, and 30 × 10 kcal. The simulation becomes ameliorated with the adequate value of activation energy.

scholarly journals Influence of Temperature on Free Radical Generation in Propolis-Containing Ointments

2016 ◽  
Vol 2016 ◽  
pp. 1-8 ◽  
Author(s):  
Paweł Olczyk ◽  
Pawel Ramos ◽  
Katarzyna Komosinska-Vassev ◽  
Lukasz Mencner ◽  
Krystyna Olczyk ◽  
...  
Keyword(s):  
Free Radicals ◽  
Free Radical ◽  
Heating Temperature ◽  
Radical Formation ◽  
Paramagnetic Resonance ◽  
Influence Of Temperature ◽  
Spin Lattice ◽  
Influence Of Temperature On ◽  
Free Radical Formation ◽  
C 50

Free radicals thermally generated in the ointments containing propolis were studied by electron paramagnetic resonance (EPR) spectroscopy. The influence of temperature on the free radical concentration in the propolis ointments was examined. Two ointment samples with different contents of propolis (5 and 7%, resp.) heated at temperatures of 30°C, 40°C, 50°C, and 60°C, for 30 min., were tested. Homogeneously broadened EPR lines and fast spin-lattice interactions characterized all the tested samples. Free radicals concentrations in the propolis samples ranged from 1018 to 1020 spin/g and were found to grow in both propolis-containing ointments along with the increasing heating temperature. Free radical concentrations in the ointments containing 5% and 7% of propolis, respectively, heated at temperatures of 30°C, 40°C, and 50°C were only slightly different. Thermal treatment at the temperature of 60°C resulted in a considerably higher free radical formation in the sample containing 7% of propolis when related to the sample with 5% of that compound. The EPR examination indicated that the propolis ointments should not be stored at temperatures of 40°C, 50°C, and 60°C. Low free radical formation at the lowest tested temperatures pointed out that both examined propolis ointments may be safely stored up to the temperature of 30°C.

scholarly journals О термической устойчивости некоторых квазифуллеренов

2019 ◽  
Vol 61 (3) ◽  
pp. 604
Author(s):  
А.И. Подливаев ◽  
Л.А. Опенов
Keyword(s):  
Activation Energy ◽  
Molecular Dynamics ◽  
Thermal Stability ◽  
Frequency Factor ◽  
Arrhenius Law ◽  
Method Of Molecular Dynamics ◽  
Temperature Dependences ◽  
Thermal Stability Of

AbstractThe thermal stability of recently predicted quasi-fullerenes С_20, С_42, С_48, and С_60 is studied by the method of molecular dynamics. The routes of their decomposition and the temperature dependences of their lifetimes are determined. The activation energy and frequency factor values that appear in the Arrhenius law are found. New isomers are detected.

scholarly journals Kinetics of barite reduction from refractory barite-sulphide ore

10.30544/237 ◽  
2016 ◽  
Vol 22 (4) ◽  
pp. 261-268 ◽  
Author(s):  
Miroslav D Sokić ◽  
Vladislav Matković ◽  
Jovica Stojanović ◽  
Branislav Marković ◽  
Vaso Manojlović
Keyword(s):  
Experimental Data ◽  
Activation Energy ◽  
Kinetic Model ◽  
Copper Sulphide ◽  
Influence Of Temperature ◽  
Sulphide Ore ◽  
Lead Zinc ◽  
Complex Structural ◽  
Kinetics Of ◽  
Maximum Removal

Refractory sulphide–barite ore was reduced with carbon in order to release lead, zinc, and copper sulphide from barite-pyrite base. Mineralogical investigations showed that due to the complex structural-textural relationships of lead, copper and zinc minerals with gangue minerals, it is not possible to enrich the ore using the conventional methods of mineral processing. The influence of temperature and time was studied to optimize the conditions, and to determine the kinetics of the barite reduction. The maximum removal of barite from ore was 96.7% at 900oC after 180 min. Chemically controlled kinetic model showed the best compliance with the experimental data. An activation energy of 142 kJ/mol was found.

scholarly journals Kinetic Degradation of Myristicin, Elemicin, and Safrole in Encapsulated Banda Nutmeg (Myristica fragrans Houtt) Oleoresin

2017 ◽  
Vol 14 (1) ◽  
pp. 43
Author(s):  
Dewi Amrih ◽  
Chusnul Hidayat ◽  
Pudji Hastuti
Keyword(s):  
Activation Energy ◽  
Physicochemical Properties ◽  
Spray Drying ◽  
Myristica Fragrans ◽  
Drying Techniques ◽  
Myristica Fragrans Houtt ◽  
Dark Glass ◽  
C 50 ◽  
Flavoring Agent

Spices, in the form of oleoresin, have advantages as a flavoring agent. Nutmeg oleoresin compounds that play an important role in the formation of nutmeg flavor are myristicin, elemicin, and safrole. These compounds are not stable, so that the quality of oleoresin decreased easily. An alternative to overcome this problem is the encapsulation of oleoresin using spray drying techniques. The objective of this research was to evaluate the physicochemical properties of oleoresin with respect to the degradation of myristicin, elemicin, and safrole of nutmeg oleoresin. Microencapsulated nutmeg oleoresin was prepared using 12% WPC and 88% maltodextrin as encapsulate materials. It was stored in dark glass bottles at a various temperature, namely 30°C, 40°C, 50°C, 60°C, and 70°C, for 0, 4, 7, 10, 14, 21, 28, 35, 42, 49, 56 and 63 days. The content of myristicin, elemicin, and safrole were analysed. The results showed that myristicin, elemicin, and safrole in the encapsulated nutmeg oleoresin decreased during the storage until 28 days of storage and then they were relatively stable until 63 days. The activation energy of myristicin, elemicin, and safrole were 2.21 kJ/mol.K, 2.71 kJ/mol.K and 3.22 kJ/mol.K, respectively.

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