Wien effect in molten magnesium chloride

Shabanov, O. M.; Gadzhiev, S. M.; Iskakova, A. A.; Kachaev, R. T.; Magomedova, A. O.; Suleimanov, S. I.

doi:10.1134/s1023193511020145

Cited by 5 publications

(4 citation statements)

References 3 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The effect of a high field in their binary mixtures with KCl is 150%, 120%, and 230%, respectively. These results are comparable to those obtained previously for MgCl 2 260% [5], KAlCl 4 700% [6], and MgCl 2 -KCl 470% [5,7].…”

Section: Methodssupporting

confidence: 91%

Intensification of electrochemical properties of the molten chloride electrolytes of the cerium subgroup lanthanides

Shabanov

Suleymanov

Magomedova

2017

IOP Conf. Ser.: Mater. Sci. Eng.

View full text Add to dashboard Cite

Abstract. The electrical conductivity of molten chloride electrolytes of the cerium subgroup lanthanides increases with rising electric field strength and strive to achieve the limiting high voltage values (Wien effect). On exposure of the high-voltage microsecond pulsed fields, the melts are transited into a prolonged non-equilibrium state with increased electrical conductivity and electrolyze current density. During the relaxation processes in non-equilibrium melts, increased electrical conductivity tends to restore the values that are specific to equilibrium systems. IntroductionIn various modern industries there is an increasingly widespread use of rare earth metals (REM). In an industrial scale mainly REM alloys and relatively pure lanthanum, cerium and neodymium are produced. REM and their alloys are advantageously prepared by electrolysis of anhydrous molten chloride mixtures Ln-MCl (Ln = REM and M = Na, K). The structures of the molten electrolytes, as well as the nature and distribution their structural species, determine their observed physicochemical properties, the mechanisms and kinetic pathways that decrease energetic efficiency of metals production technologies [1]. For better understanding the structure of equilibrium molten electrolytes and improving the chemical and electrochemical technologies, their properties should be studied in a non-equilibrium state, which can be achieved by various external influences, for example, by the action of strong electric pulses [2]. We have found that electrical conductivity of molten alkaline-earth chlorides and their mixtures with alkaline chlorides increase with increasing external electric field strength (EFS) and strive to achieve the limiting high-voltage values in the fields of the order of 1 MV/m [3], in the same way as in the Wien effect in the aqueous electrolyte solutions.After the high-voltage pulsed discharges in the electrolytes having been completed, their low voltage conductivity (measured by usual AC Bridge) turns out to be increased [4] i.e., in them the phenomenon of activation (the "memory effect") is observed. The activation degree of electrical conductivity reaches up to 20 % in the case of individual alkali earth metals chlorides and to 55 % in the case of their mixtures with potassium chloride. These observations were interpreted as a consequence of the stimulated dissociation of complex formations. The activation of the melts is followed by the recombination of complex ions during prolonged relaxation processes in the nonequilibrium melts.

show abstract

Section: Methodssupporting

confidence: 91%

Intensification of electrochemical properties of the molten chloride electrolytes of the cerium subgroup lanthanides

Shabanov

Suleymanov

Magomedova

2017

IOP Conf. Ser.: Mater. Sci. Eng.

View full text Add to dashboard Cite

show abstract

“…The activation degree of conductivity also rises with increasing number of pulses and their voltage amplitude, and tends to the saturation. In Figure 7, as examples, these dependences are presented for a magnesium electrolyte Similar results were obtained for other compositions of molten mixtures [7][8][9][10][11][12][13][14][15]. The results obtained in Sections 3.1 and 3.3 are collected in Table 1.…”

Section: Intensification Of Conductivity Of Molten Metal Chloride Electrolytessupporting

confidence: 72%

Structural Relaxation in the Activated Molten Chloride Electrolytes of Polyvalent Metals

2017

International Journal of Mining Science

View full text Add to dashboard Cite

The molten salt electrolytes from which the polyvalent active metals are extracted are strongly structured at unusually long distances that increase the energy consumption of the electrowinning cell. Under influence of strong electrical pulses they are transferred to a non-equilibrium state with modification of the structure and intensification of electrochemical properties. The observed regularities in the electrolytes activation are due to stimulated dissociation of complex ions on the simpler and more mobile complex and elementary ions. This is confirmed by the disappearance of characteristic Raman peaks when the melts are activated. During the relaxation process in non-equilibrium melts their electrochemical parameters and Raman peaks are seeking to recover their equilibrium values and pattern. All the observed patterns of the duration and the dynamics of the relaxation in non-equilibrium melts show that we definitely have deal with the structural relaxation in ionic.

show abstract

“…As an alternative to the addition of Na + [Al(OH) 4 ] À solutions, aluminum in basic form (i.e. While synthetic air, in which alumina depositions can be generated, is free of CO 2 , natural air con- www.chemeurj.org 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim tains 0.04 vol % CO 2 . Immediately after addition in one portion, k jumps to 3.50 mS cm À1 (Figure 7 b) with a pH up to 8 (Figure 8 b).…”

Section: High Voltage Electrolysis Experiments Under Semi-technical Cmentioning

confidence: 99%

Behavior of Highly Diluted Electrolytes in Strong Electric Fields—Prevention of Alumina Deposition on Grading Electrodes in HVDC Transmission Modules by CO₂‐induced pH‐Control

Weber

Mallick

Schild

et al. 2014

Chemistry A European J

View full text Add to dashboard Cite

Alumina deposition on platinum grading electrodes in high voltage direct current (HVDC) transmission modules is an unsolved problem that has been around for more than three decades. This is due to the unavoidable corrosion of aluminum heat sinks that causes severe damage to electrical power plants and losses in the range of a million Euro range per day in power outage. Simple experiments in a representative HV test setup showed that aluminates at concentrations even below 10(-8) mol L(-1) can deposit on anodes through neutralization by protons produced in de-ionized water (κ≤0.15 μS cm(-1)) at 20-35 kV (8 mA) per electrode. In this otherwise electrolyte-poor aqueous environment, the depositions are formed three orders of magnitude below the critical precipitation concentration at pH 7! In the presence of an inert electrolyte such as TMAT (tetramethylammonium-p-toluenesulfonate), at a concentration level just above that of the total dissolved aluminum, no deposition was observed. Deposition can be also prevented by doping with CO2 gas at a concentration level that is magnitudes lower than that of the dissolved aluminum. From an overview of aqueous aluminum chemistry, the mystery of the alumina deposition process and its inhibition by CO2 is experimentally resolved and fully explained by field accumulation and repulsion models in synergism with acid-base equilibria. The extraordinary size of the alumina depositions is accounted for in terms of proton tunneling through "hydrated" alumina, which is supported by quantum chemical calculations. As a consequence, pulse-purging with pure CO2 gas is presented as a technical solution to prevent the deposition of alumina.

show abstract

Wien effect in molten magnesium chloride

Cited by 5 publications

References 3 publications

Intensification of electrochemical properties of the molten chloride electrolytes of the cerium subgroup lanthanides

Intensification of electrochemical properties of the molten chloride electrolytes of the cerium subgroup lanthanides

Structural Relaxation in the Activated Molten Chloride Electrolytes of Polyvalent Metals

Behavior of Highly Diluted Electrolytes in Strong Electric Fields—Prevention of Alumina Deposition on Grading Electrodes in HVDC Transmission Modules by CO₂‐induced pH‐Control

Contact Info

Product

Resources

About

Wien effect in molten magnesium chloride

Cited by 5 publications

References 3 publications

Intensification of electrochemical properties of the molten chloride electrolytes of the cerium subgroup lanthanides

Intensification of electrochemical properties of the molten chloride electrolytes of the cerium subgroup lanthanides

Structural Relaxation in the Activated Molten Chloride Electrolytes of Polyvalent Metals

Behavior of Highly Diluted Electrolytes in Strong Electric Fields—Prevention of Alumina Deposition on Grading Electrodes in HVDC Transmission Modules by CO2‐induced pH‐Control

Contact Info

Product

Resources

About

Behavior of Highly Diluted Electrolytes in Strong Electric Fields—Prevention of Alumina Deposition on Grading Electrodes in HVDC Transmission Modules by CO₂‐induced pH‐Control