Formation of Barrier Oxide Film on Lead in Borate Solutions

1994 ◽  
Vol 59 (6) ◽  
pp. 1305-1310 ◽  
Author(s):  
Emad E. Abdel Aal ◽  
Mohamed M. Hefny
Keyword(s):  
Oxide Film ◽  
Current Density ◽  
High Field ◽  
Empirical Relation ◽  
Field Approximation ◽  
Ion Concentration ◽  
Solution Temperature ◽  
Oxide Growth ◽  
Rate Of Growth ◽  
Barrier Type

Galvanostatic anodization of lead in borate solutions reveals that lead can form a barrier type oxide film. The rate of growth, R, fulfils the empirical relation, R = aib within the current density i range from 1.16 .10-4 to 3.19 .10-4 A cm-2. The magnitudes of the parameters a and b are 6.9 . 103 and 1.6, respectively, it has been found that the high field approximation is applicable for the oxide growth on lead. The coefficients of the dependence of R on solution temperature, T, pH and borate ion concentration, c, viz. (∂R/∂T), (∂R/∂pH) and (∂R/∂log c) are -18 . 10-4, -0.13 and 0.41, respectively.

Superior high-field current density in slightly Mg-deficient MgB2 tapes

2005 ◽  
Vol 87 (25) ◽  
pp. 252505 ◽  
Author(s):  
C. H. Jiang ◽  
T. Nakane ◽  
H. Kumakura
Keyword(s):  
Current Density ◽  
High Field

scholarly journals Pristine and Magnetic Kenaf Fiber Biochar for Cd2+ Adsorption from Aqueous Solution

2021 ◽  
Vol 18 (15) ◽  
pp. 7949
Author(s):  
Anwar Ameen Hezam Saeed ◽  
Noorfidza Yub Harun ◽  
Suriati Sufian ◽  
Muhammad Roil Bilad ◽  
Zaki Yamani Zakaria ◽  
...  
Keyword(s):  
Adsorption Capacity ◽  
Photoelectron Spectroscopy ◽  
Textural Properties ◽  
Ion Concentration ◽  
Solution Temperature ◽  
Maximum Adsorption Capacity ◽  
Magnetic Biochar ◽  
X Ray ◽  
Study Results ◽  
Capacity Surface

Development of strategies for removing heavy metals from aquatic environments is in high demand. Cadmium is one of the most dangerous metals in the environment, even under extremely low quantities. In this study, kenaf and magnetic biochar composite were prepared for the adsorption of Cd2+. The synthesized biochar was characterized using (a vibrating-sample magnetometer VSM), Scanning electron microscopy (SEM), X-ray powder diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS). The adsorption batch study was carried out to investigate the influence of pH, kinetics, isotherm, and thermodynamics on Cd2+ adsorption. The characterization results demonstrated that the biochar contained iron particles that help in improving the textural properties (i.e., surface area and pore volume), increasing the number of oxygen-containing groups, and forming inner-sphere complexes with oxygen-containing groups. The adsorption study results show that optimum adsorption was achieved under pH 5–6. An increase in initial ion concentration and solution temperature resulted in increased adsorption capacity. Surface modification of biochar using iron oxide for imposing magnetic property allowed for easy separation by external magnet and regeneration. The magnetic biochar composite also showed a higher affinity to Cd2+ than the pristine biochar. The adsorption data fit well with the pseudo-second-order and the Langmuir isotherm, with the maximum adsorption capacity of 47.90 mg/g.

Enhancement of flux pinning and high-field critical current density in carbon-alloyedMgB2thin films

2006 ◽  
Vol 74 (17) ◽  
Author(s):  
J. Chen ◽  
V. Ferrando ◽  
P. Orgiani ◽  
A. V. Pogrebnyakov ◽  
R. H. T. Wilke ◽  
...  
Keyword(s):  
Critical Current Density ◽  
Critical Current ◽  
Current Density ◽  
Flux Pinning ◽  
High Field

Growth of passive oxide films on iron and titanium under non-stationary state

2018 ◽  
Vol 36 (1) ◽  
pp. 87-104 ◽  
Author(s):  
Toshiaki Ohtsuka
Keyword(s):  
Oxide Film ◽  
Stationary State ◽  
Ph Dependence ◽  
Ring Electrode ◽  
Constant Current ◽  
Oxide Growth ◽  
Potential Sweep ◽  
Constant Current Density ◽  
Positive Direction ◽  
Passive Oxides

AbstractGrowth of passive oxides on iron and titanium under the non-stationary state was studied during constant current density (CD) oxidation and potential sweep oxidation. Increase and decrease of the thickness of the passive oxide film were determined from the relation between dissolution and growth CDs. By using rotating Fe disc-Pt ring electrode, the CDs of the dissolution from the oxide to solution and the growth of the passive oxide on iron were simultaneously measured. From the ratio of the growth CD to the dissolution CD and the pH dependence of the growth CD, a possible mechanism was discussed. Next, the growth of passive oxides on iron in pH 8.4 borate solution and on titanium in 0.1 m sulfuric acid solution during the potential sweep oxidation was examined by using three-parameter ellipsometry. Oxide growth was initially delayed when the sweep in the positive direction was started, and then the oxide film linearly grew with the potential increase. It was found that the oxide growth rate influenced the properties of the oxide film. The electric field in the oxide film during the non-stationary growth was discussed, concerned with the CD of the oxide film formation.

scholarly journals PECULIARITIES OF PROCESS KINETICS OF FORMING CATHODE MATERIAL OF COMPOSITION LiХLaYMn1-YO2(C60)n FOR LITHIUM – ION BATTERY

2019 ◽  
Vol 62 (11) ◽  
pp. 99-105
Author(s):  
Ekaterina S. Guseva ◽  
Svetlana S. Popova
Keyword(s):  
Lithium Ion ◽  
Ion Concentration ◽  
Redox Activity ◽  
Solution Temperature ◽  
Stable Phase ◽  
Potential Range ◽  
Unusual Structure ◽  
Kinetics Of ◽  
New Phase ◽  
Mno2 Electrode

The effect of the magnitude of cathodic polarization and the temperature of a solution of lanthanum salicylate on the kinetics of the formation of elecrode LаyMn1-yO2 has been described. It has been established that two phases are formed on the electrode: the phase of the solid solution of the introduced lanthanum in MnO2 at potentials negative -2.5V turns into a new phase LаyMn1-yO2; last on the curve Eб/т-Ек the potential delay characteristic of the process of forming a new phase with an independent crystal lattice corresponds. Thus, to obtain a time-stable phase of the introduction of lanthanum into the structure of the electrode LаyMn1-yO2 the potential range from –2.9 V to –2.5 V can be recommended. The influence of the solution temperature on the kinetic characteristics of the process is ambiguous and is associated with a change in the degree of disorder in the structure of the forming phase at the boundary MnO2 electrode/solution (La3+), which hampers diffusion of ions La3+ into the electrode and leads to a decrease in ion concentration La3+, involved in the act of electrochemical introduction and, accordingly, to a decrease in the value of i (0). At temperatures above 10 °С the structure is stabilized and the characteristics (k, i (0)) increase. The composition of the formed phases is determined LixMnO2, LayMn1-yO2, LixLayMn1-yO2, current-free chronopotentiometry method calculated on the basis of equilibrium potentials Ep of these phases with pulsed galvanostatic polarization mode. Stability formed in the structure of MnO2 electrode chemical compounds of lanthanum was established. The activating effect of fullerene additives С60 composed of modified lanthanum LаyMn1-yO2 electrodes due to the high redox activity and the unusual structure of the molecules С60. Data on the effect of modified MnO2 electrodes on their potentials in an open circuit and during polarization in the working solution are in good agreement in terms of increasing the capacity of lithium with the results of cycling LiхMnO2, LiхLayMn1-yO2, LiхLayMn1-yO2-σ(C60)n in galvanostatic mode. The results of galvanostatic cycling showed that the discharge capacity of the electrodes increases in the series: LixMnO2 > LixLayMn1-yO2 > LiхLayMn1-yO2-σ(C60)n. With the help of cyclic chronovamperometry a good reversibility for LiхLayMn1-yO2-σ(C60)n electrode was established.

High-field magnetisation and the critical current density in superconducting BiSrCaCu2Ox

1988 ◽  
Vol 18 (6) ◽  
pp. L123-L125 ◽  
Author(s):  
P A J de Groot ◽  
P C Lanchester ◽  
M T Weller ◽  
J R Grasmeder ◽  
G P Rapson ◽  
...  
Keyword(s):  
Critical Current Density ◽  
Critical Current ◽  
Current Density ◽  
High Field

scholarly journals Removal of the Rhodamine B Dye at Ti/Ru0.3Ti0.7O2 Anode Using Flow Cell System

2019 ◽  
Vol 2019 ◽  
pp. 1-10 ◽  
Author(s):  
Ali Baddouh ◽  
Brahim El Ibrahimi ◽  
Elhassan Amaterz ◽  
M. Mohamed Rguiti ◽  
Lahcen Bazzi ◽  
...  
Keyword(s):  
Current Density ◽  
Rhodamine B ◽  
Removal Rate ◽  
Flow Cell ◽  
Cell System ◽  
Cod Removal ◽  
Color Removal ◽  
Ion Concentration ◽  
Applied Current ◽  
Rhodamine B Dye

The electrochemical oxidation of the Rhodamine B dye (Rh-B) was carried out using dimensionally stable type anode (DSA, Ti/Ru0.3Ti0.7O2). The work was performed using the electrochemical flow cell system. The effect of several operating factors, such as supporting electrolytes, current density, electrolysis time, temperature, and initial concentration of Rh-B dye, were investigated. The UV-visible spectroscopy and chemical oxygen demand (COD) measurements were conducted to monitor the removal and degradation of Rh-B. The best color removal achieved was found to be 98.3% after 10 min applying 3.9 mA·cm−2 as a current density using 0.07 mol·L−1 of NaCl. Meanwhile, the highest COD removal rate (93.0%) was obtained for an applied current density of 3.9 mA·cm−2 as the optimal operating condition after 180 min reaction time, with 2.98 kW h·m−3 as energy consumption. This shows that the best conditions for color removal are not certainly the same as those for the COD removal. The rises in the concentration of NaCl, and applied current increased the Rh-B color removal rate. The decline in Rh-B dye concentration followed pseudo-first-order kinetics. The obtained values of apparent rate constant were increased by increasing chloride ion concentration. It is concluded that the electro-oxidation on DSA electrode using a flow cell is a suitable process for the removal of Rh-B dye in aqueous solutions.

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