Surface charging parameters of charged particles in symmetrical electrolyte solutions

2020 ◽  
Vol 22 (35) ◽  
pp. 20123-20142
Author(s):  
Hadi Saboorian-Jooybari ◽  
Zhangxin Chen
Keyword(s):  
Charge Density ◽  
Surface Charge ◽  
Electrolyte Solution ◽  
Surface Charge Density ◽  
Potential Surface ◽  
Research Work ◽  
Charged Particles ◽  
Electrolyte Solutions ◽  
Surface Charging ◽  
Curvature Dependence

This research work is directed at development of accurate physics-based formulas for quantification of curvature-dependence of surface potential, surface charge density, and total surface charge for cylindrical and spherical charged particles immersed in a symmetrical electrolyte solution.

Effect of Fe/Al oxides on desorption of Cd2+ from soils and minerals as related to diffuse layer overlapping

Soil Research ◽  
2011 ◽  
Vol 49 (3) ◽  
pp. 231 ◽  
Author(s):  
Yan-ping Wang ◽  
Ren-kou Xu ◽  
Jiu-yu Li
Keyword(s):  
Charge Density ◽  
Surface Charge ◽  
Surface Charge Density ◽  
Charged Particles ◽  
Double Layers ◽  
Mineral Particles ◽  
Variable Charge ◽  
Electrical Double Layers ◽  
Oppositely Charged ◽  
Positively Charged

Cadmium is a toxic metal with high reactivity in acid variable charge soils. Adsorption and desorption of Cd2+ in soil and mineral particles can be affected by the interaction between the electrical double layers on oppositely charged particles, because the interaction can decrease the surface-charge density of the particles. We studied the effect of Fe/Al oxides on desorption of Cd2+ from soils and minerals and proposed the desorption mechanisms based on the overlapping of diffuse layers between negatively charged soils and mineral particles and positively charged Fe/Al oxide particles. Our results indicate that the overlapping of diffuse layers of electrical double layers between positively charged Fe/Al oxides [crystalline and amorphous Al(OH)3 and amorphous Fe(OH)3] and negatively charged Ultisol, Alfisol, kaolinite, and bentonite caused the effective negative surface-charge density on the soils and minerals to become less negative, and thus the adsorption affinity of these negatively charged surfaces for Cd2+ declined as a result of the incorporation of the Fe/Al oxides. Consequently, the release of exchangeable Cd2+ from the surfaces of the soils and minerals increased with the amount of Fe/Al oxides added. The more positive the charge on the surfaces of the Fe/Al oxides, the stronger the interaction of the electrical double layers between the oxides and soils and minerals, and thus the greater the release of Cd2+ from the soils and minerals. A decrease in pH led to an increase in the positive surface charge on the Fe/Al oxides and enhancement of the interaction of the electrical double layers between the oxides and soils and minerals. As a result, more Cd2+ was desorbed from the soils and minerals. This study suggests that the interaction between oppositely charged particles of variable charge soils can enhance the mobility of cadmium in the soils and thus increase its environmental risk.

Supporting the surface charging mechanism of seismic-electromagnetic phenomena by the direct measurements of the electron and hole trapping centers

2021 ◽  
Author(s):  
Kiriha Tanaka ◽  
Hiroyuki Nagahama ◽  
Jun Muto ◽  
Toshitaka Oka ◽  
Yasuo Yabe
Keyword(s):  
Charge Density ◽  
Surface Charge ◽  
Surface Charge Density ◽  
Rock Fracture ◽  
Surface Charges ◽  
Low Velocity ◽  
Hole Trapping ◽  
Surface Charging ◽  
Charging Mechanism ◽  
Trapping Centers

<p>The mechanisms of the seismic-electromagnetic phenomena (SEP) attracted as precursors of short-term earthquake forecast have been suggested, however, it is still incompletely understood. Among the possible mechanisms of the SEP is the surface charging mechanism related to the electron and hole trapping centers in quartz. Previous studies evaluated the plausibility of the mechanism from the surface charge density by the measurement of current or potential changes. On the other hand, only a few studies have evaluated the plausibility from the direct measurements of the trapping centers’ concentration.</p><p>We have performed low-velocity friction experiments mimicking the fracture with low-frictional heating for simulated fault gouges (commercial natural quartz sands) at a normal stress of 1.0 MPa with displacements up to 1.4 m. In order to measure the concentration of the trapping centers in the simulated-fault gouges, we conducted electron spin resonance for the standard sample, TEMPOL (4-hydroxy-2,2,6,6-tetramethyl-piperidine-1-oxyl), and the gouges before and after friction. In recent decades, researchers also have obtained the concentrations of the trapping centers in the quartz damaged in the rock fracture experiments using ESR and a radical scavenger. From those concentrations with the measured or assumed surface areas, we calculated the surface charge density of the quartz and discussed the plausibility of the surface charging mechanism of the SEP.</p><p>In our friction experiments, the E’ type centers were detected at g<sub>2</sub> = 2.001 (e.g., E<sub>1</sub>’ center; ≡Si･, E<sub>S</sub>’ center; ≡Si･, E<sub>α</sub>’ center; =Si:, where − is an electron pair, : is a lone pair, and ･ is an unpaired electron) in the ESR spectra of the simulated-quartz gouges and the trapping center increased by the fracture of low-velocity friction. Assuming that the trapping centers were produced on the grain surfaces by the fracture, the range of the increase in the surface charge density was (0.21–8.0) ×10<sup>-4</sup> C/m<sup>2</sup>. The rock fracture experiments found the E<sub>1</sub>’ center, non-bridging oxygen hole center (NBOHC; ≡Si−O･), and peroxy center (≡Si−O−O･) in quartz. On the same assumption, the total surface charge density of those trapping centers and the density of the E<sub>1</sub>’ center or NBOHC were estimated as 2.7×10<sup>-1</sup> and 5.0×10<sup>-2</sup>–3.94 C/m<sup>2</sup>, respectively.</p><p>The surface charge density required for a corona discharge that can cause the SEP in the air over a flat plane is reported over 5.0×10<sup>-5</sup> C/m<sup>2</sup>. The quantities calculated above are almost enough to induce a corona discharge. The surface charges can form the electric dipoles on the fault plane, inducing the electric and magnetic fields. Our experiment showed that the fracture by fault motions could produce the surface charges on the fault. It proves that the electromagnetic abnormalities by the fault motions may also be observed through the surface charging mechanism. Therefore, our study supports that the surface charging mechanism is plausible.</p>

Sign in / Sign up

Export Citation Format

Share Document