Diffusion density effect

Effects of current density(I) on the recovery of copper in the reactor can be seen in Fig. 5. As can be seen, the value of R increased gradually with increasing ciurent density, since the mass transfer rate of copper ion is proportional to the current density. Effects of amount of fluidized particles on the recovery of copper can be seen in Fig. 6. Note that the addition of a small amount of fluidized particles (W=1.0wt.%) to the reactor could increase the copper recovery up to 10 25%. It has been mderstood that the contacting of fluidized solid particles with the cathode plate could clean the siuface as well as decrease the diffusion layer of copper ion, which results in the increases of reaction rate and current efficiency, thus, the recovery of copper could be increased. 

Theoretically, diffusion should effect the difficult separation of isotopic gases from one another because of the difference in rates of diffusion of the constituent gaseous isotopes. However, the problem faced in such a separation by fractional diffusion is the one that arises from the fact that difference in respective densities of isotopes is generally very slight, so that die method in practice is a very laborious one. It is obvious that if diffusion were allowed to proceed for a long time, the composition of the gas mixture would become identical at both sides of the partition. If, however, only half of the gaseous mixture is allowed to diffuse... 

More rapid drilling (slim holes, optimised bit choice, good hydraulics and mud design) reduces shale exposure time. Since all of the diffusive processes are time-dependent, instability is less commonly observed, and slim holes are inherently easier to drill. However, the hydraulic system must be studies to insure adequate hole cleaning without excessive flow pressure effects (called equivalent circulating density effects in the oil industry). 

An eqnation has been derived relating the effective diffusivity of porous foodstuffs to various physical properties such as molecular weight, bulk density, vapor space permeability, water activity as a function of material moisture content, water vapor pressure, thermal conductivity, heat of sorption, and tanperature [80]. A predictive model has been proposed to obtain effective diffusivities in cellular foods. The method requires data for composition, binary molecular diffusivities, densities, membrane and cell wall permeabilities, molecular weights, and water viscosity and molar volume [81]. The effect of moisture upon the effective diffusivity is taken into account via the binding energy of sorption in an equation suggested in Ref. [77]. 

The DRIFTS spectrum of a powdered sample is greatly influenced by sample packing due to two different effects [156]. A surface particle size effect refers to the segregation of larger particles at the surface of the sample upon packing. This effect decreases the reflectance, as is also observed when the mean particle size increases. A more pronounced effect is the volume density effect, in which diffusely reflected light is strongly dependent on the powder density. 

In this model, the drop of voltage due to a variation of fuel utilization is modelled also considering the effect on the cathode diffusion. The effect of diffusion on the cell voltage sensitivity to fuel utihzation has a significant effect when the limiting current density is approached, or for low value of the air stoichiometry. It should also be noticed that in the equations (34) and (35), as posed in [3], the variable L has not the meaning of excess of oxidant with respect to the stoichiometric requirement, and so it has a different meaning compared to the air stoichiometry Xax as defined and used in this Chapter. 

Reactions with water involve the energy of activation much higher than that required for diffusion. They are too slow to be observed at room temperature, but may significantly contribute to the overall oxidation kinetics at nuclear reactor and SCWO operating temperatures. Reactions (15.19) to (15.21) have been invoked as a partial explanation for the experimentally observed water density effects on SCWO reaction rates. The importance of reaction... 

The effect known either as electroosmosis or electroendosmosis is a complement to that of electrophoresis. In the latter case, when a field F is applied, the surface or particle is mobile and moves relative to the solvent, which is fixed (in laboratory coordinates). If, however, the surface is fixed, it is the mobile diffuse layer that moves under an applied field, carrying solution with it. If one has a tube of radius r whose walls possess a certain potential and charge density, then Eqs. V-35 and V-36 again apply, with v now being the velocity of the diffuse layer. For water at 25°C, a field of about 1500 V/cm is needed to produce a velocity of 1 cm/sec if f is 100 mV (see Problem V-14). 

Figure A3.6.13. Density dependence of die photolytic cage effect of iodine in compressed liquid n-pentane (circles), n-hexane (triangles), and n-heptane (squares) [38], The solid curves represent calculations using the diffusion model [37], the dotted and dashed curves are from static caging models using Camahan-Starling packing fractions and calculated radial distribution fiinctions, respectively [38],...

---