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Limiting diffusivity

For many cooling waters, including seawater and also drinking water, where corrosion rates are 70 to 100% of the limiting diffusion current, the use of dimensionless group analysis can then be applied. [Pg.317]

By substituting the appropriate values for viscosity and diffusion at various temperatures, they found that corrosion rates could be calculated which were confirmed by experiment. The corrosion rates represent maxima, and in real systems, corrosion products, scale and fouling would reduce these values often by 50%. The equation was useful in predicting the worst effects of changing the flow and temperature. The method assumes that the corrosion rate is the same as the limiting diffusion of oxygen at least initially this seems correct. [Pg.320]

Using the expression for the limiting diffusion current density, we can rewrite the surface concentration as... [Pg.57]

Curve 1 of Fig. 6.8 corresponds to pure kinetic control (i is very large), while the other curves for which the exchange CD has the same value show the influence of a gradual decrease in limiting diffusion CD caused by decreasing diffusional transport constants (e.g., when the electrode is rotated more and more slowly, but not when the concentration is reduced, since this would alter the exchange CD). [Pg.96]

In many cases the concentration of a substance can be determined by measuring its steady-state limiting diffusion current. This method can be used when the concentration of the substance being examined is not very low, and other substances able to react in the working potential range are not present in the solution. [Pg.389]

Characteristic parameters of each wave are the valne of the half-wave potential i/2> which is dehned by Eq. (6.26), and the wave height [the valne of the limiting diffusion cnrrent, determined by the llkovic eqnation (23.1) for c j = 0]. The... [Pg.392]

Polarograms are sometimes distorted by polarographic maxima, where the current in individual segments of the I vs. E curves is much higher (several times) than the limiting diffusion current. A number of reasons exist for the development of these maxima. [Pg.393]

In agreement with the theory of electrolysis, treated in Sections 3.1 and 3.2, the parts of the residual current and the limiting current are clearly shown by the nature of the polarographic waves because for the cathodic reduction of Cd2+ and Zn2+ at the dme we have to deal with rapid electron transfer and limited diffusion of the cations from the solution towards the electrode surface and of the metal amalgam formed thereon towards the inside of the Hg drop, we may conclude that the half-wave potential, Eh, is constant [cf., Fig. 3.13 (a ] and agrees with the redox potential of the amalgam, i.e., -0.3521V for Cd2+ + 2e - Cd(Hg) and -0.7628 V for Zn2+ + 2e -> Zn(Hg) (ref. 10). The Nernst equation is... [Pg.129]

As at the limiting (diffusion-controlled) current c0 - 0, the Ilkovic equation... [Pg.133]

A PP sample after ozonization in the presence of UV-irradiation becomes brittle after 8 hrs of exposure, whereas the same effect in ozone is noticeable after 50-60 hours.Degradation of polymer chain occurs as a result of decomposition of peroxy radicals. The oxidation rapidly reaches saturation, suggesting the surface nature of ozone and atomic oxygen against of PP as a consequence of limited diffusion of both oxygen species into the polymer. Ozone reacts with PP mainly on the surface since the reaction rate and the concentration of intermediate peroxy radicals are proportional to the surface area and not the weight of the polymer. It has been found that polyethylene is attacked only to a depth of 5-7 microns (45). [Pg.197]

Together with the boundary condition (5.4.5) and relationship (5.4.6), this yields the partial differential equation (2.5.3) for linear diffusion and Eq. (2.7.16) for convective diffusion to a growing sphere, where D = D0x and = Cqx/[1 + A(D0x/T>Red)12]- As for linear diffusion, the limiting diffusion current density is given by the Cottrell equation... [Pg.292]

The properties of the voltammetric ultramicroelectrode (UME) were discussed in Sections 2.5.1 and 5.5.1 (Fig. 5.19). The steady-state limiting diffusion current to a spherical UME is... [Pg.309]

If all the constants in the expression for the limiting diffusion current are known, including the diffusion coefficient, then the number of electrons consumed in the reaction can be found from the limiting current data. However, this condition is often not fulfilled, or the limiting diffusion... [Pg.314]

Fig. 4. Migration contribution to the limiting current in acidified CuS04 solutions, expressed as the ratio of limiting current (iL) to limiting diffusion current (i ) r = h,so4/(( h,so, + cCuS(>4). "Sulfate refers to complete dissociation of HS04 ions. "bisulfate" to undissociated HS04 ions. Forced convection" refers to steady-state laminar boundary layers, as at a rotating disk or flat plate free convection refers to laminar free convection at a vertical electrode penetration to unsteady-state diffusion in a stagnant solution. [F rom Selman (S8).]... Fig. 4. Migration contribution to the limiting current in acidified CuS04 solutions, expressed as the ratio of limiting current (iL) to limiting diffusion current (i ) r = h,so4/(( h,so, + cCuS(>4). "Sulfate refers to complete dissociation of HS04 ions. "bisulfate" to undissociated HS04 ions. Forced convection" refers to steady-state laminar boundary layers, as at a rotating disk or flat plate free convection refers to laminar free convection at a vertical electrode penetration to unsteady-state diffusion in a stagnant solution. [F rom Selman (S8).]...
The major function of cutin is to serve as the structural component of the outer barrier of plants. As the major component of the cuticle it plays a major role in the interaction of the plant with its environment. Development of the cuticle is thought to be responsible for the ability of plants to move onto land where the cuticle limits diffusion of moisture and thus prevents desiccation [141]. The plant cuticle controls the exchange of matter between leaf and atmosphere. The transport properties of the cuticle strongly influences the loss of water and solutes from the leaf interior as well as uptake of nonvolatile chemicals from the atmosphere to the leaf surface. In the absence of stomata the cuticle controls gas exchange. The cuticle as a transport-limiting barrier is important in its physiological and ecological functions. The diffusion across plant cuticle follows basic laws of passive diffusion across lipophylic membranes [142]. Isolated cuticular membranes have been used to study this permeability and the results obtained appear to be valid... [Pg.37]

Matrix isolation has many limitations, even for metal carbonyls (i) it cannot easily be used for charged species2 (ii) very little kinetic information can be obtained because of the restricted temperature range and limited diffusion (iii) the solid matrix cage can effectively block some... [Pg.279]


See other pages where Limiting diffusivity is mentioned: [Pg.117]    [Pg.42]    [Pg.345]    [Pg.118]    [Pg.238]    [Pg.311]    [Pg.312]    [Pg.62]    [Pg.62]    [Pg.283]    [Pg.82]    [Pg.55]    [Pg.55]    [Pg.57]    [Pg.230]    [Pg.233]    [Pg.314]    [Pg.375]    [Pg.376]    [Pg.407]    [Pg.695]    [Pg.223]    [Pg.76]    [Pg.72]    [Pg.18]    [Pg.131]    [Pg.134]    [Pg.422]    [Pg.292]    [Pg.296]    [Pg.300]    [Pg.308]    [Pg.309]   
See also in sourсe #XX -- [ Pg.340 ]




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Activation energy diffusion-limited

Aggregation diffusion-limited

Aggregation diffusion-limited, computer

Algorithm diffusion limited aggregation

Bulk diffusion limitations

Burning of small particles - diffusion versus kinetic limits

Carbon monoxide diffusion-limited model

Carbonic diffusion-limitation

Catalysis, general base diffusion limit

Catalysts diffusion limitations

Coarsening diffusion-limited

Colloidal diffusion-limited aggregation

Combination of External and Internal Diffusion Limitations

Consecutive reactions diffusion limited

Crystal growth diffusion-limited aggregation

Current diffusion-limited steady-state

Current-limiting diffusion polarization

Diffuse-reflectance spectroscopy limitations

Diffusion Monte Carlo limits

Diffusion Upper limit

Diffusion coefficient limited current

Diffusion control limit

Diffusion controlled limit

Diffusion controlled limit, reaction

Diffusion controlled limiting current

Diffusion conversion limit

Diffusion current density, limiting

Diffusion current, limiting, concept

Diffusion flame, extinction limits

Diffusion impedance Capacitance, limiting

Diffusion impedance Limitations

Diffusion impedance Resistance, limiting

Diffusion layer limitation

Diffusion limit

Diffusion limit

Diffusion limit model

Diffusion limit rates

Diffusion limitation

Diffusion limitation

Diffusion limitation effects

Diffusion limitation region

Diffusion limitation theory

Diffusion limitations, internal, Fischer-Tropsch

Diffusion limitations, internal, Fischer-Tropsch catalyst

Diffusion limitations, internal, Fischer-Tropsch modeling

Diffusion limited adsorption

Diffusion limited aggregation (DLA

Diffusion limited aggregation particle-cluster

Diffusion limited current

Diffusion limited current density

Diffusion limited current density Diffusivity

Diffusion limited current density effective

Diffusion limited energy migration

Diffusion limited molecular collisions

Diffusion limited transport

Diffusion limited water exchange

Diffusion limiting

Diffusion limiting

Diffusion limiting equivalent capacitance

Diffusion limiting equivalent resistance

Diffusion mass transfer-limited reactions

Diffusion pumps limitations

Diffusion, facilitated, limits

Diffusion-Limited Aggregation and Growth

Diffusion-Limited Capture

Diffusion-controlled limit on reaction rate

Diffusion-convection layer electrode rotation rate limits

Diffusion-limited

Diffusion-limited agglomeration

Diffusion-limited aggregates

Diffusion-limited aggregation computer simulation

Diffusion-limited amperometric devices

Diffusion-limited cluster aggregation

Diffusion-limited cluster aggregation DLCA)

Diffusion-limited cluster aggregation example

Diffusion-limited cluster aggregation restructuring

Diffusion-limited clustering

Diffusion-limited coefficient

Diffusion-limited complex formation

Diffusion-limited conditions

Diffusion-limited corrosion rate

Diffusion-limited current plateau

Diffusion-limited current, planar and spherical electrodes

Diffusion-limited exchange kinetics

Diffusion-limited extractions

Diffusion-limited field

Diffusion-limited growth

Diffusion-limited oxidation regime

Diffusion-limited oxygen sensor

Diffusion-limited oxygen sensor structures

Diffusion-limited rate constant Debye theory

Diffusion-limited reactions

Diffusion-limited reactions, Smoluchowski equation

Diffusion-limited regime

Diffusion-limited regime effectiveness factor

Diffusion-limited surface reaction

Diffusion-limited uptake

Diffusion-limited uptake metal

Diffusion-limited, bimolecular elementary

Diffusion-limited-aggregation model

Diffusive limit

Diffusive limit

Diffusivities rate-limiting step

Dropping mercury electrode diffusion limited current

Effect of external diffusion limitation

Effect of internal diffusion limitation

Effective diffusivity limiting cases

Electrochemical cell diffusion limitations

Electrochemical cell diffusion limited

Electrochemical techniques diffusion-limited

Electron transfer diffusion control limit

Electron transfer, activation control diffusion limit

Energy transfer rapid diffusion limit

Enhancement factor diffusion-limited regime

Enzyme kinetics diffusion-limited

Excitation transfer diffusion limitations

External diffusion limitations

External mass transfer and intraparticle diffusion limitations

Facilitated diffusion fast reaction limit

Fast Diffusion Limit

Ferrocenes diffusion limited

Fractal diffusion limited growth

Gas-phase diffusion limitation

Growth Limited by Heat Conduction and Mass Diffusion Simultaneously

Heterogeneous polymer degradation oxygen diffusion limited

Internal diffusion limitations

Interrelationships of limiting diffusive transport quantities

Intraparticle diffusion limitations

Intraparticle diffusion limitation—pores

Kinetic expressions derived for diffusion limited reactions

Kinetics external diffusion limitations

Limiting Diffusion Resistance of the Disperse Phase

Limiting diffusion coefficient

Limiting diffusion current

Limiting diffusion current, voltammetry

Limiting diffusion resistance

Limiting permeability diffusion limitation

Limiting-current measurement diffusion coefficients

Mass transfer coefficient diffusion-limited regime

Mass transfer diffusion-limited

Mean limiting diffusion current

Methanol synthesis, diffusion limitations

Microelectrodes diffusion-limited current

Monolayers diffusion limitation

Neutral molecules, diffusion-limited

Neutral molecules, diffusion-limited transport

Oxygen diffusion limited degradation

Oxygen diffusion limited degradation examples

Oxygen reduction reaction limiting diffusion current densities

Particle limiting diffusion coefficient

Permeability coefficient solubility-diffusion limit

Pore diffusion, limiting process

Process diffusion-limited

Pure diffusion limit

RET in the Rapid-Diffusion Limit

Rate constant diffusion-limited

Rate-limiting diffusion

Rate-limiting diffusion carrier requirements

Rate-limiting diffusion control

Rate-limiting diffusion implications

Rate-limiting diffusion metal

Rate-limiting diffusion phytoplankton

Rate-limiting steps film diffusion

Rate-limiting steps particle diffusion

Reaction rates, diffusion controlled limit

Reactions rate-limited by a diffusion process

Reactive spreading diffusion limited

Reduction process diffusion limited

Relaxation, diffusion-limited, rate defined

Rigid particles, limiting diffusion

Severe diffusion limitations

Solubility-diffusion mechanism limitations

Spatial diffusion limit

Spin echo diffusion limits

Spin-diffusion limit

Support diffusion limitations

Surfactants diffusion-limited adsorption

The Effect of Diffusion Limitation

Transport Limitations and the Thiele Diffusion Modulus

Transport limitation by reaction-diffusion interaction

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