Interfacial transfer

In a gas-liquid dispersed system, the total interfacial transfer rate W( ) from a population of bubbles in the size range a da is then given by... 

The total interfacial transfer rate in the whole dispersed system, W(0< is found by summing the interfacial transfer rate over the entire population of the bubbles, taking into account the variation in their sizes. 

Gratzel M (1994) NanocrystaUine solar cells. Renew Energy 5 118-133 Peter LM, Ponomarev EA, Franco G, Shaw NJ (1999) Aspects of the photoelectrochemistry of nanocrystalhne systems. Electrochim Acta 45 549-560 Peter L (2007) Transport, trapping and interfacial transfer of electrons in dye-sensitized nanocrystalline solar cells. J Electroanal Chem 599 233-240... 

Rate of interfacial transfer of component i y into the system J... 

The theoretical results described have implications for the design of experimental approaches for the study of transfer processes across the interface between two immiscible phases. The current response in SECMIT is clearly sensitive to the relative diffusion coefficients and concentrations of a solute in the two phases and the kinetics of interfacial transfer over a wide range of values of these parameters. 

The interfacial transfer kinetics were then investigated by perturbing the equilibrium, through the depletion of Cu + in the aqueous phase, by reduction to Cu at an UME located in close proximity to the aqueous-organic interface. This process promoted the transfer of Cu into the aqueous phase, via the transport and decomplexation of the cupric ion-oxime complex, resulting in an enhanced steady-state current at the UME. Approach curve measurements of i/i oo) vs. d allowed the kinetics of the transfer process to be determined unambiguously [9,18]. 

The driving force for the transfer process was the enhanced solubility of Br2 in DCE, ca 40 times greater than that in aqueous solution. To probe the transfer processes, Br2 was recollected in the reverse step at the tip UME, by diffusion-limited reduction to Br . The transfer process was found to be controlled exclusively by diffusion in the aqueous phase, but by employing short switching times, tswitch down to 10 ms, it was possible to put a lower limit on the effective interfacial transfer rate constant of 0.5 cm s . Figure 25 shows typical forward and reverse transients from this set of experiments, presented as current (normalized with respect to the steady-state diffusion-limited current, i(oo), for the oxidation of Br ) versus the inverse square-root of time. 

M sulfuric acid to air [34]. As discussed above, for the aqueous-DCE interface, the rate of this irreversible transfer process (with the air phase acting as a sink) was limited only by diffusion of Bt2 in the aqueous phase. A lower limit for the interfacial transfer rate constant of 0.5 cm s was found [34]. 

In this connection, it is speculated that the two electron reduction of O2 by CQH2 [Eq. (18)] might proceed even at potentials more positive than those for the polarogram of curve 1 in Fig. 9 as illustrated by the broken line (curve 3), though the current due to the reaction might be canceled out by the current due to the interfacial transfer of CQ [Eq. (20)]. 

The intrinsic constitutive laws (equations of state) are those of each phase. The external constitutive laws are four transfer laws at the walls (friction and mass transfer for each phase) and three interfacial transfer laws (mass, momentum, energy). The set of six conservation equations in the complete model can be written in equivalent form ... 

Byron and coworkers [7,8] developed and evaluated a transport cell which proved to be useful in predicting interfacial transfer kinetics between aqueous and organic boundary layers. In this system, stirring is generated by using paddles in each phase. These investigators demonstrated that successful prediction of the transfer kinetics of any homologue in a series was possible in all cases from... 

P Byron, M Rathbone. Prediction of interfacial transfer kinetics. I. Relative importance of diffusional resistance in aqueous and organic boundary layers in two-phase transfer cell. Int J Pharm 21 107, 1984. 

As pointed out earlier, the conventional method of treating the problem is by assuming an interfacial equilibrium between C2 Cj. Based on the reported solubility, 50 ppm, of TBTC1 in sea water (12), "m" may be assigned a value of 5 x 10-5. However, an assumption is being made here that the equilibration is fast. Since Cardarelli has pointed out the possibility of a rate controlling interfacial transfer, we have decided to consider the phase transfer rate rather than interfacial equilibrium. 

We consider a transfer reaction of redox electrons in which the interfacial transfer of electrons is in quasi-equilibrium ( Hh =0) and the diffusion of redox particles determines the overall reaction rate. The anodic diffusion current, and the anodic limiting current of diffusion, inm, in the stationary state of the electrode reaction are given, respectively, in Eqns. 8-33 and 8-34 ... 

The amount of interfacial transfer area created by the action of the flowing gas on the liquid is proportional to some fraction of the power transferred from the gas per unit volume of liquid. 

Interfacial transfer is the transport of a chemical across an interface. The most studied form of interfacial transfer is absorption and volatilization, or condensation and evaporation, which is the transport of a chemical across the air-water interface. Another form of interfacial transfer would be adsorption and desorption, generally from water or air to the surface of a particle of soil, sediment, or dust. Illustration of both of these forms of interfacial transfer will be given in Section l.D. 

Interfacial transfer of chemicals provides an interesting twist to our chemical fate and transport investigations. Even though the flow is generally turbulent in both phases, there is no turbulence across the interface in the diffusive sublayer, and the problem becomes one of the rate of diffusion. In addition, temporal mean turbulence quantities, such as eddy diffusion coefficient, are less helpful to us now. The unsteady character of turbulence near the diffusive sublayer is crucial to understanding and characterizing interfacial transport processes. 

Complexation of Pb(II) by cyclic thioethers facilitates reversible interfacial transfer in ion-transfer voltammetry for the water-nitrobenzene and water-1,2-dichloroethane systems [95, 96]. 

To achieve a transport of ions Iz+ across a membrane, there must be an interfacial transfer of the type... 

Tafel s law is the primary law of electrode kinetics, in the sense that Arrhenius law is the basic law of thermal reaction. It applies universally to all processes that are controlled in rate by the interfacial transfer of electrons or by a rate-determining surface reaction that may be coupled to the interfacial electron [Fig. 9.25(a)]. Redox reactions without surface intermediates demonstrate Tafel s law well [Fig. 9.25(b)]. 

In this work the authors summarize their own studies of photoprocesses on CdS colloids with particles of various size. In these studies, attention was given precisely to photocatalytic reactions on CdS, the photocatalytic reactions on TiC>2 were considered concurrently with the reported ones. In most cases photocatalytic reactions on semiconductors are the redox reactions. So of special interest was to study the regularities of reactions of interfacial transfer of photoexcited electron by the pulse photolysis and luminescence quenching methods. Many interesting phenomena were found while studying the model photocatalytic reactions by the method of stationary photolysis, i.e., under the conditions of real photocatalysis. 

The assumption on the electric charge effect of excess electrons on the rate constant of their interfacial transfer is supported by an evident similarity of these semiconductor colloidal systems with metal colloids, for which effect of the charge of electrons captured by the particle is well known and agrees with the microelectrode theory . Moreover, kinetic curves similar to those we found for CdS colloids were observed previously for silver colloids in ref. [17], where the particles charge q was shown to decrease by the law... 

The rate of the photobleaching relaxation of ultradispersed CdS, and hence the rate of the electron interfacial transfer from CdS to the surrounded media (finally, to protons yielding the hydrogen) appeared to depend on the size of the colloidal particles (see Fig. 2.10). The photobleaching relaxation rate increases as the size of the CdS semiconductor particles decreases. Such behavior may be caused by the increasing of reductive potential of photoexcited electron with decreasing size of semiconductor nanocolloids. In this case, according to the modern concepts of electron interfacial transfer reaction [19], the rate of electron transfer to the surrounded media should increase. 

The surface properties of ultradisperse semiconductor CdS which are determined in during its preparation, were shown to make a decisive influence on the regularities of interfacial transfer of photoexcited electron. In this section, we consider the effect of surface properties of ultradisperse CdS on the regularities of photoreduction of various substances under stationary illumination of CdS. 

Surface Active Agents and Interfacial Transfer in Gas Liquid Chromatography A New Tool for Measuring Interfacial Resistance, M. R. James, J. C. Giddings, and H. Eyring, J. Phys. Chem., 69, 2351 (1965). 

Investigation of the effect of membrane type on the interfacial transfer of methyl nicotinate... 

---