Strickland-Constable

Strickland-Constable, R.F., 1979. Journal of the Chemical Society Faraday Transaction, I, 75, 921. 

It is usually believed that the growth of dendritic crystals is controlled by a bulk diffusion-controlled process which is defined as a process controlled by a transportation of solute species by diffusion from the bulk of aqueous solution to the growing crystals (e.g., Strickland-Constable, 1968 Liu et al., 1976). The appearances of feather- and star-like dendritic shapes indicate that the concentrations of pertinent species (e.g., Ba +, SO ) in the solution are highest at the corners of crystals. The rectangular (orthorhombic) crystal forms are generated where the concentrations of solute species are approximately the same for all surfaces but it cannot be homogeneous when the consumption rate of solute is faster than the supply rate by diffusion (Nielsen, 1958). 

ILLUSTRATION 2.2 DETERMINATION OF EQUILIBRIUM COMPOSITIONS IN THE PRESENCE OF SIMULTANEOUS REACTIONS [ADAPTED FROM STRICKLAND-CONSTABLE (2)]... 

Strickland-Constable, R. F., Chemical Thermodynamics, in Volume 8 of Chemical Engineering Practice, edited by H. W. Cremer and S. B. Watkins, Butterworths, London, 1965. Used with permission. 

Nucleation, the creation of crystalline bodies within a supersaturated fluid, is a complex event, since nuclei may be generated by many different mechanisms. Most nucleation classification schemes distinguish between primary nucleation - in the absence of crystals and secondary nucleation - in the presence of crystals. Strickland-Constable 27 and Kashchiev 28 have reviewed nucleation, and Garside and Davey(29) have considered secondary nucleation in particular. 

Condensation is generally a transient operation in which, as discussed by Ueda and Takashima(106), simultaneous heat and mass transfer are further complicated by the effects of spontaneous condensation in the bulk gaseous phase. After the creation of supersaturation in the vapour phase, nucleation normally occurs which may be homogeneous in special circumstances, but more usually heterogeneous. This process is followed by both crystal growth and agglomeration which lead to the formation of the final crystal product. As a rate process, the condensation of solids from vapours is less well understood than vaporisation(98). Strickland-Constable(107) has described a simple laboratory technique... 

Strickland-constable, R. F. Kinetics and Mechanism of Crystallisation (Academic Press, London, 1968). 

Unfortunately, OH and O concentrations in flames are determined by detailed chemical kinetics and cannot be accurately predicted from simple equilibrium at the local temperature and stoichiometry. This is particularly true when active soot oxidation is occurring and the local temperature is decreasing with flame residence time [59], As a consequence, most attempts to model soot oxidation in flames have by necessity used a relation based on oxidation by 02 and then applied a correction factor to augment the rate to approximate the effect of oxidation by radicals. The two most commonly applied rate equations for soot oxidation by 02 are those developed by Lee el al. [61] and Nagle and Strickland-Constable [62],... 

Nagle, J., Strickland-Constable, R. F., Proceedings of the Fifth Carbon Conference,... 

Equation 7 shows the exponential variation of the homogeneous nucleation rate with an increasing supersaturation ratio. Equation 8, coming from the model of Strickland-Constable [59], establishes that a linear relation exists between growth rate and supersaturation ratio. The direct comparison of Nr and Gr is difficult because of their different units. However, Fig. 7, although only schematic, shows the variation of these two rates versus S, predicting that for a certain value of S the nucleation rate will become preponderant on the growth rate. Moreover, it also shows, that, in the case of preponderance... 

Key (46) and Strickland-Constable (47) also support mechanism B for the carbon-carbon dioxide reaction. Strickland-Constable concludes from earlier measurements (46) that the rate of adsorption of carbon monoxide on carbon is too low to account for the retardation. 

Strickland-Constable (47), observing that hydrogen is not only strongly but very rapidly adsorbed on carbon, supports the view the hydrogen retardation in the carbon-steam reaction is caused by its chemisorption on active sites. 

Workers reporting orders of reaction for the carbon-carbon dioxide reaction include Graham (41), Strickland-Constable (48), Vulis and Vitman (60), Thring and Price (61), Armington (62), Vastola (63), Duval (64), and Karzhavina (65). As expected, they find reaction orders which vary from zero to one depending upon temperature, pressure, type of carbon reacted, purity of carbon, and geometric dimensions of the sample. 

Secondary nucleation deals with the situation in which nuclei are generated in the vicinity of crystals of the solute already present in a supersaturated solution. The solute crystals may have resulted from primary nucleation or may be deliberately added. This subject has also been covered by Mullin, as well as in a number of reviews (Strickland-Constable 1968 Botsaris 1976 DeJong 1979 Garside and Davey 1980 Garside 1985 Nyvlt etal. 1985). 

J. Nagle and R. F. Strickland-Constable, Proc. Fifth Conf. on Carbon, vol 1,... 

R. F. Strickland-Constable, Second Conf. on Industrial Carbon and Graphite, Soc. Chem. Ind. London, 235 (1966). 

Inherent in the developments given is the assumption that all adsorption sites will yield a product oxide. In considering the heterogeneous oxidation of coal char or soot particles, however, it is most apparent not all sites are reactive, nor do they all have the same reactivity. In an effort to obtain a more detailed analysis of the burning rates of such materials as a function of temperature, Radcliffe and Appleton [31] proposed a mechanism that leads to the development of the semiempirical correlation of Nagle and Strickland-Constable [32]. Indeed, on the basis of structural similarities, these investigators have suggested that the rate of oxidation of soot and char-like materials should be equivalent. In their mechanism of surface oxidation, they posited two types of reaction sites in the exposed area... 

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