Wilbur S. Hall

Bio: Wilbur S. Hall is an academic researcher. The author has contributed to research in topics: Freundlich equation & Langmuir. The author has an hindex of 2, co-authored 3 publications receiving 21 citations.

Reaction velocity in the system iron: Dilute acetic acid at 40°C

Abstract: The rate-determining factors in corrosion reactions have been reviewed in the light of the work of Nernst, Langmuir, and others, and the characteristics of diffusion and activation control in such reactions have been discussed. Following Freundlich and Langmuir, corrosion inhibitors are assumed to act by adsorption on the metal surface. Rate equations containing the function s , the fractional surface covered by adsorbed inhibitor, are given to express the reaction velocity in diffusion and activation controlled systems. A detailed discussion is given of equipment and procedure devised for studying the velocity of corrosion reactions under conditions where the amounts of corrodents, both liquid and gaseous, are under careful control. A study of the corrosion system iron: acetic acid is made at 40° C., where the amount of acetic acid is 1000 ppm., in the absence of oxygen. The behavior of the system is studied in the presence and absence of corrosion inhibitors. Two commercial corrosion inhibitors were selected for study. The results of the experiments have been plotted according to the velocity equation given for diffusion-controlled reactions and are shown to be in agreement with that equation. They can, however, agree with an activation-controlled mechanism. Further experiments at higher temperatures, now being carried out in this laboratory, should shed light on the actual mechanism. The apparent value of s , the fractional surface covered by inhibitor, is calculated for each experiment. It is shown that s is a useful concept in corrosion testing, and that inhibitors can be evaluated and their inhibitor efficiency expressed in terms of this quantity. In the experimental work, two series of corrosion experiments were carried out: one in the presence of an oil phase (mineral spirits), and one in the absence of an oil phase. The experiments showed a very considerable acceleration of the reaction velocity in the presence of the oil phase. The possible influence of an oil phase in corrosion reactions is discussed. Of the two inhibitors studied, one exerts its inhibiting action either in the presence or absence of an oil phase. Apparently it is strongly adsorbed. The other inhibitor shows some inhibiting action in the presence of an oil phase, but little in the absence of the oil phase. This casts some interesting light on the “adsorption” and “water displacing” theories of inhibitor action in oil wells.

Researches on corrosion and inhibition reaction velocity in the system iron: dilute acetic acid at 40°C.

Abstract: The rate-determining factors in corrosion reactions have been reviewed in the light of the work of Nernst, Langmuir, and others, and the characteristics of diffusion and activation control in such reactions have been discussed. Following Freundlich and Langmuir, corrosion inhibitors are assumed to act by adsorption on the metal surface. Rate equations containing the function s, the fractional surface covered by adsorbed inhibitor, are given to express the reaction velocity in diffusion and activation controlled systems. A detailed discussion is given of equipment and procedure devised for studying the velocity of corrosion reactions under conditions where the amounts of corrodents, both liquid and gaseous, are under careful control. A study of the corrosion system iron: acetic acid is made at 40° C., where the amount of acetic acid is 1000 ppm., in the absence of oxygen. The behavior of the system is studied in the presence and absence of corrosion inhibitors. Two commercial corrosion inhibitors were selected for study. The results of the experiments have been plotted according to the velocity equation given for diffusion-controlled reactions and are shown to be in agreement with that equation. They can, however, agree with an activation-controlled mechanism. Further experiments at higher temperatures, now being carried out in this laboratory, should shed light on the actual mechanism. The apparent value of s, the fractional surface covered by inhibitor, is calculated for each experiment. It is shown that s is a useful concept in corrosion testing, and that inhibitors can be evaluated and their inhibitor efficiency expressed in terms of this quantity. In the experimental work, two series of corrosion experiments were carried out: one in the presence of an oil phase (mineral spirits), and one in the absence of an oil phase. The experiments showed a very considerable acceleration of the reaction velocity in the presence of the oil phase. The possible influence of an oil phase in corrosion reactions is discussed. Of the two inhibitors studied, one exerts its inhibiting action either in the presence or absence of an oil phase. Apparently it is strongly adsorbed. The other inhibitor shows some inhibiting action in the presence of an oil phase, but little in the absence of the oil phase. This casts some interesting light on the “adsorption” and “water displacing” theories of inhibitor action in oil wells.

The action of polar organic inhibitors in the acid dissolution of metals

Abstract: : A mechanism based on recent advances in the field of chemisorption on metals is presented for inhibition by polar organic compounds. Electrostatic bonding at the cathode areas contributes to the over-all inhibition. However, polarization of anodic dissolution because of chemisorption of the inhibitor is more pronounced than cathodic polarization. Inhibitor chemisorption occurs through coordinate covalent bond formation with surface atoms of the metal. This mechanism satisfactorily explains the dependence of inhibitive power on the electronic structure of the functional group, on the solubility, and on the substituents of the inhibitor. The theory allows for different metals and permits positive and negative temperature coefficients. Sterochemical effects occur, but they are of less importance than previously thought. The results reported in the literature for N- and S- containing compounds, aldehydes,and ketones are in agreement with the mechanism. The effect of the ethylenic linkage in the inhibitor and the ortho effect are also consistent with this mechanism.

On dimensionless numbers

Abstract: The goal is to provide a little review on dimensionless numbers, commonly encountered in chemical engineering. Both their sources are considered: dimensional analysis and scaling of governing equations with boundary conditions. The numbers produced by scaling of equation are presented for transport of momentum, heat and mass. Momentum transport is considered in both single-phase and multi-phase flows. The numbers obtained are assigned the physical meaning, and their mutual relations are highlighted. Certain drawbacks of building correlations based on dimensionless numbers are pointed out.

Liquid-liquid mixing in stirred vessels: a review

Abstract: Liquid-liquid mixing is a key process in industries that is commonly accomplished in mechanical agitation systems. Liquid-liquid mixing performance in a stirred tank can be evaluated by various parameters, namely minimum agitation speed, mixing time, circulation time, power consumption, drop size distribution, breakup and coalescence, interfacial area, and phase inversion. The importance of these liquid-liquid mixing parameters, the measurement method, and the results are discussed briefly. Input parameters such as impeller type, power number, flow pattern, number of impellers, and dispersed phase volume fraction, in addition to physical properties of phases such as viscosity and density, are reviewed. Scale-up aspects are also included.

The meaning of developmental time: a metric for comparative embryology

Abstract: The lack of a suitable metric for developmental time has prevented a comparison of developmental rates and tempos between species, thus precluding analyses of heterochronic processes in evolution that do not depend on the use of morphology or size as an index of age At least two problems exist in using clock time itself as the measure of developmental time: temperature effects within a species, and size effects across species Consideration of two important distinctions that can be made in the notion of time-that between time as sequence and time as duration and that between extrinsic and intrinsic time-suggests that a metric, to be useful, must satisfy seven criteria: (1) it should be independent of morphology; (2) it should be independent of size; (3) it should depend on only one a priori homologous event; (4) it should be unaffected by changes in temperature for any given species; (5) closely related organisms should undergo homologous events at similar developmental ages as measured by the metric; (6

Experimental linkage issues of petroleum site bioremediation

Abstract: Bioremediation of petroleum-contaminated sites is expected to be a cost-effective remediation technology. However, many potential users of the technology expect the reliability of this technology to be similar to other candidate technologies for widespread consideration. In particular, candidate technologies should possess the property of reliable experimental linkage — there should be reasonable confidence that experiments done at one scale can be reliably related to another. An important example is bench-scale treatability studies that should result in linkages with commercial-scale operations. In this respect comparison of bioremediation to other candidate technologies reveals that bioremediation is in an early stage of its evolution. It is being pursued at a variety of sites and scales with practitioners from a variety of disciplines. Integration of activities between disciplines and an ability to quantitatively compare results at different sites and scales is proceeding. This paper addresses a number of physical, chemical, biological, analytical, and statistical issues regarding the successful comparison of results between experiments.