The kinetics and mechanism of the chloride-chlorate reaction

The kinetics of the reaction have been studied at 25°C. in strong acid solution; the effects of acidity, chloride, chlorate and chlorine are reported. A mechanism is postulated to interpret the peculiar features of this reaction as well as the stoichiometry and some of the kinetics of the parallel reaction The mechanism involves HClO₂ and HOCl as intermediates General rate expressions are derived for the formation of chlorine dioxide and chlorine, and the individual rate constants are calculated. An expression is obtained for the relationship between the ratio of chlorine dioxide to chlorine produced and the ratio of chlorate to chloride.     

Struktur und eigenschaften von ABS-polymeren II.. Grenzviskositäts-molekulargewichtsbeziehungen für azeotrope styrol/acrylnitril-copolymerisate

Limiting viscosity numbers of azeotropic copolymers of styrene and acrylonitrile were measured in dimethylformamide (DMF) and in methyl ethyl ketone (MEK). Their weight average molecular weights (10⁴ g/mole ? M_w ? 10⁶ g/mole) were determined by light scattering. The viscosity – molecular weight relationships obtained, are for DMF and for MEK The number average molecular weights were determined by osmotic pressure measurements, and now molecular weight heterogenities were calculated. The homogenity in composition was investigated by light scattering measurements in different solvents. In addition the viscosity-molecular weight relationship for polystyrene in DMF was determined and compared with the relationship for the azeotropic poly (styrene-co-acrylonitriles) and for polyacrylonitrile: On account of the results a possibility is shown for calculating molecular weights of poly (styrene-co-acrylonitrile) of any composition from limiting viscosity numbers and the acrylonitrile contents.     

Transferts thermiques entre un serpentin et des fluides newtoniens ou non—newtoniens agités par une turbine à pales inclinées dans une cuve

The present work deals with the heat transfer from a hélicoïdal worm to newtonian or non-newtonian liquids, which and stirred by a 4 pitched blade-turbine in a cylindrical tank. The effective viscosity of the pseudoplastic liquids is determined by the Metzner-Otto model combined with the Ellis rheological equation. The heat transfer in the newtonian fluids in a turbulent system is most precisely represented by the following equations: (a) (b) In the case of non-newtonian fluids and of downward pumping, the following equation enables to obtain a very precise evaluation of the heat-transfer coefficient in a transitional flow.      

Spin coating behavior of polyimide precursor solutions

Experimental data confirm the utility of the following simple equation in predicting the spin coating behavior of polyimide precursor solutions: in which .     

Heat transfer to agitated non-newtonian fluids

Heat transmission to agitated non-Newtonian liquids in a jacketed vessel has been studied. Heat transfer tests were conducted under unsteady-state conditions with pseudo-plastic solutions (behavior index range: 0.343 to 0.633). For a generalized Reynolds number ranging from 100 to 5000, two correlations were found: The use of a generalized Sieder and Tate number resulted in an equation combining both heating and cooling data with a somewhat higher mean deviation (19.3%):      

Prediction of steady-state dispersion height in the disengaging section of an extraction column from batch settling data

The decay of a dense dispersion formed under calm conditions is given by Experiments in a batch vessel with different liquid-liquid systems and initial drop diameters show that the dimensionless constant K is equal to 26,000. This agrees with the value previously determined from the variation in steady-state dispersion height with throughput in spray columns, the analogous equation being The results can thus be used to predict the height of the dispersion formed in the disengaging section of extraction columns.     

Catalytic oxidation of benzene to maleic anhydride in a continuous stirred tank reactor

The kinetics of the vapor phase oxidation of benzene has been studied over an industrial catalyst in a continuous stirred tank reactor in the temperature range from 280 to 430°C and at atmospheric pressure. The products obtained are maleic anhydride, carbon oxides and water. The rate of the overall reaction (disappearance of benzene) is represented by the following expression based upon a steady state adsorption model The rate of formation of maleic anhydride is correlated by the equation which allows for a homogeneous depletion of maleic anhydride. The rate constants k_B, k_O, k_2(g) were found to follow Arrhenius behavior.      

Drop size distribution in a graesser contactor

An investigation was conducted of drop size distribution in a Graesser contactor, employing five liquid – liquid systems, viz., kerosene/water, benzene/water, xylene/water, hexane/water and n–butyl acetate/water. A 100 mm (4 inch) diameter Graesser contactor was used for this purpose It was found that the drop size distribution in a Graesser contactor obeys the upper – limit distribution expressed as: where A correlation was developed relating the Sauter mean diameter (d₃₂) to other effective groups      

A one-point intrinsic viscosity method for polyethylene and polypropylene

A statistical analysis of dilute solution viscosity data for a wide range of polyethylene and polypropylene samples in Decalin at 135°C has shown that the Martin equation fits the experimental data better than the Huggins equation at higher values of [η]c. A grand average k of 0.139 is applicable to both polymers. Based upon this, tables have been calculated permitting the ready determination of [η] from a single relative viscosity measurement at a known concentration. The Martin equation has been put into a universal form, permitting [η] to be calculated from a measured η_sp if k and c are known. Graphs relating η_sp to [η] are included for use of the Martin equation over wide ranges of both k and c. It was found that the Solomon and Ciuta equation fits the experimental polyethylene and polypropylene data, and the reasons for this are discussed.     

The molecular weight average obtained by combining quasielastic light-scattering and intrinsic viscosity measurements

For “monodisperse”, randomly coiled macromolecules, we find that the molecular weight, intrinsic viscosity, and diffusion coefficient are accurately related by This equation holds for denatured proteins in 6M GuHCl(aq) as well as for narrow polystyrene fractions in tetrahydrofuran. For a Schulz distribution of molecular weights, the weight measured from combining diffusion and viscosity data is closely approximated by These equations are verified with measurements of wide molecular distributions of polystyrene in toluene and data from the literature. These relations provide a rapid, nondestructive method to determine a well-specified molecular weight average of small quantities of polymers in a wide diversity of solvents using quasielastic light scattering techniques to evaluate polymer diffusion coefficients.     

Die Größenänderung von Polyvinylpyrrolidon bei der Adsorption von Blankophorionen (Vzskosimetrie und Lichtstreuung)

Anionic fluorescent dyes of the class of Blankophors adsorb in aqueous solution on polyvinylpyrrilidon. The electrostatically loading of the polymer through the covering with Blancophor ions increases the to end distance in dependence of the concentration of the counter-ions. The equivalent volume is pursued by viscosity measurements. When Blankophor or salt is in excess the increasing of the end to end distance does not take place. The average end to end distance of Polyvinylpyrrolidon is determined as a function of coverage with Blancophor and counter-ion concentration by light scattering measurements. The found linear expansion coefficients α are compared with the theories of HERMANS -OVERBECK , KUHN -KATCHALSKI and ALEXANDROWICZ . It is shown that the discrepancy between measured values and theory is not explicable by ion pair binding.     

Elutriation characteristics of solids from liquid fluidized bed systems Part I: Onset of elutriation

Experimental data for the minimum elutriation velocity u_me of solids for 134 different systems have been correlated by The ranges of the different groups investigated were as follows: For all of the experiments, the fluidizing liquid was water and the tube had an inside diameter of 4.92 cm. The standard deviation for the above correlation is 21.6 per cent.     

Some aspects of liquid-solid fluidized beds

Hydrodynamic characteristics of randomly packed fluidized beds were investigated using particles of different sizes and densities fluidized with water. The minimum fluidization velocity was found to be independent of the initial bed height. The minimum fluidization velocity was found to be Bed expansion followed the Richardson Zaki relationship and the exponent 'n' has been correlated as:      

A modified correlation to predict the minimum velocity required to elutriate solids from a liquid-fluidized bed

The consideration of sphericity of solids for the prediction of u_me gives rise to some improvement of the correlation proposed earlier by the author. In the absence of wall-effect, the following correlation is obtained: which gives a standard deviation of ± 16.3% for 138 different experiments as against ± 21.6% for 134 runs by the correlation reported earlier. The ranges of the various groups are      

Thermal reactions between MII sulphates and acid orthophosphates in the solid state

Two general types of high temperature reactions between M^II sulphates and acid orthophosphates have been found and a survey of some representative examples has been made. The reactions are typified by two examples using Ca²⁺ salts: and . Similar reactions have been found for other alkaline earth sulphates and phosphates and for corresponding mixed alkaline earth systems. The products have been found to be largely determined by the phase relationships in the respective M^IIO–P₂O₅ systems.     

Direct contact heat transfer between two immiscible liquids during vaporisation

A cine-photographic technique was used to study the evaporation of single droplets of furan, cyclopentane and isopentane rising in water. Measurements were possible over a range from zero to 10% evaporation. The best correlation of the data for the three systems over the measurable range of parameters was: All the data was fitted by this equation to within ± 20%. A second correlation with a slightly larger variance because of the manner in which the density ratio term varies with % evaporation, was recommended for extrapolation to higher percentage evaporations.     

Studies on graft copolymerization of methyl methacrylate onto poly(vinyl chloride)

The grafting of methyl methacrylate on suspension-grade poly(vinyl chloride) in the presence of lauroyl peroxide has been studied. The reaction was carried out in a water suspension of the starting PVC polymer swollen with the monomer. The influence of reaction temperature, T, starting monomer/polymer ratio, M/P, and initiator concentration, I, in the monomer on the grafting efficiency of both polymers present in the system was found to be well described by the following linear regression equations: and      

Drainage in thin planar non-newtonian fluid films

Equations for the radial and linear drainage of non-Newtonian fluids in horizontal and inclined films are presented. For a power law fluid with index m, the variation in dimensionless film thickness Δ with dimensionless time T is given by: where Δ and T are appropriately defined for drainage in radial horizontal and linear inclined films. The corresponding approximate expression for a Bingham plastic fluid is: in which A is the minimum film thickness defined appropriately at the asymptotic limits when Δ » A and Δ ? A.     

The experimental determination of velocity profiles in smooth falling liquid films

A new photographic technique using tracer particles is described for measurement of the fluid velocity distribution in falling liquid films. The distribution for fully-developed ripple free flow was measured with a precision of 1% for velocity and 4 microns for depth and was found to follow the theoretical Nusselt equation … over the Reynolds number range 75–250 where the Reynolds number is defined as the ratio of the peripheral mass flow rate to the viscosity. The technique is also applicable to flow close to any smooth reflecting planar boundary.     

Gravity settling in liquid/liquid dispersions

An empirical expression for the prediction of dispersed phase hold-up and slip velocity in droplet dispersions settling under gravity is presented. Analysis of 998 published experimental results for 29 liquid/liquid systems from 14 different data sources shows that the slip velocity of the drop swarm is given in terms of drop diameter and physical properties of the system by: Good agreement between experimental and predicted values of slip velocity is obtained over a wide range of hold-up (0.01 to 0.76) and Reynolds number (0.16 to 3169).