Pullulan in a solid growth medium can be precipitated selectively with ethanol. Clear zones due to pullulan hydrolysis surround microbial colonies which produce the appropriate enzyme. When this procedure was applied to 297 strains representing 26 species of the genus Bacillus, 138 (46%) of the organisms were shown to hydrolyze pullulan.
AbstractThe reactions occurring between gaseous hydrogen chloride and lead (II) carbonate and lead (II) hydroxide carbonate (white lead) have been studied over a range of temperatures and partial pressures of hydrogen chloride. The only solid reaction product is lead (II) chloride which is formed in a single stage. Kinetic studies show that the diffusion of HCI is probably the rate‐controlling step and Arrhenius parameters for this process are given.
The relative position of the phase boundary curves and changes in group chemical composition have been studied, in a single stage extraction system, with three solvents for medium viscosity, raw dewaxed lube distillate. Results obtained indicate that solvents with hydrogen-bonding tendency show low critical solution temperatures and %N + P in raffinate tends to be directly proportional to the product VI with the increase in S:F ratio. Refining effectiveness number and lube refining index together makes it possible to evaluate the solvent refining behaviour of any raw lube distillate for the desired VI level.
AbstractIn a previous paper1 we described how empirical slopes and parameters, derived from graphs of experimental solubility properties, could be effectively used to predict the solubility and related properties for 18 gases in 30 relatively non‐polar solvents. In this paper the “empirical slopes approach” is extended to provide predictions of solubility and entropy of solution for these gases in binary mixtures of the same solvents. Predictions of solubility and entropy of solution have been calculated for several of the gas‐mixture systems that have been measured experimentally and the agreement is found to be satisfactory. The merits of this approach are compared with those of other theories which can be used to yield gas solubility predictions in mixed solvents.
AbstractChopped reed stalks and depithed bagasse were pulped in alkaline media separately and in admixtures. Almost all paper‐making characteristics of pulps were improved under milder cooking conditions, with 14% alkali and 120°C being optimum. When part of the NaOH was substituted by Na2S, at 21% sulphidity, little or no effect was observed at the optimum conditions. When reed and bagasse were pulped in admixtures of equal proportions, mixed pulps showed the good inherent properties of both reed and bagasse fibres with improved tensile, burst and tear strength. The mixed soda reed‐bagasse pulps were produced on a mill scale and showed the same trend of properties.
AbstractGrowth kinetics of Streptomyces erythreus were studied and mathematical equations developed to model the results. Computer simulations gave good agreement with experimental data. Owing to the use of complex media direct measurement of biomass was impossible. It was therefore evaluated by measurement of α, ϵ‐LL‐diamin‐opimelic acid in cell walls, or by determining the reciprocal of the methylene blue reduction time.
AbstractAn equation which relates the volume term (V=M/(ρL‐ρg)) of unassociated liquids to pressure P and temperature T has been obtained by the combination of (a) 03V(∂I/∂V)P→0=Tx‐T for the effect of temperature on V at low (atmospheric) pressure and (b) ‐ V(∂P/∂V)T = Px Vx/6/V6 p→0+9(P‐p) for the effect of pressure on volume at constant temperature. In the equations, p is the vapour pressure; pL the density of the liquid and pg the vapour density. Often pg can be neglected compared with pL and p is small compared with the large pressures required to affect the densities of liquids appreciably. There are three constants: Tx, Px, which equals 4.455 × 109 N m2, and Vx which can be calculated by the addition of atomic values for all the atoms in the molecule and subtraction of a value (6.56 × 106 m3 mol1) for each bond. When V approximates to M/ρL, the molar volume, the equation can be integrated to give the work and heat of isothermal compression. The viscosity of a liquid is related to the work of compression and solubilities in a liquid to the work required to bring the solute to the compressibility of the liquid. Many relationships can be derived and can be used to estimate properties of unassociated liquids.
AbstractThe thermal reactivity of ammonium perchlorate was found to be dependent on the pH of the solution from which it had been crystallised. A nitric acid‐crystallised sample reacted faster than an ammonium hydroxide‐crystallised one.
AbstractBleaching of rice straw soda pulp was investigated under various conditions. The rate of the chlorination and hypochlorite reactions were studied; the best properties were attained by shortening the chlorination time to about 20 min. The extraction efficiency of ammonium hydroxide on chlorinated soda pulp was also investigated. The effectiveness of extraction can be deduced from the reduction of the kappa number, cuprammonium viscosity and the brightness obtained after the hypochlorite step. Extraction can be carried out with ammonium hydroxide instead of sodium hydroxide used in the conventional method. The strengths of unbleached and fully bleached pulps were evaluated. The fully bleached ammonium hydroxide extracted pulps were beaten faster and were usually stronger than the corresponding pulps extracted with sodium hydroxide.
AbstractKinetics and interfacial tension studies concerning the liquid cation exchanger dinonylnaphthalene sulphonic acid (HD) and the liquid anion exchangers trilauryl‐ammonium chloride and nitrate (TLAHCI and TLAHNO3), performed in the laboratory, are reviewed. The interfacial tension studies have shown that, due to the very strong surface active properties of these compounds, even at very low bulk organic concentrations, the interfacial plane gets completely saturated with a strongly adsorbed monomolecular layer of the exchanger. The structure of the interface is such that the ion‐exchange group faces the aqueous phase while its organic part is completely immersed in the organic diluent. Extraction kinetic experiments performed with a quiescent interface cell (Lewis cell) as a function of the stirring speed, interfacial area and volume of the phases have shown that (a) a region always exists where the extraction kinetics is independent of the stirring speed and (b) the exchange kinetics is directly proportional to the interfacial area and inversely proportional to the volume of the phases. These two facts, together with the knowledge of the interfacial structure of the exchanger, are a strong indication that interfacial chemical reactions can have a predominant effect in determining the extraction kinetics. Experiments performed at relatively high stirring speeds of the phase as functions of the chemical composition of the system have produced a set of interfacial chemical reactions which completely describe the kinetics of the liquid ion‐exchange process. This set of reactions consists basically of the following steps: (a) formation of an interfacial complex between the interfacially adsorbed molecules of ion‐exchanger and the metal cation or complex present in the aqueous solution, (b) replacement at the interface of the interfacial complex with bulk organic molecules of the ion‐exchanger; this process, with a rate which is proportional to the organic concentration of the exchanger, occurs through the reaction with bulk molecules of the extractant, and (c) the reverse steps occur when organic to water transfer takes place. By applying the stationary condition to the interfacial complex its concentration has been evaluated and a rate expression derived which has led to the calculation of the rate constants of the chemical reactions. The following metal ions have been studied experimentally: Fe+3, Eu+3, Ce+3, Gd+3, Tm+3 with HD; FeCln3‐n with TLAHCI and Pu(NO3)n4‐n with TLAHNO3. By using the derived rate expressions and rate constants, distribution laws have been obtained to calculate equilibrium distribution data in good agreement with experimental results.
AbstractThis paper reviews the heterogeneous nucleation of melts of some inorganic salt hydrates. Five salt hydrates were tested as materials for heat storage.
AbstractThe biomass productivity of cyclically operated variable volume fermenters has been investigated as a function of the initial volume and the feed flow rate. The results of computer simulations show that the productivity‐dilution rate curves are similar to those for a constant volume chemostat, which represents a limiting case for the cyclic operation. Both cyclic fed batch and fed batch plus batch operation have been studied for Monod and substrate inhibition kinetics. The results obtained for variable volume operation can be used to estimate the loss in productivity when a chemostat inadvertently undergoes volume fluctuations.
Studies have been made of the kinetics of carbon deposition on supported nickel catalysts used for steam reforming. Comparison with results obtained with nickel foils show that the support has little effect on the rate of deposition, except that hydrogen did not affect the kinetics of the process on supported catalysts. This is explained in terms of the initial production of nickel crystallites, which are then carried with the growing carbon by a process of diffusion of carbon through the nickel. Calculations show that this diffusion process may well involve the formation of an intermediate carbide.
AbstractStudies have been carried out of the optimisation of a bismuth oxide based catalyst for the oxidation of isobutene to p‐xylene. Using a Bi2O3‐P2O5 (Bi:P = 2) catalyst located sequentially before a 3% Pt/Al2O3 catalyst, up to 60% selectivity can be observed at 50% conversion. The kinetics of the oxidation of isobutene over the Bi2O3‐P2O5 catalyst have been measured for all major products. The results support a mechanism involving allylic oxidation of isobutene. Dimethylhexadiene and p‐xylene are suggested to originate from reaction between two adsorbed isobutene molecules and monatomic oxygen species adsorbed at different sites. A major side product, methacrolein, appears to originate from reaction between two adsorbed isobutene molecules and a diatomic oxygen species.
AbstractThe surface acidic strength distribution in a series of silica‐alumina catalysts prepared by coprecipitation and stepwise precipitation techniques has been measured by the butylamine adsorption method. The amount of silica in the finished catalysts ranged from 86.0 to 96.9%. A linear relationship between the pH of the final gel (i.e. pH values of the solution in equilibrium with the gel material before washing) and X[=Al2O3/(SiO2+Al2O3)] was observed up to a certain level of pH; for coprecipitated catalysts it was 6.0 whereas for those precipitated stepwise the limit of pH was 7.0. Coprecipitated silica‐aluminas were more enriched with weak acid sites or Bronsted sites (pKa = +6.8) and their concentration reached a maximum at about 87% silica. Stepwise precipitated silica‐aluminas, on the other hand, have a greater population of strong acid sites, thus making them useful for cracking reactions.
AbstractDifferent laboratory crystal populations of potassium chloride are described and compared with similar types of industrial crystals. Laboratory experiments have shown that the crystal characteristics, i.e. size distribution, crystal habit and degree of agglomeration are strongly affected by the degree of supersaturation at the beginning of crystallisation. Similarity of crystal characteristics indicates similarity of factors governing growth conditions, hence the industrial growth conditions, especially supersaturation in a crystalliser, may be determined by inspection of the final product.
AbstractStructural composition of two distillate waxes obtained from Ankleshwar crude oil tank bottoms have been determined using physical properties correlations, high temperature g.l.c., 1H‐n.m.r. and 13C‐Fourier transform n.m.r. spectroscopy. Both waxes seem to contain predominantly n‐paraffins.
The effect of washing on the texture of silica gel has been investigated in terms of parameters such as porosity, pore size distribution, surface area and absorption of moisture. It was observed that if silica gel (before activation) is washed with water containing dissolved ions such as Ca and Mg wider pores are formed at the expense of smaller ones. This phenomenon has been explained in terms of change in the size distribution of gel particles which is brought about by solution of very fine particles followed by growth, through condensation, of larger particles. The experimental observations have been interpreted to suggest guidelines to control the texture of gels by washing with solutions comaining different cations.
