scholarly journals The theory of metallic corrosion in the light of quantitative measurements.— Part II

1928 ◽  
Vol 121 (787) ◽  
pp. 88-121 ◽  
Keyword(s):  
Potassium Chloride ◽  
Initial Period ◽  
Metallic Zinc ◽  
Dilute Solutions ◽  
Experimental Conditions ◽  
Limited Volume ◽  
Quantitative Measurements ◽  
Chlorine Ions ◽  
Oxygen Gas ◽  
Metallic Corrosion

In a previous paper it was shown that if dilute solutions of potassium chloride were allowed to act upon metallic zinc in the presence of oxygen, the corrosion-time curves obtained by means of the observed absorption of oxygen gas were exponential for part of their course. The reason why this particular form of curve was obtained was considered to be the gradual falling off in the concentration of chlorine ions in the experimental conditions of limited volume of solution. For N/10000 and N/5000 solutions the agreement between the experimental and calculated curves was satisfactory up to about 25 days except for a short initial period of two or three days. After about 25 days the experimental curves fell notably below the calculated values, and the suggestion that the reason for this discrepancy was mainly the barring out of chlorine ions from the anodic areas by means of accumulations of corrosion products received some support from the fact that chlorine ions were actually found in solution even after long periods of experiment with the N/5000 solution, in which this discrepancy was most pronounced, but since none were found in the more dilute solutions it seemed probable that some other factor was also operative.

scholarly journals The theory of metallic corrosion in the light of quantitative measurements.—Part IV

1931 ◽  
Vol 131 (817) ◽  
pp. 494-517 ◽  
Keyword(s):  
Potassium Chloride ◽  
Oxygen Supply ◽  
Experimental Methods ◽  
Metallic Surface ◽  
Potassium Sulphate ◽  
Corrosion Rates ◽  
Quantitative Measurements ◽  
Series Of Experiments ◽  
Metallic Corrosion ◽  
Reactive Metals

The present paper includes some experiments suggested by criticisms of Part III of the research, and describes work upon the effect of depth of im­mersion on the corrosion of zinc in potassium chloride solutions. Some of the factors which influence the distribution of corrosion over the metallic surface are discussed with particular reference to the effect of differential aeration. Curves are given showing the effect of concentration of potassium chloride and potassium sulphate on the initial corrosion rate of zinc in tranquil conditions. The experimental methods used are those described in previous papers, supple­mented by micrographic work and a few potential measurements. The criticism has been made that the tranquil conditions in which the present series of experiments is being conducted cause abnormally slow rates of oxygen supply which dictate the corrosion rates; these, therefore, are not considered characteristic of the metal under test, but merely of the rate of penetration of oxygen through the liquid and any corrosion products which cover the metal. It has also been suggested that much faster rates of oxygen supply would be required to bring out the true corrosion characteristics of a metal or even to differentiate between two fairly reactive metals.

scholarly journals The theory of metallic corrosion in the light of quantitative measurements.—Part III

1930 ◽  
Vol 127 (804) ◽  
pp. 42-70 ◽  
Keyword(s):  
Oxygen Absorption ◽  
Absorption Method ◽  
Quantitative Measurements ◽  
Loss Of Weight ◽  
Weight Method ◽  
Chlorine Ions ◽  
Comparative Results ◽  
Set Up ◽  
Metallic Corrosion ◽  
Source Of Error

The present paper describes an investigation into the degree of reproducibility obtainable by the oxygen absorption method of measuring corrosion, and gives comparative results for this and the loss of weight method. The work described in Part II which dealt with the corrosion of zinc in dilute potassium chloride has been extended up to 4N solution, and to a series of potassium sulphate solutions from N/10,000 to N. Slight vibration of the apparatus has been found to have been the source of error in three of the experiments described in Part II, namely those performed in N/200 and N/10 KCl. The corrosion-time curves for these solutions show too steep a slope owing to convection of oxygen set up by the vibration. Curves more nearly representing corrosion in truly stagnant conditions are given in fig. 4 of the present paper. The effect of vibration was only important in those experiments which were controlled by the rate of oxygen supply, whereas most of the experiments of Part II were controlled by the concentration of chlorine ions.

scholarly journals THE INACTIVATION OF DILUTE SOLUTIONS OF CRYSTALLINE TRYPSIN BY X-RADIATION

1955 ◽  
Vol 38 (5) ◽  
pp. 581-598 ◽  
Author(s):  
Margaret R. McDonald
Keyword(s):  
Sulfuric Acid ◽  
Nitric Acid ◽  
Hydrochloric Acid ◽  
Radiation Effects ◽  
Reaction Yield ◽  
X Rays ◽  
Dilute Solutions ◽  
Experimental Conditions ◽  
Ph Range ◽  
Ph Curve

The proteolytic activity of dilute solutions of clystalline trypsin is destroyed by x-rays, the amount of inactivation being an exponential function of the radiation dose. The reaction yield increases steadily with increasing concentration of trypsin, varying, as the concentration of enzyme is increased from 1 to 300 µM, from 0.068 to 0.958 micromole of trypsin per liter inactivated per 1000 r with 0.005 N hydrochloric acid as the solvent, from 0.273 to 0.866 with 0.005 N sulfuric acid as the solvent, and from 0.343 to 0.844 with 0.005 N nitric acid as the solvent. When the reaction yields are plotted as a function of the initial concentration of trypsin, they fall on a curve given by the expression Y α XK, in which Y is the reaction yield, X is the concentration of trypsin, and K is a constant equal to 0.46, 0.20, and 0.16, respectively, with 0.005 N hydrochloric, sulfuric, and nitric acids as solvents. The differences between the reaction yields found with chloride and sulfate ions in I to 10 µM trypsin solutions are significant only in the pH range from 2 to 4. The amount of inactivation obtained with a given dose of x-rays depends on the pH of the solution being irradiated and the nature of the solvent. The reaction yield-pH curve is a symmetrical one, with minimum yields at about pH 7. Buffers such as acetate, citrate, borate and barbiturate, and other organic molecules such as ethanol and glucose, in concentrations as low as 20 µM, inhibit the inactivation of trypsin by x-radiation. Sigmoid inactivation-dose curves instead of exponential ones are obtained in the presence of ethanol. The reaction yields for the inactivation of trypsin solutions by x-rays are approximately 1.5 times greater when the irradiation is done at 26°C. than when it is done at 5°C., when 0.005 N hydrochloric acid is the solvent. The dependence on temperature is less when 0.005 N sulfuric acid is used, and is negligible with 0.005 N nitric acid. The difficulties involved in interpreting radiation effects in aqueous systems, and in comparing the results obtained under different experimental conditions, are discussed.

Fixation of Chromium in Wood from Trivalent Chromium Salt Solutions

Holzforschung ◽  
1999 ◽  
Vol 53 (5) ◽  
pp. 465-473 ◽  
Author(s):  
F. C. Jorge ◽  
T. M. Santos ◽  
J. Pedrosa de Jesus ◽  
W.B. Banks
Keyword(s):  
Trivalent Chromium ◽  
Alcoholic Solution ◽  
Metallic Zinc ◽  
Wood Degradation ◽  
Reaction Conditions ◽  
Experimental Conditions ◽  
Nitrate Addition ◽  
Solution Reaction ◽  
Sulphate Salts ◽  
Chromium Salt

Summary The aim of this study was to fix chromium chemically in wood from trivalent chromium solutions. Chromium(III) nitrate, chloride and sulphate salts were applied, both in aqueous and in methanolic solutions. To improve chromium fixation metallic zinc was used as a strong reductant to generate labile Cr(II) species from Cr(III), and base was added (NaOH for water and NaMeO for methanol). Aqueous solution reaction conditions were always acidic in spite of base addition, leading to unacceptable levels of wood degradation (e. g., weight loss), although relatively high chromium levels were attained in some cases. Methanolic solutions did not lead to wood degradation, and there was fixation of high levels of chromium. Although the addition of NaMeO seemed to improve chromium fixation, a chromium precipitate always formed, usually after a long reaction time (> 4h). Therefore the following experimental conditions for chromium fixation are suggested: alcoholic solution of Cr(III) chloride or nitrate, addition of metallic zinc, at reflux. To avoid using large amounts of zinc, Cr(III)-solutions can also be reduced electrochemically.

Activation of a sepiolite with dilute solutions of HNO3 and subsequent heat treatments: III. Development of porosity

Clay Minerals ◽  
1981 ◽  
Vol 16 (4) ◽  
pp. 315-323 ◽  
Author(s):  
F. Rodríguez-Reinoso ◽  
A. Ramírez-Sáenz ◽  
J. De D. López-González ◽  
C. Valenzuela-Calahorro ◽  
L. Zurita-Herrera
Keyword(s):  
Adsorption Isotherms ◽  
Heat Treatments ◽  
Acid Activation ◽  
Dilute Solutions ◽  
Experimental Conditions ◽  
Porosity Development

AbstractPorosity development in a sepiolite from Toledo, Spain, has been studied as a function of acid (0·25, 0·50, 0·75 and 1·0 m HNO3) and subsequent heat treatments (110–400°C). Adsorption isotherms of N2 at 77 K have been analysed by f-plot, t-plot, αs-plot and the Cranston & Inkley methods. Results are compared with those obtained on products heated without previous acid activation. Experimental conditions favouring porosity development are discussed.

scholarly journals The theory of metallic corrosion in the light of quantitative measurements

1927 ◽  
Vol 116 (774) ◽  
pp. 425-467 ◽  
Keyword(s):  
Relative Importance ◽  
Improved Method ◽  
Salt Solutions ◽  
Present Communication ◽  
Technical Problems ◽  
The Third ◽  
Quantitative Measurements ◽  
Number Of Factors ◽  
Metallic Corrosion

The principal object of the present research is the discovery of a satisfactory way of measuring the corrosion of metals in water and dilute salt solutions, and the use of it to test the adequacy of the newer electrochemical theory of corrosion as applied to such media. The theory suggests that a large number of factors can influence the rate of corrosion, but does not indicate quantita­tively their relative importance in given conditions, in fact, the theory is based at present upon qualitative or only roughly quantitative measurements. It is desirable, therefore, that a determined attempt should be made to place it upon a sounder basis, on account, both of the inherent interest of the theory and of its importance in technical problems of steadily increasing insistence. The present communication is the first portion of an extensive research; it is divided into three sections, the first gives an outline of the theory as understood by the authors; the second, a brief review of the kind of measurement upon which it rests; the third an improved method of measuring corrosion as applied to the metal zinc, together with an interpretation of the results so far obtained.

scholarly journals Potassium chloride: impacts on soil microbial activity and nitrogen mineralization

2019 ◽  
Vol 49 (5) ◽  
Author(s):  
David Gabriel Campos Pereira ◽  
Isadora Alves Santana ◽  
Marcio Mahmoud Megda ◽  
Michele Xavier Vieira Megda
Keyword(s):  
Potassium Chloride ◽  
Microbial Activity ◽  
Crop Residues ◽  
Initial Period ◽  
Chloride Content ◽  
Soil Microbial Activity ◽  
Soil Microbial ◽  
Continuous Use ◽  
Banana Crop ◽  
Soil Chloride

ABSTRACT: Potassium chloride is the most widely used potassium source worldwide, and due to its continuous use, the accumulation of its salts in the soil and in plants is becoming more common. Excess available ions can cause a series of physiological disturbances in organisms and can become a biocide in the soil. The objective of this study was to evaluate the effects of the application of KCl and banana crop residues on soil chloride content, microbial activity, and soil ammonification. The experiment utilized a completely randomized 2 × 4 factorial design with four replicates. Treatments were as follows: two doses of vegetal residue (200 and 400 mg dm-3) × four doses of KCl (0, 167, 334, and 668 mg dm-3 of KCl) and a control (untreated soil). The CO2 emission, ammonium (N-NH4 +) and soil chloride (Cl-) content, and mineralization/immobilization rates of the soils in each treatment were measured 4, 45, and 130 days after incubation (dai). Higher KCl dosages reduced soil microbial activity at 4 dai, regardless of the residue dosage. Microbial activity was reduced at 130 dai in all treatments when compared to the initial period. Higher dosages of banana crop residues increased the Cl- content of the soil and promoted the immobilization of N-NH4 +. We concluded that dosages of KCl (above 400 mg dm-3), when applied to soils that already contain crop residues, reduce microbial activity and mineralization of N in the soil.

scholarly journals VIII. The ionization of dilute solutions at the freezing point

1900 ◽  
Vol 194 (252-261) ◽  
pp. 321-360 ◽  
Keyword(s):  
Potassium Chloride ◽  
Electric Current ◽  
Sulphuric Acid ◽  
Electric Charge ◽  
Chemical Nature ◽  
Freezing Point ◽  
Barium Chloride ◽  
The Other ◽  
Dilute Solutions ◽  
The Subject

The existence of a relation between the depression of the freezing point, produced by dissolving an acid or a salt in water, and the electrolytic conductivity of the solution thus obtained was pointed out by Arrhenius in 1887, and has been the subject of much experiment and discussion since that date. As is well known, the facts of electrolysis indicate that an electric current, when passing through a solution, is associated with a passage in opposite directions of the constituents of the salt. Faraday called these mobile parts ions. The number of the ions depends on the chemical nature of the salt, and is usually indicated by its formula. Thus for one molecule of potassium chloride we have two ions, the potassium travelling in one direction and the chlorine in the other. For barium chloride or sulphuric acid we have three ions, and, since the electric charge of an ion is proportional to its valency, the electrically equivalent weights of these substances are represented by ½BaCl 2 and ½H 2 So 4 , respectively.

scholarly journals The theory of metallic corrosion in the light of quantitative measurements. Part VI.— The distribution of corrosion

1933 ◽  
Vol 140 (841) ◽  
pp. 399-425 ◽  
Keyword(s):  
Mild Steel ◽  
Metal Surface ◽  
Salt Concentration ◽  
Oxygen Supply ◽  
Irregular Distribution ◽  
Quantitative Measurements ◽  
Physical Heterogeneity ◽  
Wide Range ◽  
Protective Films ◽  
Metallic Corrosion

In previous parts of this research it has been shown that the rate of oxygen supply to the whole metal surface is the factor which generally controls the rates of corrosion of zinc and mild steel in the conditions studied, though other factors may affect them appreciably in special conditions. Such factors are the evolution of hydrogen and the formation of protective films or masses of corrosion products which may result from increased alkalinity, or other causes. Neither the basic potential of the metal nor the conductivity of the electrolyte exercised control over a wide range of salt concentration. Corrosion distribution was at first sporadic but was soon concentrated at a few large irregularly shaped areas. For many purposes distribution is more important than the total amount of corrosion, especially when it is so localized as to be called pitting. The irregular distribution of corrosion was formerly believed to be caused by chemical and physical heterogeneity of the metal, but differential aeration is now usually believed to be a more frequent cause of local corrosion and this view was accepted in Parts I to III of this research.

scholarly journals The theory of metallic corrosion in the light of quantitative measurements. Part V. —The corrosion of iron and mild steel

1931 ◽  
Vol 134 (823) ◽  
pp. 308-343 ◽  
Keyword(s):  
Mild Steel ◽  
High Frequency ◽  
Oxygen Absorption ◽  
Absorption Method ◽  
Secondary Oxidation ◽  
Electro Deposition ◽  
Quantitative Measurements ◽  
Corrosion Of Iron ◽  
Metallic Corrosion ◽  
Made In

The measurement of corrosion by the oxygen-absorption method developed for zinc has now been applied to iron. Since the corrosion products contain mixtures of ferrous and ferric compounds, analyses must be made at the end of various corrosion periods to determine the proportions of oxygen used in corrosion and in the secondary oxidation to the higher valency. Notwith­ standing this additional operation, the corrosion measurements have nearly the same order of reproducibility as those for zinc except in special conditions which will be noted later. Three materials have been used, namely :— (1) Highly purified iron prepared by electro-deposition and subsequently melting in vacuo in a high frequency furnace. (2) Mild steel made in the usual way for tube manufacture, but specially examined for homogeneity. (3) An ordinary sample of mild steel rod taken from a workshop store.

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