Dilute Sulfuric Acid Solution Research Articles

Silent Discharge Reactions in Aqueous Solutions. III. Acidic Aqueous Solutions of Ferrous Sulfate and Ceric Sulfate in a Hydrogen Atmosphere

Abstract A study has been made of silent discharge reactions in aqueous solutions of ferrous sulfate and ceric sulfate acidified with sulfuric acid in a hydrogen atmosphere. The present study has confirmed that silent discharge leads to the formation of hydrogen peroxide from water molecules in a dilute sulfuric acid solution, the oxidation of ferrous ions to ferric ions, and the reduction of ceric ions to cerous ions. The same reactions were previously studied in inert gases. A satisfactory interpretation can be made of their mechanisms by taking into consideration the action on the solvent of slow electrons produced in the gaseous phase. In a hydrogen atmosphere, the yields of the foregoing reactions were very small when compared with those in the case of inert gases; however, a good linear correlation was observed between the yield and the duration time of discharge. From these results it has been concluded that the yields can be well interpreted by taking into consideration the action of active species of hydrogen generated in the gaseous phase on the radicals formed from liquid water, besides the action of slow electrons; moreover, the action of active species on the solute cannot be serious. The absorbed dose in the solution was estimated to be approximately 1.9×107 r./hr. from the relation of the dissipated energy calculated electrically to the absorbed dose.

Anodic Behaviors of Iron and Its Oxides in Dilute Sulfuric Acid and Akaline Solutions

Anodic behaviors of pure iron and iron oxides in dilute sulfuric acid and alkaline solutions were investigated to clarify the significance of passivation and other oxidizing potentials of iron. The anodic polarization curve of pure iron indicated four current peaks at potentials of about −0.1, 0.3, 0,6 and 1.4 V in 1 N H2SO4 and −0.9, −0.7, −0.4 and 0∼0.4 V (vs S.C.E.) in 1 N KOH. The anodic polarization curves of FeO1.05, FeO1.1 and Fe3O4 indicated three, two and one peaks, respectively, and the potentials of the peaks of the oxides agreed with those of pure iron. From these anodic behaviors of the oxides, it was suggested that the four potentials at the current peaks in the potential-current curve of iron show four redox potentials of Fe/FeO1.05, FeO1.05/FeO1.1, FeO1.1/Fe3O4 and Fe3O4/γ Fe2O3, where FeO1.05 and FeO1.1 are two Wüstites containing minimum and maximum combined oxygen, respectively. These potentials were also confirmed from the measurements of potential decay curves of iron and iron oxides. From these results, it was concluded that the passivation potential of iron in 1 N H2SO4 corresponded to the redox potential of FeO1.05/FeO1.1, whereas that in 1 N KOH corresponded to the redox potental of Fe/FeO1.05.

Silent Discharge Reactions in Aqueous Solutions. I. An Acidic Aqueous Solution of Ferrous Sulfate in Atmospheres of Helium and Argon

Abstract In an atmosphere of helium or argon, the silent discharge reactions of aqueous solutions have been investigated from the point of view of radiation chemistry. A discharge tube with two coaxial glass tubes was used. In a dilute oxygen-free aqueous solution of sulfuric acid, hydrogen peroxide appeared as a result of discharge. Also, the oxidation of ferrous ions to ferric ions has been found. It has been confirmed, first, that neither the effect of metastable excited states of helium and argon nor that of luminescence is serious, and, second, that the reaction may well be interpreted by taking into consideration the actions of slow electrons generated in the gas phase on the liquid water. The yield of hydrogen atoms plus hydroxyl radicals has been estimated from the yields of hydrogen peroxide and ferric ions. The ratios of the yield of hydrogen peroxide to that of radicals show that the silent discharge reaction corresponds to the reaction by ionizing radiation of high LET, the value of which apparently equals 3eV./Å in helium and 8 eV./Å in argon. The G(Fe3+) value and the absorbed dose (E) estimated were, respectively, as follows: In helium: G(Fe3+)=4.6, E=3.8×106 r./hr.; in argon: G(Fe3+)=4.3, E=7.2×106 r./hr.

ULTRAVIOLET STUDY OF THE IONIZATION OF BISULFATE ION

Studies of the ultraviolet absorption of dilute aqueous solutions of lithium, sodium, potassium, and ammonium sulfates show that the concentration of sulfate ion in the presence of univalent cations can be determined from the optical density of the solution at 190 mμ. The concentrations of sulfate ion thus determined in dilute solutions of sulfuric acid are in agreement with values reported previously from Raman spectral, conductivity, and other studies, which indicate a dissociation constant K2 = 0.01 for the second stage in the ionization of sulfuric acid.

Studies on Chitin and Glucosamine. (II). : Oxidation of Chitin with Permanganate or Periodate.

Chitin was submitted to oxidation with potassium permanganate in dilute solution of sulfuric acid, hydrochloric acid or sodium hydroxide. Both copper value and the amount of methylene blue adsorbed were increased with the amount of permanganate used for oxidation. Copper value, however, was not increased when the oxidation was carried out in dilute sodium hydroxide solution. On the other hand, in the case of oxidation with sodium periodate, the copper value for purified chitin and chitosan were considerably increased. Further, these oxidation products, chitin or its derivatives were treated with hydrochloric acid under reflux. Appreciable difference in the yield of the glucosamine was not observed between purified chitin and its oxidation products, but in the case of chitin derivatives such as regenerated chitin, carboxymethylchitin or glycolchitin, yields of glucosamine were remarkably increased, so they seem to be less stable than purified chitin against hydrochloric acid. From the results of the copper value and methylene blue adsorption, it will be concluded that decolorization with potassium permanganate should be avoided in preparation of purified chitin.

Dissolution of Brass in Sulfuric Acid Solutions: II .95/5 Brass

Dissolution rates of 95/5 brass cylinders in dilute sulfuric acid solutions have been determined as a function of rotational speed, acid concentration, oxygen partial pressure, temperature, apparent surface area, and corroding solution volume. The dissolution of copper from 95/5 brass was found to be auto‐ catalytic as in the case of pure copper and copper from 85/15 brass, and a similar mechanism/was indicated. Deviations due to changes in the brass surface were observed. The slower copper rate for 95/5 brass as compared to pure copper indicated that zinc entered solution by a displacement mechanism. At long times, the rate of dissolution of copper from 95/5 brass became independent of cupric ion concentration and was controlled mainly by the diffusion of oxygen to the metal‐solution interface.

946. The radiolysis of ferro- and ferri-cyanide solutions

The oxidation of potassium ferrocyanide in dilute sulfuric acid solution by gamma radiation was investigated and compared with that of ferrous sulfate. Significant differences between the two systems are discussed. (auth)

Oxidation Potential of the Cerous‐Ceric Electrode in Dilute Sulfuric Acid Solutions

AbstractThe oxidation potential of the Ce(III)‐Ce(IV) couple in sulfuric acid over the concentration range of 0.05 to 0.5F was observed at 25°C by using the Pt‐PbO2/PbSO4, SO4 = electrode as the reference electrode. The free energy change for the reaction 2Ce+3 + PbO2 + 4H+ + SO4 = 2Ce+4+PbSO4+2H2O was estimated.

ESR Spectra of Solid Phthalocyanines

Phthalocyanine complexes of paramagnetic metal ions show ESR spectra characteristic of the metals; phthalocyanine complexes of diamagnetic metal ions show strong single ESR lines characteristic of free radicals. The source of this latter resonance is not understood. Intimate molecular mixtures of ``paramagnetic'' copper and ``dimagnetic'' zinc phthalocyanines exhibit exchange between the copper unpaired electron and the ``free radical'' electron in the zinc phthalocyanine. Nickel and zinc phthalocyanine also exhibit a single sharp resonance in dilute solutions of concentrated sulfuric acid.

Experiments on the Decomposition of Silicates and Discussion of Chemical Weathering

AbstractExperimental investigations of chemical weathering in which powders of potassium feldspar, albite, leucite, muscovite, tremolite, olivine, and volcanic glass are treated with pure water and with dilute solutions of sulfuric, carbonic, and hydrochloric acid have been performed in an apparatus in which the mineral powder is exposed to a circulating water flow. The experiments have been continued recently by treating kaolinite and montmorillonite. The course of decomposition of these minerals depends on water flow rate, grain size, temperature, and pH of the solutions. These experiments in open systems are compared with investigations reported in the literature and with the conditions of natural weathering.

EMULSION XANTHATION OF PULP

In the previous paper, it was found that the marcerization-resistance curve (M-W curve) obtained by varying concentrations of sodium hydroxide solution in emulsion xanthation is influenced by socalled lateral order distribution of pulp.According to O. Samuelson et a12)., “the reason why the pulp viscosity can be used as a criterion of filterbility of a viscose prepared from the pulp is that the decrease in viscosity in a given, process, e. g. the ordinary sulfite cooking, is parallel to the attack upon the fiber structure.” They added also that “experiments on emulsion xanthation can be used as a complement and be of considerable value for the comparison of similar types of the biological structure of which has been, attacked to a different degree.”It seems to be very important for estimating the value of M-W curve as an indication of reactivity of pulp, how the opinion mentioned above can be adapted in the comparison of different types, of pulps prepared from different raw materials or by different processes.In order to obtain the relation between M-W curve and average degree of polymerization of cellulose, dissolving sulfite pulp (DSP), dissolving sulfate pulp (DKP), linters pulp (Li. P) and mercerized DSP were degradated by various treatments to various degrees, and M-W curves of these samples were determined in this paper.The results obtained are as follow:The solubility of pulp in emulsion xanthation increases as average degree of polymerization of cellulose is lowered. Influence of the differences of lateral order found amoung DSP, DKP and Li. P upon the solubility in emulsion xanthation do not diminish, though each pulp has been hydrolyzed with dilute sulfuric acid solution and cellulose has been degradated as low as 300 of average degree of polymerization of cellulose. The fact shows the influence of fine structure of cellulose on M-W curve is very significant. Then M-W curves of DKP treated with dilute sulfuric acid solution, dilute ligninsulfonic acid solution or ultra violet ray, and of DSP hydrolyzed with dilute sulfuric acid solution after mercerization or aged in air after mercerization were determined. It was found also that the properties of fine structure of cellulose has more effect on M-W curve than average degree of polymerization of cellulose. For the similar type pulps degradated with similar type treatments, the solubility in emulsion xanthation is parallel to average degree of polymerization of cellulose, but for the different types of pulp, M-W curves are governed mainly by the fine structure of cellulose. This means M-W curve can not be used as a criterion of filterbillity of a viscose preparad from the different type of pulp.

Anion exchange behaviour of some rare earths in dilute sulphuric acid solutions containing ethanol

Anion exchange characteristics of Y, Nd, Pr, and La in dilute sulfuric acid solutions containing ethanol were investigated. Sorption of these rare earths by amberlite IRA400 in solutions containing 80% ethanol was measured. As the percentage of the non-aqueous component of the solution was increased, the rare earths showed increased sorption by the resin. (L.N.N.)

Trennung des Thoriums von seltenen Erden am Kationenaustauscher FN

The pattern of the sorption of thorium and some rare earths from sulfuric and hydrocbloric acid solutions was followed on FN cation exchangers. On the basis of the variations established in the sorption of the elements selected. , a methcd was proposed for the separation of thorium from rare earths from dilute sulfuric acid solutions. (tr-auth)

A Fluorescent Dye Method for Foliar Penetration Studies

lish the location of the penetrant on the cellular level. Histochemical techniques have been employed with great success by Knight et al. (10), Rohrbaugh (14), Rice and Rohrbaugh (13), and others to demonstrate the sites of entry and routes of movement of oils. In the case of aqueous solutions, on the other hand, most evidence is indirect in nature, and histochemical evidence is limited to very few reports such as those of Palmiter et al. (12) and Wylie (24) for penetration and movement of iron. Many workers (3, 5, 15, 21, 22, 23) have compared stomatal with cuticular penetration by such indirect methods as measurement of plant response to growth regulators or nutrients, autoradiography or counting of tissues containing radioactive tracers, or measurement of nonabsorbed chemical. The importance of stomatal entry has not been clearly established by these methods. More direct evidence is obtained by using other techniques. For example, Aslander (2) and Crafts (6) studied the penetration of dilute sulfuric acid solutions by microscopic detection of injury resulting from the toxic action of the penetrant; however, conflicting observations were reported. Autoradiography of leaf sections has been used by Gustafson and Schlessinger (9) to demonstrate penetration of cobalt60 into bean leaves in the dark, but to date this promising method has not been widely applied in attempts to determine the route of penetration. Because most of the conventional methods yield only indirect evidence, a more direct method involving a fluorescent dye has been testedl. This type of tracer was used to study foliar absorption of dew water by Steubing (18), who followed entry and movement of berberine sulfate with the fluorescence microscope. By a similar method, Butterfass (4) observed foliar penetration via the club-shaped hairs of Vicia faba L. and Phaseolus coccineus L. Orgell3 used both fluorescent and nonfluorescent dyes to study penetration of isolated plant cuticles. In the work reported here, the fluorescent tracer method has been considerably expanded and improved for application to the problem of foliar absorption of aqueous solutions.

Stabilization of viscose rayon by heat treatment

AbstractViscose fibers preswollen by treatment with very dilute sulfuric acid solutions of various concentrations (pH 2.4–5.1) were heat treated at various temperatures (60–200°C.). The effects of the heat treatment were considered from the measurements of: (1) The transition modulus of elasticity and other constants of a three‐parameter model for viscoelasticity, as well as the dynamic modulus of elasticity. (2) The breaking strength as well as elongation. (3) The percentage crystallinity. (4) The amount of water absorbed. Thus it was concluded that the effects of heat treatments of stabilizing viscose rayon, as exhibited by the above‐mentioned properties of the fibers, make their most prominent appearance in the range of pH optimal for the maximal hydration of regenerated cellulose, that is, pH = 3.0–5.0 of the acid bath, in which the fibers are soaked and swollen, and in the range of the temperature for the heat treatment near, or just above, the glass transition temperature of cellulose hydrate, i.e., at 60–70°C. where the acid‐bath‐treated fibers are heat treated. From the results of these measurements and also from the characteristic features of x‐ray diagrams qualitatively observed, it was considered that the heat treatment affects mainly the more disordered (amorphous) regions so that the more ordered regions are newly developed at the expense of the former.

Microdetermination of Zirconium in Sulfuric Acid Solutions with Pyrocatechol Violet

S>The blue color of zirconium-pyrocatechol violet complex is used in a very sensitive colorimetric method for zirconium in dilute sulfuric acid solutions. Molar absorbance index of complex is 32,600 at 650 m mu . It conforms to Reer's law up to 2 gamma zirconium per ml. Aluminum, titanium, and vamadium interfere seriously. (auth)

Galvanic Corrosion Behavior of Titanium and Zirconium in Sulfuric Acid Solutions

Aluminum alloys are the anodic members of titanium‐aluminum alloy couples in dilute sulfuric acid solutions in the presence of air. In stronger acid solutions, particularly when air is absent, aluminum alloys are anodic only at the beginning of the immersion period. After an induction period titanium becomes anodic. Aluminum alloys are always anodic in zirconium‐aluminum alloy couples immersed in sulfuric acid solutions. The rate of galvanic attack increases with the supply of air. The direction of flow of the galvanic current is always in agreement with the relative values for the electrode potentials of the single metal specimens. Little, if any, galvanic corrosion occurs in couples of titanium or zirconium with stainless steel, although there are generally sizeable differences of potential between single specimens of these metals. In solutions in which single specimens of titanium are inert and cathodic with respect to aluminum alloys, contact with these alloys may cause titanium to corrode. This is attributed to activation of titanium surfaces by the hydrogen evolved. Contact with stainless steel in solutions in which titanium is the anodic member of the couple results in marked decreases in corrosion rates of titanium because of anodic polarization of titanium surfaces.

Studies on Corrosion at Power Generation Stations Using Acid River Water (12th Report). On the Corrosion of Copper Alloys

The corrosion rate of copper alloys by dilute aqueous solutions of sulfuric acid has been measured. The corrosion rate increases nearely in proportion to relative velocity in the range of low speed, but it becomes gradually constant as the velocity increases. The higher the concentration of hydrogen ions, the larger the corrosion rate. The corrosion is mainly controlled by the diffusion and the adsorption of dissolved oxygen on the copper alloys.

Equilibrium in the Exchange of Hydrogen between Phosphine and Water

The exchange equilibrium PH2D(g)+H2O(l)=PH3(g)+HDO(l) has been measured at 25°C by the use of dilute sulfuric acid and buffer solutions as a catalyst. From this measurement and the ratio of the vapor pressures of H2O and HDO the equilibrium constant for the exchange PH2D(g)+H2O(g)=PH3(g)+HDO(g) is calculated to be 1.52 at 25°C. The latter experimental value is combined with a theoretical computation of the temperature independent factor of the equilibrium constant to evaluate the difference in the zero point energies of PH3 and PH2D. This leads to the equation, which is valid up to about 500°K, Kg=0.781e198/T. This equation is in good agreement with calculations based on the spectra of PH3 and PD3 and the rule of the geometric mean.

Electrolytic Oxidation of Ethyl Alcohol to Acetic Acid

The influence of current density, ethanol concentration, and current concentration on the oxidation of ethanol to acetic acid in dilute sulfuric acid solution at platinum gauze anodes has been investigated. The maximum current efficiency, 85%, was obtained at 40° C and 0.2 amp./cm.2, the highest current density tried. Optimum alcohol concentration is about 20%. Efficiency can be raised 2% to 3% by the use of an oxygen carrier, and, at the same current density, is higher at higher current concentration, no maximum being found for this relation within the limits studied. Upwards of 5% increase in efficiency was obtained by substituting sheet lead for platinum gauze as anode material. Energy consumption ranged from 9.9 to 13.8 kw.‐hr./kg. acetic acid, depending on conditions of operation and cell design.