Effect of current density and perchloric acid concentration on the formation of lead anodes in sulphuric acid baths

1972 ◽  
Vol 23 (2) ◽  
pp. 105-109 ◽  
Author(s):  
A. Ragheb ◽  
W. Machu ◽  
W. H. Boctor
Keyword(s):  
Sulphuric Acid ◽  
Acid Concentration ◽  
Current Density ◽  
Perchloric Acid

scholarly journals THE RATE CONSTANT OF THE REACTION BETWEEN FERROUS IONS AND HYDROGEN PEROXIDE IN ACID SOLUTION

1957 ◽  
Vol 35 (5) ◽  
pp. 428-436 ◽  
Author(s):  
T. J. Hardwick
Keyword(s):  
Hydrogen Peroxide ◽  
Acid Solution ◽  
Sulphuric Acid ◽  
Acid Concentration ◽  
Rate Constant ◽  
Perchloric Acid ◽  
Ferrous Ion ◽  
Ferrous Ions ◽  
Bimolecular Rate Constant

Identical values of the bimolecular rate constant of the ferrous ion – hydrogen peroxide reaction were obtained from intercomparisons of the methods previously used in following this reaction. In perchloric acid the bimolecular rate constant is unaffected by acid concentration; in sulphuric acid it increases slightly in acid concentrations above 10−2N. The results agree with and explain the differences between those obtained by Baxendale and by Dainton, but are only in marginal agreement with those recently reported by Weiss.

THE BEHAVIOR OF LEAD ELECTRODES IN SULPHURIC ACID SOLUTIONS

1964 ◽  
Vol 42 (6) ◽  
pp. 1355-1364 ◽  
Author(s):  
K. Ekler
Keyword(s):  
Sulphuric Acid ◽  
Acid Concentration ◽  
Current Density ◽  
The Self ◽  
Acid Solutions ◽  
Time Data ◽  
Passivation Time ◽  
Lead Electrodes ◽  
Passivation Potential

Lead electrodes were anodically etched in NH2SO3H. Immersion potentials, self-passivation potentials, passivation times, PbO2/O2 potential, and the potential of the first discharge plateau were determined in H2SO4 solutions ranging from 0.5 to 20.0 N and were found to be concentration-dependent. Interruption of the anodizing current had no detectable influence on passivation time. Data obtained with the anodizing current turned on fall into three categories; those obtained with (1) short-immersion anodes, (2) anodes which had reached a hydrogen-like potential, and (3) anodes which were self-passivated before the current was switched on. An inflection in the relation between potential and time during charging was investigated. Its length was dependent upon acid concentration and current density, while its potential was +300 ± 30 mv, and seemed to correspond to the self-passivation potential. The lengths of the first and second discharge plateaus increased with the number of coulombs passed and were dependent upon acid concentration, but were identical for electrodes treated by four different methods. The hydrogen-like potential appeared to be due to the presence of PbO•PbSO4. The self-passivation potential seemed to be caused by formation of PbO.

Influence of Malonic Acid on the Corrosion and SCC Behaviour of Anodic Coated 1050 Al-Alloys

2010 ◽  
Vol 438 ◽  
pp. 155-162 ◽  
Author(s):  
Panayotis Spathis ◽  
Efthimios Papastergiadis ◽  
Georgios Stalidis ◽  
Georgios Papanastasiou
Keyword(s):  
Stress Corrosion ◽  
Acid Concentration ◽  
Malonic Acid ◽  
Stress Level ◽  
Current Density ◽  
Stress Corrosion Cracking ◽  
Corrosion Cracking ◽  
Al Alloy ◽  
Applied Potential ◽  
Protective Properties

Aim of the present work is the study of corrosion and stress corrosion cracking behaviour of 1050 Al-Alloy anodised in a 3M H2SO4 anodising bath with the presence in it of malonic acid, in various concentrations and anodising current densities. The investigation was carried out by SCC (Stress Corrosion Cracking) tests and electrochemical measurements. The influence of applied potential on SCC behaviour was also examined. The corrosion and SCC behaviour of anodised 1050 Al-Alloy was found to vary with malonic acid concentration, anodising conditions, applied potential and stress level. In SCC conditions all prepared coatings protected the bare alloy, with better protective properties in the case of 0.015M concentration of malonic acid prepared with a 6 A.dm-2 anodising current density. The coating prepared in these conditions had better mechanical properties as indicated from the increased protection at a high stress level and also the better behaviour in corrosion, without stress, conditions of coatings prepared in different conditions of malonic acid concentration and anodising current density. For the interpretation of the results, properties of the anodic coatings as thickness, packing density, coating ratio, roughness, were also studied. The anodic coating formed in a electrolytic bath of 0.015M concentration of malonic acid and a 6 A.dm-2 anodising current density was found to be less porous, more compact and rough, with better oxide structure. Prepared coatings were found to increase protective properties in an area of applied potentials slightly more anodic than the free corrosion potential values.

scholarly journals Corrosion Behavior of AA 1100 Anodized in Gallic-Sulfuric Acid Solution

Coatings ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 405
Author(s):  
Marlon L. Mopon ◽  
Jayson S. Garcia ◽  
Dexter M. Manguerra ◽  
Cyril John C. Narisma
Keyword(s):  
Corrosion Resistance ◽  
Sulfuric Acid ◽  
Acid Solution ◽  
Gallic Acid ◽  
Acid Concentration ◽  
Sulfuric Acid Solution ◽  
Current Density ◽  
Electrochemical Impedance ◽  
Anodized Aluminum ◽  
The Common

Sulfuric acid anodization is one of the common methods used to improve corrosion resistance of aluminum alloys. Organic acids can be added to the sulfuric acid electrolyte in order to improve the properties of the anodized aluminum produced. In this study, the use of gallic acid as an additive to the sulfuric acid anodization of AA1100 was explored. The effect of varying anodization current density and gallic acid concentration on the properties of anodized aluminum samples was observed using electrochemical impedance spectroscopy, linear polarization, and scanning electron microscopy. It was observed that the corrosion resistance of samples anodized in gallic-sulfuric acid solution at 10 mA·cm−2 is lower than samples anodized in sulfuric acid. It was also observed that higher anodization current density can lead to lower corrosion resistances for aluminum samples anodized in gallic-sulfuric acid solution. However, samples anodized at 5 mA·cm−2 and at a gallic acid concentration of 5 g·L−1 showed better corrosion performance than the samples anodized in sulfuric acid only. This suggests that the use of low amounts of gallic acid as an additive for sulfuric acid anodization can lead to better corrosion resistances for anodized aluminum.

scholarly journals Atmospheric sulphuric acid and aerosol formation: implications from atmospheric measurements for nucleation and early growth mechanisms

2006 ◽  
Vol 6 (12) ◽  
pp. 4079-4091 ◽  
Author(s):  
S.-L. Sihto ◽  
M. Kulmala ◽  
V.-M. Kerminen ◽  
M. Dal Maso ◽  
T. Petäjä ◽  
...  
Keyword(s):  
Time Delay ◽  
Sulphuric Acid ◽  
Acid Concentration ◽  
Particle Formation ◽  
Early Growth ◽  
Activation Mechanism ◽  
Aerosol Formation ◽  
Atmospheric Measurements ◽  
Nucleation Mechanisms ◽  
Sulphuric Acid Concentration

Abstract. We have investigated the formation and early growth of atmospheric secondary aerosol particles building on atmospheric measurements. The measurements were part of the QUEST 2 campaign which took place in spring 2003 in Hyytiälä (Finland). During the campaign numerous aerosol particle formation events occurred of which 15 were accompanied by gaseous sulphuric acid measurements. Our detailed analysis of these 15 events is focussed on nucleation and early growth (to a diameter of 3 nm) of fresh particles. It revealed that new particle formation seems to be a function of the gaseous sulphuric acid concentration to the power from one to two when the time delay between the sulphuric acid and particle number concentration is taken into account. From the time delay the growth rates of freshly nucleated particles from 1 nm to 3 nm were determined. The mean growth rate was 1.2 nm/h and it was clearly correlated with the gaseous sulphuric acid concentration. We tested two nucleation mechanisms – recently proposed cluster activation and kinetic type nucleation – as possible candidates to explain the observed dependences, and determined experimental nucleation coefficients. We found that some events are dominated by the activation mechanism and some by the kinetic mechanism. Inferred coefficients for the two nucleation mechanisms are the same order of magnitude as chemical reaction coefficients in the gas phase and they correlate with the product of gaseous sulphuric acid and ammonia concentrations. This indicates that besides gaseous sulphuric acid also ammonia has a role in nucleation.

IONIZATION OF ORGANIC COMPOUNDS: III. BASICITIES OF PROPIONIC ACID AND PROPIONAMIDE

1962 ◽  
Vol 40 (5) ◽  
pp. 966-975 ◽  
Author(s):  
J. T. Edward ◽  
I. C. Wang
Keyword(s):  
Sulphuric Acid ◽  
Propionic Acid ◽  
Organic Compounds ◽  
Acid Concentration ◽  
Ultraviolet Absorption ◽  
Protonation Constants ◽  
Acidity Function ◽  
Hammett Acidity Function ◽  
Ionization Ratio

Protonation constants (pKBH+) of −6.8 and −0.9 have been determined for propionic acid and propionamide, respectively, from measurements of their ultraviolet absorption in various concentrations of sulphuric acid. The ionization ratio of propionamide and of other amides increases more slowly than the Hammett acidity function, h0, with increase in acid concentration. This may be explained by assuming that in a given concentration of sulphuric acid the protonated amide is more heavily hydrated than the protonated Hammett indicator used to establish the h0 scale for this region of acid concentrations.

Bioenergy II: Furfural Destruction Kinetics during Sulphuric Acid-Catalyzed Production from Biomass

2009 ◽  
Vol 7 (1) ◽  
Author(s):  
Gianluca Marcotullio ◽  
Miguel A. Tavares Cardoso ◽  
Wiebren De Jong ◽  
Ad H.M. Verkooijen
Keyword(s):  
Sulphuric Acid ◽  
Acid Concentration ◽  
Reaction Products ◽  
Arrhenius Law ◽  
Exponential Factor ◽  
Oil Derivatives ◽  
Destruction Kinetics ◽  
Acid Catalyzed ◽  
Effects Of Temperature

The interest for furfural has increased in the last years due to its potential for competing with oil derivatives as platform chemical. In addition, furfural, derived from C5 sugars, can play a key role in the valorization of the hemicellulose contained in biomass when considering the development of a modern biorefinery concept. The development of such new and competitive biorefinery processes must be based on accurate kinetic data for the reactions involving furfural in the conditions used for its production.This work addresses the determination of furfural destruction kinetics in aqueous acidic environment, using sulphuric acid as catalyst, in the temperature range 150 - 200°C, acid concentration range 36.4 - 145.5 mM and furfural initial concentration between 60.4 and 72.5 mM. These studies were carried out using a recently built lab-scale titanium reactor that enables liquid phase reactions in a relatively broad range of conditions.The obtained results show that destruction of furfural follows first-order reaction kinetics within the range of temperature and acid concentration evaluated. Moreover, the proposed kinetic model takes into account the effects of temperature and acid dilution on the ions activity, and thus H3O+, by using the electrolyte Non-Random Two-Liquid (eNRTL) model. By using this approach, the rate constant dependence on temperature could be described by the Arrhenius law and thus the activation energy could be estimated as being 125.1 [kJ/mol] and the pre-exponential factor 3.71•1011[s-1]. Separation of different reaction products was achieved by means of HPLC, these products were not yet completely identified. Contrarily to what is reported in previous works, formic acid formation from furfural under the tested conditions can be regarded as playing a far less pronounced role than suggested before.

The acid-catalyzed demetalation of 1-(tri-n-butylstannyl)-2-phenylethyne. A surprisingly small β-stannyl effect

1996 ◽  
Vol 74 (7) ◽  
pp. 1366-1368 ◽  
Author(s):  
I. Egle ◽  
V. Gabelica ◽  
A.J. Kresge ◽  
T.T. Tidwell
Keyword(s):  
Key Words ◽  
Isotope Effect ◽  
Acid Concentration ◽  
Rate Constant ◽  
Perchloric Acid ◽  
Hydronium Ion ◽  
Stabilizing Effect ◽  
Aromatic Product ◽  
Acid Catalyzed ◽  
The Difference

Rates of conversion of 1-(tri-n-butylstannyl)-2-phenylethyne to phenylethyne in H2O and D2O solutions of perchloric acid were found to be proportional to acid concentration, giving the hydronium ion rate constant [Formula: see text] and the isotope effect [Formula: see text]. The magnitude of this isotope effect suggests that the reaction occurs by rate-determining hydron transfer to the substrate, producing a vinyl carbocation; this carbocation then loses its tributylstannyl group, giving phenylacetylene as the only detectable aromatic product. The hydronium ion rate constant, when compared to the rates of protonation of phenylethyne and 1-(trimethylsilyl)-2-phenylethyne, gives a β-stannyl stabilizing effect of δΔG≠ = 6.6 kcal mol−1 and a differential β-stannyl/β-silyl effect of δΔG≠ = 3.2 kcal mol−1. These stabilizations are very much smaller than previously reported β-stannyl effects. Possible reasons for the difference are suggested. Key words: β-stannyl effect, β-silyl effect, carbocation stabilization, protodemetalation.

scholarly journals Untersuchungen am System Triphenylphosphingold(I)/Sulfat: Synthese und Röntgenstrukturanalyse von (Ph3PAu)2SO4 · CH3OH/ Studies of the System Triphenylphosphinegold(I)/Sulphate: Synthesis and Crystal Structure of (Ph3PAu)2SO4 · CH3OH

1985 ◽  
Vol 40 (8) ◽  
pp. 1029-1031 ◽  
Author(s):  
Rainer Hohbein ◽  
Peter G. Jones ◽  
Karen Meyer-Bäse ◽  
Einhard Schwarzmann ◽  
George M. Sheldrick
Keyword(s):  
Crystal Structure ◽  
Sulphuric Acid ◽  
Acid Concentration ◽  
Synthesis And Crystal Structure

AbstractThe reaction between (triphenylphosphine)acetatogold(I) and concentrated sulphuric acid in methanol leads to (Ph3PAu)2SO4 (1) or [(Ph3PAu)3O]+ HSO4- , depending on the acid concentration. The crystal structure of the methanol solvate of (1) was determined [C2/c, a = 1348.3(2), b = 1451.0(2), c = 1853.8(3) pm, β = 99.90(2)°, Z = 4, R = 0.037 for 3138 unique observed reflections], 1 possesses crystallographic twofold symmetry, with Au -O 206.3, Au -P 221.6 pm. The corresponding selenate is isomorphous.

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