1N Sulphuric Acid Research Articles

Chemical Processes in PEO Coatings Formation and Destruction on Titanium Alloy VT-1

Plasma electrolytic oxidation (PEO) method allows obtaining multifunctional ceramic-like coatings with unique properties. This article examines the relevant problem of the electrolyte effect on the chemical composition of PEO coating. The corrosion resistance of titanium alloy various PEO coatings in corrosive liquids has been studied: 1N sodium hydroxide solution, concentrated sulphuric acid (80%), 1N sulphuric acid solution, concentrated hydrochloric acid (30%), 1N hydrochloric acid solution. Comparative analysis of the VT-1 titanium alloy chemical resistance showed that the most resistant to the effects of corrosive substances were samples with PEO coating formed in a hydrophosphate electrolyte Na2HPO4.

Determination of Salbutamol Using Spectrophotometric Method Depending on Chromium-1,5-diphenylcarbazide Complex

A rapid, simple, accurate, and economized spectrophotometric method for the determination of salbutamol sulfate(SAL) has been suggest using an oxidation-reduction reaction. This method depends on the oxidation of SAL medication with an excess amount of chromate (CrO42- ) as an oxidant agent in the acidic medium of 2N Sulphuric acid and the presence of Sodium oxalate as a catalyst of the oxidation process. Then the remaining quantity of chromate will be reacted with 1,5-diphenylcarbazide to form a pink-reddish and stable water-soluble complex which is exhibiting maximum absorption at 543 nanometers. The optimum conditions for the present work were studied experimentally. The linearity of the proposed method follows Beer’s law in the concentration range of 50 to 900 μg in a final volume of 25ml with a molar absorptivity which is equal to 0.538×104 l.mol-1.cm-1. The proposed method shows good recovery values, accuracy, and precision. The present method was so good to be successfully applied for the determination of SAL medication in its pure form and pharmaceutical preparations.

Spectrophotometric study for the determination of trace amount of an important medication used in the cardiovascular diseases

In this work, a simple, fast, inexpensive and an accurate two methods was suggested for the spectrophotometric estimation of medication used for cardiovascular diseases such as atenolol. The first method was depend on oxidizing-reducing process which was happened between that’s medication and an excess quantity of chromium as an oxidizing agent in acidic medium of 2N sulphuric acid. The residual chromium was then reacted with 1,5- diphenylcarbazide to form a reddish-violet soluble complex measured at 543 nm. while the second method depends on charge transfer reaction between atenolol and alizarin reagent to produce a wine-red water soluble and very stable product measured at 523 nm. Beer’s low was obeyed from 1.2 to 40 ppm and 2 to 30 ppm for first and second method respectively. While the sensitivity of the present work was measured using molar absorptivity 0.4661 × 104 and 0.8656 × 104 μg.mol1.cm−1 of first and second method respectively. Sandell’s sensitivity was 0.0571 μg.cm−2 of first method and 0.0307 μg.cm−2 for second method. This method was successfully applied to determine atenolol in pharmaceutical preparation.

Acidic and Neutral Monosaccharide Analysis of Cold Water Soluble Polysaccharide from Hippophae salicifolia D. Don Leaves

Hippophae salicifolia D. Don is a shrub used in traditional medicine system since ages due to its diverse pharmacological effects and health benefits. The leaves of the species have immense therapeutic applications viz. antioxidant, antibacterial, anti-microbial, anti-inflammatory, immuno-modulatory etc. due to diverse array of chemical constituents. The cold water soluble polysaccharide (CWSP) was isolated from the leaves in 3.6% yield. Complete hydrolysis of the polysaccharide was accomplished using 2N sulphuric acid. Paper chromatography and gas liquid chromatography (GLC) of the hydrolysate identified that CWSP was composed of L-rhamnose, L-arabinose, D-xylose, D-mannose, D-galactose and D-glucose in the mole percent of 13.2, 21.5, 4.2, 9.4, 29.3 and 22.4 respectively. Uronic acid estimation was performed by reduction of the acidic moiety in polysaccharide followed by derivatisation to alditol acetates and GLC analysis of resultant neutral polysaccharide which led to quantification of D-galacturonic acid in 9.6 mole percent. The study resulted in composition of constituent monosaccharides of CWSP alongwith uronic acid content. The results may be useful in determination of structural moiety of the polysaccharide responsible for its bio-efficacy.

Two-stage hydrothermal liquefaction of a high-protein microalga

Hydrothermal liquefaction (HTL) is a promising route for producing renewable fuels and chemicals from algal biomass. However, the protein fraction of the alga gives rise to nitrogen compounds in the oil fraction, which may render the oil unattractive for use in conventional refining processes. We report a two-stage HTL approach with the primary aim of reducing the nitrogen concentration in the bio-crude oil. A mild (<200°C) pre-treatment step (Stage I) is performed before more severe (250–350°C) HTL conditions (Stage II) are applied to the microalga Chlorella for the production of bio-crude in a batch reactor. The pre-treatment resulted in up to 50wt.% of the input nitrogen crossing into the Stage I aqueous phase and, following Stage II processing, reductions in the bio-crude nitrogen contents of up to 55%, relative to the direct HTL of untreated Chlorella were observed. However, since considerable amounts of the starting material were lost in Stage I, overall lower quantities of bio-crude were isolated after Stage II processing, as compared to single-stage processing. Nitrogen extraction during Stage I is enhanced by the addition of acids (1N sulphuric or formic acid) but the process remains unselective. Overall, it is concluded that the two-stage approach to reducing the nitrogen content of bio-crudes from a protein-rich alga requires careful evaluation of the trade-off between the desired bio-crude properties and the yield obtained.

English

English

Inhibiting Properties of Morpholine as Corrosion Inhibitor for Mild Steel in 2N Sulphuric Acid and Phosphoric Acid Medium

The inhibition effect of morpholine on the corrosion of mild steel in 2N sulphuric acid and phosphoric acid has been studied by mass loss and polarization techniques between 302K and 333K. The inhibition efficiency increased with increase in concentration. The corrosion rate increased with increase in temperature and decreased with increase in concentration of inhibitor compared to blank. The adsorption of inhibitor on the mild steel surface has been found to obey Temkin′s adsorption isotherm. Potentiostatic polarization results reveal that morpholine act as mixed type inhibitor. The values of activation energy (Ea), free energy of adsorption (∆Gads), enthalpy of adsorption (∆H), and entropy of adsorption (∆S) were also calculated.

Inhibition Effect of &lt;i&gt;Parthenium Hystophrous&lt;/i&gt; L Extracts on the Corrosion of Mild Steel in Sulphuric Acid

The inhibition effect of Parthenium hystophrous L extract on the corrosion of mild steel in 1N sulphuric acid has been studied at different concentrations as well as different temperatures of inhibitor by mass lossstudies, adsorption isotherms, Tafel polarization and electrochemical impedance spectroscopy (EIS) between 308 and 338K. The exposed mild steel surface in the presence of inhibitor using Scanning Electron Microscope (SEM) is also studied. The corrosion rate increased with increase in temperature and decrease with increase in concentration ofinhibitor compared to blank. The adsorption of this extracts has been found to obey Tempkin and Langmuir adsorption isotherm. Polarization results reveal that the extract is a mixed type inhibitor. The maximum inhibitionefficiency of this extract observed at room temperature is 95.12%.

Assessing the bleaching capacity of some Cameroonian clays on vegetable oils

Four Cameroonian clays, constituted mainly of smectites associated to minor amounts of kaolinite and quartz, have been used to bleach palm oil, cottonseed oil and maize germ oil. Kinetic studies show that the best temperature and contact time for optimum bleaching of vegetable oil varied with the type of oil; these are: 95 °C and 2.5 h for palm oil, 85 °C and 0.25 h for cottonseed oil, and 85 °C and 0.5 h for maize germ oil. The bleaching ability of natural clays was poor when compared with that of industrial adsorbents. Acid activation of Cameroonian clays with 1N sulphuric acid solution increased tremendously their adsorptive capacity, which therefore matches those of the industrial adsorbents. Further increase of the concentration of the acid solution used for clay activation did not induce a noticeable increase in the bleaching power of the adsorbents. This was attributed to the fact that the increase in the surface area is due to the formation of silica but the surface area of H-clays remains almost constant over strong acid leaching and silica has very poor bleaching power of vegetable oils. FT-IR spectroscopy studies of the adsorbents after bleaching suggest strong interactions between the clays and adsorbent surface. Acid and iodine values of bleached oils reveal that oils are not deteriorated by clays during the bleaching process. The overall results lead to the conclusion that Cameroonian clays can be converted into potent adsorbents for bleaching vegetable oils.

Corrosion behaviour of electrodeposited nanocrystalline Ni–W and Ni–Fe–W alloys

The present work deals with evaluation of corrosion behaviour of electrodeposited nanocrystalline Ni–W and Ni–Fe–W alloys. Corrosion behaviour of the coatings deposited on steel substrates was studied using polarization and electrochemical impedance spectroscopy techniques in 3.5% NaCl solution while their passivation behaviour was studied in 1N sulphuric acid solution. The corrosion resistance of Ni–W alloys increased with tungsten content up to 7.54 at.% and then decreased. In case of Ni–Fe–W alloys it increased with tungsten content up to 9.20 at.% and then decreased. The ternary alloy coatings exhibited poor corrosion resistance compared to binary alloy coatings due to preferential dissolution of iron from the matrix. Regardless of composition all the alloys exhibited passivation behaviour over a wide range of potentials due to the formation of tungsten rich film on the surface.

Adsorption kinetics of benzyl triphenyl phosphonium chloride on mild steel in 1N sulphuric acid

The inhibitive effect of benzyl triphenyl phosphonium chloride (BTPPC) on the corrosion of mild steel in aerated 1N sulphuric acid at different temperatures was investigated using galvanostatic polarisation, potentiostatic polarisation, infrared spectroscopy, scanning electron microscopy and quantum chemical studies. Corrosion potential, corrosion currents, cathodic and anodic Tafel slopes, heat of adsorption and effective activation energies were calculated in the presence and absence of the BTPPC. Inhibition efficiencies of BTPPC at different concentrations and temperatures were studied. The nature of the adsorption of BTPPC on metal surface was also examined. It is concluded that the passivation parameters depend on the presence of the already adsorbed anions. BTPPC is one of the rare inhibitors that only passivate the metal at lower concentrations while passivation at higher concentrations is not observed. The electrochemical data fit Temkin’s isotherm. The results of surface morphology and quantum chemical analysis are in agreement with the electrochemical results.

Substituted Dithiobiurets, their Molybdenum and Tungsten Complexes as Corrosion Inhibitors for Mild Steel in Sulphuric Acid

The inhibition of mild steel corrosion in 1N sulphuric acid was studied in the presence of various concentrations (10-150 ppm) of substituted dithiobiurets and their molybdenum and tungsten complexes at 25 o C. All the compounds behaved as ambiodic corrosion inhibitors for mild steel and were considered to inhibit the corrosion by getting adsorbed on the surface. The inhibition efficiencies (IEs) of the complexes, in general, were found to be appreciably higher than those of corresponding ligands. However, the IE values of the complexes of molybdenum and tungsten of the same ligand did not differ much in their magnitude indicating thereby that the nature of central metal ions hardly influenced the inhibition efficiency. The slight difference in the IEs of the complexes at a given concentration seems to be caused by the slight difference in their size. The variation in IEs of different derivatives of ligands has been attributed to change in their size, number of active sites for adsorption and the electron density on these active sites. Scanning Electron Microscopy was used to study the surface of corroded and inhibited specimens.

4-Amino-3-butyl-5-mercapto-1,2,4-triazole: a new corrosion inhibitor for mild steel in sulphuric acid

A new corrosion inhibitor namely 4-amino-3-butyl-5-mercapto-1,2,4-triazole (ABMT) has been synthesized and its inhibitive performance towards the corrosion of mild steel in 1N sulphuric acid (H2SO4) investigated by weight loss and potentiodynamic polarization techniques. Potentiodynamic polarization measurements clearly reveal that the investigated inhibitor is of mixed type. The adsorption of the inhibitor on the metal surface in the acid solution was found to obey Temkin’s adsorption isotherm. The influence of temperature, immersion time and acid concentration was also studied in the presence of ABMT in H2SO4.

Dianils as new and effective corrosion inhibitors for mild steel in acidic solutions

The influence of some substituted dianils on corrosion of mild steel in 1N hydrochloric acid and 1N sulphuric acid has been studied using weight loss and electrochemical techniques. Among the five compounds studied, 1,4-dicinnamyledene aminophenylene (DCAP) showed the best performance. All of the compounds showed good inhibition efficiency in both the acids. Inhibition efficiency of these compounds has been found to vary with nature and concentration of these compounds, solution temperature, immersion time and nature of acid solutions. The adsorption of these compounds on the steel surface from both the acids has been found to obey Temkin’s adsorption isotherm. The values of activation energy and free energy of adsorption of all the dianils were calculated to investigate the mechanism of corrosion inhibition. The potentiodynamic polarization studies were carried out at room temperature, according to which all the compounds were found to be mixed type inhibitors and inhibited the corrosion of mild steel by blocking the active sites of the metal.

The influence of some condensation products on corrosion inhibition of mild steel in acidic solutions

Selected condensation products of aromatic aldehydes and thiosemicarbazide have been synthesized and evaluated as corrosion inhibitors of mild steel in 1N hydrochloric acid and 1N sulphuric acid by weight loss and potentiodynamic polarization methods. The values of activation energy and free energy of adsorption have also been determined to understand the mechanism of inhibition. The potentiodynamic polarization studies carried out at room temperature revealed that all the compounds are of mixed type inhibitors in both the acids. The adsorption of all the condensation products on the mild steel surface from both the acids has been found to obey Temkin’s adsorption isotherm. The inhibition efficiency of these compounds has been found to vary with the nature and concentration of the compounds, temperature, immersion time and nature of the acids.

The Inhibiting Action of Indole and Some of its Derivates on Corrosion of Mild Steel in 1N Sulphuric Acid

The Inhibiting Action of Indole and Some of its Derivates on Corrosion of Mild Steel in 1N Sulphuric Acid

The effect of Zr-implantation on the thermal oxidation and aqueous corrosion of AISI 321 stainless steel

The effect of Zr-implantation (energy: 40 keV, dose: 1 × 10 17 ions/cm 2) on the oxidation of AISI 321 austenitic stainless steel (Fe/Cr18/Ni8/Ti) has been studied at temperatures of 450, 550 and 650°C, in air. The duration of the oxidation was varied between one and six days. The oxygen distribution on the oxidized samples has been determined using the 16O(d, p) 17O nuclear reaction whereas the zirconium depth profile by means of Rutherford backscattering spectroscopy (RBS) using α-particles as projectiles. X-ray photoelectron spectroscopy (XPS) was used as support to these measurements. The morphology and the surface microstructure of the specimens were investigated by scanning electron and scanning transmission electron microscopy (SEM and STEM). The evaluation of the data has indicated that the implantation of Zr-ions leads to a chromium depletion in the near-surface layers and enhances the oxidation of the implanted samples compared to the initial material. Electrochemical experiments of the Zr-implanted steel performed in 1N sulphuric acid solution (H 2SO 4 1N) showed an increase of the corrosion resistance.

Inhibition of mild steel corrosion in 1N sulphuric acid through indole

AbstractThe corrosion inhibition of mild steel in 1N sulphuric acid containing various concentrations of indole was studied in the temperature range of 25–70°C through the use of potentiodynamic polarization curves. The indole was found to shift the corrosion potentials to positive values and to decrease the dissolution of mild steel and hydrogen evolution reaction. The effect, however, was more pronounced on the anodic rather then the cathodic process. Indole did not generally affect the corrosion reaction mechanism (blocking effect). The reported activation energy (Ea) values indicate that the inhibiting effect increased with the indole concentration. At temperatures of 25, 40, 55 and 70°C the adsorption behaviour of the indole follows Temkin's isotherm with a standard free energy of adsorption of −54.49, −39.41, −43.49 and −55.25 kJ/mol, respectively.

Electrochemical characterization and corrosion behaviour of Ni 3Al (0.1B) modified by ion beam techniques: a comparative study

The corrosion behaviour of Ni 3Al (0.1B) treated with different ion beam techniques has been characterized by multisweep cyclic voltammetry and optical microscopy. The results revealed that ion implantation, ion beam mixing and ion beam assisted deposition are very effective to reduce the corrosion and improve the passivation behaviour of specimens in a solution of 1N sulphuric acid.

A Comparison Of The Corrosion Behaviour Of Nanocrystalline And Normal Crystalline Nickel

ABSTRACTThe effect of grain size on the corrosion behaviour of nickel in 2N sulphuric acid is evaluated by potentiodynamic testing and characterization of the corrosion morphology for grain sizes ranging from 100μ to 32nm. The influence of the grain boundary component on key electrochemical parameters (free corrosion potential, passivation current density and potential, transpassive dissolution rate) is discussed.