Water Solution Of Sulfuric Acid Research Articles

Effects of Sulfuric Acid-Water Immersion on the Properties of Ethylene Propylene Diene Monomer, Thermoplastic Vulcanizates, and Eco-Friendly Thermoplastic Vulcanizates

Abstract This research investigates the impact of sulfuric acid-water solutions on the physico-chemical characteristics of ethylene propylene diene monomer rubber (EPDM), thermoplastic vulcanizates (TPV), and ECO TPV materials. We evaluated the deterioration of these materials by subjecting them to acidic environments and using methods such as differential scanning calorimetry (DSC), volume and weight measurements, hardness measures, and scanning electron microscopy (SEM). The samples were submerged in solutions of H2SO4 with concentrations of 1M, 0.1M, and 0.001M at a temperature of 90°C for a duration of 1000 h. The results indicated that EPDM had superior chemical and thermal stability, accompanied by negligible changes in weight and volume. The TPV exhibited moderate stability, however the ECO TPV showed severe deterioration, as seen by major increases in weight and volume, as well as notable changes in DSC profiles. Surface degradation and cracking, especially in ECO TPV samples, were observed using SEM investigation. The hardness results indicated little changes in hardness after exposure to the various chemical aging techniques. The results indicate that EPDM and TPV are better suited for use in acidic conditions, such as fuel-cell systems. However, ECO TPV may need extra stabilization in order to enhance its endurance.

Feasibility of Waste Engine Oil Electrooxidation with Ni-Co and Cu-B Catalysts

To implement a circular economy policy, methods of using waste products as a starting point for other technologies are constantly researched. One of the waste products that should be disposed of after use is waste engine oil (WEO). Despite the permanent introduction of the electrification of cars, the number of combustion vehicles (and, thus, the production of WEO) is constantly increasing. For these reasons, the reuse of WEOs is extremely important; e.g., to use these oils for energy purposes. One of the potential uses of this type of oil is as fuel for fuel cells (for direct electricity production). To lower the production costs of electrodes for fuel cells, catalysts that do not contain precious metals are being constantly sought. This work shows the research of WEO electrooxidation feasibility with Ni-Co and Cu-B catalysts. The results showed the feasibility of the electrooxidation of WEO emulsion on Ni-Co and Cu-B electrodes in an electrolyte (a water solution of sulfuric acid). Moreover, it was shown that the electrooxidation of the WEO emulsion occurred for all concentrations of WEO in the emulsion for all measurement temperatures (20–80 °C). The highest current density obtained in the measurements was 11 mA cm−2 (at 60 °C) for the Ni-Co electrode.

SO3 and sulfuric acid (H2SO4) aerosol detection by UV absorption spectroscopy of liquid H2SO4 solution

SO 3 and sulfuric acid (H 2 SO 4 ) aerosol are common air pollutants in the burning process of coal. Detection of SO 3 and sulfuric acid (H 2 SO 4 ) aerosol in gaseous form is difficult and expensive. A concentration detection sensor system for sulfuric acid-water solution is developed based on ultraviolet absorption spectroscopy in 185–210 nm wavelength range in this work. An absorption at 193 nm for sulfuric acid (H 2 SO 4 ) is observed. Spectra of sulfuric acid-water solution in different concentration are measured at room temperature of 294 K. When the concentration is below 500 ppm w, the absorption intensity is proportional to solution concentration. By continuous monitoring, a detection limit of 2 ppm w is obtained with 0.5 s sampling time for this system.

Scale heights and detached haze layers in the mesosphere of Venus from SPICAV IR data

Abstract SPICAV IR, one channel of SPICAV/SOIR instrument suite onboard Venus Express, performed solar occultation measurements of the atmosphere at terminators in 0.65–1.7 µm spectral range. We analyze the properties of the upper part of the Venus aerosol layer (upper haze, 70 − 95 km altitude) from 798 observations performed from May 2006 through November 2014. Vertical profiles of slant optical depth, extinction coefficient, effective radius, and number density of haze particles from 222 orbits were analyzed in a previous publication (Luginin et al., 2016); their diurnal, latitudinal, and interannual variabilities were investigated. The present paper is devoted to analysis of scale heights and properties of detached haze layers from 147 orbits at mid-to-high northern latitudes, where the best spatial resolution was obtained. Scale heights retrieved from 43 orbits were equal to 4 − 5.5 km at the North Pole (82°N-90°N) decreasing to 2 − 4 km at 60°N − 80°N latitudes. As an explanation of such latitudinal variations, we propose a mechanism based on vertical transport driven by winds that are directed upward at the North Pole and downward at 60°N − 80°N latitudes. Detached layers were detected in 93 occultations at 58°N − 90°N. The detached layers are presumably formed through condensation of water vapor on droplets of sulfuric acid water solution; they were mostly seen at 80 − 88 km at the morning terminator, and at 84 − 90 km at the evening one. This difference in altitude of the detached layers can be explained by diurnal variations in thermal structure of Venusian mesosphere. The vertical optical depth of detached layers varies broadly around the mean τDL ∼ 0.8 − 3·10−3; no difference between the morning and the evening terminators was observed. The effective radius and number density of aerosol particles in the detached layers group around a very wide maximum at the morning terminator (0.65 ± 0.25 µm and 0.6 ± 0.4 cm−3) and two maxima at the evening terminator (0.4 ± 0.1 µm and 0.85 ± 0.15 µm; 0.3 ± 0.2 cm−3 and 4.5 ± 2.5 cm−3). This could be explained by differences in initial altitudes at which condensation of particles occurs.

Electrical and Optical Properties of Soda-Lime Glass Coated Using High Voltage Electrodeposition Technique

High voltage electrodeposition technique was successfully employed in coating a low conductive glass. The technique involved the use of constant input voltage (e.g., 2000V) to coat the soda-lime glass electrode. Dissolved copper sulfate pentahydrate in sulfuric acid-water solution served as the electrolyte in the deposition process. The surface conductivity of the electrodeposited coated glass improved compared to that of the uncoated glass. The surface conductivity increased as high as 735% at 30 minutes deposition time using 2000 V input voltage. However, the transmittance decreased with surface conductivity. This indicated that the conductive particles that adhered on the surface were blocking the passage of light. Furthermore, the AFM image shows that the adhered particles were deposited besides the scratched region. This observation supports the need to roughen the glass surface before employing the high voltage electrodeposition technique.

Influence of the pulsed plasma treatment on the corrosion resistance of the low-alloy steel plated by Ni-based alloy

This paper presents investigation results of the influence of high temperature pulsed plasma flows (HTPPF) treatment on the corrosion resistance of low-alloy steel 0.2C-Cr-Mn- Ni-Mo cladded by the rapidly quenched nickel-based alloy. A technique that allows obtaining a defect-free clad layer with a good adhesion to the substrate was developed. It is shown that the preliminary treatment of steel samples by nitrogen plasma flows significantly increases their corrosion resistance in the conditions of intergranular corrosion test in a water solution of sulfuric acid. A change of the corrosion mechanism of the clad layer from intergranular to uniform corrosion was observed as a result of sub-microcrystalline structure formation and homogeneous distribution of alloying elements in the plasma treated surface layer thus leading to the significant increase of the corrosion resistance.

Photoluminescence of f-centers in films of anodic alumina

Results are reported from a study of the optical properties of porous alumina films obtained by anodizing in a water solution of sulfuric acid and modified by thermal annealing in air at T ≥ 850°C. A comparative analysis of the data shows that the near-UV and visible photoluminescence of alumina anodized in a sulfuric acid solution is caused primarily by oxygen divacancies (F2, F $$ _2^{+} $$ , and F $$ _2^{2 + } $$ centers), while sulfate ions have little effect on the luminescence properties of anodic alumina in this spectral range.

Collisions of noble gases with supercooled sulfuric acid–water solutions

The collisions of hyperthermal noble gases (He, Ne, Ar, Kr, Xe) with supercooled binary sulfuric acid-water mixtures (57-77 wt%) were explored in the temperature range between 210 and 240 K. The experiments were performed by directing a molecular beam of the respective gases onto a continuously renewed liquid surface and monitoring the velocity of the scattered molecules by mass spectrometry. Depending on the initial translational energies and molecular masses, we observe both inelastic scattering from the surface as well as thermalization followed by subsequent desorption. The experiments indicate that the repulsive momentum transfer in the inelastic scattering channel increases with increasing mass of the impinging gas, while it is only weakly affected by the initial velocities. The final energy of the thermally desorbing atoms can always be approximated by a Maxwell-Boltzmann distribution equal to the liquid bulk phase temperature. The influence of the binary composition of the liquid phase is only noticeable in the case of Ne, whilst this dependence diminishes for gases with molecular masses >or=40 amu. The probability of thermalisation relative to inelastic scattering increases with the bulk phase temperature, independent of the molecular masses of the colliding gas. In contrast, the fractional energy transfer during collision does not increase with temperature, except for Neon. These results can be interpreted in the model framework of hard-sphere collisions of noble gases with the surface, during which water and sulfuric acid molecules interact independently with the impinging gas.

Studies of electrical properties of polyaniline irradiated by X-rays

Recent development and studies of physical and chemical properties of the conducting polymers have been calling the interest of many scientists. Among this group of materials, the polyaniline (PANI) deserves special attention because of its high chemical and thermal stability under normal conditions, simple process of polymerization and low cost. This polymer is also known due to its strongly pronounced and well studied electrochemical characteristics. In the present work, the variations of the electrical resistance of polyaniline caused by X-rays radiation have been studied. The polymer has been synthesized by electrochemical method in stainless steel and graphite electrodes. The data concerning the electrical resistance of PANI were measured just after the synthesis. This has been performed in the water solution of sulfuric acid within monomer of aniline where the polyaniline has been submitted to the applied voltages in the range from 200mV to 600mV. Polymeric samples have been irradiated using the X-rays with the energy 50keV and 100keV. After the irradiation, the electrical measurements have been repeated. The whole experimental procedure was performed several times. The obtained results have clearly shown the potential of polyaniline as a dose sensitive material that could be applied as a radiation sensor.

Performance of a double catalyst fuel cell cathode with a tubular oxygen breathing and preliminary reduction zone

This paper discusses a mathematical model for a liquid phase reacting flow occurring at the cathode of a patent pending novel fuel cell geometry, where a non homogeneous catalysis carried by gold and Prussian Blue, with the first reducing air O2 and the second the resulting H2O2. The breathing zone is porous walls microtubes, with three different types of pores in its walls. Inside the microtubes there is water solution of sulfuric acid. The microtubes possess an external layer of extremely porous polymer hydrophobic agent. A Prussian Blue thin porous layer is over the selective membrane. Appropriate porous and tubular connecting elements close the fluid loop. The asymmetry induces proper current and electric potential profiles, which leads to a mainly electrocapillary electrokinetic flow, which enhances the oxygen transport and assures the H2O2 flow to its reduction layer.

Corrosion and wear behaviors of ferrous powder thermal spray coatings on aluminum alloy

Abstract Atmospheric plasma spray coating was performed on a cast AA383 Aluminum alloy plate, and this process formed a 170-μm thick spray coating layer by using tentative Fe–C powders with nickel added (up to 14 mass%) or without supplementary nickel. Hardness test, microstructure observation, corrosion and wear tests in engine oil with or without sulfuric acid water solutions added were performed as well. The corrosion performance was dependent upon the nickel content. On the contrary, the wear resistance testing under two engine oil lubrication conditions (with or without sulfuric acid water solution) showed the different tendency instead.

Potentiometric pH measurements in acidic sulfate solutions at 250 °C relevant to pressure leaching

Abstract A flow-through yttria-stabilized zirconia (FTYSZ) electrode has been employed for pH measurements at 250 °C in concentrated electrolyte systems relevant to hydrometallurgical processing of nickeliferous laterites. Experiments were conducted using a custom-made flow-through titanium electrochemical cell specially designed for high-temperature potentiometric pH measurements. In the present work, we assess the accuracy and validity of pH measurements with theory at 250 °C on concentrated sulfate process solutions. First, binary sulfuric acid–water solutions were measured at concentrations ranging from 0.05 to 0.5 mol kg −1 and showed 0.3 pH unit increase on the average between 25 and 250 °C. The measurements were then extended to ternary and quaternary systems containing 0.0076–0.038m Al 2 (SO 4 ) 3 and 0.0276–0.276m MgSO 4 , respectively. Autoclave passivation against corrosion was successfully achieved using sodium chromate or hydrogen peroxide. In this technique, the potentials are measured against a Ag/AgCl flow-through external reference electrode (FTEFE). A reference solution of 0.1 mol kg −1 NaCl(aq) flows permanently through the electrode at a constant flow rate, so that the thermal liquid junction and streaming potentials are kept constant. The experimental results were compared with theory using available thermodynamic data for estimating the quality of pH measurements. An average difference of 0.15 pH unit was observed between measured and theoretical values at temperature.

Does molecular HNO3 adsorb onto sulfuric acid droplet surfaces?

Room temperature surface tension measurements on the ternary system: nitric acid‐sulfuric acid‐water are reported. There is a dramatic decrease in the surface tension of sulfuric acid‐water solutions as nitric acid is added. This decrease is most pronounced in the stratospherically‐relevant range of sulfuric acid concentrations, between 50 and 75 wt% sulfuric acid. The surface tension decrease indicates a change in surface energy and surface composition and/or structure associated with partitioning of molecular HNO3 to the surface. The presence of HNO3 at the surface may be related to the reported changes in heterogeneous reactivity of sulfuric acid solutions when exposed to nitric acid.

Nucleation simulations in the wake of a jet aircraft in stratospheric flight

Abstract An efficient method for calculating the nucleation rates of H 2 SO 4 H 2 O aerosol droplets is developed using classical nucleation theory for a binary vapor system. The nucleation model is used to predict binary homogeneous and heterogeneous nucleation rates in the exhaust stream of a supersonic aircraft flying in the stratosphere. Calculations indicate that, assuming at least 0.01% of sulfur is emitted as H 2 SO 4 , the H 2 SO 4 H 2 O particle formation rate is large enough to enhance the background sulfate aerosol concentration substantially. Heterogeneous nucleation, although somewhat slower, may convert a substantial fraction of the soot particles into acid aerosols (notwith-standing rapid water vapor condensation on the soot). Model results are compared with a balloon measurement taken in the aircraft exhaust plume in which the sulfuric acid aerosol concentration was greatly enhanced above the background. The observed aerosols consist of pure sulfuric acid-water solutions without a nucleating “core”, which is consistent with the prompt homogeneous binary sulfuric acid nucleation in the jet plume. Simulations do not support an alternative delayed mechanism that requires photooxidation of SO 2 into H 2 SO 4 followed by homogeneous nucleation in the humid air (like the formation of new sulfate aerosols in volcanic eruption clouds).

Thermodynamic activities and equilibrium partial pressures for aqueous sulfuric acid solutions

Published room-temperature and azeotropic composition data for solutions together with recently published high-temperature P-T-X data and room-temperature values for the equilibrium vapor pressure of sulfur-bearing species over concentrated sulfuric acid-water solutions are evaluated critically for self-consistency. The adjusted data are used to calculate activity coefficients at 0 o C and at the normal azeotropic boiling temperature and to generate expressions for the partial molar beat capacities in H 2 SO 4 -H 2 O solutions

Properties of the clouds of Venus, as inferred from airborne observations of its near-infrared reflectivity spectrum

The shape and absolute value of Venus' reflectivity spectrum is measured in the 1.2- to 4.0 micrometer spectral region with a circular variable filter wheel spectrometer having a spectral resolution of 1.5%. Comparing these spectra with synthetic spectra generated with a multiple-scattering computer code, a number of properties of the Venus clouds are inferred. Evidence is obtained indicating that the clouds are made of a water solution of sulfuric acid in their top unit optical depth, and that the clouds are made of this material down to an optical depth of at least 25. In addition, the acid concentration is 84 plus or minus 2% H2SO4 by weight in the top unit optical depth, the total optical depth of the clouds is 37.5 plus or minus 12.5, and the cross-sectional weighted mean particle radius lies between 0.5 and 1.4 micrometers in the top unit optical depth of the clouds. It is found that the average volume mixing ratio of H2SO4 and H2O contained in the cloud material both equal approximately 2 x 10 to the -6. Employing vapor pressure arguments, the acid concentration is shown to equal 84 plus or minus 6% at the cloud bottom and the water vapor mixing ratio beneath the clouds lies between 6 x 10 to the -4 and 10 to the -2.

Microphysical Processes Affecting Stratospheric Aerosol Particles

Physical processes which affect stratospheric aerosol particles include nucleation, condensation, evaporation, coagulation and sedimentation. Quantitative studies of these mechanisms to determine if they can account for some of the observed properties of the aerosol are carried out. It is shown that the altitude range in which nucleation of sulfuric acid-water solution droplets can take place corresponds to that region of the stratosphere where the aerosol is generally found. Since heterogeneous nucleation is the dominant nucleation mechanism, the stratospheric solution droplets are mainly formed on particles which have been mixed up from the troposphere or injected into the stratosphere by volcanoes or meteorites. Particle growth by heteromolecular condensation can account for the observed increase in mixing ratio of large particles in the stratosphere. Coagulation is important in reducing the number of particles smaller than 0.05 micron radius. Growth by condensation, applied to the mixed nature of the particles, shows that available information is consistent with ammonium sulfate being formed by liquid phase chemical reactions in the aerosol particles. The upper altitude limit of the aerosol layer is probably due to the evaporation of sulfuric acid aerosol particles, while the lower limit is due to mixing across the tropopause.

A Determination of the Composition of the Venus Clouds from Aircraft Observations in the Near Infrared

Summary of the evidence showing that the first optical depth of the Venus cloud layer is composed of a water solution of sulfuric acid, including earlier aircraft observations of Venus' reflectivity in the region from 1 to 4 microns obtained at a phase angle of 120 deg. Analyses of these aircraft results indicated that of all the proposed cloud candidates only a sulfuric acid solution with a concentration of 75% or more H2SO4 by weight was consistent with the observed 3-micron cloud feature. Aircraft observations of Venus are presented which were obtained in the same spectral region at a phase angle of 40 deg and in the region from 3 to 6 microns at a phase angle of 136 deg. Comparing the two sets of observations in the region from 1 to 4 microns, a striking phase effect is found: the reflectivity is much lower in the 3-micron region and there is a much more marked decline between 1.3 and 2.5 microns for the data obtained at the smaller phase angle. The observations made at the 40-deg phase angle are consistent with the theoretical behavior of a sulfuric acid cloud and imply that the sulfuric acid is present to at least many tens of optical depth below the cloud tops. Arguments concerning the concentration of the solution are reviewed, and it is concluded that the best current estimate is about 85% H2SO4 by weight.

Aircraft observations of Venus' near-infrared reflection spectrum: Implications for cloud composition

A comparison of aircraft-based measurement data on Venus' near-infrared (1.2- to 4.1-micron) reflection spectrum with computer generated spectra of a number of cloud candidates shows a 75-% or more concentrated water solution of sulfuric acid to give the only acceptable match to the profile of Venus' strong 3-micron absorption feature. However, the measurement data obtained also show a modest decline in reflectivity from 2.3-micron to 1.2-micron wavelength, which is inconsistent with the flat spectrum of sulfuric acid in this spectral region. It is hypothesized that this decline is due to impurities in the sulfuric acid droplets.

Radiation Absorption by Droplets of Sulfuric Acid Water Solutions and by Ammonium Sulfate Particles

Abstract The absorption spectra of 49% 73% and 98% sulfuric acid water solutions for wavelengths of 0.3–6.5.μ and those of ammonium sulfate for 0.3–25 μ are either measured for the purposes of this study or quoted from the literature. Sulfuric acid water solutions have an absorption in the range 1.6–6.5μ. Absorption by 49% and 73% solutions is particularly strong. It is much stronger than absorption by liquid water over most of the range. Ammonium sulfate has no absorption of any significance from 0,3 to 2.85μ but has four absorption bands in the range 2.85-25μ, the largest absorption occurring at about 9.25μ in the terrestrial radiation “window.” The conclusions are as follows: 1) sulfuric acid water solution droplets will absorb solar radiation in the near IR, about 2μ 2) ammonium sulfate particles will not absorb solar radiation; and 3) both will, of course, scatter solar radiation. The above results are relevant to the absorption of solar radiation by droplets or by solid particles in the lower strato...