Aqueous Sulfuric Acid Solutions Research Articles

Chemical recycling of hemp waste textiles via the ionic liquid based dry-jet-wet spinning technology

The chemical recycling of hemp fabric into high-tenacity man-made cellulose fibers was demonstrated. The fabric was laundered 25 and 50 times to mimic the wear cycles of post-consumer textile waste. Despite the launderings, the molar mass of the material was still too high for recycling via dry-jet-wet spinning. Thus, the fabrics were treated with an aqueous sulfuric acid solution to adjust the intrinsic viscosity to the targeted level of 400–500 ml/g. The acid hydrolyzed sample was dissolved in 1,5-diazabicyclo[4.3.0]non-5-enium acetate and man-made cellulose fibers were regenerated by dry-jet-wet spinning. The properties of hemp and regenerated fibers were determined by tensile testing, birefringence measurements, and X-ray diffraction. Regenerated fibers were spun into yarn and knitted into a fabric. The tensile properties of the yarn and the abrasion and pilling resistance of the fabric were determined. Regenerated fibers showed a higher modulus of toughness (55.9 MPa) compared with hemp fibers (28.7 MPa). The fineness and staple length uniformity of regenerated fibers resulted in a high yarn structure evenness, a yarn tenacity of 28.1 cN/tex, and an elongation at break of 7.5%. Due to the even fabric structure, the fabric from regenerated fibers showed higher abrasion resistance than the hemp fabric.

Locked-energy at first-order Stokes stimulated Raman scattering for an aqueous sulfuric acid solution

We introduced a locked-energy coherent Stokes radiation scheme based on multi-mode stimulated Raman scattering (SRS) of aqueous sulfuric acid solutions. SRS of pure sulfuric acid has only one vibrational characteristic peak. Mixing sulfuric acid with water leads to the appearance of bisulfate, and the energy transfer between adjacent vibrational energy levels in a 17.0 mol/l aqueous sulfuric acid solution leads to generation of five different vibrational modes in a solution. The competition between these five SRS modes prevents the vibrational energy from being transferred to high-order Stokes waves, thereby locking most of the energy in the first-order Stokes SRS and outputting a very strong, broadband, and coherent Raman radiation ranging from 555 to 570 nm. This study demonstrates the possibility of producing an intense single longitudinal mode laser.

Experimental and theoretical study on corrosion inhibition of mild steel by meso-tetraphenyl-porphyrin derivatives in acid solution

The inhibition effect of meso-tetraphenyl-porphyrin (TPPH2), meso-tetra4-methophenyl-porphyrin TPPH2(p-Me), and meso-tetra4-actophenyl-porphyrin (TAcPPH2) on the corrosion of XC52 mild steel in aerated 0.5 M aqueous sulfuric acid solution was studied by potentiodynamic polarization experiments and quantum chemical calculations. Results from potentiodynamic polarization showed that inhibition efficiency of three compounds increased upon increasing of the inhibitor concentration and they are acting as mixed type inhibitors, having dominant anodic reactions. Adsorption of all compounds follows the Langmuir adsorption isotherm with moderate values of free energy of adsorption. Quantum chemical calculation using DFT/B3LYP method confirmed a strong bond between meso-tetraphenyl-porphyrins and mild steel surface. The inhibition mechanism was also determined by the potential of zero charge (PZC) measurement at the metal/solution interface.

Selective Ozone-Assisted Acid Leaching of Copper from Copper Smelter Slag by Using Isopropanol as a Solvent

Copper content in copper smelter slag exceeds that in copper ores, which has attracted increasing interest to recover copper from this by-product of pyrometallurgical copper production. The isopropanol-sulfuric acid-ozone system has been tested under different conditions to extract this metal from copper smelter slag containing chalcopyrite as a copper mineral. Isopropanol as a solvent played a key role in increasing the copper recovery to 87% after 5 h of leaching, while the use of an aqueous solution of sulfuric acid allowed only 13% of copper to be recovered. Iron extraction under these conditions was only 10%. The role of ozone was spectroscopically proven to oxidize ferrous ions to form ferric ions, which are effective oxidizers of chalcopyrite. The presence of copper in solution in the form of cuprous (Cu+) ions was proven electrochemically. The increased copper extraction in the solution was caused by the stabilization of cuprous ions by isopropanol. The limiting stage of the process was the chemical reaction on the chalcopyrite surface with the activation energy of 73.4 kJ mol−1.

Preparation of Porous Carbon from SB-HPC (Sub-Bitumious) Solution Derived from Low Quality Coal and Its Application to EDLC

Introduction Hypercol (HPC), which is ashless coal obtained from thermal extraction of coal, is soluble in organic solvents and is mainly produced by carbonization of carbon precursors prepared by the precipitation method from its solution. Porous carbon mainly with micropores can be obtained from HPC by the precipitation method. Porous carbon prepared from SB-HPC, which is an HPC derived from low-grade coal, has a high specific surface area and abundant micropores. It has been clarified that the electrode material used for EDLC is preferably a material having a high specific surface area and exhibiting electrical conductivity, and in addition, it strongly depends on its pore structure. In this study, carbon powder is prepared from the SB-HPC solution by the precipitation method, and the pore characteristics are evaluated, and the EDLC characteristics when this carbon powder is used for the electrode are evaluated. ExperimentalSB-HPC derived from low-grade coal was used as a starting material, and the HPC powder (particle size: <250 m m) was dissolved in pyridine. The obtained HPC solution was added to water to precipitate and precipitate HPC. The obtained HPC powder was insolubilized by holding it in an air atmosphere at 300 oC for 1 h, and then carbonized by holding it in a nitrogen atmosphere at 800-1000 oC for 30 min. The morphology of the prepared sample was observed using a scanning electron microscope (SEM), a nitrogen gas adsorption / desorption measuring device with surface characteristics of 77 K was used, and temperature desorption analysis (TPD) was used to quantify the surface functional groups. Was used. In addition, the specific surface area value was obtained by the s analysis method using the adsorption isotherm obtained by nitrogen adsorption / desorption measurement. The electrodes were prepared by mixing them in a weight ratio of carbon powder: acetylene black: PTFE = 8: 1: 1. The EDLC characteristics were evaluated using a triode cell, and an aqueous sulfuric acid solution was used as the electrolytic solution. Galvanostatic charge / discharge measurements were performed with a current density in the range of 50–1000 mA g-1. The capacitance at each current density was calculated in the range of 0.2 V to 0.8 V of the discharge curve obtained by the galvanostatic charge / discharge measurement. The sample code was SB- (carbonization temperature). Results and Discussions From the nitrogen gas adsorption / desorption isotherm of carbonized powder of SB-HPC derived from low-grade charcoal at 900 to 1300 oC, the amount of adsorption in the low relative pressure region increased as the heat treatment temperature increased. This suggests the formation of micropores. The specific surface area calculated by the α s analysis method is 900 oC at the heat treatment temperature, and the specific surface area (737 m2 g-1) is higher than that of HPC carbon powder (400 m2 g-1) derived from high-grade coal. It is inferred that the fact that the specific surface area was nearly doubled by the same heat-treatment as for high-grade coal is due to the difference in the characteristics of the starting materials. Furthermore, as the heat treatment temperature increased, the specific surface area of SB-1200 showed a maximum value of 1268 m2 g-1 and decreased after 1200 oC. In addition, the obtained capacitance was higher (284 F g-1) than the carbon powder (210 F g-1) 1) of HPC derived from high-grade coal. The discharge curve obtained from the charge / discharge curve at a current density of 50 mA g-1 for each carbon powder showed a decrease in linearity around 0.4 V to 0.8 V, and the resistance due to the oxygen-containing functional group of the carbonpowder. It was considered to be an ingredient. From the relationship between the specific surface area and the capacitance of each carbon powder, although the specific surface area increased as the heat treatment temperature increased, there was no significant difference in the capacitance and it was almost constant. Therefore, it is inferred that the contribution of capacity to the surface area is constant, there are other factors, and one is the pseudo-capacity due to the oxygen-containing functional group.

Spectroscopy and in‐situ X‐ray diffraction analysis on the corrosion process at the interface Pb/H2SO4 using a low‐cost electrochemical cell

AbstractSimple and low‐cost electrochemical cells for in‐situ X‐ray powder diffraction (XPD) at 8.04 keV (CuKα) and ex‐situ scanning electronic microscope (SEM) with energy dispersive spectroscopy (EDS) on the electrode surfaces are presented. Lead (Pb) and aqueous sulfuric acid (H2SO4) solution (molar concentration of 5.35) were chosen as electrode and electrolyte, respectively. A formation of a crystalline lead sulfate (PbSO4) on the Pb electrode surface with initial precipitation/nucleation at 1 h and a posterior crystal grow (with orthorhombic crystalline structure) on the Pb electrode surface, over the time (from 4 h to 12 weeks) was observed. The result is consistent with the literature, showing the full characterization capability of the proposed cells.

Improvement of the technology of fatty acids obtaining from oil and fat production waste

Fatty acids are an important component in the pharmaceutical, food, chemical industries. The production of various types of products requires a certain purity and quality of fatty acids. To obtain these compounds, it is promising to use soapstocks, which are waste products of alkaline refining of oils. The peculiarity of the work lies in determining the effect of the process parameters of soapstock decomposition with sulfuric acid on the saponification number, which is an important production characteristic of fatty acids. The study used sunflower soapstock according to DSTU 5033 (CAS 68952-95-4) with a mass fraction of total fat of 69.5 %, fatty acids – 64.5 %. The soapstock was treated with a sulfuric acid solution at a temperature of 90 °C, the process duration was 40 min. Rational parameters of soapstock treatment were determined: concentration of sulfuric acid in the reaction mass is 80 %, concentration of an aqueous solution of sulfuric acid – 50 %. In the experiment interval, the settling duration of the reaction mass does not affect the saponification number of fatty acids. The settling time of 1 hour is effective for the isolation of fatty acids. Under these conditions, the saponification number of fatty acids was 186.4 mg KOH/g. The acids correspond to fatty acids of the first grade according to DSTU 4860 (CAS 61788-66-7): mass fraction of moisture and volatile substances – 1.2 %, mass fraction of total fat – 97.5 %, cleavage depth – 95.0 % oleic acid. The obtained data allow rational and most efficient use of the reagent – sulfuric acid. The results of the work make it possible to reduce the duration of fatty acids obtaining from soapstocks, since the efficiency of the process with the minimum duration of mass settling has been confirmed. The improved technology of soapstock decomposition makes it possible to obtain a valuable product – high-quality fatty acids under rational conditions

A Comparative Study on Corrosion Behaviors of Fe35Mn10Cr20Ni35 High‐Entropy Alloy and 304 Stainless Steel in Sulfuric Acid Aqueous Solution

Herein, the corrosion behaviors of Fe35Mn10Cr20Ni35 high‐entropy alloy (HEA) and commercial 304 stainless steel (304 SS) in 0.5 M H2SO4 aqueous solutions are evaluated. Potentiodynamic polarization test results indicate that both the prepared HEA and 304 SS possess a large passive interval, illustrating that they have a strong capability to form passive films. The prepared HEA possesses higher corrosion potentials and lower corrosion current densities than that of 304 SS, thus it has more superior corrosion resistance. The electrochemical impedance spectroscopy and electrical equivalent circuits results indicate that the charge‐transfer resistance of HEA is higher than that of 304 SS and the passive films of the prepared HEA is thicker than that of 304 SS. These indicate that the passive film on the prepared HEA has an excellent protective ability to prevent further corrosion. X‐Ray photoelectron spectroscopy results indicate that the passive film of the prepared HEA samples is mainly composed of compacted metal oxides, especially Cr2O3‐dense oxides, while the passive film of 304 SS is mainly composed of loose hydroxides and compacted metal oxides. That is the key reason why the prepared HEA has better corrosion resistance than 304 SS.

Robust and Transparent Antifogging Polysilsesquioxane Film Containing a Hydroxy Group.

Poly(glycidyloxypropyl)silsesquioxane (PGPS) was successfully synthesized by hydrolysis and polycondensation using the nitrogen flow method. A poly(3-(2,3-dihydroxypropoxypropyl)silsesquioxane) (PSQ-OH) film was prepared via two routes. In route A, PSQ-OH was prepared by the hydrolysis of the epoxy group of PGPS in an aqueous hydrochloric acid (HCl)/tetrahydrofuran solution, affording a diol group; then, PSQ-OH was coated on a glass substrate and heated. The antifogging performance of the PSQ-OH film was evaluated in terms of water uptake (WU) and scratch resistance. The obtained PSQ-OH film exhibited a low WU of 5% and a scratch resistance of 1.6. In route B, PGPS was coated on a glass substrate and immersed in a 0.5 mol/L aqueous sulfuric acid solution for 1-15 h at room temperature, producing a diol group. The solid-state 13C nuclear magnetic resonance spectrum indicated that the epoxy group was completely hydrolyzed after immersion for 15 h. The WU of the PSQ-OH film prepared via route B increased from 5 to 19% with the increase in the immersion time and was higher than that of the PSQ-OH film prepared via route A. The PSQ-OH film on a glass substrate retained transparency under water vapor exposure at 60 °C. The PSQ-OH film prepared via route B exhibited a high scratch resistance of 2.7-3.6, similar to that of a poly(3-(2-aminoethylaminopropyl)silsesquioxane) film. The scratch resistance of the PSQ-OH film was 5-7 times higher than that of the poly(vinyl alcohol) film. The PSQ-OH film was uniform with no pinholes and cracks. The PSQ-OH film was transparent and colorless and exhibited a high transmittance of >90% in the wavelength range of 400-800 nm. Overall, the prepared PSQ-OH film exhibits good antifogging, transparency, and mechanical properties.

ТЕРМИЧЕСКИЙ АНАЛИЗ ПРОДУКТОВ ОКИСЛЕНИЯ АКТИВИРОВАННОГО СПЛАВА АЛЮМИНИЯ RAU-85 В РАЗЛИЧНЫХ ОКИСЛИТЕЛЬНЫХ СРЕДАХ

By methods of differential thermal and thermogravimetric analysis, the composition of the thermally active part of the studied multicomponent samples of the products of the interaction of the activated aluminum alloy with various oxidizers was determined, and their thermal behavior was revealed under conditions of dynamic temperature rise. Thermal analysis was carried out in air environment, in the temperature range from 20 to 1000°C. The heating mode of the furnace was linear (dT/dt = 10 grad/min), the reference substance was calcined Al2 O3 . Water, 3% aqueous solution of hydrogen peroxide, 5% aqueous solution of sulfuric acid were used as oxidizing agents. Establishment of the material composition of the active part of powder samples was carried out according to the morphologies of thermal curves and numerical values of the intensities of endo- and exothermic effects using the thermogravimetric readings of TG-lines associated with them. A series of endo- and exothermic effects revealed during the decomposition of the test samples made it possible to follow the order of the stage of their thermal destruction and quantitatively determine the composition of volatile components. A number of features of sample decomposition were established depending on their composition and weight ratios of thermally active sample components. The obtained data on the thermal analysis of the oxidation products of the activated alloy RAU-85 in various oxidizing environments can be successfully applied to develop a technology for cleaning the bottomhole zone of the well from asphalt resin paraffin deposits, based on the thermal gas-chemical interaction of the activated aluminum alloy and formation water, which results in the formation of a large amount of heat and vapor-gas mixture.

Process development and techno-economic analysis of microwave-assisted demetallization and desulfurization of crude petroleum oil

Metals and sulfur, if not efficiently eliminated from crude petroleum oil during refining, may have severe detrimental impacts in refinery processes such as fluid catalytic cracking and hydrotreating units. Recently, the lab-scale microwave-assisted demetallization and desulfurization (MW-DMDS) of crude oil using Bis(2-ethylhexyle) phosphoric acid (D2EHPA) have shown several advantages such as high removal efficiency, being environmentally green, and lower energy requirements. This paper presents a comprehensive industrial process scheme for MW-DMDS by designing the required processing units. In addition, an effective methodology to regenerate D2EHPA using sulfuric acid and sodium hydroxide (NaOH) aqueous solutions was developed and experimentally validated. A Techno-economic investigation was carried out by adopting the ASPEN Plus process simulator to estimate the upscaling feasibility of the process to treat 50,000 barrels per stream day (BPSD) of crude oil. Total capital costs (CAPEX) and total annual operating costs (OPEX) were estimated at 6.77 MUSD and 4.23 MUSD (0.24 $/bbl), respectively. The results indicated the economic superiority of the proposed process compared to the existing technologies, like hydrodemetallization (HDM) and hydrodesulfurization (HDS) due to the remarkably lower CAPEX and OPEX costs. Sensitivity analysis by changing the primary design parameters demonstrated that the required microwave power and the corresponding purchase costs of the microwave generators have the highest share of the estimated CAPEX costs. Moreover, the annual operating costs seem to strongly depend on the reagent consumption and regeneration process effectiveness.

Simple Methods for Evaluating Acid Permeation and Biofilm Formation Behaviors on Polysiloxane Films.

The sulfuric acid permeation and biofilm formation behaviors of polysiloxane films have been investigated, and simple methods for evaluating the sulfuric acid permeation and biofilm formation behaviors have been proposed in this paper. The polysiloxane films used in these experiments were practically impermeable to the aqueous sulfuric acid solution, and the amount of biofilm formation varied depending on the composition of the films. Further, the amount of sulfuric acid permeation can be estimated by measuring the polarization curves of polysiloxane films with different thicknesses formed on iron electrodes. By measuring the adhesion work of pure water and simulated biofilm droplets on polysiloxane films of different compositions, we can estimate the resistance of biofilm formation on the polysiloxane films.

Mechanical behavior and constitutive model for loess samples under simulated acid rain conditions

Acid rain is mainly composed of sulfuric acid and nitric acid aqueous solutions, which can deteriorate the mechanical properties of soil and thus threaten the safety of soil engineerings. In this paper, the influence of sulfuric acid rain on mechanical properties of loess soil samples was studied. The diluted sulfuric acid solution has respectively pH 5.0, 4.0 and 3.0 to simulate the acid rain condition, and the triaxial compressional tests and scanning electron microscope were carried out to investigate the deteriorated properties and evolution of the microstructure of the saturated loess samples. The results demonstrated that acid rain made the porosity of loess samples larger, and changed the pore distribution and contacts of soil grains, so that the mechanical properties of loess samples varied in some degree. With the decrease of pH value, both the peak value of the deviatoric stress and volumetric contraction of loess samples decreased, which reduced the parameters of shear strength of loess samples. Furthermore, a framework of the chemical–mechanical model for loess under the action of acid rain was established, in which loess was considered as a porous medium material, and the influences of acid rain with different pH values were taken into account in the double-hardening constitutive model, and the model was also verified by the triaxial test results finally.

Autogenous Oxidation/Reduction of Polyaniline in Aqueous Sulfuric Acid

In this work, we have shown through open circuit potential experiments that in aqueous sulfuric acid solutions, a thick polyaniline film undergoes autogenous oxidation when reduced below a threshold potential and autogenous reduction when oxidized above the threshold potential. This phenomenon is associated with the high resonance stability of polarons in long polyaniline chains present in thicker films. We have determined the rates of these reactions using a linear sweep chronopotentiometry technique. We propose that the oxidation reaction of polyaniline produces polarons with a concomitant reduction of hydrogen ions to hydrogen radicals, which further combine with each other to produce the hydrogen molecule in the absence of dissolved oxygen. On the other hand, at high potentials polarons are reduced with the concomitant oxidation of water to hydroxyl radicals. Both the radicals are stabilized due to the interaction of their unpaired electrons with pi-electrons of the aromatic rings of the polymer backbone. At the equilibrium value of the open circuit potential, both the hydrogen radicals and hydroxyl radicals are generated at equal rates and react with each other to form water.

КИНЕТИКА И МЕХАНИЗМ ПЕРЕГРУППИРОВКИ КУРЦИУСА м-НИТРОБЕНЗОИЛАЗИДА В ВОДНЫХ РАСТВОРАХ СЕРНОЙ КИСЛОТЫ

The kinetics and mechanism of the Curtius rearrangement of m-nitrobenzoyl azide in aqueous solutions of sulfuric acid of various concentrations has been studied. An increase of the acidity of the reaction solution an increase in the acidity of the reaction solution leads to an acceleration of the rearrangement. The rate-limiting step of the reaction is the rearrangement of the protonated form of m-nitrobenzoyl azide to the corresponding isocyanate

Cr(VI) adsorption by the polyanyline and zeolite/polyaniline–sulphuric acid composite

The adsorption properties of the samples of polyaniline (PAn) and zeolite/polyaniline (Zt/PAn) composite regard to Cr(VI) have been studied. The samples of the PAn and Zt/PAn composite were prepared in the 0.5 M sulfuric acid aqueous solution by oxidative polycondensation of aniline by ammonium peroxydisulfate respectively under the presence and absence of the zeolite powder in the reaction mixture. The molar ratio of aniline to ammonium peroxydisulfate during synthesis was 1 : 1.1, while the weight ratio of aniline to zeolite was equal to 1 : 1. The formation of PAn and Zt/PAn composite was confirmed by X-ray phase analysis, FT-IR spectroscopy, thermogravimetric studies and results of electrical conductivity measurements. Analysis of the spectral, thermal and electrical properties of the synthesized samples of Zt/PAn composites showed their essential differences in relation to individual samples of the zeolite and polyaniline. It was determined that the structure of polyaniline in the synthesized samples of PAn and Zt/PAn is amorphous with insignificant inclusions of polyaniline crystallites (in the form of emeraldine salt of sulfuric acid) deposited on polycrystalline zeolite particles as carrier-matrices. Thermogravimetric studies of PAn samples and Zt/PAn composites confirmed the composition of composites and the dependence of their thermal stability on the content of natural mineral. The defined values of the specific conductivity for the synthesized samples of zeolite/polyaniline composites confirmed the presence of sulfuric acid in the composites. It is determined the availability and high efficiency of the use of PAn and Zt/PAn composites, in which polyaniline is doped by sulfuric acid during synthesis, for Cr(VI) sorption from aqueous solutions. It was demonstrated that Cr(VI) adsorption by produced samples can be described sufficiently good by Langmuir or Freundlich adsorption isotherms, while the kinetics of process is in good agreement with the model of pseudo second order. Keywords : polyaniline, zeolite/polyaniline, properties, adsorption of Cr(VI).

Non-linear effects in osmotic membrane transport: evaluation of the S-entropy production by volume flux of aqueous ammonia and sulfuric acid solutions under concentration polarization conditions

Non-linear effects in osmotic membrane transport: evaluation of the S-entropy production by volume flux of aqueous ammonia and sulfuric acid solutions under concentration polarization conditions

Eutectic freeze crystallization for recovery of NiSO4 and CoSO4 hydrates from sulfate solutions

In this study, eutectic freeze crystallization (EFC) was investigated to recover NiSO4 and CoSO4 hydrates from aqueous and dilute sulfuric acid solutions of metal sulfates. Binary phase diagrams were established using a combination of thermodynamic modeling and experimental data. The mixed-solvent electrolyte (MSE) model was employed to model solid–liquid phase equilibria. The predicted binary phase diagrams from the model were in good agreement with the experimental results. Experimental eutectic temperatures and eutectic metal sulfate concentrations for the NiSO4-H2O and CoSO4-H2O systems are −3.3 °C and 20.8 wt% and −2.9 °C and 19.3 wt%, respectively. For NiSO4-H2SO4-H2O and CoSO4-H2SO4-H2O systems, the eutectic temperature and eutectic metal sulfate concentration decrease with increasing H2SO4 concentration. Batch experiments were performed to study the EFC of different sulfate solutions, including 25- wt% NiSO4 in H2O, 20- wt% NiSO4 in 0.5 mol/kg H2SO4, 25- wt% CoSO4 in H2O, and 20- wt% CoSO4 in 0.5 mol/kg H2SO4. The results show that controlling the supersaturation allows high-quality ice and salt crystals to be recovered as separate phases under eutectic conditions, with the crystalline salts in the form of heptahydrates. This study shows that EFC can be a promising alternative to evaporative crystallization for recovering NiSO4 and CoSO4 hydrates from sulfate solutions.

Toward real applicability of electro-ozonizers: Paying attention to the gas phase using actual commercial PEM electrolyzers technology

This work focuses on increasing the TRL of electro-ozonizer technology by evaluating the effect of electrolyte composition and operation conditions on the production of ozone, using an actual commercial cell, CONDIAPURE®, in conditions similar to what could be expected in a real application. Not only is attention paid to the changes in the concentration of ozone in the liquid phase, but also to those observed in the gas phase. The electrolyte and its recirculation flowrate, as well as operation temperatures and pressures are found to have significant influence on production rates. The most efficient way to produce ozone is operating at low temperatures and high pressures. In this work, 0.25 and 0.21 mg O3/min were obtained operating at 10 A in electrolytes consisting of aqueous solutions of perchloric and sulfuric acid, respectively, in tests carried out at 13 °C and 2 bars of gauge pressure. The negative effect of scavengers that appear electrochemically along the production of ozone is very important and seems to be partially compensated when organics are present in the solution due to the competition between the reaction of these scavengers with ozone or organics.

The use of sorption and excess sorption isotherm in the mathematical modeling of the unsteady-state heat and humidity regime of the building envelope

In the given article the development of the moisture transfer equation based on the theory of moisture potential is considered. The task of combined heat and moisture transfer is one of the most complicated tasks in the building thermal physics field. The classical equations of moisture transfer by K.F. Fokin representing the transfer of moisture under the action of partial transfer potentials - the gradient of the partial pressure of water vapor and the gradient of humidity F - are listed. The possibility of uniform accounting of the combined water vapor transfer on the basis of the moisture potential F is described. The sorption isotherm for aerated concrete is constructed in accordance with the experiment carried out in a desiccator with an aqueous solution of sulfuric acid. A new equation of moisture transfer which takes into account moistening with vaporous moisture in the sorption zone of moisture and liquid moisture in the excess sorption zone of moisture is derived. In order to simplify the work with the obtained equation a new value of the relative potential capacity is introduced. A graph construction of sorption and excess sorption isotherms which are obtained using an analytical expression for the relative potential capacity is proposed. In the sorption zone of humidification the sorption and excess sorption isotherms coincide with the classical sorption isotherm. Meanwhile, in the excess sorption zone of humidification the sorption and excess sorption isotherms depend on temperature.