Potassium Sulfate Solution Research Articles

The electrocatalytic reduction of nitrate to ammonia (NARR) using MOF-808 enhanced by the transition metal Fe (III) and H2PO4−/HPO42−

The combustion of fossil fuels has led to a surge in global CO2 emissions, causing environmental pollution and climate change issues that cannot be ignored. Ammonia, a green and carbon-free hydrogen energy, is emerging as a promising contender for new renewable fuels. Electrocatalytic nitrate-to-ammonia reduction reaction (NARR) is an emerging green synthesis method compared to the Haber-Bosch approach, and its performance is mainly controlled by selective hydrogenation. In this work, we report an efficient Fe@MOF-808-H2PO4−/HPO42− electrocatalyst (donated as Fe@MOF-808-P) for the electrocatalytic reduction of nitrate-to-ammonia. The results showed that the highest Faraday efficiency of NH3 (FENH3) is 90.8 ± 0.5 % at −0.9 V versus reversible hydrogen electrode (vs. RHE) in a 0.5 M potassium sulfate (K2SO4) solution containing nitrite (NO3−), the corresponding NH3 yield and specific activity are 420.4 ± 18.1 μmol h−1 cm−2 and 1035.9 ± 20.1 mgNH3 h−1 mgFe, respectively.Furthermore, a comparative analysis of the catalytic performance of Fe@MOF-808-H2O, MOF-808, MOF-808-P, and carbon cloth (CC) revealed that introducing P could accelerate the hydrogenation process of NO3− in the NARR process, confirming that Fe is the primary active center. Additionally, the cyclic electrolysis experiment demonstrated that the catalyst showed excellent stability. The results highlighted the promising potential of ammonia for future applications in renewable energy systems.

INVESTIGATION OF THE NA+, K+ || VO3–, SO42– TERNARY RECIPROCAL SYSTEM AND MEASUREMENT OF THE NONVARIANT COMPOSITIONS MELTING ENTHALPY

Functional compositions based on multicomponent systems of oxygen-containing salts of s1-elements are widely used in various fields of industry, science and technology: electrometallurgy of light, refractory and heavy metals, as well as metallothermy, pyrometallurgy, promising fluxes for welding and soldering metals, chemical power sources. In the work the triangulation of the Na+, K+ || VO3–, SO42– ternary reciprocal system of sulfates and metavanadates of sodium and potassium on simplices was carried out. The phase states of the Na+, K+ || VO3–, SO42– ternary reciprocal system was investigated by differential thermal analysis (DTA). T–x diagram of the stable secant K2SO4–NaVO3 was constructed, which is the diagonal of the system composition square and which has a eutectic with a melting point of the quasi-double eutectic of 575 °C and a specific melting enthalpy value of 206 kJ/kg. In the NaVO3–Na2SO4–K2SO stable triangle, a minimum of solid solutions with a temperature of 559 °C and an enthalpy of 190 kJ/kg was determined. In the NaVO3–KVO3–K2SO4 stable triangle, the three-component eutectic with a minimum melting point in the system of 474 °C has a minimum specific melting enthalpy of 183 kJ/kg. Compositions of the triple peritectic Р 482 °С and the three-component minimum of solid solutions M 559 °С were determined. The maximum crystallization fields of the system composition square correspond to potassium sulfate and continuous solid solutions of sodium and potassium sulfates. Low-melting mixtures of quasi-double eutectic, ternary eutectic, and ternary minimum can be used as molten electrolytes for medium-temperature chemical current sources and as heat storage materials. For citation: Istomova M.A., Garkushin I.K. Investigation of the Na+, K+ || VO3–, SO42– ternary reciprocal system and measurement of the nonvariant compositions melting enthalpy. ChemChemTech [Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol.]. 2024. V. 67. N 6. P. 38-44. DOI: 10.6060/ivkkt.20246706.6983.

Arterial Embolization: A Superior Treatment for Massive Urinary Tract Bleeding in Emergency Care

Objective: To analyze the effect of arterial embolism (AE) in patients with massive urinary system bleeding (MBUS). Methods: From September 2018 to September 2023, 175 cases of MBUS patients in the emergency department of the hospital were randomly selected and divided into groups according to the length of stay. Among them, 85 cases (September 2018 – September 2020) underwent bladder irrigation treatment with aluminum potassium sulfate solution through a catheter (Group A), and 90 cases (October 2020 – September 2023) underwent AE treatment (Group B). The treatment effects of the two groups were compared. Results: The treatment effectiveness of Group B is higher than that of Group A (P < 0.05). The urinary hemoglobin level of Group B is lower than that of Group A at 1, 6, 12, and 24 hours after treatment (P < 0.05). Among the 90 cases treated with AE, 7 cases had a fever, with body temperatures ranging from 37.3°C to 38.9℃, with a mean temperature of 38.2 ± 0.3℃. Four cases experienced local pain, nausea, and vomiting, while two cases of intra-iliac AE showed transient buttock pain. These patients with adverse reactions were treated symptomatically for 7 days. All patients recovered after treatment. Intravenous urography of 87 patients in June showed that the renal pelvis and calyces were in good condition, the renal function returned to normal, and the blood urea nitrogen and blood creatinine test results were within the normal range. After 1 year of follow-up, no hypertension occurred. Conclusion: AE treats MBUS patients in the emergency department with remarkable efficacy. It has the advantages of less damage to the body, rapid hemostasis, high safety, and maximum preservation of organ function.

Analysis of sulfate resistance of concrete with RCA after one year exposure to sulfate solutions

External sulfate attack is one of the durability problems associated with concrete. Despite a perception that concrete made with recycle concrete aggregate (RCA) is of inferior quality, research has shown that RCA has the potential to satisfy the mechanical and physical requirements for a range of applications. Limited works were performed on the durability aspects of the RCA. The objective of the research described in this paper was to evaluate resistance to sulfate attack of concrete with RCA in which two types of cement (CEM I and CEM III) and two water to cement ratios (0.38 and 0.55) were combined. For the evaluation of sulfate resistance of these concretes, immersed in sodium and potassium sulfate solutions, a drop of compressive strength, length change, capillary water absorption and thermal analysis (TGA-DTA) were used. Satisfactory sulfate resistance of concrete with RCA can be achieved by applying CEM III and reducing water to cement ratios.

DEVELOPMENT OF A METHOD FOR OBTAINING A THIN TIO2 FILM WITH THE PHOTOELECTRIC PROPERTIES BY THE ELECTROCHEMICAL METHOD

One of the most important sources of renewable energy worldwide is the use of solar energy, which is developing rapidly, and solar power plants are becoming part of the energy infrastructure of many countries. In this regard, titanium dioxide, which has photovoltaic properties, and is used in the conversion of solar energy into electrical energy, is widely used. Purpose is to develop a method for attaching nanostructured titanium dioxide, stable in aqueous solutions, to the surface of a metal titanium plate. Objects. The mechanism of titanium dioxide formation on the titanium surface has been studied by removing the potentiodynamic polarization curves of the anode-cathode cycle, and conducting electrolysis under the potentiostatic conditions. It is established that during anodic polarization, its oxides are formed on the surface of the titanium electrode in the solutions of sodium hydroxide (alkaline medium) and potassium sulfate (neutral medium). Results. The curves of the anode-cathode polarization of a titanium electrode in a solution of potassium sulfate with the concentration of 100 g/l have shown that an anode current appears in the region of the potentials +0.2 V. Conclusion. It has been shown that during anodic polarization of titanium in the solutions of sodium hydroxide and potassium sulfate, an oxide film forms on its surface. It is determined that the formation of a titanium dioxide film occurs at a very low rate under the conditions of transpassivation.

Studies of the kinetic and sorption characteristics of OFAM-K and OPMN-P membranes in the process of electron-nanofiltration separation of an aqueous solution of potassium sulfate

The paper presents an analysis of existing methods of membrane separation of solutions on semipermeable and ion-exchange membranes, where their advantages and disadvantages are noted. The objects of study were OFAM-K and OPMN-P nanofiltration membranes and aqueous solutions of potassium sulfate used in the production of mineral fertilizers. The change in the retention coefficient on the near-anode OFAM-K membrane for sulfate ions and on the near-cathode membrane OPMN-P for potassium ions was studied at current densities of 12,82 and 15,38 A/m2 with varying transmembrane pressure. An analysis of the retention coefficient of the OPMN-P cathode membrane for potassium ions with increasing pressure shows its increase by 20–30%, which is probably caused by an increase in the water permeability rate, which causes permeate dilution. In the case of analysis of the retention coefficient for sulfate ions on the anode OFAM-K membrane in the region of low current densities, the retention capacity first decreases with an increase in the transmembrane pressure, and then reaches a constant value with a slight increase at a pressure of 1,5 MPa. At higher current densities, the retention coefficient for sulfate ions on the anode OFAM-K membrane with an increase in transmembrane pressure, as well as on the OPMN-P cathode membrane, for potassium ions increases. The time dependences of the specific output flux are given at transmembrane pressures of 0,75, 1, and 1,5 MPa and current densities of 12,82 and 15,38 A/m2. It is noted that the specific output flux increases on the near-anode OFAM-K membrane, while on the near-cathode membrane OPMN-P it decreases with time, which is due to the transformation of the physical properties of the membranes and boundary layers formed on their working surface. On the near-anode OFAM-K membrane, water permeability increases with time, and on the near-cathode membrane OPMN-P it decreases. The presented data on the desorption of potassium ions and sulfate ions on the near-anode membrane OFAM-K and near-cathode membrane OPMN-P indicate that the desorption of ions decreases with time, and the desorption index of potassium ions on the near-anode OFAM-K membrane is higher, although in the process Electronanofiltration ions are transferred in equivalent ratios.

Influence of polymer and inorganic modifiers on the process of phase formation in potassium sulfate saturated solutions

The process of potassium sulfate crystallization from aqueous solutions in the presence of organic modifiers containing phosphonic, phosphate, sulfonic, sulfate and carboxyl functional groups has been studied. It is shown that the introduction of organic substances has an inhibitory effect on the formation of potassium sulfate crystals. Modifiers containing sulfonic, sulfate and phosphonic functional groups have the greatest inhibitory effect. The effectiveness of modifiers containing carboxyl groups is significantly lower. The formation of stable supersaturated solutions of potassium sulfate is achieved by introducing organic modifiers in an amount of 0.25 – 0.50%.

Elution profiles of metronidazole from calcium sulfate beads.

Antibiotic beads are used to treat local bacterial infections by delivering high drug concentrations to infected tissue. This study examined the elution characteristics of metronidazole from metronidazole-calcium sulfate (MCa) and metronidazole-calcium-potassium sulfate (MCaK) beads over 20 days and the antibacterial efficacy of the beads after storage. The MCa and MCaK beads were prepared by mixing 250 mg of metronidazole and 10 g of calcium sulfate hemihydrate with water and a 3% potassium sulfate solution, respectively. The beads were placed in phosphate-buffered saline for the elution study. The metronidazole eluents were determined using high-performance liquid chromatography. The microstructures were examined by scanning electron microscopy (SEM), and the antimicrobial activity was evaluated by a microbioassay. For the 20-day study, the total amount of metronidazole released was greater in the MCa beads than in the MCaK beads by 6.61 ± 0.48 mg (89.11% ± 3.04%) and 4.65 ± 0.36 mg (73.11% ± 4.38%), respectively. The amounts of eluted drugs from the MCa and MCaK beads were higher than the minimum inhibitory concentration at 0.5 µg/mL against anaerobic bacteria at both 20 days and 14 days. SEM showed that calcium crystals on the outer surface had dissolved after elution, and thinner calcium crystals were prominent in the MCaK beads. The MCa and MCaK beads exhibited antibacterial activity after setting, followed by storage at room temperature or 4°C for 21 days. The MCa beads could release more drug than the MCaK beads, but all eluted metronidazole amounts were effective in controlling bacterial infections. Both metronidazole beads could be stored at ambient temperature or in a refrigerator.

Comparison of a novel combination of bio-organic fertilizers vis-à-vis a chemical fertilizer

Plant nutrients are essential for the production of healthy crops for the world’s expanding population and thus, they are a vital component of sustainable agriculture. Increased crop production depends on the type of fertilizers used to supplement essential nutrients for plants. The nutrient level fertilizers provide depends on their nature- each type of fertilizer has its advantages and disadvantages concerning crop growth and soil fertility. The management of using fertilizer must aim to ensure both an enhanced and safeguarded environment. Thus, a balanced fertilization strategy must be implemented. An experiment was conducted under field conditions to assess the effects of combinations of bio-fertilizers on agronomic and quality criteria of Brassica juncea (brown mustard), Basella alba (climbing spinach), and Amaranthus dubius (red spinach). Randomized block design with three replicas were used for the study, one set with the application of fertilizers containing Azotobacter, Rhizobium, Sesbania, Bacillus subtilis, Bacillus cereus, Bacillus megaterium, Pseudomonas fluorescens and Glomus (Mycorrhizal inoculant)- under bio-fertilizer; another with a mixture of urea, Potassium Nitrate, Super Phosphate, Potassium Sulfate, and Maple EM solution as chemical fertilizer and a control (water). Results indicated that yield and other plant criteria like chlorophyll content and gel volume were enhanced in bio-fertilizer treated plants compared to the plants grown with chemical fertilizer and control. In general, the application of bio-fertilizer significantly increased leaf length by 16-50%, the total number of leaves by 50-80%, plant size 19.15-63.15%, and gel volume by 147% (approximately) in comparison with untreated plants.

Recognition of kinetic transient process in corrosion scales of fuel elements by impedance spectroscopy

The presented study concerns with the corrosion kinetics of two zirconium alloys: Zr-Nb-Sn-Fe and Zr-Nb-Fe. Alloy samples were pre-exposed at 360 °C in a LiOH solution containing 70 mg/l of lithium ions. Ex-situ electrochemical impedance spectroscopy (EIS) performed in 0.5 M potassium sulphate solution at 25 °C was used to study the properties of the oxide and kinetic transient effect. Evaluation of the impedance spectroscopy data was based on application of a simple equivalent circuit. The setup of the equivalent circuit conformed to Jonscher´s universal law of dielectric response. The analysis of the impedance data was aimed at estimation of non-dispersive capacitance of the oxide formed during the pre-exposure. Effective values of dielectric constant were calculated using the non-dispersive capacitance and the oxide thickness values, calculated from weight gains. For the pre-transient samples relatively higher values of dielectric constants were obtained. Typical pre-transient dielectric constants for Zr-Nb-Sn-Fe alloy ranged between 20–21, while slightly lower values were obtained for Zr-Nb-Fe alloy. In both alloys steep and significant decrease in effective dielectric constant (e_ef = 9–13) was found for the transient samples. The decrease correlated very well with the drop in percentage of tetragonal oxide determined by Raman spectroscopy and corresponded to the increase of the weight gains of the transient samples. Literature data indicate values of dielectric constants for tetragonal zirconium oxide between 38–46, while those for monoclinic oxide are usually presented between 12–22. The evidenced changes in dielectric constants are therefore in agreement with the expected decrease of tetragonal phase fraction in the oxide layer during the transient. In the Zr-Nb-Sn-Fe post-transient samples values of dielectric constant increased again to 18–20, therefore almost to the pre-transient level. This increase was not evidenced with Raman spectroscopy data, which show constant low content of the tetragonal fraction. Possible explanation of this disagreement is the location of the newly formed post-transient tetragonal oxide presumably at the metal/oxide interface. Oxide thickness of the post-transi-ent samples is 4–7 m and the oxide/metal interface is beyond access of the laser beam of Raman spectrometer. We can conclude that using ex-situ EIS, the transient was observable in both alloys; the change in the ratio of monoclinic and tetragonal phase can be evaluated based on the difference of effective dielectric constant of the two phases. The Zr-Nb-Sn-Fe alloy showed the onset of the transient after the 105th day of pre-exposure, but the change in the ratio of the monoclinic and tetragonal phases was less significant than in the Zr-Nb-Fe alloy, in which, however, the transient could be observed only after 147 days of pre-exposure. The resulting values of the effective dielectric constant of oxides correlated well with the percentage of tetragonal oxide determined by Raman spectroscopy and with the results of the weight gain method.

Dependence of productivity of white lupine seeds on the foliar dressing with macro- and micronutrient fertilizers

The paper presents the results of the studies on the determination of the effect of foliar dressings with macro- and micronutrient fertilizers on linear growth, the mass of air-dry matter of plants, leaf surface, the formation of a symbiotic apparatus and the yield of seeds of white lupine (Lupinualbus L.) in the conditions of black soils of the Central Black Earth region of the Russian Federation. The field experiments were carried out in 2018-2020 at the Department of Crop production, Breeding and Horticulture of Belgorod State Agrarian University. The object of the research is a high-intensity variety of white Degas lupine. The subject of the research is microfertilizer Aquamix-TV, potassium sulfate fertilizer (K2SO4), phosphate-potassium monophosphate fertilizer (KH2PO4). The weather during the years of the experiments was hot and dry. During the critical periods of the development of lupine plants, a moisture deficit was observed with the excess of heat. The soil cover of the experimental site was represented by a typical medium-thick low-humus heavy loamy black soil with a granulometric composition. The accounting area of the plot was 18 m2, the replication was fourfold and the placement was systematic. The experiment included six variants: control (without fertilizers), foliar dressing with Aquamix-TV micronutrient fertilizer, foliar dressing with potassium sulfate solution, foliar dressing with potassium monophosphate solution, foliar dressing with Aquamix-TV + potassium sulfate mixture and foliar dressing with Aquamix-TV + monophosphate mixture potassium. The analysis of the obtained data showed that the highest yield of seeds of white lupine variety Dega was obtained on variants with foliar dressing with micronutrient fertilizer Aquamix-TV in combination with potassium sulfate and monopotassium phosphate, which amounted to 3.52 and 3.51 t / ha, respectively, which is 0.52 and 0.51 t / ha or 17.3 and 17.1% more than the control variant.

Concentration-dependent structure of mixed (NH4)2SO4 and K2SO4 aqueous solutions using the X-ray diffraction, Raman spectroscopy and molecular dynamics simulations

In the production of potassium sulfate by ammonium sulfate, the purity of potassium sulfate product is relatively low due to the presence of potassium sulfate and ammonium sulfate solid solution. The microstructure of mixed aqueous solution of potassium sulfate and ammonium sulfate have been studied by X-ray diffraction, Raman spectroscopy and molecular dynamics simulation. And the molality of SO42− in the solution remained unchanged, and the molality of K+ and NH4+ were changed respectively. Reduced structure function [F(Q)], reduced pair distribution function [G(r)], excess Raman spectroscopy, radial distribution function (RDF), and structure of hydrogen bond network were obtained. With the decrease of K+ concentration and the increase of NH4+ concentration, a variety of new ion contact pairs were formed in the solution. The original hydrogen bond network is disrupted, and the cations would rebuild the hydrogen bond in the solution. When the NH4+ replaces the K+, the destruction to the hydrogen bond network is reduced. The addition of NH4+ might weaken the interaction between water molecules and anions, and exceed a certain critical concentration of 0.8 mol·L-1, NH4+ could promote the interaction between water molecules and anions. Moreover, the experimental results are in good agreement with the simulation results. This article provides certain theoretical guidance for its separation by studying the microstructure of its mixed solution.

Utilizing of sunflower ash in the wet conversion of phosphogypsum – a comparative study

Nowadays, there is a tendency to consider large-scale technogenic waste not as waste, but as man-made mineral deposits. For example, phosphogypsum is today considered a source of building materials, fertilizers, rare earth elements, etc. A similar problem is typical in the agricultural sector, whose waste is recycled inefficiently, especially in developing countries. Research in both directions is now on the rise, and the most relevant are those that involve the simultaneous disposal of two or more types of waste. This article critically compares the methods of wet conversion of phosphogypsum by ammonium, sodium, and potassium carbonates. Since the sunflower ash is a cheap source of potash (K2CO3 constituting up to 40% of biomass weight), simultaneous utilization of both agricultural and industrial waste could be achieved. It was found that the leaching of sunflower ash with tap water with preliminary aeration at temperatures below 30 °C provides a K2CO3 yield of about 200 kg/t. The resulting aqueous solution of potash can be processed into commercial salt or used directly for the conversion of phosphogypsum. As a result of such processing, a solution of potassium sulfate – a costly mineral fertilizer, as well as construction chalk, can be obtained. The most valuable elements of phosphogypsum are concentrated in that chalk – strontium and rare earth elements; their isolation into individual compounds can be carried out using appropriate techniques. The method of phosphogypsum conversion by potash solution obtained from water leaching of sunflower ash provides the maximum economic effect – 2300 USD per 1 t of phosphogypsum.

Electrochemical and kinetic characteristics of electromembrane separation of potassium sulfate solution

Electrochemical and kinetic characteristics of electromembrane separation of potassium sulfate solution

Peculiarities of Low-Temperature Behavior of Liquids Confined in Nanostructured Silicon-Based Material.

This study is devoted to the confinement effects on freezing and melting in electrochemical systems containing nanomaterial electrodes and liquid electrolytes. The melting of nanoparticles formed upon freezing of liquids confined in pores of disordered nanostructured n-type silicon has been studied by low-temperature differential scanning calorimetry. Experimental results obtained for deionized water, an aqueous solution of potassium sulfate, and n-decane are presented. A model is proposed for predicting the melting point of nanoparticles formed during freezing of liquids inside the pores of a disordered nanostructured material. The model is based on the classical thermodynamic concept of the phase transition temperature dependence on the particle size. It takes into account the issues arising when a liquid is dispersed in a matrix of another material: the effect of mechanical stress resulted from the difference in the thermal linear expansion coefficients at a temperature gradient, the effect of the volumetric liquid content in the matrix, the presence of a nonfreezing liquid layer inside the pores, and the effect of wettability of the matrix with the liquid. Model calculations for water and n-decane confined in nanostructured silicon matrix have been carried out considering the volumetric liquid content. The results obtained have been compared with the differential scanning calorimetry data.

Применение атомно-абсорбционной спектроскопии для анализа химического состава Brassica rapa

This paper presents the study of the chemical composition of Petrovskaya variety of turnip after the non-root treatment of vegetating plants with the solution of trivalent chromium. The treatment has been performed with the solutions of chromic potassium sulphate with chromium concentrations of 0.002% and 0.005%. The experiment has been conducted according to the following scheme: 1. NPK (background) – control version; 2. NPK + HO Cr 0.002%; 3. NPK + HO Cr 0.005%. Nitroammophoska was used as the background macro fertiliser during the sowing at the rate of 30 g/m2. In the control versions plants have been treated with the distilled water. The content of chromium in root vegetables has been assessed using the method of atomic absorption spectroscopy. It is shown that after the treatment with the solution of chromic potassium sulphate the average content of chromium in root vegetables increased by 31.3% in NPK + Cr 0.002% version and by 55.6% in NPK + Cr 0.005% version in comparison with the control version. At the chromium concentration of 0.002% the content of dry matter in turnip remained at the level of control version, the content of dry soluble matters and ascorbic acid decreased down to 5.9% and 28.60 mg/100 g, the level of nitrates in root vegetables increased up to 286.0 mg/kg of wet mass. At the chromium concentration of 0.005% the content of dry matter in turnip decreased down to 10.4%, the content of dry soluble matters increased up to 7.3%, the content of ascorbic acid and nitrates decreased down to 27.81 mg/100 g and 210.2 mg/kg of wet mass, respectively.

Biocidal Activity of Selected Preparations for Leather Protection

This research work involved the selection of biocides for the antimicrobial treatment of leathers. The scope of the research work covered microbiological tests of leather samples tanned utilising the same technology, with microbiological treatment made using 9 different preparations, as well as a test of leather without biostabilisation. Commercial biocides taken for inwestigation were as follows: NS 500 – an aqueous solution of nanosilver 500 ppm, ODH – tea tree oil, and OP – orange oil. Preparations prepared by diluting the purchased products were as follows: S27-22 – an aqueous solution containing silver chloride and titanium dioxide, SH 22-27 – an aqueous solution containing zinc pyrithione, ST 99-19 – an aqueous solution containing dimethyltetradecyl [3-(trimethoxysilyl)propyl]ammonium chloride, SU – an aqueous solution containing polyhexamethylene biguanide, and SGP – a saturated solution of aluminum potassium sulfate. Also a preparation was made by combining NS 500 M250 – 500 ppm nanosilver solution and a 250 ppm copper colloid. Evaluation of the effectiveness of biostabilisation of the leather samples and antimicrobial activity of the preparations used was carried out. Staphylococcus aureus and Escherichia coli bacteria and Candida albicans, Aspergillus brasiliensis and Trichophyton mentagrophytes fungi were used in the study. The assessment of microbial growth on samples was carried out according to Polish standards. Assessment of the resistance to bacteria and C. albicans yeast was made according to the PN-EN ISO 20645: 2006 standard – a method of diffusion on an agar plate. Assessment of the resistance to A. brasiliensis and T. mentagrophytes fungi was made according to the PN-EN ISO 14119: 2005 standard. Among the tested preparations to protect leathers against the effects of microorganisms, overall efficacy was obtained for SH 22-27, NS 500 M 250, SU and ODH.

Iron and sulphur management options during Ni recovery from (bio)leaching of pyrrhotite tailings Part 2: Strategies for sulphur fixation during biomass-induced magnetization of goethite and jarosite

In the context of recovering Ni from pyrrhotite tailings though a (bio)leaching process, Part 1 of this investigation explored a strategy to concentrate iron from the residual jarosite-goethite assemblage using controlled release of reducing gases from biomass to promote transformation at temperatures below 500 °C to an inverse spinel phase amenable to magnetic separation. While most of the remaining sulphur is associated with K in the form of arcanite (K2SO4), a water-soluble potassium sulfate that can easily be removed through rinsing, the present study focuses on implementing a complementary fixation strategy to minimize the significant loss of sulphur to the gas phase and to access the residual amount trapped in magnetic spinel to obtain a cleaner more valuable iron product. Through the use of potassium additives (K2CO3, KOH) during biomass-induced magnetization experiments, more than 90% of the original sulphur could be stabilized in the form of arcanite. Moreover, after a further thermal oxidation treatment of the rinsed magnetite product in the presence of KOH, the residual sulphur content could be lowered from 1.8 down to 0.08 wt%. Although the major advantage of fixing the sulphur in the form of a readily-extractable arcanite phase is to easily purify the magnetite product, subsequent exchange of the potassium sulfate solution with calcium chloride to promote the precipitation of high-purity gyspum (CaSO4·2H2O) represents a viable option to contain sulphur in a highly stable form, which can also represent a by-product suitable for use in the construction industry. On the other hand, the potassium remaining in solution in the chloride form can be precipitated as sylvite (KCl) for use as fertilizer.

Increase in the intensity of life and yield of green crops due to plant growth and the development of regulatory chemicals

Yearly agriculture longs to increase the yield of green crops with the help of different agrochemical methods such as application of organic and mineral fertilizers, creation of optimum moisture and temperature mode, dressing with growth-regulating chemicals and etc. In our work it is shown that under the influence of foliar treatment with zircon solution in the concentration of 0.001 mg/l and 1% of potassium sulfate solution the processes of photosynthesis and respiration are stimulated, plant water exchange is stabilized, which leads to growth and yield increase of cultures. The highest stimulating effect is due to simultaneous spraying by zircon and potassium sulfate, herewith the effect of these regulators is summarized, i.e. additive character of their interreacting is demonstrated. Foliar treatment with potassium sulfate compensate the lack of these elements in soil, which are necessary for many physiological processes of plants, in particular, for the synthesis of protein, vitamins, sugar, the regulation of water evaporation and etc. The study was carried out on the green crops of families Solanaceae (on the example of Solanum lycopersicum and Capsicum annuum) and Fabaceae (on the example of Pisum sativum) are indicative of these facts.

Solubility analysis of homologous series of amino acids and solvation energetics in aqueous potassium sulfate solution

In this study we estimated the solubilities of glycine, D,L-alanine, D,L-nor-valine and D,L-serine in aqueous mixtures of potassium sulfate (K2SO4) at 298.15 K using analytical ‘gravimetric method’. The experimental solubilities of homologous series of amino acids in aqueous K2SO4 mixture were discussed in terms of relative solubility, salting-in and salting-out effect by evaluating the influential constants. The effect of physicochemical and chemical factors on solubility were discussed briefly and correlated with the thermodynamics. Initially, the study of solvation energetics such as transfer Gibbs energies were evaluated based on the calculations from solubility data and relative stability of the experimental molecules was discussed under the experimental condition.