Sodium Sulfide Research Articles

Bicyclic isothioureas for conjugation with tubulin targeted anticancer agents

Two bicyclic annulated isothiourea derivatives were synthesized using as a key stage either the reaction of isothiocyanate halide with sodium sulfide or cyclization of unsaturated thiourea in the presence of bromine. X-ray molecular structure of N-[(3aSR,7aRS,Z)-hexahydro-1,3-benzothiazol-2(3H)-ylidene]glycine was determined. The conjugate of colchicine with [(3aR,5S,6aS)-2-(tert-butylamino)-3a,5,6,6a-tetrahydro-4H-cyclopenta[d]thiazol-5-yl]methanol obtained demonstrated pronounced cytotoxic effect on cancer cells.

Life cycle assessment for waste acid treatment in zinc smelting

Lift cycle assessment (LCA) methodology was applied to evaluating and comparing two waste acid disposal processes in zinc smelting. The results indicate that environmental impacts of gas—liquid vulcanization technologies are human toxicity, abiotic depletion potential, and global warming risk, which are mainly caused in neutralizing— evaporating—crystallization unit and electrodialysis unit. As for traditional lime neutralization method, vulcanization unit is the main factor. In this regard, the total environmental impact of traditional lime neutralization method is much higher than that of gas—liquid vulcanization technologies. Furthermore, the sensitive analysis shows that electricity and sodium sulfide (60%) are sensitive factors in two waste acid disposal technologies. In addition, the total cost of disposing a functional unit waste acid in traditional lime neutralization process is nearly 27 times that of the gas—liquid vulcanization waste acid disposal technologies.

Distinct Pharmacological Profiles of Monosulfide and Trisulfide in an Experimental Model of Intracerebral Hemorrhage in Mice

Hydrogen sulfide and polysulfides are increasingly recognized as bioactive signaling molecules to produce various actions and regulate (patho)physiological processes. Here we examined the effects of sodium sulfide (Na2S) and sodium trisulfide (Na2S3) on an experimental model of intracerebral hemorrhage (ICH) in mice. Na2S or Na2S3 (25 µmol/kg, intraperitoneally (i.p.)) was administered 30 min before ICH induction by intrastriatal injection of collagenase. We found that Na2S significantly ameliorated sensorimotor functions of mice after ICH. Histopathological examinations revealed that Na2S inhibited neuron loss in the striatum, prevented axon degeneration in the internal capsule, and ameliorated axonal transport dysfunction in the striatum and the cerebral cortex where the edge of hematoma was located. Although Na2S did not suppress accumulation of activated microglia/macrophages in the peri-hematoma region, it suppressed ICH-induced upregulation of inflammatory mediators such as C-X-C motif ligand 2. On the other hand, Na2S3 did not ameliorate ICH-induced sensorimotor dysfunction. Although the effect of Na2S3 on several parameters such as axon degeneration and axonal transport dysfunction was comparable to that of Na2S, Na2S3 did not significantly inhibit neuron loss and upregulation of inflammatory mediators. These results suggest that the regulation of multiple pathological events is involved in the effect of Na2S leading to amelioration of neurological symptoms associated with ICH.

Recovery of Spent Liming Liquor Case study: Afrotan Tannery, Sudan

Spent liming liquor is produced from unhairing and liming processes. This study was carried out in Afrotan Tannery, by using the existing liming recovery unit in the tannery. The aim of the study is to determine and to evaluate the efficiency of the method of treatment applied in liming liquor recovery unit. The results showed that the value of pH was 12 and the values of TSS, Cl, NH4 and COD in liming liquor before treatment were 10623, 8511, 498 and 37396 mg/l, respectively. The value of pH is 11.5 and the values of TSS, Cl, NH4, COD and sulphide in liming liquor after treatment were 4321, 7796, 407, 21985 and1602mg/l, respectively. The liming liquor recovery unit receives 300 m3/day of spent liming liquor. 140 m3/day of the quantity is floated and precipitated as sludge. 60 m3/day of this sludge does not enter sludge treatment unit and directly is filled in land contaminating the soil with sulphide. 160 m3/day of the quantity is the treated spent liming liquor which is mixed with fresh makeup basic sodium sulfide and ammonium sulphate and recycled in unhairing and liming processes. The study concludes that it is important to conduct further studies to decrease COD in clear liming liquor and to send all sludge to sludge treatment unit.

Enhancement of dark fermentative hydrogen production in nitrogen-deprived halotolerant unicellular cyanobacterium Aphanothece halophytica by treatment with reducing agents

To enhance H2 production by the halotolerant unicellular cyanobacterium Aphanothece halophytica, effect of various kinds of reducing sugar and reducing agent on H2 production was investigated. The highest H2 production rate of 55.80 ± 0.50 μmol H2 g dry weight−1 h−1 was obtained when the cells were incubated in BG110 medium containing 0.189 mmol C-atom L−1 glucose under dark anaerobic condition. This rate was 1.5 folds higher than that without glucose. Among ten reducing agents tested, β-mercaptoethanol, dithiothreitol, l-cysteine and sodium sulfide had high potential as an effective reducing agent to increase H2 production by A. halophytica. Cells treated with 50 mM sodium sulfide showed the highest H2 accumulation with 4815.59 ± 194.78 μmol H2 g dry weight−1 after 24 h of dark anaerobic incubation. An increase in H2 production was ascribed to an increase of hydrogenase activity and a decrease of O2 production rate. This H2 production yield was approximately 20 folds higher than that without reducing agent. Furthermore, 50 mM sodium sulfide appeared to be non-toxic to A. halophytica cells, since the IC50 of sodium sulfide was higher than 100 mM. The reduced ferredoxin at 1.5 μM-1.5 mM, NADH and NADPH at 0.15–1.5 mM could support in vitro [NiFe]-H2ase activity, demonstrating the ability of these compounds to provide electrons towards [NiFe]-H2ase in A. halophytica.

Statistical Study of Extract Keratin Protein from Waste Chicken Feather Based on Response Surface Methodology

The feathers contain a significant amount of keratin protein, which is used in cosmetics, shampoos, hair treatment creams, and skin creams. Dissolving chicken feathers with reducing agent and then separating the protein from chemicals are the key steps involved. However, in order to enhance the amount of recovered keratin as much as possible, the best conditions for extracting keratin from chicken feathers are required. In this study, Response Surface Methodology (RSM) was used in order to simulate and optimize the operating parameters for extracting keratin from waste chicken feathers in order to increase the amount of keratin protein compared to previous studies. Dissolving chicken feathers using sodium sulphide as a reducing agent at various periods, temperatures, and concentrations is the first step in the fundamental technique. After the feathers have been dissolved with a reducing agent, the fluid is treated with an ammonium sulfate solution to precipitate the protein. As determined by a biuret test and UV-Vis analysis, the keratin protein had a maximum wavelength of 290 nm. Finally, the statistical optimization of the extraction conditions provided a better understanding of the reaction parameters. The optimum yield of keratin was achieved at 3.7 hours at 30.07°C with 0.05 M sodium sulfide.

Influence of hydrated Ca<sup>2+</sup> and Mg<sup>2+</sup> complexes on the sulfidization of smithsonite: Density functional based tight binding (DFTB+) study

Ca<sup>2+</sup> and Mg<sup>2+</sup> are the most dominating unavoidable ions in the smithsonite flotation. In this paper, the effect of Ca<sup>2+</sup> (Mg<sup>2+</sup>) on the surface of smithsonite sulfidization in a system where water molecules are present was investigated using density functional based tight binding (DFTB+) simulations for the first time. The results indicated that the adsorption of hydrated Ca<sup>2+</sup> complexes is stronger than that of hydrated Mg<sup>2+</sup> complexes on the hydrated smithsonite (101) surface. In addition, at low concentrations of sodium sulfide, there is no adsorption of HS- on the surface pre-adsorbed with hydrated Ca<sup>2+</sup> complexes, but only on the surface pre-adsorbed with hydrated Mg<sup>2+</sup> complexes. At high concentrations of Na<sub>2</sub>S, S<sup>2-</sup> weakens the adsorption of hydrated Ca<sup>2+</sup> complexes due to competitive adsorption, but the presence of S<sup>2-</sup> could desorb hydrated Mg<sup>2+</sup> complexes from the surface. The results compared the differences in effects of Ca<sup>2+</sup> and Mg<sup>2+</sup> on smithsonite sulfidization, which could provide an atomic scale basis for researching the surface sulfidization of oxide minerals.

Surface modification of malachite with tetraamminecopper (II) and its effect on sulfidation flotation

In view of the strong hydrophilicity of malachite, the sulfidation performance of conventional sulphidizing reagent sodium sulfide on malachite is not satisfactory. In this work, we discussed the effect of tetraamminecopper (II) complex pretreatment on the sulfidation and flotation behavior of malachite. The performance was evaluated by micro-flotation experiments. The flotation results showed that a better flotation recovery can be obtained with a molar concentration of tetraamminecopper (II) sulfate of only one-twentieth of the conventional activator (NH4)2SO4, all else being equal. Scanning Electron Microscope with Energy Dispersive Spectrometer (SEM-EDS) shows that the weight percentage of S and Cu on the surface of the sulfidized malachite increased significantly in the present of [Cu(NH3)4]2+. The FTIR and Raman results showed that sulfur ions could be chemisorbed on the surface of malachite and form a layer of copper-sulfide species. X-ray photoelectron spectroscopy (XPS) further confirmed the actual existence of the sulfide layer, which consists of monosulfide (S2−), disulfide(S22−) and polysulfide (Sn2−). The presence of the activator [Cu(NH3)4]2+ can significantly increase the formation of disulfide and polysulfide on the surface of malachite, thereby promoting the subsequent interfacial adsorption of xanthate.

Characterization of soils around a former chemical plant in Braila, SE Romania, using high performance atomic techniques (EDXRF, AAS, ICP-MS)

This paper presents the problem of soil pollution in the vicinity of a former chemical plant, given that production activity was stopped for more than thirty years ago. The old chemical plant was located in the southern part of Braila town, SE Romania, just a few kilometers from the left bank of the Danube River. Prior to 1990, there was a significant production of industrial chemical goods, such as sulfuric acid, carbon dioxide for synthetic fibers, chlorine gas and hydrochloric acid obtained by electrolysis processes with mercury electrodes and heavy metal catalysts (Cd, Ni, Zn), sodium sulfide and sulphate, etc. For the good development of the experimental program, a number of 10 soil samples were collected from the north, northwest, west, southwest and south of the former chemical plant. The multi-element analysis method used to determine the trace elements in the soil samples was energy-dispersive X-ray fluorescence spectrometry (EDXRF), using a Genius XRF portable spectrometer manufactured by Skyray Instruments Inc., equipped with a large surface Si with a Be window and a 40 kV/100 µA miniature X-ray tube excitation source with Ag target. The spectrometric system has an energy resolution up to 139 eV, and the detection limits of the order of ppm. A total of 21 chemical elements were identified in the target soil samples, such as: K, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, As, Hg, Rb, Sr, Y, Zr, Nb, Mo, Sn, Sb, Pb. The compositional analyses of contaminated industrial soils were completed by using the AAS and ICP-MS high performance and selectivity techniques.

L-Cys-Assisted Conversion of H2/CO2 to Biochemicals Using Clostridium ljungdahlii.

Carbon fixation and conversion based on Clostridium ljungdahlii have great potential for the sustainable production of biochemicals (i.e., 2,3-butanediol, acetic acid, and ethanol). Here, the effects of reducing agents on the production of biochemicals from H2/CO2 using C. ljungdahlii were studied. It was found that the element S and reducing power could significantly affect the production of biochemicals, and cysteine (Cys) was better than sodium sulfide for the production of biochemicals, especially for the production of 2,3-butanediol. Moreover, comparing to the control (i.e., without the addition of Cys), the gene expression profiles indicated that the fdh and adhE1 were significantly upregulated with the addition of Cys, which involved in pathways of the CO2 fixation and ethanol production. Therefore, the irreplaceability of Cys on the production of biochemicals was both caused by its utilization as a reducing agent and its effect on the metabolic pathway. Finally, compared to the control, the production of 2,3-butanediol was increased by 2.17 times under the addition of 1.7 g/L Cys.

Localized Environment Enriched with Hydrogen Sulfide for Inducing Sulfide Stress Cracking on Type-430 Stainless Steel

Exposure tests to hydrogen sulfide environments are frequently used to evaluate hydrogen sulfide stress corrosion cracking (SSC) in steel. However, there are many safety restrictions in handling hydrogen sulfide, and the maintenance of the facilities is very costly. To improve this situation, an electrochemical measurement method that can be used even in laboratories to simulate hydrogen sulfide stress corrosion tests easily. Specifically, a safe hydrogen sulfide corrosion test method was developed using a local hydrogen sulfide concentration environment near the steel surface.A local acidic environment of pH 3-4 was induced by constant potential anodic polarization of a platinum electrode below 2 VSHE in an aqueous sodium sulfide solution. Exposure of the carbon steel surface to a local acidic environment resulted in the formation of iron sulfides such as FeS and FeS2 on the surface, accompanied by a negative shift of the carbon steel electrode potential and an increase in the microelectrode current. Local acidification of a potentiostatically polarized type-430 steel surface confirmed the existence of a critical potential at which the steel surface begins to depassivate and actively dissolve. It was suggested that the substitution of iron oxide for iron sulfide in a hydrogen sulfide environment determines the sulfidation of the steel surface. Using this method, furthermore, the formation of cracks was successfully induced on the surface of type-430 steel under tensile stress loading.

Evolution of conformation and thermal properties of bovine hides collagen in the sodium sulphide solution

Conformations of secondary and super secondary structure from bovine hides collagen are very important for constructing collagen molecular space structure, and directly related to its properties. In this work, the evolutional mechanism of the collagen conformation in the environment of sodium sulphide (Na2S) solution is periodically studied by FT-IR spectroscopy, the Gaussian peak fitting of secondary derivative, and auxiliary methods such as SDS-PAGE, SEM and TG. As a result, the three polypeptide chains structure of bovine hide collagen was hardly affected by the ions of OH−, HS− and S2−. The conformation of collagen molecules such as β-turn, triple helix and β-strand were gradually evolved into unordered structure and α-helix with the sequential addition of OH−, HS− and S2−, which is because the hydrogen bond inside collagen molecular is extended or opened with the increase of the synergistic effect of pH and reducibility of HS− and S2− in the solution. The bound water content and thermal properties of the treated collagen molecules are decreased. Finally, the order of the hydrolysis ability to collagen is NaOH < NaHS < Na2S at the same condition, which was confirmed by measuring the content of hydroxyproline from their solutions after treating the collagen. This work provides very important information for understanding the evolutional mechanism of bovine hide collagen conformation in the Na2S solution, developing the alternatives of sulfide, extraction of collagen, tanning, and application of collagen in biological and material science.

Effect of Ammonium Sulfide on Sulfidization Flotation of Malachite

Recently, several studies have shown the positive effect of sulfidization flotation on malachite surfaces and its enhancing methods. Therefore, this paper was focused on the effect of ammonium sulfide and sodium sulfide on the sulfidization of malachite, respectively; this was investigated using different devices such as the micro-flotation tests, Zeta potential measurements, ToF–SIMS, XPS analysis, and FTIR. Thus, Fourier transform infrared spectroscopy results demonstrated that a new characteristic peak of Cu-S bonds was formed and adsorbed on malachite surfaces at 1694 cm−1, as confirmed by XPS analysis. Notably, malachite with ammonium sulfide ions had a significantly higher flotation recovery than malachite with an excess of sodium sulfide ions, as concerns of sulfidization types. Conclusively, all the experiments in this study confirmed that additional copper sulfide products were formed on the malachite surface, increasing the hydrophobicity of the malachite.

Electrochemically Controllable Synthesis of Low-Valence Titanium Sulfides for Advanced Sodium Ion Batteries with Ultralong Cycle Life in a Wide Potential Window.

Low-valence titanium sulfides (LVTS) have metal-like electrical conductivities and a strong polysulfide binding abilities, which are promising anodes for sodium ion batteries with high capacities and long cycle lifes. However, it is difficult for traditional synthesis methods to synthesize LVTS without impurities. The electric field regulation method possesses the advantages of flexibility and high efficiency, achieving accurate control of the metal reduction process by adjusting the electrolysis potential and reaction time. In this work, we synthesized a series of LVTS (TiS and Ti2S) using electric field control methods and investigated their electrochemical behaviors as sodium storage anodes for the first time. Compared with traditional TiS2, LVTS display remarkable Na storage properties under the condition of complete electrochemical conversion at 0.005-3 V. Especially for TiS, it demonstrates a high capacity of 409 mAh g-1 at 1 A g-1 and inspiring cyclic stability over 6000 cycles. The large number of vacancies in the crystal structure can chemically anchor polysulfides and alleviate their dissolution in the electrolyte, resulting in superior long-term cyclic stability. The high intrinsic conductivity of LVTS is in favor of rapid transfer of electrons and promotes the fast conversion of polysulfides to sodium sulfides, thus realizing high reversible capacities. Moreover, with its fast Na+ transport kinetics, the as-prepared TiS demonstrates an impressive rate performance of 321 mAh g-1 at 15 A g-1. Overall, the electric field regulation method is flexible and efficient, which provides a new route for the preparation of high-performance electrode materials. Moreover, nonstoichiometric metal compounds possess abundant active sites and rapid electron transport kinetics, which provide a new choice for promising sodium storage materials in large-scale energy storage applications.

Preparation of Sheepskin Unhairing Extracts from Locally Available Plants: Cleaner Leather Processing

Leather is made from animal hides and skins that have passed through several stages of processing, from soaking to finishing. Unhairing is a crucial processing stage in which hair is removed from the animal hide or skin through open up the hair and it facilitates subsequent operations. The conventional sodium sulfide-based unhairing process generates a high volume of effluent, which accounts for 50 to 70% of the total biochemical oxygen demand (BOD) and chemical oxygen demand (COD) load in the tanneries’ effluent. This study aimed to investigate the potential of unhairing agents prepared from locally available plants. The research employed qualitative methods. Plant materials are collected, dried, and ground. In different proportions, unhairing extracts were obtained from Phytolacca dodecandra leaves, Cucurbita foetidissima fruits, and Solanum incanum fruits. In the conventional soaking process, plant extracts were applied in various concentrations to sheepskin. The physical parameters of conventionally processed (control) and experimentally treated leather were examined using FTIR, SEM, tear strength, percentage of elongation, and organoleptic tests. The unhairing solution was prepared from a mixture of 0.5% S. incanum extract, 0.5% P. dodecandra extract, 0.6% C. foetidissima extract, and 260 g/L lime powder lime, and this solution effectively removed the hair from the sheepskin in both hairs saving and hair burning unhairing process. The study revealed that the sheepskin treated with the plant extracts based on an unhairing agent and the conventional unhairing agent showed a comparable tensile strength (42.3 kg/cm and 45.2 kg/cm), tear strength (140.1 kg/cm2 and 143.5 kg/cm2), and percent elongation at break (40.2 and 42.3), respectively, which were above the permissible limit for leather production making. According to the study findings, the plant extracts have a good potential for removing hair from sheepskin, and they are eco-friendly and cost-effective compared to unhairing chemicals such as sodium sulfide.

Identification of Hair Growth Promoting Components in the Kernels of Prunus mira Koehne and Their Mechanism of Action.

The application of the seed oil of Prunus mira Koehne (Tibetan name ཁམབུ།), a plant belonging to the Rosaceae family, for the treatment of alopecia has been recorded in Jingzhu Materia Medica (ཤེལ་གོང་ཤེལ་ཕྲེང་།) (the classic of Tibetan medicine) and Dictionary of Chinese Ethnic Medicine. This study aims to reveal the effective components and mechanism of hair growth promotion in the kernel of Prunus mira Koehne. Network pharmacology was used to predict the mechanism of action and effective components in the treatment of the kernel of Prunus mira Koehne. The contents of amygdalin in 12 batches of the kernel of Prunus mira Koehne were determined by HPLC. An animal model of the depilation of KM mice induced by sodium sulfide was created, and five effective components that promoted hair growth were initially screened. In the study of the effectiveness and mechanism of action, KM and C57BL/6 mice are selected as experimental objects, three screening tests for active components of the kernel of P. mira are performed, and three effective components are screened out from the eight components. HE staining was used to detect the number of hair follicles and the thickness of the dermis. RT-PCR and immunohistochemistry were used to evaluate the influence of the expression of indicators in the Wnt/β-catenin signaling pathway in skin, including β-catenin, GSK-3β, and mRNA and protein expression levels of Cyclin D 1 and LEF 1. The network pharmacology study showed 12 signaling pathways involving 25 targets in the treatment of alopecia by the kernel of Prunus mira Koehne. vitamin E (3.125 mg/cm2/d), β-sitosterol (0.061 mg/cm2/d), and linoleic acid (0.156 mg/cm2/d) in the kernel of Prunus mira Koehne can promote hair growth in mice, and the mechanism of action may be related to the Wnt/β-catenin pathway.

Using reagents in the form of inverse microemulsion for lead and zinc sulfide flotation

The paper presents the results of studies on the use of collecting agents in the form of an inverse microemulsion (IМE) of the «water in oil» type (i.e. suspended water droplets are in the oil phase) for the flotation extraction of lead and zinc minerals. Lead and zinc concentrates, lead-zinc ore were used as initial samples for flotation. The content of galena in the lead concentrate was 74.7 %, and the content of sphalerite in zinc was 78.7 %. Basic collecting agents in the IМE composition were potassium butyl xanthate (PBX) and kerosene. A nonionic surfactant (NSA) was used for IМE stabilization. Casein was used as additives to main reagents to remove the negative effect of osmotic pressure during the IМE preparation. Casein was transformed into the active soluble form using sodium sulfide. The particle size in the inverse microemulsion was 12.38 nm. In flotation tests, the following options for feeding reagents to the flotation pulp were studied: IМE, IМE + frother, potassium butyl xanthate + frother. The T-92 reagent was used as a frother. PBX consumption as part of IME and in the traditional feeding was 26 g/ton. The results of laboratory tests showed that the method of feeding flotation reagents in the form of IМE leads to both an increase in the flotation rate of lead and zinc sulfides and an increase in their recovery into a foam product. In addition to the increased flotation speed, tests with the use of IМE in the bulk lead-zinc ore flotation cycle showed an increase in extraction into the ultimate concentrate by 10.8 % for lead, by 38.5 % for zinc, in comparison with the traditional feeding of reagents (collector + frother). An increased selectivity of the IМE effect in relation to zinc sulfides, in comparison with lead sulfides, was noted. The flotation rate coefficient of sphalerite is 7.8 times greater than that of galena. An increase in extraction into the ultimate zinc concentrate is also higher and amounted to 16.78 %, while for the lead concentrate it is 1.9 % under the same conditions.

H2S releasing sodium sulfide protects against pulmonary hypertension by improving vascular responses in monocrotaline-induced pulmonary hypertension

Pulmonary arterial hypertension is caused by complex structural and functional changes in the endothelial and smooth muscle cells of pulmonary arteries. Hydrogen sulfide (H2S), a gasotransmitter, can potentially treat pulmonary hypertension by relaxing the pulmonary arteries and decreasing bronchial pressure. Although the role of H2S in systemic circulation has been examined, the H2S levels in pulmonary arteries, the role of H2S in endothelium-dependent vasorelaxation and the L-cysteine/H2S pathway in monocrotaline-induced pulmonary arterial hypertension have not been investigated. The rats were divided into control, monocrotaline, monocrotaline + Na2S, and Na2S groups. The right ventricular pressure and hypertrophy were evaluated. KCl, acetylcholine, and L-cysteine responses were obtained in the main pulmonary arteries by wire myograph. H2S levels were measured in pulmonary arteries and lungs by methylene blue assay. Right ventricular pressure and hypertrophy were increased by monocrotaline and ameliorated by Na2S. The KCl-induced contractions and relaxing responses to acetylcholine and L-cysteine in pulmonary arteries and H2S production in the lungs and pulmonary arteries were significantly attenuated in the monocrotaline group and augmented in the monocrotaline + Na2S group. These findings suggest that H2S levels were reduced, and L-cysteine-induced and endothelium-dependent relaxations were impaired in the pulmonary arteries in monocrotaline-induced pulmonary arterial hypertension. The H2S donor, Na2S, prevented endothelial dysfunction and increased pulmonary artery pressure and hypertrophy. Also, Na2S enhanced the L-cysteine-mediated responses and restored the diminished H2S levels in pulmonary arteries and the lungs. The treatments targeting H2S might be beneficial for promoting vascular alterations, i.e. endothelial dysfunction and impaired H2S-mediated relaxation in pulmonary arterial hypertension.

Deciphering Fast Ion Transport in Glasses: A Case Study of Sodium and Silver Vitreous Sulfides.

High-capacity solid-state batteries are promising future products for large-scale energy storage and conversion. Sodium fast ion conductors including glasses and glass ceramics are unparalleled materials for these applications. Rational design and tuning of advanced sodium sulfide electrolytes need a deep insight into the atomic structure and dynamics in relation with ion-transport properties. Using pulsed neutron diffraction and Raman spectroscopy supported by first-principles simulations, we show that preferential diffusion pathways in vitreous sodium and silver sulfides are related to isolated sulfur Siso, that is, the sulfur species surrounded exclusively by mobile cations with a typical stoichiometry of M/Siso ≈ 2. The Siso/Stot fraction appears to be a reliable descriptor of fast ion transport in glassy sulfide systems over a wide range of ionic conductivities and cation diffusivities. The Siso fraction increases with mobile cation content x, tetrahedral coordination of the network former and, in case of thiogermanate systems, with germanium disulfide metastability and partial disproportionation, GeS2 → GeS + S, leading to the formation of additional sulfur, transforming into Siso. A research strategy enabling to achieve extended and interconnected pathways based on isolated sulfur would lead to glassy electrolytes with superior ionic diffusion.

ECOLOGICAL FEATURES OF SOAKING AND ASH PROCESSES IN THE PRODUCTION OF LEATHER

Ecological and colloid-chemical features of soaking-ash processes in processing of raw cattle leather materials at production of elastic leather for uppers of footwear according to operating and developed resource-saving technologies are investigated. To evaluate the effectiveness of the technological processes used a set of physic-chemical and operational properties of leather semi-finished products at different stages of its formation to the finished material. Resource-saving ecologically oriented technology of soaking and ash processes in leather production for shoe uppers from raw salted conserved materials – bull skins has been developed. Physicochemical, technological and ecological features of existing and developed technologies are studied. The developed technology due to the increase of process temperature provides more efficient use of chemical reagents, reduction of concentrations of environmentally hazardous reagents, process duration and energy consumption per unit of output. At the same time, the total consumption of chemical reagents is reduced by 2.2 times, and in the waste technological solutions the concentration of sodium sulfide and calcium hydroxide – by 2.9 and 4.4 times, respectively. However, the developed resource-saving environmentally friendly technology is characterized by a reduction in biological and chemical oxygen demand for the destruction of organic and inorganic substances in the waste soaking-ash solution after treatment of 1 ton of raw materials by 30.0 and 21.0%, respectively. By reducing the duration of the technological process by 2.3 times, the new technology can be considered as energy efficient. The developed resource-saving technology provides the formation of leather material for shoe uppers with an increased yield of 3.9%, and its performance properties meet the requirements of DSTU 3115-95. The results obtained in the development of environmentally friendly resource-saving technology of soaking ash processes for footwear leather uppers from raw cattle leather materials can be effectively used in the development of new innovative technologies for the manufacture of leather materials from a wide range of other raw materials.