Sodium Sulfide Solution Research Articles

Synthesis of Copper Sulfides by Anion Substitution and their Resistive Switching Properties in the Presence of Cuprou‘s

AbstractCopper sulfides exhibit various significant physical properties and have wide potential applications. In order to synthesize copper sulfides and investigate the anion substitution possibility of Cu3P, we immersed Cu3P in sodium sulfide solution. From X‐ray diffraction spectra results, copper sulfides, namely Cu2S and Cu7.2S4, were observed, indicating that anion substitution between S2− and P3− ions did occur. Consequently, we investigated the resistive switching (RS) properties of these two phases in the presence of Cu3P. We found that the Cu2S‐Cu3P composite exhibited a high Off/On ratio (88) and a long retention time (>103 s). However, the Cu7.2S4‐Cu3P composite exhibited no RS performance. In addition, we discussed the conduction and resistive switching mechanisms. Our work enriches the preparation method of copper sulfides and provides a reference for enhancing RS performance.

Shape-controlled electro-synthesis of pyrrhotite

Recently, iron sulfide nanomaterials have drawn increased interest, due to their novel properties and extensive applications depending on their structure. To date, various methods have been employed for the synthesis of iron sulfide nanostructures with different shapes and morphologies. The synthesis method of iron sulfide nanomaterial is a challenge, as a small variation in sulfur content can lead to formation of different phases of iron sulfide. In this study, iron sulfide nanostructures were synthesized using our fast, simple, efficient, economical and environmentally friendly method in an electrochemical cell containing two iron sheets as electrodes in an aqueous solution of sodium sulfide. This method, with many advantages such as low-toxicity, low cost and easy handling, helps to control the properties of the products through the synthesis by tuning the growth conditions. Here, the influence of applied voltage ranging from 5 V to 25 V and annealing temperatures of 200 °C and 800 °C on the structure and magnetic properties of the products were studied. The samples were analyzed by X-ray diffraction (XRD), fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM) and vibrating sample magnetometer (VSM). XRD patterns confirmed the formation of monoclinic and hexagonal pyrrhotite at 200 °C and 800 °C, respectively. Based on SEM images, pyrrhotite in different shapes, such as quasi-spherical, feathers, sheets and flower-like structures, are formed depending on the applied voltage and annealing temperature. According to VSM results, all samples annealed at 200 °C are magnetically soft with only a little hysteresis, but the magnetization increases from 2.3 emu/g to 10.1 emu/g when applied voltage varies from 5 V to 25 V. All samples annealed at 800 °C exhibit an antiferromagnetic behavior. With increasing the applied voltage, the value of remanence magnetization and coercivity increases up to ∼2000 Oe and ∼0.14 emu/g, respectively.

AlxGa1–xAs(100) (x ∼ 0.3) surfaces treated with aqueous sodium sulfide solution: Chemistry and electronic structure

Chemical composition and electronic structure of the native-oxide-covered AlxGa1–xAs(100) (x ∼ 0.3) surfaces were investigated by x-ray photoelectron spectroscopy and photoluminescence before and after treatment at room temperature with a concentrated aqueous solution of sodium sulfide in order to get inside into mechanism of sulfide solution interaction with aluminum-containing III–V alloys. Even short treatment of the n-AlGaAs(100) surface leads to the removal of the most of the native oxide layer so that the surface is covered with a thin layer of residual aluminum and gallium oxides with a thickness of approximately 1 ML, which can be formed during air exposure after termination of the chemical treatment. Longer treatment of the n-AlGaAs(100) surface does not further reduce the amount of residual aluminum and gallium oxides. The etching of native oxide layer on the p-AlGaAs(100) surface proceeds slower and the lowest amount of residual aluminum and gallium oxides is achieved after etching for 12 min. At the same time sulfur is hardly adsorbed at the AlGaAs(100) surfaces after interaction with the solution. It is found that the lower the amount of residual aluminum and gallium oxides on n- and p-AlGaAs(100) surfaces, the higher is the photoluminescence intensity. The band bending on the native-oxide-covered n- and p-AlGaAs(100) surfaces is about 0.85 and 0.5 eV, respectively, while the ionization energy is nearly the same for both surfaces. Treatment of n- and p-AlGaAs(100) surfaces with an aqueous sodium sulfide solution causes simultaneous decrease in their ionization energy.

Improved Formulation and Optimization of Sodium Polysulfide/Bromine Electrolytes for Redox Flow Battery

Sodium polysulfide/bromine RFBs are one the most promising electrolyte couples for scale-up technology. Sodium polysulfide/bromine RFB utilizes aqueous sodium polysulfide and sodium bromide solution as anolyte and catholyte, respectively, separated by a sodium ion exchange membrane.Polysulfide electrolyte of different concentrations ranging from S:Na ratio of 0.5 that is without the addition of elemental sulfur, up to saturation limit having S:Na ratio of 2.4 with the addition of elemental sulfur are prepared.Studies of electrolyte composition have been essential to establishing the optimum conditions for practical use. These involve various parameters such as sulfide concentration, the ratio of dissolved sulfur to sulfide, speciation, pH, and the effect of temperature on battery stability and lifetime. Different experimental methodologies were used to investigate the speciation in these concentrated solutions. A titration method was developed to find the concentration of HS- and OH- species in any sodium sulfide and polysulfide solution. Sulfide and polysulfide chemistry is presented in more detail by comparing the UV-ATR spectra. It was found that polysulfide electrolyte shows very complex system containing species such as HS-, OH-, H+ and Sn 2- where n = 2-5 and sulphur oxoanions.Furthermore, we have established that controlled speciation of polysulfide solution can substantially impact on the electrochemistry in these electrolytes. Controlling the pH, concentrations of HS- and OH- ions in polysulfide electrolytes is extremely important to overcome many challenges of the polysulfide/bromine RFB system.Therefore, we have developed an improved polysulfide electrolytes with high charge densities but more soluble species in the presence of excessive HS- species. Charging and discharging data on our improved and well optimized polysulfide electrolyte will be presented.

Increasing the Photocatalytic Hydrogen Generation Activity of CdS Nanorods by Introducing Interfacial and Polarization Electric Fields.

Cadmium sulfide (CdS) is a photocatalyst widely used for efficient H2 production under visible light irradiation, due to its narrow bandgap and suitable conduction band position. However, the fast recombination of carriers results in their low utilization. In order to improve photocatalytic hydrogen production, it reports the successful introduction of metallic Cd and S vacancies on CdS nanorods (CdS NRs) by a facile in situ chemical reduction method, using a thermal treatment process. This procedure generates interfacial and polarization electric fields, that significantly improve the photocatalytic hydrogen production performance of CdS NRs in sodium sulfide and sodium sulfite aqueous solutions, under visible light irradiation (λ>420nm). The introduction of these electric fields is believed to improve charge separation and facilitate faster interfacial charge migration, resulting in a significantly optimized catalyst, with a photocatalytic hydrogen evolution rate of up to 10.6mmol-1 g-1 h-1 with apparent quantum efficiency (AQE) of 12.1% (420nm), which is 8.5 times higher than that of CdS. This work provides a useful method to introduce metallic and S vacancies on metal sulfide photocatalysts to build local polarization and interfacial electric fields for high-performance photocatalytic H2 production.

Optical properties of Ag2S quantum dots

Colloidal solutions of silver sulfide quantum dots of various sizes were synthesized from low-concentration water solutions of silver nitrate, sodium sulfide and sodium citrate as stabilizer. The size of Ag2S quantum dots in colloidal solutions was determined by dynamic light scattering. The produced Ag2S quantum dots were dispersed in a polyvinyl alcohol (PVA) film matrix. The transmission and absorption spectra of PVA films containing Ag2S were measured in the wavelength interval 190–900 nm. A comparative study of the optical properties of PVA films with Ag2S quantum dots showed that a decrease of quantum dots to ∼ 6 nm leads to an increase in the band gap Eg of silver sulfide to ∼ 1.6 eV, which is almost twice larger than the band gap of bulk Ag2S. The optical properties of PVA films with Ag2S quantum dots smaller than 5 nm exhibit specific features associated with exciton transitions.

Sulfide Immobilization: Investigating the Impact of a Protective Sulfide-Bearing Layer Formed by Siderite (FeCO3)

Sulfate-rich wastewater poses ecological hazards to freshwater ecosystems, and sulfate is highly regulated in many Minnesota lakes. Biological sulfate reduction results in the reduction of sulfate to sulfide, and this process is used to remediate acid mine drainage. Theoretically, the aqueous sulfide can be immobilized into a solid-phase material and removed from the aqueous system. This study focuses on sulfide immobilization using iron-bearing waste minerals. Specifically, the extent of reaction of siderite (FeCO3), an abundant ferrous mineral in some mining wastes, with sulfide was studied. Mildly acidic batch reactors containing powdered siderite were consecutively injected with a sodium sulfide solution. Solid reaction products were identified and characterized using powder X-ray diffraction, scanning and transmission electron microscopy, and energy-dispersive X-ray spectroscopy. Mackinawite (FeS) appeared to be the most abundant product, with greigite (Fe3S4) also detected. Results reveal that the immobilization capacity of sulfide by siderite is limited by the concentration of the Fe2+(aq) presented in the system immediately before the initial sulfide exposure as the Fe2+(aq) levels are not replenished after sulfidation. These results improve our understanding of the sulfidation of siderite and provide insight to improve the viability of using siderite-containing mining waste rock in a sulfate remediation technology.

Preparing and properties of films with Ag2S quantum dots in a polyvinyl alcohol matrix

Stable colloidal solutions of Ag2S quantum dots with a size of 2–3 to 28–30 nm were synthesized by a hydrochemical deposition in low-concentration water solutions of silver nitrate, sodium sulfide, and sodium citrate. A large absolute value of the measured zeta potential of colloidal solutions, a small change in the size of quantum dots and zeta potential during long-term storage of solutions for 1000 days after synthesis indicate their high temporal stability. The synthesized colloidal solutions were dispersed in a solution of polyvinyl alcohol. The resulting films of Ag2S quantum dots in a PVA matrix are flexible and have a thickness of no more than 0.03 mm. The use of the PVA matrix to prepare films with Ag2S quantum dots promotes the preservation and increase in the stability of colloidal particles due to their fixation in the polymer matrix. For the first time, the optical properties of Ag2S quantum dots of different sizes in PVA films were determined. Decreasing the size of Ag2S quantum dots to 2.6 nm leads to an increase in the band gap of silver sulfide to 1.85 eV. It is shown that repeated bending of the films has practically no effect on the Eg value of Ag2S quantum dots.

In Situ Gravimetric Probing of Copper Sulfide Formation on the Counter Electrode for Quantum Dot Sensitized Solar Cells

Copper sulfide is a classical counter electrode (CE) catalytic material for the high catalytic activity of polysulfide in quantum dot-sensitized solar cells (QDSSCs). Actually, copper sulfide is a complicated compound. Different preparation methods will lead to the difference in the morphology and structure of copper sulfide, which has a profound impact on its catalytic activity. However, the formation mechanism and electrochemical properties of copper sulfide are rarely reported in the field of QDSSCs. Herein, we report an approach to obtain a high-stability counter electrode material by the electrochemical synthesis in sodium sulfide solution. The in situ electrochemical quartz crystal microbalance (EQCM) method was also employed to reveal the detailed transformation mechanism of copper vulcanized into copper sulfide during cyclic voltammetry in sodium sulfide solution. According to the calculation results of mpe theory, the formation of copper sulfide is accompanied by side reactions such as the conversion of polysulfide ions and water oxidation. Copper sulfide was proven to be a copper-rich phase by X-ray photoelectron spectroscopy (XPS) and other characterization methods. The photoconversion and stability of QDSSCs were studied using CdSe QD as the sensitizing material. The results show that the performance of copper sulfide prepared by this working method is better than the CE prepared by chemical bath deposition (CBD), and the replicability of photoelectric conversion efficiency (PCE) is better than CBD-CE. This work has theoretical significance to reveal the complex formation mechanism, electrochemical process mechanism, and working mechanism of copper sulfide in QDSSCs.

Hydrothermal Synthesis of Silver Sulfide

Silver sulfide powders with submicro- and micrometer particle sizes have been synthesized by the hydrothermal method at temperatures from 373 to 453 K in aqueous and alcoholic solutions of silver nitrate, sodium sulfide and citrate, sulfur, and thiocarbamide. The crystal structures of the synthesized powders, morphology, composition, and particle size of silver sulfide have been analyzed by X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray analysis, and gas adsorption. The powder particles have a similar morphology in the form of rectangular parallelepipeds and cubes with smoothed edges; the size of the powder particles depends on the synthesis conditions and ranges from ~500 to 2000 nm.

Color change and thermochromism of sodalite, Na8[Al6Si6O24](I,S)2, synthesized by hydrothermal reaction

A sodalite material with a composition of Na8[Al6Si6O24](I,S)2 was synthesized from zeolite A via a hydrothermal reaction of a mixed solution of sodium iodide and sodium sulfide. The stoichiometric amount of NaI required to synthesize iodide sodalite (Na8[Al6Si6O24]I2) from zeolite A (Na12[Al12Si12O48]) was defined as a NaI content of 1.0, and synthesis was carried out using a NaI content of 0–25. The color of the obtained samples was almost white; however, the samples became blue or yellow following calcination. The blue color, which was attributed to the formation of S3− color centers similar to those in ultramarine, was obtained after calcination at 700–800 °C. However, samples calcined at 900 and 1000 °C were yellow. Raman spectroscopic analysis revealed that the formation of I2 molecules induced the color change to yellow. Among the prepared specimens, the yellow specimen prepared at 7.5 times the stoichiometric ratio of NaI exhibited the largest b* value in the CIELAB color space, which represents the blue–yellow component, with blue in the negative direction and yellow in the positive direction. No proportional relation was observed between the b* values and the amount of NaI added, suggesting that an appropriate I/S ratio existed for yellow coloration in sodalite. The yellow sample exhibited thermochromism with the absorption band broadening toward longer wavelengths and reddening at higher temperatures. This material has not been previously reported and is expected to have applications as a new host–guest material.

Thermal Stability of Nanocrystalline Zinc Sulfide ZnS

Nanocrystalline zinc sulfide (ZnS) powders are prepared via hydrothermal deposition from aqueous solutions of zinc nitrate and sodium sulfide in the presence of sodium citrate or Trilon B. The average particle sizes of the product ZnS nanopowders ranging from 2 to 9 nm are tuned via varying the batch concentrations of the reagents. Air-annealing of as-prepared ZnS nanopowders at temperatures of 280 to 530°C oxidizes cubic zinc sulfide to hexagonal zinc oxide. The oxidation of the finest-grained zinc sulfide nanopowders having a particle size of 2 nm starts at 280–330°C, while the coarsest-grained nanopowder having a particle size of 9 nm starts to oxidize at 530°C. In the coarsest-grained ZnS powder, the particle size increases as little as from 9 to 12 nm when temperature rises to 530°C, while the finest-grained nanopowders have their particle sizes increase from 2 to 9 nm in response to the same rise in temperature.

Влияние сульфата железа, сернистого натрия и их смеси на флотацию сфалерита в щелочной среде

Introduction. The quality of the enrichment process is affected by many factors, ranging from the characteristics of the raw materials supplied to the enrichment plant to the enrichment technology and the agents used. Strict process control is required at all stages from mining to concentrate extraction. Copper-zinc ores of Russian deposits are difficult for enrichment due to high mass fraction of pyrite in ore and fine irregular intergrowth of sulfide minerals between themselves and with rock minerals. The practice of enrichment of copper-zinc ores has established that it is impossible to obtain high-quality zinc and pyrite concentrates without adding sphalerite flotation modifier agents to various flotation operations. To improve the flotation activity of sphalerite, copper sulphate is used as an activation additive in the enrichment process chain. Purpose of work. To study the effect of sulfhydryl collectors on flotation of sulfide minerals, and development of innovative technologies of flotation of copper-zinc and polymetallic ores considering the acidity of the environment. Materials and methods. In the experimental part of the work, several methods of materials and agents preparing were used, a variety of equipment was used, as well as methods of analysis and processing of results. The material composition and grain size distribution of sphalerite was studied using the MLA System Quanta. X-ray phase analysis of sphalerite was carried out at the University of science and technology "MISIS" in Research Laboratory of ultra-hard materials on Rigaku Geigerflex device using monochromatized CuKα-radiation. Thermographic studies were carried out using a Q -1500D derivatograph. The following flotation agents were used in the work: collector - butyl potassium xanthate, foam agent MIBC, medium regulator - lime, modifiers - iron sulfate, sodium sulphide and mixture of iron sulfate and sodium sulphide. Flotation experiments were carried out on the laboratory flotation machine FL-189 G. Results. The kinetics of sphalerite flotation is characterized not by a single value of the flotation kinetics constant for all flotation mineral grains, but by a set of such values corresponding to quite certain fractions of sphalerite extracted in the foams product. It has been found that in the initial period of flotation the mineral grains with a high value of the flotation velocity constant are flotated, and in the final period of flotation the grains of the same mineral with a low value of the same flotation velocity constant are flotated. Discussion. The introduction of iron (II) sulphate into the mineral slurry leads to a redistribution of the flocculated mineral between medium and lightly flocculated fractions. This indicates that iron (II) sulphate acts as an activator for sphalerite flotation. At a low flow rate of this agent, the proportion of medium flotable fractions increases and the proportion of easily and hardly flotable fractions decreases. With increase in the agent consumption up to 400 g/t and more, the opposite picture is observed - the proportion of medium flotable fraction decreases and the proportion of easily flotable fraction increases in flocculated sphalerite. The replacement of iron (II) sulphate by sodium sulphate has the opposite effect on the flotation spectrum of sphalerite. The introduction of a mineral suspension of a solution of sodium sulfide and iron (II) sulfate into the liquid phase at a consumption of 200 g/t of each agent leads to a decrease in the proportion of easily and especially medium floatable fractions of the mineral and an increase in the proportion of difficultly floatable fractions. Conclusions: 1. An increase in the pH of pulp liquid phase leads to a decrease in the extraction of zinc concentrate in the foam product during flotation with butyl xanthate. 2. The introduction of a solution of sodium sulfide with ferrous sulfate reduces the floatability of the mineral, which is reflected in a decrease in the extraction of zinc concentrate. 3. Sodium sulfide and iron sulphate, while simultaneously dosing them into the flotation pulp, act as depressants in the sphalerite flotation process. 4. Sodium sulfide depresses sphalerite at all studied pH concentrations. Resume. The results of the research can be useful in improving the methods for processing sulfide ores (lead-zinc and copper-zinc) which are included in the group of polymetallic ores. The developed methods of flotation processing make it possible to improve the quality of enrichment and increase the extraction of a valuable component.

Stability of Colloidal Silver Sulfide Solutions

Stable colloidal solutions of silver sulfide Ag2S quantum dots of various sizes were prepared by hydrochemical bath deposition from low-concentration aqueous solutions of silver nitrate, sodium sulfide, and sodium citrate. The Ag2S quantum dot sizes determined by dynamic light scattering (DLS) were 2–3 to 28–30 nm. The great negative values of the measured ζ-potentials of the colloidal solutions and the small changes in ζ-potential and quantum dot sizes upon the long-term storage of the solutions indicate their stability across time.

Synthesis of Zinc Sulfide Nanoparticles Using Pyridinium Ionic Liquids

Zinc sulfide nanoparticles (quantum dots) were synthesized from aqueous solutions of sodium sulfide and zinc sulfate using pyridinium ionic liquids. The average sizes of zinc sulfide nanoparticles were determined by UV spectroscopy, X-ray diffraction, probe and scanning electron microscopy. The influence of the structure and concentration of pyridinium ionic liquids with the tetrafluoroborate anion of the same name on the size of zinc sulfide nanoparticles has been studied. The effect of the precursor concentration on the size of the nanoparticles formed in the ash was established.

Viscometric and Thermodynamic Studies of D-Galactose and D-Maltose in Sodium Sulfide Solution (0.25M) at Different Temperatures

Densities ρ and Viscosities ŋ of D-Galactose and D-Maltose (0.05-0.4)M in aqueous solution (0.25) M of Na2S at 298.15, 303.15 and 308.15K have been measured. From these experimental data, apparent molal Volume Limiting Apparent Molal Volume ( ) ,The slope ( ) , Jones-Dole coefficient A and B, The free energy of activation of viscous flow (ΔG*), The enthalpies (ΔH*) and Entropies (ΔS*) were calculated, A values compatible with the ( ) values of weak solute-solute interaction while B came with positive and high,which indicating the strength of the reciprocal interaction type solute-solvent. This serves to strengthen of the structure of solvent. due to hydrophobic hydration and hydrogen bonding between solute and water , sodium sulfide molecules and on the other hand the water molecules rearranges toward formation of a local cage like (clathrates) structure surrounding each solute molecule

Continuous Flow Synthesis of Cd1-x Znx S and CdS/ZnS Core/Shell Semiconductor Nanoparticles by MicroJet Reactor Technology.

From aqueous precursor solutions of metal salts and sodium sulfide using MicroJet Reactor (MJR) technology Cd1-x Znx S and CdS/ZnS core/shell semiconductor nanoparticles were synthesized. The MJR approach represents an automated, continuous, flexible and scalable route for nanoparticle synthesis, providing a tight control over process parameters and thus simple size, shape and composition control. Since particle sizes below the excitonic Bohr radius were obtained by MJR, the nanoparticulate materials exhibit quantum confinement effects. By varying the precursor ratio the band gap of Cd1-x Znx S Quantum Dots (QDs) could be targeted from 3.1 to 3.6 eV. CdS/ZnS core/shell QDs were prepared by enclosing CdS particles from MJR with ZnS produced by thermal decomposition of a Zn-MPA complex. Adjustment of the shell thickness increased the photoluminescence intensity by 43 %. Synthesis of ternary sulfides in the form of core/shell particles broadens the spectrum of materials accessible by MJR and demonstrates the extraordinary flexibility of the technology.

Ecological treatment of El Kriymat boiler ash for recovering vanadium, nickel and zinc from sulfate leach liquor

The primary goal of this work is to develop a technology that allows for the recovery of metal values from waste products, thereby promoting the wise and efficient use of our nation's resources. To achieve this goal, an industrial waste of El Kriymat boiler fly Ash was used for recovering its content of vanadium, nickel and zinc. About 97, 95 and 99% respectively of these economic elements were first dissolved from boiler fly ash magnetic concentrate (after physical concentration). Leaching experiments using optimum conditions include: 180 g/L sulfuric acid concentration and 4% solid/solid proportion manganese dioxide acts as an oxidant at 80 °C. The recovery of vanadium (V) metal ions was carried out using 3% Alamine 336 in kerosene at an equilibrium pH value of 0.9. Subsequently, 15% sodium sulfide solution was used for co-precipitation of nickel and zinc metal ions in the raffinate solution at pH value of 3.5.Graphical

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.