Sodium Polysulfide Research Articles

Sodium Polysulfides during Charge/Discharge of the Room-Temperature Na/S Battery Using TEGDME Electrolyte

The charge-discharge process of the room-temperature Na/S battery is studied using the Na/S cell with tetraethylene glycol dimethyl ether (TEGDME) and the solid electrolyte. The solid electrolyte is a barrier for chemical mass transport between the anode and the cathode. The sodium polysulfides as reaction products in TEGDME could therefore be investigated without interference from the anode side. During discharge, the color of the TEGDME electrolyte changes from transparent to brown, yellowish-green, and then back to transparent, and in the reverse order during charge. The first three colors are well-matched with those of prepared TEGDME solutions of Na2Sn (6 ≤ n ≤ 8), Na2S4 and Na2S, respectively. The solubility of sodium polysulfides (Na2Sn, 1 ≤ n ≤ 8) in TEGDME are measured systematically. The dissolution of sodium polysulfides is found to depend on the molar concentration of sulfur. The optimized Na/S cell using activated carbon delivers a high capacity of 1070 mAh g−1 at the first discharge, and remains at 782 mAh g−1 after 37 cycles. It also shows good rate capability with a discharge capacity of 569 mAh g−1 at 1/2 C. The coulombic efficiency is nearly 100% after the 5th cycle.

A room temperature Na/S battery using a β″ alumina solid electrolyte separator, tetraethylene glycol dimethyl ether electrolyte, and a S/C composite cathode

To realize a high-performance room temperature Na/S battery with an elemental sulfur cathode, it is important that sodium polysulfides stay within the cathode and that they have room enough to react freely. In this work, sodium polysulfides are confined to the cathode using a β″ alumina solid electrolyte separator and an optimal amount of tetraethylene glycol dimethyl ether (TEGDME) electrolyte. In addition, an activated carbon material, in the form of a sulfur/carbon (S/C) composite, with high surface area, porosity, and pore volume is employed in the cathode. The resulting Na/S battery shows a high first discharge capacity of 855 mAh g−1 and coulombic efficiency close to 100%, as well as stable cyclability, with a discharge capacity of 521 mAh g−1 at the 104th discharge.

A novel and large area suitable water-based ink for the deposition of cobalt sulfide films for solar energy conversion with iodine-free electrolytes

A novel, cheap, reliable water based precursor ink has been used for the large scale production of amorphous cobalt sulfide (CoS) on fluorine doped tin oxide (FTO). The method uses a metal–organic complex of Co(II) and thioglycolic acid (TGA), it is cheap and easy to prepare. The electrodes prepared using our method have been applied in the oxidation/reduction using different redox couples dissolved in liquid electrolytes containing: I−/I3−; ferrocene/ferrocenium; bipyridine [Co(bpy)3]2+/3+ complexes and sodium polysulfide. The composition, morphology and the efficiency of the CoS electrodes have been investigated. The CoS films show a good adherence to the substrate, good transparency and an excellent electrocatalytic efficiency with all of the different redox electrolytes. The electrodes have been used in DSSC devices using the organic dye D5 with efficiencies up to 6.8%.

Novel Long Cycle Life Room Temperature Sodium-Sulfur Batteries

Sulfur is natural abundant, cheap, non-toxic and has about seven times the electrochemical capacity of standard Li-ion battery cathode active materials (1672 compared to 250 mAh g-1), considering the conversion to S2-.[1] Due to likewise low costs and high reactivity towards sulfur, sodium poses as an optimal candidate for the cell reaction with sulfur.Since the 1980s sodium sulfur batteries are used as commercial stationary energy storage systems. They consist of a sodium negative electrode, a sulfur positive electrode and a β''-alumina solid electrolyte in between.[2] Due to low ion conductivity of the materials, this battery type has to be heated to temperatures above 300 °C, resulting in safety challenges related to molten sodium and to increased operation costs. To take advantage of the low cost nature of sodium and sulfur, while avoiding its downsides, sodium-sulfur batteries driven at room temperature are aspects of today’s research. One of the largest differences is the use of liquid electrolytes in room temperature cells, in order to ensure sufficient ion conductivity.However, first reports on room-temperature Na-S-cells indicate significant challenges related to a parasitic reaction of dissolved sodium polysulfide species limiting the coulomb efficiency, the specific capacity and cycle life of this system (so-called polysulfide shuttle).[3] In this work, electrolyte composition, sulfur/carbon composite cathodes as well as anode materials were tailored to result in room temperature sodium-sulfur batteries with significantly reduced polysulfide shuttle. Electrolyte additives were identified being able to enhance the cell efficiency and increase the sulfur utilization through a redox mediation mechanism. This cell chemistry enables discharge capacities of 1000 mAh g-1 as well as improved capacity retentions exceeding values from recent literature.[3+4] Our results demonstrate the feasibility of stable and low cost sodium-sulfur batteries at room temperature enduring over 1000 reversible charge / discharge cycles.

High sulfur content polymer nanoparticles obtained from interfacial polymerization of sodium polysulfide and 1,2,3-trichloropropane in water.

Sulfur-rich materials have recently attracted keen interest for their potentials in optical, electrochemical, and pesticidal applications as well as their utility in dynamic covalent bond chemistry. Many sulfur-rich polymers, however, are insoluble and processing methods are therefore very limited. The synthesis and characterization of water-dispersible polymer nanoparticles (NPs) with the sulfur content exceeding 75% by weight, obtained from the interfacial polymerization between 1,2,3-trichloropropane and sodium polysulfide in water is reported here. The interfacial polymerization yields well-defined sulfur-rich NPs in the presence of surfactants, which are capable of serving a dual role as a phase transfer catalyst on top of emulsifiers. Such dual role allows for the control of the product NP size by varying its concentration. The surfactants can be easily removed by centrifugation and redispersion in water is also reported here. The resulting sulfur-rich NPs are characterized through elemental analysis, dynamic light scattering, ζ-potential measurements, and scanning electron microscopy.

Room-Temperature Sodium–Sulfur Batteries with Liquid-Phase Sodium Polysulfide Catholytes and Binder-Free Multiwall Carbon Nanotube Fabric Electrodes

Charge/discharge of a room-temperature sodium–sulfur (Na–S) battery involves redox processes of a series of long-chain soluble sodium polysulfides (Na2Sn, 4 ≤ n ≤ 8). By taking advantage of this, a room-temperature Na–S battery is developed with dissolved sodium polysulfide catholyte and a free-standing, binder-free multiwall carbon nanotube (MWCNT) fabric electrode. Use of liquid-phase sodium polysulfide as a cathode not only provides a facile dispersion and homogeneous distribution of the sulfur active material into the conductive matrix but also supplies a unique approach to mechanistically understand the ambient-temperature Na–S battery system. With the intermediate products (polysulfides) as the starting cathode, the electrochemical characteristics of the Na–S battery in the lower-voltage-plateau region can be readily studied without the impact from the transformation process of elemental sulfur into long-chain sodium polysulfides. The nanostructured, free-standing MWCNT fabric electrode in this batt...

Carbon black/sulfur-doped graphene composite prepared by pyrolysis of graphene oxide with sodium polysulfide for oxygen reduction reaction

Sulfur doped graphene nanosheets (S-GNs) are synthesized by using graphene oxide (GO) as carbon source and sodium polysulfide as sulfur source, and then, annealing the prepared precursors (S-GO) at different temperatures up to 1000°C. The structure and morphological characteristics of the fabricated composites are investigated by Field emission scanning electron microscopy (FESEM), Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and electrochemical methods. Electrochemical results show that S-GNs has high catalytic activity toward oxygen reduction reaction (ORR) in an alkaline electrolyte in comparison with GNs. To improve the characteristics of S-GNs and prevent agglomeration of the particles, the S-GNs-1000-CB is fabricated by mixing the S-GNs-1000 with the carbon black (CB). The results show that CB particles inserted between S-GNs layers function as spacers and prevent the restacking of S-GNs during drying, and thus, most probably promote the diffusion of O2 molecules through S-GNs and enhance the ORR rate. The S-GNs-1000-CB composites show excellent electrocatalytic activity in alkaline solutions over all the studied (catalyst) samples. Our findings demonstrate that S-GNs-1000-CB is an appropriate catalyst for ORR in alkaline solutions, and could be a good candidate for replacement of the precious Pt based catalysts for this goal.

Static and Dynamic Corrosion Characteristics of Plasma-Sprayed Fe-70Cr Coatings by Molten Sulfur and Sodium Polysulfides in Sodium Sulfur Cells

The sodium sulfur (NaS) cell comprises of sodium and sulfur electrodes separated by a beta alumina solid electrolyte (BASE). To avoid radical oxidation of the sodium and sulfur by oxygen or other oxidants in ambient environments, all the electrochemical components need to be protected by a hermetically sealed metal container. Joints between the adjacent structural parts are bonded by advanced gastight sealing technologies, such as electron beam welding (EBW), thermal compression bonding (TCB), and glass sealing for metal-metal, metal-ceramic, and ceramic-ceramic joints, respectively. For a contemporary sodium central type tubular cell for energy storage systems (ESS) applications, the metal container is made of aluminum alloys, and its inner surface is exposed to molten sulfur and/or sodium polysulfides (Na2Sx), at its operating temperatures of 300~350oC. However, since aluminum sulfides (AlSx), corrosion products of the aluminum alloys formed on the inner surface, may lead to an abrupt increase in cell resistance due to their high electrical resistivities, and cause cell failure by catastrophic corrosion, the inner surface needs to be appropriately coated with a conductive material. The coating material should have a high electrical conductivity, but also form a continuous conductive layer at a sufficiently slow growth rate during service. In this study, an Fe-(65~75)Cr alloy has been coated on the inner surface of the aluminum container via the argon shrouded plasma spray process. The coated containers were used to construct different types of sodium sulfur cells, and static and dynamic corrosion experiments have been conducted for up to 9 months. Results from the experiments will be discussed focusing on the characterization of corrosion products, and corrosion kinetics in order to predict the lifetime of the coating which is critical to ensure the long term durability of sodium sulfur cells.

Electrorefining of Na in Hydrophobic Ionic Liquids

Introduction The sodium-sulfur secondary battery (Na-S battery) has several advantages such as high energy density, low material cost, long lifetime, and maintenance free1-2) and commercial scale of the battery had sold since 2003. 3) Recently, the battery has been applied to load leveling of electric power, emergency power supply for interruption in factory, and storage device of power generation from solar or wind energy. Lifetime of the battery is about 15 years and large amount of the used batteries will be discarded in near future. In the used battery, metallic sodium and sodium polysulfide remain in inside of the battery. Since metallic sodium is an active metal, effective recycle of metallic sodium is required. We have proposed electrorefining process of metallic sodium from the used Na-S battery.4) We investigated propylene carbonate as an electrolytic melt in previous study. From the results, it was found that temperature of upper limit in propylene carbonate was 373 K. In this paper, to survey the electrolytic melt that can be used above 373 K, impedance measurement, voltammogram measurement, and constant current electrolysis were carried out in NaTFSI-TEATFSI ionic liquids and NaTFSI-TBATFSI ionic liquidsExperimental NaTFSI (sodium-bis(trifluoremethylsulfonyl)imide) was prepared by HTFSI (bis(trifluoremethylsulfonyl) imide, 99% pure, Kanto chemical) and NaOH(99.99% pure, Merk). TEATFSI (Tetraethylammonium bis (trifluoremethylsulfonyl) imide, 99% pure, Kishida chemical) and TBATFSI (Tetrabuthylammonium bis (trifluoremethylsulfonyl) imide, 97% pure, Iolitech) were used as received. Electrochemical cell was made of Pyrex glass cylinder. 10-30mol%NaTFSI-TEATFSI or 10-30mol%NaTFSI-TBATFSImixture melt of 30 ml were kept at 433 K. Glassy carbon (GC, Tokai carbon, GC-20) plates were used for working and counter electrode. Pt (99.99% pure, Tanaka Kikinzoku Kogyo) wire was used as a quasi reference electrode. Impedance measurement was carried out with amplitude of 15 mV and frequency from 1 Hz to 20 kHz. Electrical conductivity was calculated from the resistance value at a high frequency limit in impedance measurement. In voltammogram measurement, metallic sodium (Aldrich, 99.9% pure, calcium content : 500 ppm) was used as a counter electrode. The electrochemical measurement was carried out in a glove box under pure argon gas atmosphere. Electrolysis was done by constant current of 1-10 mAcm-2in 20 mol% NaTFSI-TEATFSI melt or 20 mol% NaTFSI-TBATFSI melt and the electrodeposit was analyzed by ICP atomic emission spectroscopy (Thermo i-CAP6000). Results and Discussion The conductivity of electrolytic melts were determined by AC impedance measurement in 10 - 30 mol% NaTFSI-TEATFSI. The maximum conductivity was attained to 36 mScm-1 at 20 mol% NaTFSI-TEATFSI. On the other hand, maximum conductivity was 16 mScm-1 at 20 mol% NaTFSI-TBATFSI. From the result, we selected 20 mol% NaTFSI melt was a suitable concentration and the following experiment was made in the melt. In voltammogram on GC electrode in 20 mol% NaTFSI-TEATFSI, a cathodic current was observed from -1.0 V and the current increased until -3.0 V. When the potential is reversed at -3.0 V, anodic current is observed from -2.2 to 0.5 V. It is considered that the cathodic and anodic currents correspond to electrodeposition and electrodissolution of sodium. From ICP analysis, the electrodeposit formed by constant current electrolysis was found to contain sodium of 99.99 % pure and 12 ppm calcium as impurity. The calcium content was seen to be decreased to about one fortieth by the electrorefining process. References1) J. L. Sudworth and A. R. Tilley, The Sodium Sulfur Battery, Chapman and Hall, (1985).2) R. Okuyama, H. Nakashima, T. Sano, and E. Nomura, J. Power Sources, 93, 50 (2001).3) T. Oshima, M. Kajita, A. Okuno, Int. J. Appl. Ceram. Technol., 1, 269(2004).4) M. Ueda, H. Hayashi, and T. Ohtsuka, J. Japan Inst. Metals, 73, 691(2009). Acknowledgements We thank New Energy and Industrial Technology Development Organization (NEDO) and Hokkaido Bureau of Economy, Trade and Industry for supporting this research.

Chemical precipitation of sulfur nanoparticles from aqueous solutions

Process of formation and coarsening of sulfur nanoparticles deposited from aqueous solutions of calcium and sodium polysulfides and sodium thiosulfate and from solutions of elementary sulfur in a mixture of hydrazine hydrate and monoethanolamine was considered. The sulfur nanoparticles were characterized with a laser analyzer of particle sizes, X-ray diffraction analysis, and electron probe microscopy. It was shown that the sizes of primary particles strongly depend on the concentration of an acid and on the molar ratio between the sulfur-containing solutions and the acid. The antifungal effects of sulfur with nano- and micrometer dimensions were compared. The experimental results demonstrated a strong antifungal effect of sulfur nanoparticles on various kinds of fungi.

Highly Reversible Room-Temperature Sulfur/Long-Chain Sodium Polysulfide Batteries.

In a room-temperature sodium-sulfur (RT Na-S) battery, the complicated reduction reaction of the sulfur cathode generally involves two main steps: (i) transformation of elemental sulfur into long-chain soluble sodium polysulfides (Na2Sn 4 ≤ n ≤ 8) and (ii) conversion of the long-chain sodium polysulfides into solid-state short-chain polysulfide Na2S2 or disulfide Na2S. It is found that the slow kinetics of the second step limits the efficiency of discharge and induces irreversible capacity loss during cycling. Accordingly, we present here a RT Na-S cell operated with the sulfur/long-chain sodium polysulfide redox couple to avoid the capacity fade. An advanced cathode structure has been developed by inserting a carbon nanofoam interlayer between the sulfur cathode and the separator to localize the soluble polysulfide species and prevent its migration to the anode. The highly reversible sulfur/long-chain sodium polysulfide cell presented here can provide a stable output energy density of 450 Wh kg(-1) at an extremely low energy cost of ∼$10 kWh(-1) (based on the active material of anode and cathode).

Preparation and properties of polyvinylenepolysulfides based on trichloroethene and sodium polysulfides

Interaction of trichloroethene with sodium tetra- and pentasulfide (prepared in turn from sodium sulfide and elemental sulfur) has lead to new family of polyvinylenepolysulfides containing up to 94% of sulfur. The polymers were found highly electrochemically active when applied as active cathode for lithium batteries.

Hydrolysis of Sugar for Dyeing of Cotton Fabric with Sulphur Black

The importance of sulfur dyeing of cellulosic fibers, particularly cotton, is realized economically throughout the dyeing industry. At the present time, dyeing with sulfur dyes requires the use of various auxiliaries, many of which have adverse effects on the environment. The most damaging of these is the reducing agent sodium sulfide, required to reduce the dye molecules to a water-soluble leuco form to enable adsorption and diffusion into the fiber. Different researchers have made attempts to replace the sodium sulfide used within the sulfur dyeing process with a variety of environmentally friendly reducing sugars. But most of the researchers did not mention the waiting time of the hydrolyzed sugars. So, this papers mainly concentrates the impact of the hydrolyzed sugar waiting time on dyeing of cotton fabric with sulphur black and subsequently, cotton was dyed with the world's most important sulfur dye, using hydrolyzed sugars under alkaline conditions, and compared to dyeing secured by employing commercial sulfide reducing agents. It was observed that reducing sugars gave comparable, and in many cases superior, color strength and wash fastness results, with respect to the commercial sulfide-based reducing agents, which still account for the vast majority of sulfur dyeing processes and that pose significant environmental concern. Employment of reducing sugars in sulfur dyeing could provide a sustainable, nontoxic, biodegradable, cost-effective alternative to sodium polysulfide and sodium hydrogen sulfide.

Municipal waste conversion to hydrogen sulfide adsorbents: Investigation of the synergistic effects of sewage sludge/fish waste mixture

Mixtures of sewage sludge and fish waste of various compositions were prepared and pyrolyzed at 950°C in an inert atmosphere. On the pyrolyzed samples an activation with CO2 was carried out at 850°C. The materials were used as H2S adsorbents at ambient conditions. Initial and spent samples were characterized using thermal analysis, XRD, XRF, SEM/EDX, sorption of nitrogen and surface pH measurements. An enhancement in the H2S removal capacity on the composite samples was linked to the synergistic effects of chemical composition. The adsorbents’ surface reactivity was linked to the presence of Na, K, Ca, Mg and Fe in various configurations. Activation had a detrimental effect on the composites’ performance as adsorbents of H2S. The sludge component provides an active iron phase, which is important for hydrogen sulfide oxidation. Potassium and sodium polysulfides and iron sulfite, sulfate, sulfide are the products of reactive adsorption. The strongest synergistic effect was found for the composite with the lowest content of the fish component. With an increase in the content of the fish waste this effect diminishes owing to the reactions of alkaline metals with silica during pyrolysis.

대용량 에너지 저장시스템을 위한 나트륨 유황전지

나트륨 유황전지(NAS)는 대용량 에너지 저장시스템(energy storage system, ESS) 중 하나로서, 최근 풍력에너지, 태양에너지, 해양에너지 등 그린재생에너지의 사용증가로 ESS에 대한 수요가 급증함에 따라 NAS 전지에 대한 관심이 고조되고 있다. NAS 전지는 에너지 밀도가 높고(납 축전지밀도의 3배), 사이클 수명이 길고, 자가방전이 없어 대용량 전력저장 시스템에 적합하다. NAS 전지는 양극으로 황(Sulfur), 음극으로 나트륨(Na), 고체전해질 및 분리막으로 ${\beta}$ -알루미나( $Al_2O_3$ )로 구성되어 있고, 양극 활물질인 황은 부도체이기 때문에 도전재인 탄소섬유(carbon felt)에 함침시켜 양극으로 사용해야 함으로, 양극재 구성 및 특성은 전지성능에 상당한 영향을 미치게 된다. 따라서 본 논문에서는 NAS 전지의 구성, 다황화나트륨( $Na_2S_x$ , 방전생성물) 및 양극재의 특성, 전지 성능에 미치는 영향인자들에 대해서 알아보고자 한다. 【Sodium sulfur (NAS) battery is a high energy storage system (ESS). These days, as the use of renewable green energy like wind energy, solar energy and ocean energy is rapidly increasing, the demand of ESS is increasing and NAS battery is considered to be one of the most promising ESS. Since NAS battery has a high energy density(3 times of lead acid battery), long cycle life and no self-charge and discharge, it is a good candidate for ESS. A NAS battery consists of sulfur as the positive electrode, sodium as the negative electrode and ${\beta}$ -alumina as the electrolyte and a separator simultaneously. Since sulfur is an insulator, carbon felt should be used as conductor with sulfur and so the composition and property of the cathode could largely influence the cell performance and life cycle. Therefore, in this paper, the composition of NAS battery, the property of carbon felt and sodium polysulfides ( $Na_2S_x$ , intermediates of discharge), and the effects of these factors on cycle performance of cells are described in detail.】

ChemInform Abstract: Decoration of Sulfur with Porous Metal Nanostructures: An Alternative Strategy for Improving the Cyclability of Sulfur Cathode Materials for Advanced Lithium—Sulfur Batteries.

AbstractPt@S nanostructures are prepared from mixtures of pristine sulfur microparticles (obtained from aqueous mixtures of sodium polysulfide, ZnCl2, and H2O2), aqueous H2PtCl6, and NaBH4 solutions.

The Efficancy of Micron and Nanoscale Sulfur the Schutte Fungi

Investigations of antifungal activity of micron and nanoscale forms of sulfur on two types of pathogenic Schutte fungi have been studied. As micronized sulfur used crushed in a roller mill, and as nanosized sulfur precipitated from a solution of sodium polysulfide. The size and shape of the particles of sulfur were characterized using a laser analyzer and probe microscope, the structure by X-ray diffractometer. Antifungal effects of sulfur particles in Sabouraud medium and field expierence have been studied. It is found that in all cases of laboratory and field expierence, antifungal activity of nanosized sulfur with an average particle size of 25 nm, 5-10 times higher than the sulfur micron with an average particle size of 8 microns. The results can be used to create more effective than conventional sulfur plant protection products.

First Gewald reaction ignited by sodium polysulfide: greener ultrasound-promoted synthesis of substituted 2-aminothiophenes in the absence of catalyst

In this paper, a modified and facile Gewald reaction triggered by sodium polysulfide in the absence of catalytic base was developed. This approach involves a one-pot ultrasound-irritated aqueous reaction between ketones or aldehydes, malononitrile, and sodium polysulfide, which are converted into the corresponding 2-aminothiophene derivatives in moderate to high yields. In comparison with conventional methods, the prominent features of this sonocatalyzed procedure are experimental simplicity, good functional group tolerance, atom efficiency, and the use of water as a green solvent.

Polysulfide Chemistry in Sodium–Sulfur Batteries and Related Systems— A Computational Study by G3X(MP2) and PCM Calculations

The sodium-sulfur (NAS) battery is a candidate for energy storage and load leveling in power systems, by using the reversible reduction of elemental sulfur by sodium metal to give a liquid mixture of polysulfides (Na(2)S(n)) at approximately 320°C. We investigated a large number of reactions possibly occurring in such sodium polysulfide melts by using density functional calculations at the G3X(MP2)/B3LYP/6-31+G(2df,p) level of theory including polarizable continuum model (PCM) corrections for two polarizable phases, to obtain geometric and, for the first time, thermodynamic data for the liquid sodium-sulfur system. Novel reaction sequences for the electrochemical reduction of elemental sulfur are proposed on the basis of their Gibbs reaction energies. We suggest that the primary reduction product of S(8) is the radical anion S(8)(˙-), which decomposes at the operating temperature of NAS batteries exergonically to the radicals S(2)(˙-) and S(3)(˙-) together with the neutral species S(6) and S(5), respectively. In addition, S(8)(˙-) is predicted to disproportionate exergonically to S(8) and S(8)(2-) followed by the dissociation of the latter into two S(4)(˙-) radical ions. By recombination reactions of these radicals various polysulfide dianions can in principle be formed. However, polysulfide dianions larger than S(4)(2-) are thermally unstable at 320°C and smaller dianions as well as radical monoanions dominate in Na(2)S(n) (n=2-5) melts instead. The reverse reactions are predicted to take place when the NAS battery is charged. We show that ion pairs of the types NaS(2)˙, NaS(n)(-), and Na(2)S(n) can be expected at least for n=2 and 3 in NAS batteries, but are unlikely in aqueous sodium polysulfide except at high concentrations. The structures of such radicals and anions with up to nine sulfur atoms are reported, because they are predicted to play a key role in the electrochemical reduction process. A large number of isomerization, disproportionation, and sulfurization reactions of polysulfide mono- and dianions have been investigated in the gas phase and in a polarizable continuum, and numerous reaction enthalpies as well as Gibbs energies are reported.

Improvement on Determination of the Components of Industrial Sodium Polysulfide

The analytical method on sodium sulfide, sodium sulfite, sodium hydroxide and sodium thiosulfate in sodium polysulfide solution was studied in this paper. The questions in concealing sodium sulfite by formaldehyde and precipitating sodium sulfide by zine acetate, a common method reported in some papers before, was discussed. The improvement on concealing Na2SO3 by SrCl2 instead of formaldehyde and precipitating Na2S by Zn(OH)2 instead of Zn(Ac)2 and testing concentration of NaOH in the mixture, was studied. The results showed that new method is simpler, more rapid, more completely and accurate, the overwhelming reason being that it had no effect on stability of sodium polysulfide.