The sampling of hydrogen fluoride in air with impregnated filter paper

A method isproposed for the quantitative collection of hydrogen fluoride in air by drawing a known quantity of the air through filter paper impregnated with solutions of potassium hydroxide and glycerol or triethanolamine. Somu possibilities and limitations of the method are discussed.     

A rapid field test method for the determination of hydrogen sulfide and sulfides in waters with gas preextraction

A rapid test method was developed for the determination of hydrogen sulfide and sulfides in waters using a potassium chloride-impregnated test paper with color intensity evaluation of the formed CdS zone by colorimetry and diffuse reflectance spectroscopy. The determination conditions, viz. acidity, gas preexraction time, air pumping rate, and working concentration range (0.005–0.16 mg of Н₂S/L), were optimized. The procedure proposed is easy-to-perform, and the time of single determination is 20 min; in addition, the procedure is cost effective, sensitive, selective, does not require expensive equipment and expertise of executor, and is not inferior in accuracy to photometric methods. The procedure was tested on real water samples. The concentration hydrogen sulfide in the Don and Temernik rivers in Rostov-on-Don is not higher than the maximum permissible concentration (MPC).     

Fe-K/AC催化氧化脱硫剂制备及反应机理研究

采用正交实验法制备了负载铁、钾的活性炭(Fe-K/AC)热煤气催化氧化脱硫剂,考察了活性组分铁、钾含量、二价铁和三价铁比例、煅烧温度对催化氧化脱硫反应活性的影响。由正交实验极差分析可知,各因素影响程度依次为:钾含量>铁含量>煅烧温度> Fe²⁺/Fe³⁺,最优制备条件为,铁含量0.5%、钾含量5.0%、煅烧温度600 ℃、Fe²⁺/Fe³⁺比0.5。通过对脱硫剂的孔隙结构和表面形貌分析可知,活性炭表面负载的铁金属氧化物具有催化氧化硫化氢生成单质硫的活性,碱金属氧化物具有协同作用,可以改变表面酸碱性,促进硫化氢的催化转化,但过高的金属氧化物负载量会阻塞孔道,减小反应比表面积,从而降低脱硫剂的反应活性。     

Reactions of 1,2,4-trichlorotrifluorobenzene with nucleophiles

1,2,4-Trichlorotrifluorobenzene reacted with potassium hydrogen sulfide, potassium hydroxide, sodium isopropoxide, liquid ammonia, and ethyl cyanoacetate via nucleophilic substitution of one fluorine atom with predominant formation of the isomer in which the new substituent replaced fluorine atom in the 5-position.     

Chemical and electrochemical processes in low-temperature superionic hydrogen sulfide sensors

Effect the morphology of the surface of the working electrode (PbS) exerts on the sensitivity of a low-temperature potentiometric hydrogen sulfide sensor is studied. The sensor, which is based on electrochemical cell Na _x WO₃/NASICON/PbS, may be used for fast selective detection of hydrogen sulfide in air in natural conditions. It is demonstrated that the sensors with PbS that are deposited out of solution have a faster response than the pressed-to ones. The dependence of EMF on the hydrogen sulfide concentration for the former is linear in semilogarithmic coordinates. Thus difference is explained by the microstructure of the lead sulfide layer. It is shown that the lead sulfide interaction with hydrogen sulfide involves a reversible partial reduction of sulfur and lead at the surface. The species that form in so doing contain sulfur atoms in lower oxidation degrees (poly-and oligo sulfides, sulfite). A mechanism of the sensor operation is proposed on the basis of data yielded by experiment and quantum-chemical simulation. The mechanism includes reversible transport of hydrogen from sulfur atoms to oxygen atoms.     

A turn-on fluorescent probe for selective and sensitive detection of hydrogen sulfide

An imidazolethione based turn-on fluorescent probe was synthesized for the detection of hydrogen sulfide, a biologically relevant molecule and an important air pollutant. The probe rapidly and selectively reacted with hydrogen sulfide to produce a strongly fluorescent product, resulting in the fluorescence enhancement of the system. The detection limit was determined to be 30 nM at the probe concentration of 1.0 μM. An indicating paper for visual detection of hydrogen sulfide gas has been fabricated by immobilizing the probe on a piece of appropriate paper substrate, and the detection limit of the visual method reached as low as 0.7 ppm. Moreover, the fluorescence turn-on/off of the system showed good reversibility when exposed alternately to hydrogen sulfide and mercuric ion, which was utilized to make an INHIBIT logic circuit for the presence of the two species.     

Determination of Sulfur Compounds in Air by Chemiluminescence

Abstract

The present review is devoted to applications of chemiluminescence to the analysis of trace sulfur species in air. Determinations of oxidized (sulfur dioxide and sulfite), reduced (hydrogen sulfide, dimethyl sulfide, carbonyl sulfide, carbon disulfide and mercaptans) and/or sulfur compounds in general are described and some practical considerations are discussed. The development of detectors based on chemiluminescence in the aproximately last fifteen years is also reviewed.     

Changes in Reduced Gaseous Sulfur Compounds Collected in Glass Gas Sampling Bulbs

Abstract

Changes which volatile reduced sulfur species (hydrogen sulfide, carbonyl sulfide, methanethiol, dimethyl sulfide and carbon disulfide) undergo in glass gas sampling bulbs were determined as influenced by the balance gas matrix and moisture. Results have shown that differences in reduced sulfur gas concentrations compared with the initial values were less than 5% in each sulfur compounds within 24 hours if the balance gas was dry nitrogen. There was no change in composition if dry air sample was measured within 3 hours. Significant decrease in hydrogen sulfide and methanethiol concentrations was observed with a short period of time following sampling if moisture was present within the bulb atmosphere.     

Gas-chromatographic determination of volatile sulfur-containing impurities in industrial emissions and aqueous solutions

Procedures are developed for determining volatile sulfur-containing impurities, hydrogen sulfide, simple mercaptans, sulfides, and disulfides in air and aqueous solutions. The procedures are based on the principle’s headspace gas chromatography and equilibrium preconcentration. The procedures differ from the officially approved ones in that the operations of sampling and sample preparation to gas-chromatographic analysis considerably reduce the loss of hydrogen sulfide and mercaptans unstable in humid air. The procedures provide the determination of sulfur-containing substances at the level of their maximum permissible concentrations (MPC) in industrial emissions and natural waters and the analytical range of four orders of magnitude; they can be implemented on gas chromatographs with flame ionization and flame photometric detectors, a quartz capillary column, and a thermostated gas-sampling valve.     

Reaction of pentachloropyridine N-oxide with potassium hydrogen sulfide

Depending on the conditions, the reaction of pentachloropyridine N-oxide with potassium hydrogen sulfide leads to the N-oxide of the potassium salt of 3,4,5,6-tetrachloropyridin-2-thiol or the dipotassium salt of 3,4,5-trichloropyridine-2,6-dithiol, which are converted by the action of dimethyl sulfate into the corresponding methylthio derivatives. Oxidation of the latter has given sulfones. It has been shown that for these sulfones,reactions with nucleophilic reagents take place at the methylsulfonyl group and not at the chlorine atoms.     

Materials Design Principles for Air‐Stable Lithium/Sodium Solid Electrolytes

Sulfide solid electrolytes are promising inorganic solid electrolytes for all‐solid‐state batteries. Despite their high ionic conductivity and desirable mechanical properties, many known sulfide solid electrolytes exhibit poor air stability. The spontaneous hydrolysis reactions of sulfides with moisture in air lead to the release of toxic hydrogen sulfide and materials degradation, hindering large‐scale manufacturing and applications of sulfide‐based solid‐state batteries. In this work, we systematically investigate the hydrolysis and reduction reactions in Li‐ and Na‐containing sulfides and chlorides by applying thermodynamic analyses based on a first principles computation database. We reveal the stability trends among different chemistries and identify the effect of cations, anions, and Li/Na content on moisture stability. Our results identify promising materials systems to simultaneously achieve desirable moisture stability and electrochemical stability, and provide the design principles for the development of air‐stable solid electrolytes.     

硫化氢热分解制氢过程的化学动力学研究

采用化学热平衡分析方法研究了硫化氢热分解制氢过程,研究了硫化氢在不同温度和体积分数下的分解过程,并与试验数据进行了比较。结果表明,基元反应机理能较好地模拟硫化氢热分解制氢过程。硫化氢的热分解率依赖于反应温度,高温下能获得较好的分解制氢效果;温度较低时,时间是硫化氢趋于平衡的主要影响因素,随着温度的提高,温度成为影响硫化氢趋于平衡的主要影响因素。硫化氢初始体积分数对热分解制氢反应具有较大的影响,采用较低体积分数的硫化氢混合气有利于获得高的硫化氢热分解制氢率。     

Creation of active sites by impregnation of carbon fibers: application to the fixation of hydrogen sulfide

Activated carbon fibers, which exhibit high specific area and numerous active surface sites, constitute very powerful adsorbents and are widely used in filtration to eliminate pollutants from liquid or gaseous effluents. The fibers studied in this work are devoted to the filtration of gaseous effluent containing very small amounts (few vpm) of hydrogen sulfide. Preliminary experiments evidenced that these fibers weakly adsorb hydrogen sulfide. To improve their fixation capacity toward H(2)S the activated fibers are impregnated in an aqueous solution of potassium hydroxide. The impregnation treatment usually takes place before activation but in this work it occurs at room temperature after activation of the fibers. A further thermal treatment is performed to increase the efficiency of the system. The overall treatment leads to the creation of basic sites showing a great activity for H(2)S gas in the presence of water vapor. The mechanism has been established by a series of characterizations before, during, and after the different operation units. The KOH deposited after impregnation is carbonated into KHCO(3) at room temperature and then decomposed into K(2)CO(3) during the thermal treatment. K(2)CO(3) and H(2)S dissolve in a liquid aqueous solution formed on the fiber surface. Then carbonate ions and H(2)S molecules react together almost completely to yield HS(-) species. As a consequence the sorption capacities of hydrogen sulfide on the impregnated fibers are much higher, even for small hydrogen sulfide volume fractions.     

Ion chromatographic measurement of sulfide, methanethiolate, sulfite and sulfate in aqueous and air samples

Simultaneous measurement of sulfur species was investigated using ion chromatography. Sulfide, methanethiolate, sulfite and sulfate are representative of sulfur species. The aqueous sulfur species were simultaneously measured using a two-detector system: suppressor-type conductivity detector for sulfite and sulfate, and fluorometric or electrochemical detector for the reduced sulfur compounds. The major sulfur-containing gases, hydrogen sulfide, methyl mercaptan and sulfur dioxide are collected into aqueous solution as the species listed above. Collection of sulfur gases using a membrane-based cylindrical diffusion scrubber was investigated. Atmospheric hydrogen sulfide and sulfur dioxide are measured by the diffusion scrubber collection and subsequent measurement by ion chromatography without an enrichment column. In addition to the two gases, methyl mercaptan was also determined using a dual scrubber system.     

Plasma Chemical Reactor with Exploding Water Jet

Exploding water jet discharge simultaneously generating powerful UV radiation, non-thermal plasma, and aerosol of fine water droplets has potential applications for removal of chemical and biological pollutants from air and water streams. A model plasma chemical reactor based on the exploding water jet discharge is considered. The radiation properties of the discharge, reactions of nitrogen oxide and hydrogen peroxide formation, and reactions of carbon dioxide and hydrogen sulfide decomposition are studied experimentally.     

Electrochemical sensing of gases based on liquid collection interfaces

Although many electrochemical gas sensors have been reported, electrochemical gas sensors based on liquid collection constitute a smaller subset. Minimally, a liquid interface based electrochemical gas sensor is composed of two electrodes and an ion conducting electrolyte. There is a large number of possible arrangements of these parts, and many choices exist for their composition and preparation methods. This results in a diverse and rich technology now available for gas sensing. The measurement of some analyte gases of interest, notably ozone, nitrogen oxides, hydrogen peroxide, formaldehyde, ammonia, sulfur dioxide and hydrogen sulfide are specifically discussed. Finally, the recent reviews that are likely to be the most relevant to the further development of electrochemical detection approaches for gases with a liquid collection interface are cited and discussed.     

紫外光分解硫化氢制氢的研究

以10W低压汞灯(特征谱线波长,λ=253.7nm,简称UVC)作为光源,硫化钠的水溶液作为反应介质,进行了UVC直接分解硫化氢制氢反应(简称UVC-H₂S-H₂)的研究.考察了反应介质中硫的存在形式、硫化钠的浓度、反应介质pH值以及连续通入硫化氢的流量等反应条件对UVC-H₂S-H₂的影响.实验结果表明,UVC可以在无催化剂条件下直接分解硫化氢制氢.当以0.6mol/L硫化钠水溶液为反应介质,以25mL/h流量连续向反应介质中通入硫化氢时,UVC-H₂S-H₂产氢速率可达3.0mL/W·h.     

Combined adsorption and oxidation mechanisms of hydrogen sulfide on granulated coal ash

Hydrogen sulfide is highly toxic to benthic organisms and may cause blue tide with depletion of dissolved oxygen in water column due to its oxidation. The purpose of this study is to reveal the combined adsorption and oxidation mechanisms of hydrogen sulfide on granulated coal ash that is a byproduct from coal electric power stations to apply the material as an adsorbent for hydrogen sulfide in natural fields. Sulfur species were identified in both liquid and solid phases to discuss removal mechanisms of the hydrogen sulfide with the granulated coal ash. Batch experiments revealed that hydrogen sulfide decreased significantly by addition of the granulated coal ash and simultaneously the sulfate ion concentration increased. X-ray absorption fine structure analyses showed hydrogen sulfide was adsorbed onto the granulated coal ash and successively oxidized by manganese oxide (III) contained in the material. The oxidation reaction of hydrogen sulfide was coupling with reduction of manganese oxide. On the other hand, iron containing in the granulated coal ash was not involved in hydrogen sulfide oxidation, because the major species of iron in the granulated coal ash was ferrous iron that is not easily reduced by hydrogen sulfide.     

Chromium oxide catalysts with low valence state ions for heterocyclic ring formation

Conclusions In aluminum-chromium catalysts promoted by potassium and rare-earth oxides, used in the synthesis of 2-methylthiophene by heterocyclization of n-pentane with hydrogen sulfide, there are present low-valence cations of chromium and the rare-earth that enter into the active centers of the catalysts.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 4, pp. 782–784, April, 1986.     

A multidimensional gas chromatography method for the analysis of hydrogen sulfide in crude oil and crude oil headspace

Two‐dimensional heart‐cutting gas chromatography is used to analyze dissolved hydrogen sulfide in crude samples. Liquid samples are separated first on an HP‐PONA column, and the light sulfur gases are heart‐cut to a GasPro column, where hydrogen sulfide is separated from other light sulfur gases and detected with a sulfur chemiluminescence detector. Heart‐cutting is accomplished with the use of a Deans switch. Backflushing the columns after hydrogen sulfide detection eliminates any problems caused by high‐boiling hydrocarbons in the samples. Dissolved hydrogen sulfide is quantified in 14 crude oil samples, and the results are shown in this work. The method is also applicable to the analysis of headspace hydrogen sulfide over crude oil samples. Gas hydrogen sulfide measurements are compared to liquid hydrogen sulfide measurements for the same sample set. The chromatographic system design is discussed, and chromatograms of representative gas and liquid measurements are shown.