H2S Treatment Research Articles

Retrofitting existing chemical scrubbers to biotrickling filters for H2S emission control.

Biological treatment is a promising alternative to conventional air-pollution control methods, but thus far biotreatment processes for odor control have always required much larger reactor volumes than chemical scrubbers. We converted an existing full-scale chemical scrubber to a biological trickling filter and showed that effective treatment of hydrogen sulfide (H2S) in the converted scrubber was possible even at gas contact times as low as 1.6 s. That is 8-20 times shorter than previous biotrickling filtration reports and comparable to usual contact times in chemical scrubbers. Significant removal of reduced sulfur compounds, ammonia, and volatile organic compounds present in traces in the air was also observed. Continuous operation for >8 months showed stable performance and robust behavior for H2S treatment, with pollutant-removal performance comparable to that achieved by using a chemical scrubber. Our study demonstrates that biotrickling filters can replace chemical scrubbers and be a safer, more economical technique for odor control.

New Preparation Method of CdS Clusters Encapsulated in Y-Type Zeolites

CdS clusters encapsulated in Y-type zeolite were prepared by a novel technique with non-aqueous systems. The mechanical mixture of CdCl2· 2.5H2O crystal with Y-type zeolite was heated at 773 K, followed by the H2S treatment at 373 K, resulting in the formation of CdS clusters with the size <2.3 nm.

Hydrogen Sulfide Gas Treatment of Cr(VI)-Contaminated Sediment Samples from a Plating-Waste Disposal SiteImplications for in-Situ Remediation

Twenty sediment samples were collected at depths ranging from 5 to 100 feet beneath a chromate-contaminated plating-waste site and analyzed for Cr(VI), total chromium, and related constituents. Three of the samples were selected for treatment with dilute hydrogen sulfide (H2S) gas to evaluate this approach as a possible in-situ remediation technique. Gas treatment was performed in soil-packed columns using 100 ppm (μL L-1) H2S mixtures, and treatment progress was assessed by monitoring the breakthrough of H2S. Evaluation of treatment efficacy included (1) water-leaching of the treated and untreated columns for 10 days, (2) repetitive extraction of treated and untreated subsamples by water, 0.01 M phosphate (pH 7) or 6 M HCl solutions, and (3) Cr K-edge X-ray absorption near-edge structure (XANES) spectroscopy of treated and untreated subsamples. Results of the water-leaching studies showed that the H2S treatment decreased Cr(VI) levels in the column effluent by 90% to nearly 100%. Repetitive extractions b...

Photoluminescence and x-ray photoelectron spectroscopy study of S-passivated InGaAs(001)

The influence of sulfur passivation on the surface composition of In0.53Ga0.47As(001) was investigated with photoluminescence (PL) and x-ray photoelectron spectroscopy (XPS). Films of In0.53Ga0.47As(001), epitaxially grown on InP(100) substrates, were S passivated using a dry electron cyclotron resonance (ECR)-plasma deposition process and were either passivated as-prepared, or exposed to a BCl3 pre-etch prior to passivation. In the spectral range from 1450 to 1750 nm, S passivation enhances the PL yield by approximately an order of magnitude. XPS shows that S binds both to In and As, although preferably to In, and that oxidation is essentially eliminated by the passivation process. The In–S bonds are more stable upon annealing than are the As–S bonds. Furthermore, the pre-etched+H2S treatment enhances the PL yield beyond that of the H2S passivation treatment alone and produces a higher ratio of In–S to As–S bonds at the surface. In a second set of experiments, the influence of the ECR power applied to the sample during passivation was examined. The variation of this processing parameter has little effect on the surface composition.

XPS and NO Adsorption Studies on Alumina-Supported Co-Mo Catalysts Sulfided by Different Procedures

In the present work we studied the distribution of the active phase at the surface of the support, by XPS, of four HDS catalysts, each of them sulfided according to five different procedures. The procedures employed were known to yield catalysts with distinct activities and selectivities. The results of the XPS study were refined with data from an IR study on NO adsorbed on the catalysts. The major consequence of the modification of the activation procedure was a change in the dispersion of the active phase rather than the modification of the oxidation states of the active elements. The diameter of the MoS2 crystallites, rather than the number of slabs per crystallite, was most affected. When H2S was employed in the absence of hydrogen, catalysts containing only Mo contained a large excess of surface sulfur, whereas Co-Mo catalysts still presented S/Mo XPS ratios close to the stoichiometric ones. In these activations, the NO adsorption capability of the catalysts depended on whether the H2S treatment was applied before or after the sulfidation with H2/H2S.

Effect of the surface chemical modification on the optical properties of polymer-stabilized PbS nanoparticles

PbS Nanoparticles in the range 3.8–4.5 nm have been prepared in solution by H2S treatment of a Pb2+- containing copolymer (P-Pb). The variations of the P-Pb molecular weight before and after reacting with H2S implied that there existed some chemical bonds between the surface of the PbS nanoparticles and the copolymer. IR results proved that the chemical bond was Pb—OOC. When the molar ratio (the ratio H2S:Pb2+) was ⩽ 1, there existed Pb—OOC bonds on the particle surface, while most of the Pb—OOC bonds were broken when the molar ratio increased to 2.5:1. Different surface bonding situations are represented by different absorption spectra, the higher the molar ratio, the larger the absorption coefficient. These effects prove that the surface defects relative to the Pb—OOC bonds on the particle surface, can trap the electron–hole pairs effectively and cause a decrease in the absorption coefficient. On the other hand, excess H2S removed the Pb—OOC bonds and saturated the sulfur vacancies on the particle surface, where the radiation combination of the charge carriers occurred. As a result, the laser-induced luminescence bands appearing for the 0.75:1 and 1:1 colloids disappeared completely for the 2.5:1 colloid.

Sulfobetaine polyurethane ionomers, 2. Dielectric relaxation in polyether‐based polymer and related compounds with Co2+

AbstractDielectric relaxation processes in sulfobetaine polyurethane ionomers based on polyether, were studied comparatively to nonionic polyurethane and related compounds with Co2+ (complexed and H2S‐treated forms) by using thermally stimulated depolarization currents (TSDC).Four relaxation processes denoted as γ, βs, β′ and βh in polyurethane ionomers over the 110–370 K range were observed. Molecular origin of these processes was suggested. The effects of the hard segments content, complexation and H2S treatment on the relaxation processes were explained in terms of the structural modifications of the hard and soft microphases.

H2S-treated GaP(001) surface studied by low-energy electron diffraction, Auger electron spectroscopy, and x-ray photoelectron spectroscopy

The GaP(001) surface treated by H2S has been studied using low-energy electron diffraction (LEED), Auger electron spectroscopy (AES), and x-ray photoelectron spectroscopy (XPS). We, for the first time, find the new surface structure, S/GaP(001)-(1×2), obtained by H2S treatment at 450 °C. The coverage of sulfur is estimated to be half monolayer by AES measurement. XPS results indicate that only Ga—S bonds are formed on the surface.

Ultraviolet photoemission studies of GaAs(100) surfaces chemically stabilized by H2S treatments

We report photoemission studies of GaAs(100) surfaces treated with H2S. Our high-resolution core level photoemission data show that these surfaces are completely terminated by a GaSx species and the treated surface is stable in air or water. Thus a H2S treatment might result in better device quality surfaces and interfaces than the surfaces prepared by recently proposed chemical treatments involving Na2S or (NH4)2S.

Mössbauer Spectroscopic Characterization of Iron Supported on Y Type Zeolites after Sulfiding

Abstract Iron supported on zeolite catalysts, prepared by treating NH4Y with aqueous solutions containing Fe3+ or Fe2+ ions followed by calcination in air, were subjected to Mössbauer spectroscopic investigations before and after sulfiding treatments to elucidate the states and properties of Fe species supported. At least three types of Fe3+ species could be distinguished in the prepared samples. The first Fe3+ species were those located at the cation-exchange sites of zeolite. This type was reduced easily to Fe2+ species with the H2S treatment, but was resistant to aggregation to form Fe1−xS. The second Fe3+ species were those which had precipitated on the surface of zeolites as hydroxides. These were sulfided to crystalline Fe1−xS after H2S treatment. Finally, the third Fe3+ species were those which were quite resistant to both reduction to Fe2+ and sulfiding to Fe1−xS. These species were preferentially supported under the conditions where dealumination from zeolite framework took place simultaneously. Thus it was speculated that these species were bonded to zeolite framework to be stabilized. The distribution of the three Fe3+ species were quite different depending on the sample preparation. Comparison with the catalytic data clearly indicated that the third Fe3+ species acted as highly active sites for the toluene disproportionation reaction in the presence of H2S.

A Striking Effect of H2S Treatment of Catalyst on the Improvement of Acetic Acid Selectivity in High Pressure CO Hydrogenation over Rh–Ir–Mn–Li/SiO2

Abstract A selective synthesis of acetic acid from syngas was investigated. Acetic acid was produced with nearly 70% selectivity in carbon efficiency over H2S-modified Rh–Ir–Mn–Li/SiO2 catalyst at the expense of the activity. The role of H2S modification was also studied.

Breaking Bud Dormancy in Corms, Tubers, and Trees with Sulfurcontaining Compounds

Abstract Sulfur-containing compounds, H2S, SO2, allyl sulfide, and allyl isothiocyanate broke dormancy in gladiolus (Gladiolus x Tubergenii Hort., Gladiolus spp.), Platycodon grandiflorum A. DC., or tree peony (Paeonia suffruticosa Andr.). A 1% H2S treatment for 1-8 hr was most effective with the least phytotoxicity. Garlic paste/vapor, which included allyl sulfide, also was effective. H2S, allyl sulfide and garlic vapor increased the respiration rate of tubers in Platycodon grandiflorum within 15 hr after treatment.

Sulphur-35 radiotracer studies of the effect of hydrogen sulphide on a molybdenum disulphide catalyst in the hydrogenation of buta-1,3-diene

Hydrogenation of buta-1,3-diene on a molybdenum disulphide catalyst has been studied in order to determine the change in the pattern of butene product distribution with catalyst treatment (with hydrogen, a buta-1,3-diene + hydrogen mixture, air, hydrogen sulphide or a thiophene + hydrogen mixture). Catalyst treatment with sulphur compounds (H2S or thiophene + H2) resulted in a butene product distribution closer to thermodynamic equilibrium proportions than for a catalyst treated with hydrogen or air. 35S has been used as a tracer in H2S to measure the quantity of H2S necessary to change the catalytic function on fresh and hydrogen-treated catalysts and to observe the extent of sulphur isotopic exchange of gas-phase H2S with MoS2-lattice sulphur and with adsorbed H2S. Evidence is presented for the participation in the hydrogenation reaction of hydrogen present as adsorbed HS groups on the MoS2 surface, and the change of catalytic function with H2S treatment has been interpreted in terms of the change in distribution of these HS groups.

Cobalt staining of Actinia equina nematocysts.

Nematocysts of Actinia equina are stained black by incubation in 2% CoCl2 followed by an aqueous wash and H2S treatment. They are also stained positively by morin. Nematocysts isolated from the acrorhage were found to have a high concentration of calcium of which only 30% was "free." It is suggested that the high concentration of calcium in the nematocysts accounts for their staining by cobalt and morin. Cobalt staining offers a simple and effective technique for investigation of nemotocysts.

Loss of Ascorbic Acid During Estimation by the Roe‐Kuether Method

SUMMARYApplication of the 2,4‐dinitrophenylhydrazine method of Roe and co‐workers to plant extracts, wherein ascorbic acid was present largely or completely in the form of DHA and DKA, resulted in abnormal data, in the sense that the value of AA + DHA + DKA was significantly lower than that of DHA + DKA. Such a discrepancy, though not to the same degree, was observed also when the analyses were carried out on solutions of DHA. The loss is believed to take place during H2S treatment, there being a correlation between the extent of loss and the duration of H2S treatment, in the majority of the experiments.

Loss of Ascorbic Acid During Estimation by the Roe‐Kuether Method

SUMMARYApplication of the 2,4‐dinitrophenylhydrazine method of Roe and co‐workers to plant extracts, wherein ascorbic acid was present largely or completely in the form of DHA and DKA, resulted in abnormal data, in the sense that the value of AA + DHA+ DKA was significantly lower than that of DHA + DKA. Such a discrepancy, though not to the same degree, was observed also when the analyses were carried out on solutions of DHA. The loss is believed to take place during H2S treatment, there being a correlation between the extent of loss and the duration of H2S treatment, in the majority of the experiments.

The Relative Growth of the Root and Shoot in Rice Plants

It has been found that the relative growth of the root and shoot in rice plants (Oryza sativa L.) may be expressed by allometric formula, y=bxα, where x is the dry weight of shoot, and y the dry weight of root, while b and α are constants. The constant α represents, in this report, the ratio of the logarithmic growth rate of root over the logarithmic growth rate of shoot, and b the weight of the root when the shoot weighs one gram. The formula may also be written as log y=log b+α log x, so that when the measurements are plotted on a double logarithmic grid the points fall on a straight line. The value of α is therefore equivalent to the regression of log y on log x. As it did not vary greatly in any of the experiments with one exception of H2-S treatment the effect of treatment on the value of α may be supposed not to be so large. The value of α drops strikingly at respective heading stage showing minus value. It has also been shown that this formula can be applied to the results reported by many other investigators of root and shoot growth in rice plants, however the values of α were higher than those of the author's data.

合金中Moの定量(第1報)MoS3の沈澱化に就て

Difficulty is frequently experienced in obtaining accurate result in the determination of molybdenum in metals and alloys by the method based on the separation of MoS3. According to the Author's experience, the chief source of error ought to be an errornious adjustment of the acidity of the solution, taken before it is precipitated as MoS3. For instance, in the case of the precipitation in an acidic solution, if the solution is too slightly acid, H2S treatment causes a deep red coloured colloidal state of MoS3 in it, on the other hand, when the solution is too acid, the partical precipitation is obtained together with a blue colouration of the filtrate. There are many papers published already on the special acidity in the MoS3 precipitation, but to know the safty range of acidity in which the precipitation goes to completion is highly disirable. In this paper, the result obtained about the range of acidity for the complete precipitation of Mo in the form of MoS3 from an acid, or alkaline solution followed by dilute acid, with or without increased pressure, are given.