Mechanism for the Formation of Elemental Sulfur from Aqueous Sulfide in Chemical and Microbiological Desulfurization Processes

Steudel, Ralf

doi:10.1021/ie950558t

Cited by 266 publications

(199 citation statements)

References 48 publications

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“…Zero-valent S was identified in the samples, and accounted for 3 -25% of the total S. This S group is attributed to the presence of elemental and polysulfidic S. In sulfidic environments, zero-valent S species can be produced in situ via partial oxidation of aqueous sulfide as a result of chemical and/or microbial processes (Steudel 1996, Yang et al 2005, Sher et al 2008). For example, elemental S is formed through a series of reactions which consist of the sequential formation of polysulfides from aqueous sulfide (Steudel 1996).…”

Section: Major S Species In Laboratory and Full-scale Cstbrsmentioning

confidence: 99%

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Chemical speciation of sulfur and metals in biogas reactors – Implications for cobalt and nickel bio-uptake processes

Yekta

Skyllberg

Danielsson

et al. 2017

Journal of Hazardous Materials

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A balanced supply of micronutrients, including metals such as iron (Fe), cobalt (Co), and nickel (Ni), is required for the efficient and stable production of biogas. During biogas formation, the uptake of micronutrient metals by microorganisms is controlled by a complex network of biological and chemical reactions, in which reduced sulfur (S) compounds play a central role. This thesis addresses the interrelationship between the overall chemical speciation of S, Fe, Co, and Ni in relation to the metals bio-uptake processes. Laboratory continuous stirred tank biogas reactors (CSTBR) treating S-rich grain stillage, as well as a number full-scale CSTBRs treating sewage sludge and various combinations of organic wastes, termed codigestion, were considered. Sulfur speciation was evaluated using acid volatile sulfide (AVS) extraction and S X-ray absorption near edge structure (XANES). The chemical speciation of Fe, Co, and Ni was evaluated through the determination of aqueous metals and metal fractions pertaining to solid phases, as well as kinetic and thermodynamic analyses (chemical speciation modelling).The relative Fe to S content in biogas reactors, which in practice is regulated through the addition of Fe for the purpose of sulfide removal or prior to the anaerobic digestion of sewage sludge, is identified as a critical factor for the chemical speciation and bio-uptake of metals. In the reactors treating sewage sludge, the quantity of Fe exceeds that of S, inducing Fe(II)-dominated conditions under anaerobic conditions, while sulfide dominates in the co-digestion and laboratory reactors due to an excess of S over Fe. Under sulfide-dominated conditions, chemical speciation of the metals is regulated by hydrogen sulfide and the formation of metal sulfide precipitates, which in turn restrict the availability of metals for microorganisms. However, despite the limitations set by sulfide, aqueous concentrations of different Co and Ni species were shown to be sufficient to support metal acquisition by the microorganisms under sulfidic conditions. Comparatively, the concentrations of free metal ions and labile metalphosphate and -carbonate complexes in aqueous phase, which directly participate in bio-uptake processes, are higher under Fe-dominated conditions. This results in an enhanced metal adsorption on cell surfaces and faster bio-uptake rates. It is therefore suggested that the chemical speciation and potential bioavailability of metals may be controlled through adjustments of the influent Fe concentration in relation to S content. The results also indicated that the pool of metal sulfides in the biogas reactors could be regarded as a source of metals for microbial activities. Thus, the recovery and utilisation of this fraction of metals may be considered as a measure with which to minimise the metal dosing concentrations to CSTBRs.Keywords: Biogas, Anaerobic digestion, Chemical speciation, bio-uptake, Sulfur, Iron, Cobalt, Nickel SammanfattningFör att en effektiv och stabil biogasproduktion från organiskt a...

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Section: Major S Species In Laboratory and Full-scale Cstbrsmentioning

confidence: 99%

“…For example, elemental S is formed through a series of reactions which consist of the sequential formation of polysulfides from aqueous sulfide (Steudel 1996). The chemical reduction of …”

Section: Major S Species In Laboratory and Full-scale Cstbrsmentioning

confidence: 99%

Chemical speciation of sulfur and metals in biogas reactors – Implications for cobalt and nickel bio-uptake processes

Yekta

Skyllberg

Danielsson

et al. 2017

Journal of Hazardous Materials

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“…5 were typical for all runs and, in addition to pH, show redox and COD profiles during runs. An elevation in redox potential from around −230 mV in the influent to −155 mV in the effluent is important given that the oxidation of sulphide to elemental sulphur, rather than to more oxidised states, occurs in a narrow redox window around −150 mV (Steudel, 1996). The influent COD was reduced by approximately 200 mg•ℓ −1 during the course of flow through the reactor.…”

Section: Temperaturementioning

confidence: 99%

Technical note: Development of a Linear Flow Channel Reactor for sulphur removal in acid mine wastewater treatment operations

Molwantwa¹,

Rose

2013

WSA

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Where sulphate removal is targeted in the biological treatment of acid mine drainage wastewaters, a step additional to sulphate reduction is required to prevent the complete oxidation of sulphide back to sulphate. This linearisation of the biological sulphur cycle has presented a technological bottleneck, particularly in passive treatment operations. We report an investigation of sulphur production in floating sulphur biofilms as a means for addressing this problem. These 50 µm to 500 µm structures may be seen to form on the surface of sulphidic, organic waters and in which sulphide is partly oxidised to S o and polysulphide. A Linear Flow Channel Reactor was developed in which the formation of the floating sulphur biofilm could be optimised and studied under controlled conditions. In this study the sulphide feed was sourced from a lignocellulose packed bed reactor treating a synthetic acid mine water (2 000 mg•ℓ −1 Na 2 SO 4 solution) and the Liner Flow Channel Reactors (surface area 1.1 m 2 and 2.2 m 2 ) were operated in a controlled environment chamber. The floating sulphur biofilm was harvested by settling to the bottom of the reactor where it remained largely unreacted until removed. It was shown that up to 88% of sulphide in the feed stream may be removed in this way and that this was achieved mainly by oxidation of sulphide to sulphur (including a polysulphide fraction). A mass balance accounting for the process showed that up to 66% of total sulphur species entering the system were recovered as S o . Oxidation of sulphide to thiosulphate and sulphate was not found to be significant. A fraction of fine particulate sulphur is released into the stream on harvesting of the biofilm which does not readily settle in the reactor and may thus be lost to the mass balance account. The effects of temperature, loading rate and reactor surface area were investigated in optimising the performance of the reactor. Scale-up application studies in the use of the Linear Flow Channel Reactor in an acid mine drainage passive treatment environment have been undertaken in field studies.

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“…However, the mechanism of polysulfide ion decomposition in aqueous solutions is not well understood. For example, the oxidation of S 2y , catalyzed by transition-metal ions, is believed to be a free radical reaction (Steudel 1996), as evidenced by the fact that when S 2y was treated with ions such as V 5q , Fe 3q or Cu 2q , it was transformed to hydrosulfide radical anion, HS y• . At neutral pH values, these radicals were thought to exist as sulfur radical anions S y• (Steudel et al 1989).…”

Section: Introductionmentioning

confidence: 99%

Quantitative 1H NMR analysis of alkaline polysulfide solutions

et al. 2005

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A novel analytical protocol for the absolute determination of the various polysulfide species present in alkaline aqueous media was developed. The method is comprised of alkylating polysulfide ions with dimethyl sulfate, followed by quantitative proton NMR spectroscopy using 1,3,5-tributyl benzene as the internal standard. In order to arrive at a quantitative acquisition protocol, a number of variables were examined in detail for their effect on the alkylation reaction, including the presence of oxygen, the amount of dimethyl sulfate and sodium hydroxide, and the various modes of adding the alkylating reagent to the reaction mixture. Most of these variables were found to play a role in determining the quantitative reliability of the procedure. Consequently, a method is described that can be used for the efficient and reliable quantitative detection of polysulfide ions. The protocol developed could be particularly useful in promoting our understanding of the intricate and delicate chemistry of polysulfide equilibria in aqueous alkaline media.

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Mechanism for the Formation of Elemental Sulfur from Aqueous Sulfide in Chemical and Microbiological Desulfurization Processes

Cited by 266 publications

References 48 publications

Chemical speciation of sulfur and metals in biogas reactors – Implications for cobalt and nickel bio-uptake processes

Chemical speciation of sulfur and metals in biogas reactors – Implications for cobalt and nickel bio-uptake processes

Technical note: Development of a Linear Flow Channel Reactor for sulphur removal in acid mine wastewater treatment operations

Quantitative 1H NMR analysis of alkaline polysulfide solutions

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