Mechanism for the formation of elemental sulfur from aqueous sulfide in chemical and microbiological desulfurization processes
Mechanism for the formation of elemental sulfur from aqueous sulfide in chemical and microbiological desulfurization processes
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DOI：
10.1021/ie950558t
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发表时间：
1996-04-01
影响因子：
4.2
通讯作者：
Steudel, R
中科院分区：
文献类型：
--
作者：
Steudel, R
提出了一个详细的反应机理为形成结晶元素硫从硫化物的水溶液氧化与过渡金属离子，如钒，铁III，铜II等的第一步是HS的形成。通过HS-离子的单电子氧化形成自由基。这些自由基在pH值接近7时主要以S-.-形式存在。它们的自发衰变导致形成二硫离子S-2（2-）。二硫化物被S-.-自由基或过渡金属离子产生更高级的多硫化物离子，由此形成同素环硫分子S-6、S-7和S-8。在水中，这些疏水分子形成簇，簇生长成液体硫的液滴（硫溶胶）。取决于水相的组成，液态硫作为α-或β-S-8的结晶是快速的或延迟的。表面活性剂延缓了这种固化，而某些阳离子则促进了这种固化。所有这些反应都建议在采用Stretford、Sulfolin、Lo-Cat、SulFerox或Bio-SR工艺的脱硫装置中进行。此外，氧化硫细菌从硫化物中产生的硫是通过相同的机制形成的，这现在解释了以前的许多观察结果（包括副产物硫代硫酸盐，连多硫酸盐和硫酸盐的形成）。
A detailed reaction mechanism is proposed for the formation of crystalline elemental sulfur from aqueous sulfide by oxidation with transition-metal ions like V-V, Fe-III, Cu-II, etc. The first step is the formation of HS. radicals by one-electron oxidation of HS- ions. These radicals exist at pH values near 7 mainly as S-.-. Their spontaneous decay results in the formation of the disulfide ion S-2(2-). The further oxidation of disulfide either by S-.- radicals or by the transition-metal ions yields higher polysulfide ions from which the homocyclic sulfur molecules S-6, S-7, and S-8 are formed. In water these hydrophobic molecules form clusters which grow to droplets of liquid sulfur (sulfur sol). Depending on the composition of the aqueous phase, crystallization of the liquid sulfur as either alpha- or beta-S-8 is rapid or delayed. Surfactants delay this solidification, while certain cations promote it. All these reactions are proposed to take place in desulfurization plants working by the Stretford, Sulfolin, Lo-Cat, SulFerox, or Bio-SR processes. In addition, the sulfur produced from sulfide by oxidizing sulfur bacteria is formed by the same mechanism, which now explains many observations made previously (including the formation of the byproducts thiosulfate, polythionates, and sulfate).