School of Environmental and Chemical Engineering, Shanghai University , No. 333 Nanchen Rd., Shanghai 200444, P. R. China.
Environ Sci Technol. 2014;48(1):599-606. doi: 10.1021/es403884e. Epub 2013 Dec 20.
In this investigation, kirschsteinite-dominant stainless steel slag (SSS) has been found to decompose sulfur hexafluoride (SF6) with the activity higher than pure metal oxides, such as Fe2O3 and CaO. SSS is mainly made up of CaO·FeO·SiO2(CFS)/MgO·FeO·MnO(RO) phase conglomeration. The SF6 decomposition reaction with SSS at 500-700 °C generated solid MF2/MF3 and gaseous SiF4, SO2/SO3 as well as HF. When 10 wt % of SSS was replaced by Fe2O3 or CaO, the SF6 decomposition amount decreased from 21.0 to 15.2 or 15.0 mg/g at 600 °C. The advantage of SSS over Fe2O3 or CaO in the SF6 decomposition is related to its own special microstructure and composition. The dispersion of each oxide component in SSS reduces the sintering of freshly formed MF2/MF3, which is severe in the case of pure metal oxides and inhibits the continuous reaction of inner components. Moreover, SiO2 in SSS reacts with SF6 and evolves as gaseous SiF4, which leaves SSS with voids and consequently exposes inner oxides for further reactions. In addition, we have found that oxygen significantly inhibited the SF6 decomposition with SSS while H2O did not, which could be explained in terms of reaction pathways. This research thus demonstrates that waste material SSS could be potentially an effective removal reagent of greenhouse gas SF6.
在这项研究中，已发现钙铁辉石为主的不锈钢渣 (SSS) 分解六氟化硫 (SF6) 的活性高于纯金属氧化物，如 Fe2O3 和 CaO。SSS 主要由 CaO·FeO·SiO2(CFS)/MgO·FeO·MnO(RO) 相团聚体组成。在 500-700°C 下，SSS 与 SF6 的分解反应生成固体 MF2/MF3 和气体 SiF4、SO2/SO3 以及 HF。当 10wt%的 SSS 被 Fe2O3 或 CaO 替代时，在 600°C 下 SF6 的分解量从 21.0 降至 15.2 或 15.0mg/g。SSS 在 SF6 分解方面优于 Fe2O3 或 CaO，与其自身特殊的微观结构和组成有关。SSS 中各氧化物成分的分散降低了新形成的 MF2/MF3 的烧结，这在纯金属氧化物的情况下更为严重，并抑制了内部成分的连续反应。此外，SSS 中的 SiO2 与 SF6 反应并生成气态 SiF4，这会使 SSS 产生空隙，从而使内部氧化物暴露出来，以进行进一步的反应。此外，我们发现氧显著抑制了 SSS 对 SF6 的分解，而 H2O 没有，这可以从反应途径来解释。因此，这项研究表明，废物 SSS 可能是一种有效的温室气体 SF6 去除试剂。
