Moon Deok Hyun, Grubb Dennis G, Reilly Trevor L
WM Keck Geoenvironmental Laboratory, Center for Environmental Systems, Stevens Institute of Technology, Hoboken, NJ 07030, USA.
J Hazard Mater. 2009 Sep 15;168(2-3):944-51. doi: 10.1016/j.jhazmat.2009.02.125. Epub 2009 Mar 6.
Stabilization/solidification (S/S) processes were utilized to immobilize selenium (Se) as selenite (SeO(3)(2-)) and selenate (SeO(4)(2-)). Artificially contaminated soils were prepared by individually spiking kaolinite, montmorillonite and dredged material (DM; an organic silt) with 1000 mg/kg of each selenium compound. After mellowing for 7 days, the Se-impacted soils were each stabilized with 5, 10 and 15% Type I/II Portland cement (P) and cement kiln dust (C) and then were cured for 7 and 28 days. The toxicity characteristic leaching procedure (TCLP) was used to evaluate the effectiveness of the S/S treatments. At 28 days curing, P doses of 10 and 15% produced five out of six TCLP-Se(IV) concentrations below 10mg/L, whereas only the 15% C in DM had a TCLP-Se(IV) concentration <10mg/L. Several treatments satisfied the USEPA TCLP best demonstrated available technology (BDAT) limits (5.7 mg/L) for selenium at pozzolan doses up to 10 times less than the treatments that established the BDAT. Neither pozzolan was capable of reducing the TCLP-Se(VI) concentrations below 25mg/L. Se-soil-cement slurries aged for 30 days enabled the identification of Se precipitates by X-ray powder diffraction (XRD) and scanning electron microscopy (SEM)-energy dispersive X-ray spectroscopy (EDX). XRD and SEM-EDX analyses of the Se(IV)- and Se(VI)-soil-cement slurries revealed that the key selenium bearing phases for all three soil-cement slurries were calcium selenite hydrate (CaSeO(3).H(2)O) and selenate substituted ettringite (Ca(6)Al(2)(SeO(4))(3)(OH)(12).26H(2)O), respectively.
采用稳定化/固化（S/S）工艺将亚硒酸盐（SeO(3)(2-)）和硒酸盐（SeO(4)(2-)）形式的硒固定下来。通过分别向高岭土、蒙脱石和疏浚物（DM，一种有机淤泥）中添加1000 mg/kg的每种硒化合物来制备人工污染土壤。熟化7天后，用5%、10%和15%的I/II型波特兰水泥（P）和水泥窑灰（C）对受硒影响的土壤进行稳定化处理，然后养护7天和28天。采用毒性特性浸出程序（TCLP）评估S/S处理的效果。养护28天时，10%和15%的P剂量使六个TCLP-Se(IV)浓度中的五个低于10mg/L，而在DM中只有15%的C的TCLP-Se(IV)浓度<10mg/L。几种处理满足了美国环保署TCLP最佳示范可用技术（BDAT）对硒的限值（5.7 mg/L），所用火山灰剂量比确定BDAT限值的处理低至十分之一。两种火山灰都无法将TCLP-Se(VI)浓度降低到25mg/L以下。对老化30天的硒-土壤-水泥浆进行X射线粉末衍射（XRD）和扫描电子显微镜（SEM）-能量色散X射线光谱（EDX）分析，从而鉴定硒沉淀物。对Se(IV)和Se(VI)土壤-水泥浆的XRD和SEM-EDX分析表明，所有三种土壤-水泥浆中主要的含硒相分别是水合亚硒酸钙（CaSeO(3).H(2)O）和硒酸盐取代钙矾石（Ca(6)Al(2)(SeO(4))(3)(OH)(12).26H(2)O）。
