聚合物
浸出(土壤学)
硫化物
粉煤灰
溶解度
铬
化学
盐(化学)
无机化学
硫化钠
核化学
冶金
废物管理
材料科学
有机化学
环境科学
土壤水分
土壤科学
工程类
作者
Jian‐Guo Zhang,John L. Provis,Dingwu Feng,J.S.J. van Deventer
标识
DOI:10.1016/j.cemconres.2008.01.006
摘要
The use of fly ash-based geopolymer binders to immobilize chromium is investigated in detail, with particular regard to the role of the sulfide ion as a reductant for Cr(VI) treatment. In the absence of sulfide, Cr added as Cr(VI) is highly leachable. However, addition of a small quantity of Na2S reduces the Cr to Cr(III), and enables leaching efficiencies in excess of 99.9% to be reached after 90 days' exposure to deionized water, Na2CO3 or MgSO4 solutions. Leaching in H2SO4 is somewhat greater than this, due most probably to the oxidation of the Cr(III) present. Addition of the Cr(VI) as a highly soluble salt is preferable to its addition as a sparingly soluble salt, because a higher salt solubility means the Cr(VI) is more available for reduction prior to geopolymeric setting. The potential value of geopolymer technology as an immobilization process for problematic heavy metal waste streams is highlighted by these results, and the need for a full understanding of binder chemistry in any immobilization system outlined.
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