摘要
采用硫酸亚铁(Fe SO_4)对铬污染土进行稳定化处理。基于浸出试验、碱性消解和改进BCR形态提取试验,研究了p H和粒径对铬污染土稳定性能的影响规律。试验结果表明,粒径和p H对铬污染土稳定性能有较大影响,随着粒径的降低,Cr(Ⅵ)、总Cr的浸出浓度和Cr(Ⅵ)含量均降低,粒径的降低可促使铬从弱酸态(F1态,活性态)向可还原态(F2态,较稳定态)转化。Cr(Ⅵ)浸出浓度和Cr(Ⅵ)含量均随着p H降低而降低,而总Cr的浸出浓度呈相反的变化规律。p H对铬形态分布存在临界值,当p H高于临界值时,随着p H的降低,稳定土中F1、F3态铬含量显著降低,F2态铬含量明显增加;当p H低于临界值时,p H的降低稳定土中F1态铬含量明显增加,F2、F3态铬含量显著降低。铬赋存形态的变化是铬污染稳定性能变化的本质原因。
Ferrous sulfate(Fe SO_4) is used to stabilize chromium-contaminated soils. Leaching test, alkaline digestion test and sequential extractions test are conducted to investigate the variation of stabilize properties of Fe SO_4 treated chromium-contaminated soils along with particle size and p H. The results show that the leaching concentration(hexavalent chromium and total chromium), hexavalent chromium content of the soil are decreased significantly with particle size decreased. Sequential extractions test show that: with the decreased of particle size, the weak acid soluble fraction(F1) of chromium content decreased, while the reducible(F2) and oxidisable(F3) changed oppositely. The hexavalent chromium leaching concentration and hexavalent chromium content were decreased significantly with p H decreased; while the total chromium leaching concentration changed oppositely. There is a threshold value for p H in terms of its influence on chromium speciation. The weak acid soluble and oxidisable fraction of chromium content decreased with the p H decreased before its reached the threshold value; while the reducible changed oppositely. The weak acid soluble of chromium content increased with the p H decreased after its reached the threshold value; while the reducible and oxidisable fraction changed oppositely. The changing in stabilized properties and risk assessment of stabilized soil can be attributed to the change of chromium speciation.
出处
《岩土力学》
EI
CAS
CSCD
北大核心
2017年第S2期82-88,共7页
Rock and Soil Mechanics
基金
国家自然科学基金(No.41602315
No.51479194)
湖北省自然科学基金(No.2016CFA082)
湖北省科技支撑计划项目(No.2015BCA252)~~
关键词
铬污染土
稳定化
浸出特性
形态演化
chromium contaminated soil
stabilization
leaching properties
speciation evolution
