疏水改性石灰对土壤中高浓度硝基苯的强化固定

石灰是一种常见的应用于污染土壤固化稳定化的水硬性胶结材料,但对于紧急事故情况下释放到土壤中的高浓度毒性有机物的固定能力十分有限.为了增强石灰对于毒性有机物的定向捕获的固定能力,本研究用硬脂酸对石灰进行疏水改性,并通过分散性实验、粒度测试、扫描电镜测试、红外光谱测试和接触角测试对改性前后的石灰进行表征.然后用改性石灰对硝基苯含量为8163 mg·kg~(-1)的污染土壤进行固化稳定化实验,测试在固化稳定化过程中硝基苯的挥发率和浸出率.结果表明,与不添加石灰的空白组和只添加30%未改性石灰的对照组相比,添加20%的改性石灰和10%的未改性石灰,可分别减少94.44%和88.46%的硝基苯挥发量,99.10%和88.11%的酸浸出条件下的硝基苯浸出量,及98.51%和59.74%的水浸出条件下的硝基苯浸出量.经硬脂酸疏水改性后的石灰可作为定向捕获快速固定土壤中高浓度毒性有机物的固化剂.

Hydrophobilized modification of lime and its enhanced solidification/stabilization of nitrobenzene-contaminated soil

Lime is a common hydraulic binder used in solidification/stabilization of contaminated soil. However, lime encapsulation is not effective to capture high-concentration toxic organic compounds released accidentally for emergency response. In order to enhance lime''s performance to capture and immobilize toxic organic compounds, lime powder was hydrophobilized by stearic acid, and characterized with contact angle, scanning electron microscopy, Fourier transform infrared spectroscopy, particle size and dispersivity tests. Then the hydrophobilized lime was used to stabilize simulated soil contaminated by nitrobenzene with the average concentration of 8163 mg·kg^-1, and its effects on reducing volatilization and leaching of nitrobenzene were investigated. The results showed that 20% (lime to soil) hydrophobilized lime and 10% raw lime (lime to soil) addition reduced volatilization by 94.44% and 88.46%, acid leaching by 99.10% and 88.11%, and water leaching by 98.51% and 59.74%, compared with the blank (with no lime addition) and the control (with 30% raw lime addition). Lime hydrophobilized by stearic acid could be an efficient material to capture and immobilize high-concentration toxic organic compounds in contaminated soil.