Purpose

The remediation of diesel-contaminated hydrophobic soil is difficult due to the inability of aqueous phase remedial agents to infiltrate the soil. This novel laboratory study enhanced the gravity-driven infiltration of water and oxidant solution into the hydrophobic soil by pretreatment. For this purpose, the hydrophobic soil was pretreated (partially liquid saturating) using 0.1% sodium hexa-metaphosphate (Na-HMP) and 0.5% alpha olefin sulfonate (AOS).

Methods

The diesel-contaminated soil (34,167 ± 560 mg TPH/kg) was partially saturated with 0.5 pore volumes of Na-HMP and surfactant mixture solution. The infiltration experiment of the pretreated soil was conducted by pouring a solution (water/oxidant) provided from the Marriott reservoir over the digital balance.

Results and discussion

This study did not observe any natural infiltration of water or oxidant reagent into the diesel-contaminated soil. After the pretreatment, the cumulative infiltration of water to the pretreated soil increased to 5.17 cm after 40 min. The natural infiltration occurred due to the dispersion of soil particles and reduction of hydrophobicity by the Na-HMP and AOS, respectively. Widened soil pores were observed after pretreatment using the scanning electron microscopy (SEM) analysis. The infiltration of 5% Na₂S₂O₈ solution was 5.80 cm after 40 min when the diesel-contaminated soil was pretreated with 0.1% Na-HMP and 0.5% AOS.

Conclusions

Pretreatment using Na-HMP and AOS can enhance the remediation of highly hydrophobic and low-permeability soils. This finding can provide an insight into enhancing the soil remediation efficiency by increasing the gravity-driven uniform delivery of the remediation agent into the undisturbed soil.

Graphical abstract

中文翻译：

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使用表面活性剂和六偏磷酸钠（Na-HMP）预处理柴油污染的疏水性土壤，以改善水相修复剂在非饱和土壤中的渗透

目的

由于水相修复剂无法渗透到土壤中，因此很难修复被柴油污染的疏水性土壤。这项新颖的实验室研究通过预处理增强了重力驱动的水和氧化剂溶液向疏水性土壤的渗透。为此，使用0.1％的六偏磷酸钠（Na-HMP）和0.5％的α-烯烃磺酸盐（AOS）对疏水性土壤进行预处理（部分进行液体饱和）。

方法

柴油污染的土壤（34,167±560 mg TPH / kg）用0.5孔体积的Na-HMP和表面活性剂混合溶液部分饱和。通过将万豪水库提供的溶液（水/氧化剂）倒入数字天平上，进行预处理过的土壤的渗透实验。

结果和讨论

这项研究没有观察到水或氧化剂自然渗透到被柴油污染的土壤中。预处理后，经过40分钟后，水对预处理土壤的累积渗透增加至5.17 cm。天然的渗透是由于土壤颗粒的分散和Na-HMP和AOS的疏水性降低所致。预处理后，使用扫描电子显微镜（SEM）分析观察到土壤孔隙变宽。当用0.1％Na-HMP和0.5％AOS预处理被柴油污染的土壤时，40分钟后5％Na ₂ S ₂ O ₈溶液的渗透为5.80 cm。

结论

使用Na-HMP和AOS进行预处理可以增强对高疏水性和低渗透性土壤的修复。该发现可以通过增加将补救剂向不受扰动的土壤中的重力驱动的均匀输送来增强土壤修复效率。

图形概要