胶态微泡沫在非饱和多孔介质中的迁移规律及影响因素

传统原位土壤淋洗修复存在淋洗效率低、淋洗液迁移难控制、污染范围易扩大的弊端。胶态微泡沫（CGAs）密度轻、粒径小、流动性好，可以有效解决传统液相淋洗修复中的问题。在修复过程中，压力作为一项重要的指标，可以有效地反映CGAs在介质中的迁移分布；因而本研究通过一维和二维动态模拟实验探讨了介质粒径、介质含水量、聚合物（黄原胶）添加等对土壤修复体系压力的影响以及CGAs在土壤中的运移规律。研究表明：随着介质粒径、介质含水量、黄原胶质量浓度的增大，体系中压力总体呈现降低趋势；CGAs从模拟槽一侧单点注入介质时，其在介质中的迁移轨迹呈现近似半圆形，在覆盖区域分布均匀，能够有效克服重力对其迁移分布的影响；随着介质粒径的增大，CGAs在介质中的波及效率先增大后减小，介质粒径为0.8~1.0 mm时波及效率最大，为34.77%；随着含水量的增加，CGAs的波及效率随之增加；黄原胶的添加有效增加了CGAs在介质中的波及效率，黄原胶质量浓度为500 mg/L时CGAs波及效率最大，为40.28%，是未添加黄原胶时的1.48倍。

Migration Characteristics of CGAs and the Influencing Factors in Unsaturated Porous Media

Traditional surfactant flushing technology has some disadvantages such as low elution efficiency, difficult control of liquid transport, and contaminated area extension. Colloidal gas aphrons (CGAs) can effectively avoid these problems with the characteristics of light density, small particle size, and good fluidity. Pressure can be used as a crucial parameter in the remediation process to efficiently reflect the CGAs migration distribution. One-dimensional and two-dimensional models were designed in this research to discuss the effects of medium grain size, moisture content, and polymer (xanthan gum) addition on the pressure of the system and the transport patterns of CGAs in soil. The results demonstrated that with the increase of the medium grain size, moisture content, and xanthan gum concentration, the pressure of the system decreased. Besides, the results of the CGAs injection into soil from a single point on one side of the simulated tank indicated that the migration traces in the medium was nearly semicircular and CGAs distributed uniformly in the coverage area, which effectively overcame the influence of gravity to its distribution in the medium. With the increase of medium grain size, the CGAs sweep efficiency increased first and then decreased. The maximum value of sweep efficiency reached 34.77% when the medium grain size was 0.8-1.0 mm. The moisture content augmentation of the medium also stimulated the increase of the sweep efficiency. Moreover, the addition of xanthan gum significantly improved the sweep efficiency of CGAs:when the mass concentration of xanthan gum was 500 mg/L, the sweep efficiency reached 40.28%,which is 1.48 times greater than that without xanthan gum addition.