Gas permeability and microscopic mechanisms of Xanthan gum-amended compacted lean clay as a gas barrier material

IF 6.9 1区工程技术 Q1 ENGINEERING, GEOLOGICAL

Engineering Geology Pub Date : 2025-04-28 DOI:10.1016/j.enggeo.2025.108095

Ying-Zhen Li , Jia-Lei Wan , Fei Jin , Krishna R. Reddy , Ning-Jun Jiang , Yan-Jun Du

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Abstract

Compacted clays are extensively used as cover barriers to control rainfall infiltration and upward migration of greenhouse gases at municipal solid waste landfills and volatile organic compounds at industrially contaminated sites. Xanthan gum (XG) amendment offers a green and low-carbon solution to improve gas breakthrough pressure and reduce gas permeability of compacted clays, sustainably improve earthen structures. This study aimed to systematically investigate the effects of XG amendment on gas breakthrough pressure, gas permeability, and hydraulic conductivity of compacted clay liners. The gas breakthrough pressure increased from 0.6 kPa to 2.2 kPa (improve ∼4 times) and the gas permeability decreased from 2.2 × 10⁻¹⁴ m² to 4.8 × 10⁻¹⁶ m² (reduce ∼200 times) when the XG dosage increased from 0 % to 2 % and apparent degree of saturation was 100 %. Hydraulic conductivity of XG-amended soil at 1 % XG dosage was 2.6 × 10⁻¹⁰ m/s, which was 3 % of the value measured in unamended soil. Mechanisms of enhanced gas barrier and hydraulic performance were interpreted by the combined effects of (i) soil pore filling substantiated by the analyses of scanning electron microscopy and pore size distribution; (ii) high viscosity of XG hydrogels, validated by the measurement of rheological properties; and (iii) increased diffuse double layer thickness of the amended soils evidenced by the zeta potential analysis.

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黄原胶改性压实稀粘土阻气材料的透气性及微观机理

压实粘土被广泛用作覆盖屏障，以控制城市固体废物填埋场的降雨入渗和温室气体的向上迁移，以及工业污染场地的挥发性有机化合物。黄原胶（XG）改进剂提供了一种绿色低碳的解决方案，可以提高气体突破压力，降低压实粘土的透气性，可持续改善土质结构。本研究旨在系统研究XG添加剂对压实粘土衬层气侵压力、透气性和水力导电性的影响。当XG添加量从0%增加到2%，表观饱和度为100%时，瓦斯突破压力从0.6 kPa增加到2.2 kPa（提高~ 4倍），渗透率从2.2 × 10−14 m2下降到4.8 × 10−16 m2（降低~ 200倍）。XG添加量为1%时，XG改良土壤的水导率为2.6 × 10−10 m/s，为未改良土壤的3%。通过扫描电镜和孔隙尺寸分布分析，分析了土体孔隙填充对气阻和水力性能增强的影响机制；（ii）高粘度的XG水凝胶，通过流变特性的测量验证；(3) zeta电位分析表明，改性土壤的扩散双层厚度增加。

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来源期刊

Engineering Geology 地学-地球科学综合

CiteScore

13.70

自引率

12.20%

发文量

327

审稿时长

5.6 months

期刊介绍： Engineering Geology, an international interdisciplinary journal, serves as a bridge between earth sciences and engineering, focusing on geological and geotechnical engineering. It welcomes studies with relevance to engineering, environmental concerns, and safety, catering to engineering geologists with backgrounds in geology or civil/mining engineering. Topics include applied geomorphology, structural geology, geophysics, geochemistry, environmental geology, hydrogeology, land use planning, natural hazards, remote sensing, soil and rock mechanics, and applied geotechnical engineering. The journal provides a platform for research at the intersection of geology and engineering disciplines.