Biopolymers have attracted much attention in the field of geo-environmental engineering as they provide a carbon–neutral alternative for soil stabilization and heavy metal removal. This study explores the possibility of using guar gum-stabilized soil (GGSS) as a landfill liner by improving the hydromechanical behaviour and heavy metal attenuation capacity of the poorly graded sand–clay mixture. The results demonstrate that the unconfined compressive strength improved by 1.75 folds, and hydraulic conductivity after 120 days of curing decreased by 2.72 × 10⁵ folds at 2% guar gum addition. Additionally, it withstands adverse environmental conditions and increases the heavy metal attenuation capacity of the soil. Leachate studies show that GGSS has a good capacity to adsorb heavy metals like lead, copper, cadmium and zinc. Micrographs from the scanning electron microscope demonstrate gel plug formation and bioclogging in the soil matrix with the addition of guar gum leading to favorable modifications in the geotechnical properties of the stabilized soil. The durability of the stabilized soil strongly depends on the biopolymer concentration. The soil stabilized with a higher dosage shows better resistance against alternate cycles of wetting and drying than lower dosages due to weak inter-particle connection. Guar-stabilized soil is also more economic than conventional bentonite liners. The study demonstrates that guar gum can be considered as an ideal liner material for landfills with specific advantages like replacing a nonrenewable material, bentonite with clean and renewable material, guar gum.

Graphic abstract

中文翻译：

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瓜尔胶稳定的土壤：用于垃圾填埋场的清洁，可持续，经济的替代衬垫材料

生物聚合物在地质环境工程领域引起了极大的关注，因为它们为土壤稳定和重金属去除提供了碳中和的替代方法。这项研究探索了通过改善低梯度砂土混合物的水力学行为和重金属衰减能力，将瓜尔胶稳定土（GGSS）用作垃圾填埋场的可能性。结果表明，无边压缩强度提高了1.75倍，固化120天后的水力传导率降低了2.72×10 ⁵瓜尔胶添加量为2％时可折叠。此外，它可以承受不利的环境条件并增加土壤中重金属的衰减能力。渗滤液研究表明，GGSS具有很好的吸附重金属的能力，例如铅，铜，镉和锌。扫描电子显微镜的显微照片表明，在添加了瓜尔胶的情况下，在土壤基质中形成了凝胶塞并发生了生物堵塞，从而导致了稳定化土壤的岩土特性发生了有利的变化。稳定土壤的耐久性在很大程度上取决于生物聚合物的浓度。由于颗粒间的连接较弱，与较低的剂量相比，以较高的剂量稳定的土壤表现出更好的抵抗湿润和干燥交替循环的能力。瓜尔胶稳定的土壤也比传统的膨润土衬里更经济。

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