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 similar to 4 times) and the gas permeability decreased from 2.2 x 10(-14) m(2) to 4.8 x 10(-16) m(2) (reduce similar to 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 x 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.

In this paper, pectin-based plastic films were developed by grafting vanillin to pectin chains and introducing Fe3+ ions. The mechanical properties, thermal stability, moisture resistance, UV-light barrier property, biodegrad-ability, and practical application of fabricated plastic film were evaluated. Results confirmed the successful grafting of vanillin and the presence of hydrogen bonds and metal-ligand bonds, giving the plastic film highest fracture stress of 41.68 +/- 4.10 MPa, which was nearly 481.31% enhancement than that of neat pectin film. Additionally, the thermal stability, moisture resistance, and UV-blocking property (200-400 nm) of fabricated plastic film were significantly improved. Moreover, the plastic film exhibited satisfying processability, which can be processed to bag and appearing excellent food preservation ability. After use, the plastic film can be completely biodegradable in soil (degradation time approximate to 7 weeks) and seawater without manual interference. Thus, our proposed pectin-based plastic film can be recommended as a non-polluting and sustainable food packaging substitute.