Xanthan gum modification to surface and interfacial properties between soil-based matrixes and petroleum oils to minimize soil pollution

A novel approach exploiting surfaces and interfaces between liquid oils and porous soil media was used to investigate the role of xanthan gum (XG) in minimizing the spread of petroleum oil spills on land. 1.6 wt% XG added to soil-based mixture matrixes (topsoil, sand, clay, and moisture) resulted in a 50% reduction in oil spreading area at 0 and 5 wt% moisture content, at 1.3 cm depth of soil matrix. Also recorded was a 45% increase in time taken for the low- and medium-viscosity oils to penetrate this soil depth. XG alters the surface energy and roughness of the soil matrixes, which additionally contributes to a reduction in oil spreading capabilities. Interfacial phenomena between individual oil droplets and soil matrixes demonstrated variable findings of droplet spreading and penetration with XG, depending upon the heterogeneity of the soil matrix itself. XG assisted a reduced lateral spread in heterogeneous soil matrixes and a reduced vertical penetration in clay-based matrixes. These interfacial results highlighted the often-observed differing transport phenomena at the interface compared with the bulk. This initial study demonstrates a novel approach to incorporate surface energy phenomena into the suite of soil remediation efforts by introducing natural biopolymers in high-risk land oil-spill areas to slow oil contaminant spread. Future studies will further characterize the benefits of XG in containing oil flow.