Lindane Affinity to Silica Sand as Related to Surface Properties

Abstract

In this study, the affinity of lindane to silica sand was investigated by means of laboratory column experiments and related to lindane‐silica sand interactions, which were calculated based on independently determined lindane, silica sand, and solution surface thermodynamic properties according to the traditional and extended Deryagin‐Landav/Verivey–Overbeek (DLVO) theory. Column experiments were carried out under saturated and steady state water flow conditions and lindane's affinity to silica sand was quantified in terms of the retardation factor. In addition, impact of goethite coating of silica sand and variations in solution chemistry on Lindane's affinity were also explored. After goethite coating, lindane had negatively greater interaction free energies, and consequently, more lindane was partitioned on the solid phase as compared to uncoated silica sand. In the presence of rhamnolipid biosurfactant, lindane showed less affinity to silica sand than it did in its absence. With the increase of rhamnolipid biosurfactant concentrations, interaction free energies between lindane and silica sand increased, and consequently lindane's affinity to silica sand decreased.

Keywords:

• Lindane
• silica sand
• affinity
• rhamnolipid biosurfactant