Enhanced mobility of non aqueous phase liquid (NAPL) during drying of wet sand.

摘要: Enhanced upward mobility of a non aqueous phase liquid (NAPL) present in wet sand during natural drying, and the absence any external pressure gradients, is reported for first time. This was significantly higher than that expected from capillary rise. Experiments were performed glass column with small layer NAPL-saturated trapped between two layers water-saturated sand. Drying induced by flow air across top surface The movement NAPL, direction water transport, commenced when drying effect reached location NAPL continued as long there significant evaporation vicinity indicating clear correlation rise evaporation. magnitude rate measured at different rates, initial locations grain size type (on basis NAPL-glass contact angle, viscosity density). A positive observed average while negative obtained properties density. There no variation 0.1 to 0.5mm. Based on these observations previous studies literature, possible mechanisms are hypothesized -a) spreading coefficient resulting wetting films created b) moving film due "drags" upwards. this paper has implications fate transport chemicals contaminated porous media such soils exposed dredged sediment material, which subjected varying saturation levels rewetting.