Transport of montmorillonite colloid in unsaturated packed column: The combined effects of sand grain size, flow rate and colloid concentration

The transport of colloid in unsaturated porous media affects the migration contaminants and thus is closely related to groundwater resources protection. To figure out combined effects grain size, concentration injection flow rate on montmorillonite characteristics quartz sand, a total 27 sets column experiments were conducted with three kinds sand (20, 40, 60 mesh), rates (1.98, 3.96, 5.94 cm 3 /min) concentrations (300, 600, 900 mg/L), using packed columns inner diameter 11 height 40 cm. experimental results showed that Na-montmorillonite particles columnoccurred significant retention. In 20 mesh column, average peak values penetration curves for low high colloidal solutions 300 mg/L increased by 44% 27%, respectively, as from 1.98 /min. value solution 17% more than increasing rate. When was /min, effect most obvious, followed particle while least. calculation based potential energy Derjaguin-Landau-Verwey-Overbeek (DLVO) collision efficiency further explained retention colloids media.