Experimental study on effect of dissolved organic matter on mobility of soil colloids

Soil colloids are widely distributed in underground environment. They can facilitate or retard the migration of pollutants in soils, depending on the mobility of the colloids. By choosing the humic acid and bovine serum albumin as the typical dissolved organic matters and the bentonite colloid as the typical soil inorganic colloid, a series of colloid migration tests are carried out to investigate the effect of different dissolved organic matters on the mobility of the soil colloids under different ionic strengths. The mobility mechanism of the colloids is explored according to the DLVO theory. The results show that the mobility of the bentonite colloids decreases with the increasing ionic strength. Both the humic acid and the bovine serum albumin can facilitate the mobility of the bentonite colloid, among which the enhancement by the humic acid is more obvious than that of the bovine serum albumin. Under the same ionic strength, the mobility of the bentonite colloid in column with larger pore volume is higher than that with smaller pore volume.