CHEMICAL EFFECTS OF GOETHITE COLLOID ON THE TRANSPORT OF RADIONUCLIDES THROUGH A QUARTZ-PACKED COLUMN

Laboratory experiments were carried out to investigate the effects of inorganic colloids on the transport of radionuclides through quartz sa nd packed columns. Submicrometre size particles, goethite (alpha-FeOOH ), were used to represent the colloids. The radionuclides were Cs-137, N-22 and I-131 (as iodate). It was found that pH is a controlling par ameter affecting goethite transport. At low pH, goethite is strongly r etained by the quartz. At high pH, the breakthrough of goethite follow ed predictions based on the electrostatic repulsion between the colloi ds and the quartz. In addition, the flow rate and the initial goethite colloid concentration influenced the colloid breakthrough from the qu artz column. There is not any similarity between either sodium and goe thites or cesium and goethites breakthrough curves. The transport of i odate, however, is greatly altered in the presence of goethite at low pH. No such similarity was found at high pH.