Dispersant Lab Report

Laboratory tests are relatively simple to use and they are used to evaluate performance of dispersants and study chemical and physical mechanisms of dispersion. They have been used also for dispersant screening (Blondina, et al., 1997) (Venosa, et al., 1999) (Sorial, et al., 2001) (Venosa, et al., 2002), comparing different oil-dispersant combinations (Fingas, et al., 1991) (Moles, et al., 2002) (Venosa, et al., 2002) (Stevens, et al., 2003) and studying effects of oil composition and environmental conditions to dispersant effectiveness (Belk, et al., 1989) (Fingas, et al., 1991) (Blondina, et al., 1999) (Canevari, et al., 2001) (Moles, et al., 2002) (White, et al., 2002) (Chandrasekar, et al., 2003). Although it is difficult to quantitatively

There is a 9 cm in diameter aluminum containment ring in the center of the glass vessel to constraint on the surface the oil and dispersant, during preparation phase of an experiment. The oil is added to water surface in the center of the containment ring. After that, the dispersant is added to oil inside containment ring and soaked for one minute before the air inflow. As soon as airflow starts, the containment ring is removed. Air is provided tangentially over water surface with velocity between 6 and 20 m/s to mix and create 2 to 4 cm surface waves. After 10 minutes of mixing, the water is sampled from the point located 3 cm from the bottom and 2 cm from the wall of glass vessel. The sampling is done without stopping the airflow. The dispersed oil is extracted with methylene chloride and concentration is measured by absorbance in 580 nm light (Mackay, et al., 1978). It was found that, observed dispersion efficiency was highly sensitive to air inflow rate and angle of entry (Mackay, et al., 1978) (National Research Council, 1989). Some of the researchers questioned the reproducibility of this test (Fingas, et al., 1989) (Fingas, et al.,

The Swirling flask test uses 120 ml of seawater and 0.1 ml of oil. The 0.1 ml oil added into 120 ml of seawater in a modified 125 ml Erlenmeyer flask with side spout. Dispersant is added onto the oil surface floating on water surface. Another variant is to premix the dispersant with oil and adding them to water (Sorial, et al., 2001). Then, the flask is put on shaker table and mixed at 150 rounds per minute before allowing them to settle for 10 minutes. After settling, the water sample is poured from side spout which is connected to the bottom of the flask. Some researchers reported better reproducibility with modified flask where stopcock is installed at the bottom of the flask, instead of side spout to pour the water sample (Blondina, et al., 1997) (Sorial, et al., 2004a) (Sorial, et al., 2004b). The dispersed oil in the removed water sample is extracted into methylene chloride for further analysis. Then, the oil concentration is evaluated using 340, 370 and 400 nm light absorbance (Environmental Protection Agency,