(251d) Cactus Based-Mucilage As an Alternative Natural Dispersant for Oil Spill Clean-up Operations

Authors: 
Guo, F., University of South Florida
Peng, T., University of South Florida
Stebbins, D. M. L., University of South Florida
Zhao, W., University of South Florida
Falahat, R., University of South Florida
Thomas, S., University of South Florida
Toomey, R., University of South Florida
Alcantar, N. A., University of South Florida

The effect of the cactus plant-based mucilage was evaluated on the toxicity, surface tension, droplet size and stability of dispersed crude oil in oil/water emulsions. The mucilage is extracted from the cactus plant, and the extraction process yields two types of mucilage: the non-gelling extract (NE) and the gelling extract (GE). A standard EPA toxicity test using Daphnia magna colonies exposed to both NE and GE mucilage extracts in concentrations ranging from 0 to 5000 mg/L has shown that mucilage can be classified as non-toxic to the evaluated species with a LC50 above 2000 mg/L. Cactus mucilage extracts and conventional dispersants has been evaluated by testing the surface tension and measuring the droplet size of oil/water emulsions under different concentrations, including three concentrations of oil (3, 6, 30% v/v) and several dispersant to oil ratios (1:1, 1:3, 1:10). Synthetic seawater and surrogate oil from BP were used. The results of the dispersion obtaned using mucilage extracts were compared with using conventional dispersants, Corexit 9500A. The surface tensions of emulsions with cactus mucilage were similar as with Corexit. The average droplet size were smaller in the systems with cactus mucilage (1.5% of NE has generated 5 µm droplets) when compared with the systems using the Corexit (1.5% of EC9500A has formed 6.2 µm droplets). In addition, baffled flask test will be perfomed to further test the dispersion effectiveness. Cactus mucilage is readily available through sustainable agriculture, it is inexpensive to extract, and has exhibited a long shelf live. Cactus mucilage can be an alternative technology to mitigate the damage that oil may cause to the aquatic ecosystem and minimize undesired effects associated with the use of synthetic dispersants in oil spills.