(730f) Evaluation of Mucilage From the Common Cactus As a Natural Dispersant for Oil Spill Clean-Up Operations

Authors: 
Guo, F., University of South Florida
Stebbins, D. M. L., University of South Florida
Alcantar, N., University of South Florida
Peng, T., University of South Florida



The purpose of this work is to assess the Opuntia ficus-indica (Ofi) cactus plant-based mucilage as a natural oil dispersant. We have evaluated the biodegradation and efficiency of cactus mucilage to disperse crude-oil in sweet and salty environments. We have also determined that this material is non-toxic to cold blooded animals because the median lethal dose (LD50) of cactus mucilage was found to be large (i.e., above 1000 mg/kg). Cactus mucilage is natural biomaterial that has up to 55 sugars, mainly arabinose, galactose, rhamnose, xylose, glucose, and uronic acids. The extraction process is relatively simple, and yields two types of mucilage: the non-gelling extract (NE) and the gelling extract (GE). The characterization of dispersed oil-mucilage droplets in oil/water emulsions was evaluated by transmission electron microscopy (TEM), optical microcopy and UV-VIS spectroscopy. Mucilage aids the dispersion and stabilization of oil droplets by lowering the surface tension and maintaining the interfacial forces differential close to zero. Biochemical oxygen demand (BOD) was also assessed in seawater samples with crude oil (0.5 to 50 g/L) using concentrations of mucilage ranging from 0.5 to 2000 mg/L. Studies have also shown that mucilage increased biodegradation of the crude oil in seawater samples by adding a readily available source of carbohydrates to the system. The toxicity of the mucilage extracts were performed by a standard test using Daphnia magna organisms at room temperature. Daphnia colonies were exposed to both NE and GE mucilage extracts in concentrations ranging from 0 to 5000 mg/L. After 24 hours, the number of living organisms in each the test group was determined. It was observed that mucilage did not influence Daphnia magna colonies at all. Cactus mucilage is readily available through sustainable agriculture, it is inexpensive to extract, and has exhibited a long shelf live. Therefore, 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.

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