Objective/Goals: Organophosphate pesticides often end up in the ocean as they frequently used in agriculture and landscaping. These pesticides greatly harm marine life as many species such as the manatee lack the PON1 gene that allows them to filter the organophos phates out of their blood. However, these pesticides can be removed. The objective of my project is to use magnetic nanopar ticles suspended in a liquid, ferrofluid, to magnetize and remove these pesticides from ocean water.

Methods/Materials: Ferrofluid Synthesis: The iron oxide nanoparticles were made by heating 7M ammonia hydroxide and adding a mixture of iron (II) and iron (III) chloride solution dropwise; this resulted in the formation of the particles of -10 nm in diameter. Then, citric acid was added as a surfactant, which prevented the particles from clumping up together. The particles were then sus pended through a decanting process, which involved rinsing the particles with de-ionized water. Finally, oleic acid was added as a second surfactant, which gave the particles a nonpolar coating and allowed them to interact with the pesticide.

Quantification: The pesticide was quantified through a spectrophotometric method that used a reaction with cerium (IV) sul fate. Cerium (IV) sulfate and 5M sulfuric acid were added to the sample of temefos pesticide solution and were left to sit for 10 minutes. Following this, methyl orange was added and the solution was left to sit for 5 minutes. The spectrophotometer was calibrated with a sample prepared the same way, but with 1 mL of water instead of methyl orange and then methanol in stead of pesticide. The absorbance was then measured at 508 nm. When there is no pesticide the cerium (IV) sulfate would bleach the methyl orange, however, when more pesticide was present the cerium (IV) sulfate would attack the pesticide rather than the methyl orange resulting in a sample with a higher absorbance. A standard curve was then created with values of 0,5, 10, and 15ug/mL of temefos.

Testing: To test the ferrofluid, a solution of 35 ppt salt and 40 ppm pesticide water was created. The quantification method was then used to test for the amount of pesticide in the water. One gram of ferrofluid was added to 125 mL of the pesticide ocean water. The ferrofluid was mixed and left in for 30 seconds, and then a magnet in a ziploc bag was ran through the water to collect the ferrofluid. The quantification method was ran again against a blank prepared the same way, but with water that ferrofluid was ran through which accounted for slight discoloration of the treated water,

Results:

The ferrofluid was able to remove pesticide an average of 4.46 ug/mL of pesticide and about 79.5% of the ferrofluid was re covered, T-tests of drastically significance (with 95% confidence interval) show significant differences (p=.0274) between the before and after treatment water samples.

Conclusions: Ferrofluid is able to successfully magnetize and remove organophosphates from the ocean water. It has the potential to significantly help marine life, especially the animals that lack the ability to filter these pesticides from their system and are greatly impacted by exposure to pesticides. Future studies include testing different environmentally friendly carrier fluids, different amounts of ferrofluid, and methods to reuse the ferrofluid.