Falling Iron

This week I shifted gears.  Instead of working with environmental water samples I was given the opportunity to work with a graduate student in Dr. Tratnyek's lab named Dimin.  He is working with nano zero valiant iron (nZVI).  The overall practical use of his project is the injection of nZVI particles into the ground.  These particles are very reactive and can be used to remove contaminants from groundwater.  However, these particles are so reactive that they sometimes only travel a few centimeters after release before they react and are used up.  By adding a certain compound into the mix (lets call it X), the nZVI is coated.  This coating acts almost like slow release drug capsules.  They basically aid in the nZVI particles staying reactive longer by limiting the surface area available for reaction.
For this project I measured the settling of nZVI without compound X and with X at various concentrations.  I did this by using a spectrophotometer to measure the absorbance of light at 508 nm, the wavelength that these particles are known to absorb light.  By measuring and recording absorbance over time, a settling curve can be made.  This curve will be useful in determining how long the nZVI can stay in suspension, and therefore possibly can tell how far they will be able to travel once injected into the ground.
The rest of the week was spent analyzing this data and also taking sample measurements in the DLS.  While no conclusions are yet available, I have high hopes that the resulting settling curves will agree with the theory that nZVI with higher concentrations  of X will take longer to settle.  It would be very interesting if a concentration of X was found that resulted in a steady suspension of nZVI.