Week 1 - Getting Started

Hello, this is Stuart Ness, an undergraduate intern at IEH for the summer of 2014. I will be working this year with my mentor Ali Salter-Blanc studying the Environmental Degradation of Munition Compounds. Specifically, I will be focused on the kinetics of oxidation reactions between MnO₂ and aromatic amines. Various authors have looked at the reactions of specific amines with manganese oxides, but not nearly as comprehensive a set as we hope to study.

After meeting with Ali and going over the background of our project, I started this week by synthesizing MnO₂. Many authors have synthesized MnO₂ for use in oxidation experiments before, so we had a clear recipe to follow. I created stock solutions of KMnO₄, NaOH, and MnCl₂, the required materials for our MnO₂ synthesis. Then, using the work of Laha and Luthy, I combined stoichiometric amounts of the constituents in a flask to create our MnO₂.

This initial batch of MnO₂ did not settle well in its flask, and was too large for our future purposes, so on Wednesday I modified our recipe to create 50 mL suspensions of MnO₂ in vials that could be centrifuged. After centrifuging, the supernatant was decanted and replaced with de-ionized water. The vial was centrifuged again, and the supernatant again decanted. This process was repeated four times to ensure the purity of our samples. This procedure should suit us well for MnO₂ preparation the rest of the summer.

On Thursday, I flash dried our MnO₂. We want to send our samples to Lewis and Clark so a colleague could perform x-ray diffraction (XRD) analyses to confirm we had made the correct form of MnO₂. This flash drying took a few tries, as we had to identify the correct filter paper to use, and had to modify a previous procedure used for iron compounds to properly accommodate the properties of our MnO₂. Unfortunately, this testing wasted some of our MnO₂, so I will likely have to flash dry more samples in the future to acquire enough material for the XRD.

On Friday, we began setting up the procedure to be used for our reaction experiments the rest of the summer. Our reactions will be carried out in a buffer solution of specified ionic strength to ensure that reaction conditions are essentially the same throughout the experiment’s length, and so I spent much of the day calculating the correct proportions and ingredients for the buffer.

Afterwards, I created a stock solution of 4-chloroaniline. 4-chloroaniline has been studied in reaction with MnO₂ by a few other authors, so we will be testing its kinetics first to ensure that our experimental procedure is valid and conforms to literature expectations. If these experiments prove successful, our procedure should be valid for our other compounds of interest. After creating this stock solution, Ali taught me how to use our high-performance liquid chromatograph (HPLC). This is the machine we will be using throughout the summer to measure the concentration of amines in our reaction experiments. The HPLC is relatively simple to operate, and I am excited to use it in the future to acquire data on our kinetics experiments.