Moving into Week 4: Design Specifications and Lab Work

As week 4 begins, the team has been busy researching our approach to the filtration problem. Polyethylene Oxide has been assigned by our adviser for us to spin. Polyethylene Oxide has been spun in the lab many times and can be easily spun when dissolved in water. The parameters for the setup had to be researched in order to give a direction to our lab work. There are several parameters that must be taken into account for the process to work efficiently. These parameters include the distance between the needle and the collector, the voltage, humidity, area of the target on the collection plate, molarity of the polymer solution, the temperature of the room and several others. These parameters must be met in order to create the optimal fiber length, diameter and density of the mat. Through our research, we have decided that the best approach to design a semi-permeable membrane capable of effectively filtering water would include using fibers of a small diameter that are densely packed. This approach will give the most effective water filtration properties. Nano-filtration can filter out particles as small as .001 micrometers (see below).

Source: http://www.dowwaterandprocess.com/products/uf/mfs.htm

The many contaminants found in water are of all different sizes and molecular compositions. We have chosen nano-filtration because it is effective at filtering a wide array of particles of different sizes. Polyethylene Oxide is being used to create the nano-fibrous mats in the hope that filtration of bacteria, macromolecules, pharmaceuticals, and other contaminants can be effectively filtered.

 Source: http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=1657971

The images above display scanning electron microscope (SEM) images of different PEO fibers. These fibers have different diameters and fiber densities which have an effect on the porosity of the mat.

If the weather holds up, we hope to begin spinning in the lab tomorrow. The problem is that humidity has a large effect on the electrospinning process. High humidity levels will make it difficult to spin the PEO in water. Desirable humidity is below 50% and above 70%, fibers will not effectively form.