סמינר מחלקתי Adi Radian

School of Mechanical Engineering Seminar
Monday, March 16, 2015 at 15:00
Wolfson Building of Mechanical Engineering, Room 206

Harnessing material chemistry and microbiology to develop self-regenerating remediation solutions

Adi Radian

Department of Mechanical Engineering, University of Minnesota

Widespread pollution of water and soil are among the greatest challenges we face today. Yet, most remediation strategies offer only a partial solution; requiring follow-up steps to regenerate the system and leaving concentrated byproducts that need further processing. Developing self-regenerating materials that remove and biodegrade pollutants is therefore highly advantageous. Presented here are two examples of such materials which are composed of biodegrading bacteria encapsulated in functionalized silica gel matrices:

A phenyl-functionalized silica-gel, containing hydrophobic microspherical patches with adhered biodegrading bacteria, was developed to clean-up hydrophobic pollutants from water. The patches strongly and rapidly adsorb the pollutants and facilitate their diffusion to the adhering degrading bacteria - constantly freeing up binding sites and regenerating the material.

An Amine-functionalized silica gel was developed to protect encapsulated cells from bleach oxidation. Tricloro is a widely used water disinfectant that generates bleach and the byproduct cyanuric acid. Removal of this byproduct is crucial for safe disinfection and can be achieved with certain soil microorganisms. However, these microorganisms are susceptible to the Tricloro whose job is, after all, to kill them. We demonstrate a solution to the problem by engineering the cyanuric acid degrading enzyme to be highly bleach resistant. Furthermore, we encapsulate the bacteria in a silica gel functionalized with amine groups which act as sacrificial reactive sites creating a protective barrier. The resulting system can withstand ten times higher amounts of bleach compared to free cells in solution.