(532a) Ultra-Rapid Elimination of Biofilms On Metal and Ceramic Surfaces Via the Combustion of a Nanoenergetic Coating

In Heat Exchangers and Cooling-Water Systems, which are an integral part of a wide variety of industrial processes, the presence of biofilms can reduce the effective heat transfer coefficient  by as much as 50%.  Biofilms consist of microbials colonies embedded on the surface of the equipment, and protected by a layer of extra-cellular polymeric substances secreted by the same microbes.

Removal of the biofilms requires that the equipment be taken “offline” and subjected to chemical and physical treatments that not only take a long time, but also require the use of toxic chemicals. Reducing the down-time for the equipment and the development of processes that do not require the use and disposal of toxic chemicals, is thus highly desirable from both economic and environmental points of view. 

We present here a novel process that uses nano-energetic materials to eliminate biofilms in just a few seconds. The process involves spray-coating of an approximately 100 µm thick layer of nano-energetic material on top of the biofilm, allowing it to dry, and igniting the dried coating to incinerate the biofilm. The nanoenergetic material used is a two component mixture consisting of aluminum nanoparticles (fuel) dispersed in a THV220A (fluoropolymer oxidizer) matrix. Upon ignition, the Al nanoparticles react with THV 220A exothermically, producing high temperatures ( > 2500K) for an extremely brief period (~100mS) that destroys the biofilm underneath, along with the bacteria harbored within. However, due to the small mass of nanoparticles present (~1 mg/cm² of coating), the total amount of heat produced is low (~0.1 KJ/cm²) and the underlying metal or ceramic surface does not suffer observable damages. Since the byproducts of the process consist only of carbonaceous residue (that can be easily washed away) and gaseous combustion products, the process is not extremely fast, but also environmentally friendly.