Bacteria are persistent and harmful in several industries, such as water treatment and distribution, food and beverage processing, cooling towers, and medical device implants. For example, Pseudomonas aeruginosa (POA) biofilms are formed naturally in the environment and can cause cystic fibrosis and other chronic lung infections. Strategies have been developed to combat the growth of biofilms on pipes, heat exchangers, membranes, medical tools and implants, and other surfaces. Electrochemical techniques offer economic and technical advantages over traditional methods, as chemical reagents are not needed for biofouling control. However, the mechanisms for bacteria inactivation on conductive surfaces under low applied potentials is not fully understood and represents a gap in understanding of biofouling control. Thus, this work is focused on POA attachment and subsequent inactivation on polarized electrode surfaces, and thus seeks to determine mechanism responsible for inactivation of bacteria for applications related to biofouling control.<br/>Different charged conductive substrates were prepared by monolayer coatings on boron-doped diamond optically transparent electrodes (BDD/OTEs) for POA biofouling control under low applied potentials ranging from -0.2 to 1.0 V (vs Ag/AgCl). These monolayers provided positively charged amine and amine/hydroxyl surface coatings that affected PAO attachment and inactivation. While PAO attachment was primarily attributed to electrostatic interactions, there were several different mechanisms responsible for PAO inactivation. These mechanisms included modification of the near surface pH, reactive oxygen species (ROS) and chlorine production, and divalent ion chelation from the PAO cell membrane. In particular, higher ratios of bacteria inactivation were observed on the functionalized surfaces relative to BDD/OTE. A mathematical model was developed that incorporated Poission-Bolzmann ion distributions, acid-basic chemistry, and surface adsorption of the bacteria surface to interpret the electrical double layer and charge at the bacteria surface as a function of variable solution conditions. Results from the mathematical model support the mechanism of divalent ion chelation as a contributing mechanism for PAO inactivation.

Biofouling control on the chelator modified conductive substrate with applying low potentials

2019 Fall National Meeting

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