CAREER: Accelerating sustainable water treatment using smart ultraviolet light emitting diodes

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Over the past few decades, light emitting diodes, or LEDs for short, have become a common feature in nearly every home. More recently, researchers have created LEDs that can shine high-energy ultraviolet (UV) rays. UV rays have been widely used in various fields, including in the water treatment industry to kill germs and to remove pollutants in water. However, the adoption of UV technology in the water industry has been hindered by relatively higher cost and low energy efficiency. UV LEDs have many advantages over existing UV light technology due to greater energy efficiency, greater durability, lower cost, and ability for digital interfacing. The goal of this CAREER project is to develop the first Smart UV LED systems utilizing novel rapid pulsed UV LEDs. This will be achieved through a series of experiments to understand the mechanisms for UV catalyzed chemical reactions to kill pathogens and degrade pollutants. Successful completion of this research will provide benefits globally through the development of hand-held devices for more efficient treatment of water at lower cost in remote places. This research will be integrated with an education program focused on engaging middle and high school students in STEM activities to increase scientific literacy. College students will have opportunities for study abroad trips to developing countries to test new devices while training graduate students to perform cutting edge scientific experiments. The overall goal of this project is to develop a mechanistic understanding of UV-LED catalyzed photochemical reactions to enable the design of Smart UV-LED technologies. Specifically, the research objectives are to: 1) identify and select for specific radicals produced during chlorine photolysis to optimize micropollutant degradation in complex water matrices; 2) harness the ability to apply a duty cycle to UV-LED lamps to enhance UV and chemical-UV disinfection processes to disrupt cellular repair and achieve targeted damage of cellular components; and 3) to include high school research interns, undergraduates, and graduate students in the process of designing and testing novel UV-LED devices for application in developing countries. The project will be accomplished using custom-designed LED photoreactors, a suite of state-of-the-science radical characterization techniques based on electron spin resonance spectroscopy, and microbiological assays to elucidate the underlying mechanisms of cellular disruption. Portable, Smart UV-LED devices will be constructed using Arduino microcontrollers to control the pulse frequency and duty cycle. Together, these improvements will pave the way for the next leap forward in sustainable water treatment, water reuse, and point-of-use technologies. Successful completion of this research will have potential to contribute to fundamental scientific advancement in related fields such as polymer curing and photolithography. The research will be tightly integrated with STEM education and outreach efforts to train and encourage the next generation of leaders in water science and technology.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.