Presentation Date: Feb 14, 2026
AGSA Abstract
Photocatalytic water treatment has been an active area of research for decades but has yet to be commercially viable. Mass transport limitations, poor light management, and high rates of recombination result in impractically low energy efficiency. Our photocatalyst consists of commercial titania nanoparticles (P25) immobilized on quartz fibers, resulting in a high surface area photocatalyst on a UV-transparent support. The high photocatalyst surface area to reactor volume ratio (940,000 m2/m3) is advantageous for overcoming limitations in photocatalysis. In this work, we achieve a high photonic efficiency of 30% for hydrogen sulfide (H2S) degradation in groundwater by overcoming long-standing limitations in heterogeneous photocatalysis. Approximately 43 million Americans, many of them in rural areas, do not have access to public water and rely on unregulated private water sources. H2S is a naturally occurring contaminant in groundwater and private wells that is difficult to remove with traditional water treatment systems. Additionally, several industrial processes generate waste streams containing dangerously high concentrations of H2S. We show that TiO2 photocatalysis is particularly efficient in removing aqueous H2S. We determine through a combination of radical scavenger tests and in-situ characterization techniques that H2S oxidation proceeds by a photohole degradation mechanism rather than bulk oxidation by reactive oxygen species. We indirectly observe H2S adsorption to P25 using in-situ Attenuated Total Reflectance Fourier Transform Infrared spectroscopy via H2O desorption and sulfate formation. Our system achieves 100% selectivity of H2S to sulfate in a single pass through the reactor with a photonic efficiency of up to 30% and an electrical energy per order of 0.1 kWh/m3. Finally, we find that operating in groundwater causes a 12% reduction in performance after 21 hours. We suspect the relatively high TOC content (> 40 mg C/L) causes the slight reduction, but a simple DI rinse fully regenerates the catalyst.
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