Light-Environment Interactions

Our lab integrates knowledge from a variety of disciplines including physics, chemistry, biology, and public health. This allows us to look at persistent environmental problems from new angles. Research efforts span the intersection of materials science and environmental engineering, with particular focus on the detection and removal of chemical and biological contaminants in water using sunlight, engineered light sources, and light-activated nanomaterials. The research is motivated by a desire to create a healthier and safer environment with cleaner air, water, and natural landscapes.

Below are highlights from a few on-going projects in the lab:

Understanding Viral Photoinactivation Mechanisms

High energy UV lamps are widely used for disinfection and sunlight is a known biocide. The spectral shape, intensity of the light, and pathogen type are major determining factors in the photoinactivation response, with viral pathogens tending to be the most resistant. Yet, there is a paucity of literature on viral responses to photoinactivation. Since exposure to light is an important avenue for controlling viruses in both natural and engineered systems, there is a need to further our understanding of these wavelength dependent inactivation mechanisms.

Related Publications:

  • Loeb, S. K.; Jennings, W. C.; Wigginton, K. R.; Boehm, A.B. (2021) Sunlight Inactivation of Human Norovirus and Bacteriophage MS2 using a Genome-Wide PCR-Based Approach and Enzyme Pre-Treatment. Environmental Science and Technology, 55 (13), 8783–8792.

  • Chen, J.; Loeb, S. K..; Kim, J. H. (2017) LED Revolution: Fundamentals and Prospects for UV Disinfection Applications. Environmental Science: Water Research & Technology, 3 (2), 188-202.

Plasmonic Enhanced Solar Photocatalysis for Disinfection and Environmental Remediation

Harnessing solar energy for water treatment is a highly desirable approach to provide safe water in resource limited locations. The preferred photocatalytic materials for water treatment applications have a relatively wide bandgap that is not ideal for solar applications. Nanomaterials exhibiting surface plasmon resonance (SPR) can act as light antennae when incoming resonant light radiation generates an intense electric-field enhancement leading to absorption cross-sections many times greater than the size of the particle. There exists a recognized opportunity to couple small SPR nanoparticles with photocatalytic semi-conductors to enhance photocatalysis by improving light absorption, but a disconnect between material design and proposed application has limited their application in environmental technologies.

Related Publications:

  • Loeb, S. K.; Alvarez, P. J. J.; Brame, J. A.; Cates, E. L.; Choi, W.; Crittenden, J.; Dionysiou, D. D.; Li, Q.; Li-Puma, G.; Quan, X.; Sedlak, D. L.; Waite, T. D.; Westerhoff, P.; Kim, J. H. (2018) The Technology Horizon for Photocatalytic Water Treatment: A Sunrise or Sunset? Environmental Science & Technology, 53 (6), 2937-2947.

  • Loeb, S. K.; Kim, J.; Jiang, C.; Early, S. L.; Wei, H.; Li, Q.; Kim, J. H. (2019) Nanoparticle Enhanced Interfacial Solar Photothermal Water Disinfection Demonstrated in 3-D Printed Flow-Through Reactors. Environmental Science & Technology, 53 (13), 7621-7631.

  • Wei, H.; Loeb, S. K.; Halas, N. J.; Kim, J. H. (2020) Plasmon-Enabled Degradation of Organic Micropollutants in Water by Visible-Light Illumination of Janus Gold Nanorods. Proceedings of the National Academy of Sciences, 117 (27), 15473-15481.

Improving Conventional Methods and Developing New Techniques for Detection of Viral Pathogens in the Environment

For the numerous human viruses without straight-forward cell culture methods, qPCR technologies can rapidly detect the presence of a viral genome, but cannot distinguish between infectious and non-infectious material. Culture detection methods require long incubation times that delay measurement, putting populations at risk. Considered a leading-edge approach to viral detection in environmental samples, rapid small-scale sensors could improve the ability of researchers and treatment plant operators to monitor pathogen loading while providing higher quality data with greater spatial and temporal resolution. Due to their vibrant colours and sensitivity to the local environment, SPR metallic nanoparticles have potential be employed in the fabrication of colourimetric sensors for the detection of environmental contaminants.

Related Publications:

  • Graham, K. E.*; Loeb, S. K.;* Wolfe, K.; Catoe, D.; Sinnot-Armstrong, N.; Kim, S.; Yamahara, K. M.; Sassoubre, L. M.; Mendoza Grijalva, L. M.; Roldan-Hernandez, L.; Lagenfeld, K.; Wigginton, K. R.; Boehm, A. B. (2021) SARS-CoV-2 RNA in Wastewater Settled Solids Is Associated with COVID-19 Cases in a Large Urban Sewershed. Environmental Science & Technology, 55 (1), 488-498. *equal author contribution

  • Loeb, S. K.; Wei, H.; Kim, J. H. (2021) Measuring Temperature Heterogeneities during Solar-Photothermal Heating using Quantum Dot Nanothermometry. Analyst, 146, 2048-2056.