Technical advances in environmental chemistry. Practical engineering solutions.
My research mitigates the impacts of trace organic contaminants on sustainable water and nutrient sources.
Manganese Oxide-Coated Sand to
Facilitate Stormwater Recycling
Large cities in arid climates must develop their local water supplies in order to reduce the cost and uncertainty of importing water. Stormwater is a local source that can augment local water supply. However, untreated stormwater could contaminate potable water supplies with pollutants from urban watersheds. I developed a sand coated with a naturally reactive manganese oxide mineral. This material is capable of oxidizing organic contaminants and adsorbing metal cations during stormwater infiltration, and can be regenerated with mild chemical treatments.
Demonstration-scale validation geomedia for treating runoff
Engineered geomedia demonstrate tremendous promise for treating stormwater contamination in the lab, but pilot-scale long-term tests demonstrate that these technologies could be valuable for treating nutrients, metals, and organic contaminants in authentic stormwater infiltration systems.
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Treating stormwater contaminants with manganese oxide geomedia
Manganese oxide is a naturally-occurring mineral that can oxidize some organic contaminants found in stormwater and suck up harmful metals from stormwater like a sponge. Some contaminants are more amendable to treatment than others, and the stormwater quality matters.
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The use of manganese oxide-coated sand for the removal of trace metal ions from stormwater
Advanced spectroscopy informing manganese oxide geomedia regeneration
Excavating spent geomedia at the end of its life is costly and disruptive, but mild chemical treatments could regenerate manganese oxides while still in the ground. X-ray absorption spectroscopy reveals why some treatments and mineral phases are more effective.
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PFAS Forensics
Environmental contamination from PFAS (per- and polyfluoroalkyl substances) is a concern because these compounds are often persistent, bioaccumulative, mobile, and toxic . Forensic analysis of PFAS-impacted areas can help to determine which PFAS sources contributed to a plume or identify unknown sources of contamination.
PFAS Source Tracking
Determining PFAS sources could facilitate environmental remediation and human health interventions and help to establish liability for contamination. Converging lines of evidence including chemical fingerprinting, site modeling, ands statistical analysis are useful for untangling complex site dynamics.
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PFAS Impacts on Highway Construction
State DOTs grapple with PFAS impacts and mitigation in all phases of highway project development, construction, and maintenance. But standard practices vary dramatically state-to-state. This National Academies Report Synthesizes DOT practices for identifying potential PFAS contamination and mitigating its impacts on highway construction and maintenance.
Communicating Identification Confidence
Nontarget analyses are increasingly common for PFASs. The certainty of PFAS identifications must be communicated through a reliable and harmonized approach. We present a confidence scale specific to analysis of PFASs by nontarget high-resolution mass spectrometry. This publication recognized as a Best Paper of 2022 in ES&T Letters.
Flame Retardants: Chemistry and Policy
Flammability standards for furniture, building insulation and electronics are supposed to mitigate fire risk. However, many flammability standards poorly represent actual fire scenarios and require the use of toxic flame retardant chemicals in products. These flame retardants may not provide a significant fire safety benefit and are associated with adverse health effects such as diminished immune function, endocrine disruption, and cancer. Updated flammability standards can reduce the use of flame retardants while maintaining—or even increasing—fire safety.
Flammability standards for furniture, building insulation and electronics: Benefit and risk