Leanne M. Gilbertson

Upcycled plastics provide robust supports for diverse photocatalysts, enabling direct immobilization without photocatalyst modification, simple fabrication, long-term stability, and broad applicability in photocatalysis.

Liposomes are microscale lipid vesicles used in pharmaceuticals, food products, and most recently, agriculture. Several studies have shown that liposomes can deliver nutrients to plant leaves, often more efficiently than traditional forms. However, the delivery of plant nutrients to soil via liposomes remains understudied. Interactions between liposomes and soil microbes, including metabolism of the lipid carbon (C) and assimilation of liposome-encapsulated nutrients into soil microbial biomass, could alter the availability of nutrients within the soil. We assessed the impact of lecithin liposomes with nitrogen (N) cargo on C and N cycling during a 7-day incubation experiment. We quantified changes in concentrations of carbon dioxide, nitrous oxide, oxygen, and soil inorganic N pools including soil extractable nitrate (NO₃ ^–-N) and ammonium (NH₄ ⁺-N). Liposome additions increased microbial respiration and resulted in rapid soil NO₃ ^–-N immobilization, suggesting that liposomes may be a tool to immobilize N and reduce agricultural N losses.

A key aspect of circular economies is using sustainable pathways for processing advanced materials. While significant advances have been made in the discovery of novel materials that have innovative functionalities, rarely is attention provided to a holistic analysis to ensure that processes are sustainable. Rigorous analysis methodologies must be used to compare alternative processing methods. In this study, a comprehensive life cycle assessment (LCA) is conducted to evaluate a continuous and single-step aerosol synthesis approach in comparison to conventional batch pyrolysis methods for producing high-surface-area (porous) carbon materials. First, porous carbon nanoparticles (CNPs) are synthesized using a lab-scale aerosol reactor, and LCA is conducted to identify the key processing parameters contributing to their environmental impact. These results are then successfully used to guide the design of an optimized scaled-up aerosol reactor, achieving up to 75% reduction in global warming potential compared to conventional scaled-up batch pyrolysis techniques. Finally, the role of particle size and pyrolysis energy source in the environmental impact of CNP synthesis is systematically investigated. Overall, the simple (single-step, continuous, and rapid) operation and promising sustainability of the aerosol technique highlight its significant potential for the scalable synthesis of carbon nanomaterials from lignin.

Photocatalysis offers an opportunity for sustainable hydrogen and chemical production. Traditional systems require semiconductors with very specific conduction-band (CB) properties and expensive noble metal cocatalysts, limiting material availability and increasing costs. Here, we introduce an alternative photocatalytic pathway that bypasses these constraints, producing hydrogen and formic acid via a cascade process. Under illumination, oxygen and methanol are converted to hydrogen peroxide and formaldehyde, which then react in solution to yield hydrogen and formic acid. We demonstrate the viability of the process employing two limited direct photocatalysts, polymeric carbon nitride (which is not active without a cocatalyst) and tungsten oxide (which presents an unsuitable CB). Our method provides significant advantages: bandgap flexibility, reduced energy consumption and environmental impact, and elimination of noble metal cocatalyst costs. This approach expands the range of suitable semiconductor materials for efficient photocatalytic hydrogen production, offering a more economical and practical solution.

The use of inorganic nutrient fertilizers in crop agriculture is often inefficient due to rapid leaching of nutrients with percolating water in soil. To address this, a liposomal carrier was developed to slow transport and reduce leaching of inorganic nutrient loads within agricultural soils. Liposomes, spherical lipid bilayers, have been widely used in medicine but remain under-characterized for agricultural applications. Their biocompatibility, high loading capacity, and stability under certain compositions and environmental conditions suggest they could effectively deliver agrochemicals to crops. We present soil column experiments to evaluate the ability of a liposomal carrier to reduce the transport of an ionic tracer load, sodium bromide, under varying soil and water saturation conditions. Results from saturated column experiments demonstrate that encapsulation in liposomes slowed tracer transport and reduced leachate concentrations in sand and silty clay loam soils. Reduction in tracer leachate was also observed for unsaturated column experiments in silty clay loam soil. Subsequent experiments suggested a combination of processes (i.e., attachment, aggregation, physical exclusion, and biogenic immobilization) were responsible for the observed behavior of liposome encapsulated tracer in the soil column experiments. These findings support the use of liposomes as an effective carrier of inorganic nutrients to reduce leaching.

A model of nitrogen biogeochemical cycling in agriculture soil at the field scale for assessing how crop management practices affect nitrogen fertilizer fate and transport.

The incidence of waterborne disease outbreaks in the United States attributed to drinking water-associated pathogens that can cause infections in the immunocompromised DWPIs (e.g., Legionella pneumophila, nontuberculous mycobacteria (NTM), and Pseudomonas aeruginosa, among others) appears to be increasing. An emerging technology adopted to reduce DWPIs are point-of-use devices, such as showerheads that contain silver, a known antimicrobial material. In this study, we evaluate the effect of silver-containing showerheads on DWPI density and the broader microbiome in shower water under real-use conditions in a full-scale shower system, considering three different silver-modified showerhead designs: (i) silver mesh within the showerhead, (ii) silver-coated copper mesh in the head and hose, and (iii) silver-embedded polymer composite compared to conventional plastic and metal showerheads. We found no significant difference in targeted DWPI transcriptional activity in collected water across silver and nonsilver shower head designs. Yet, the presence of silver and how it was incorporated in the showerhead influenced the metal concentrations, microbial rare taxa, and microbiome functionality. Microbial dynamics were also influenced by the showerhead age (i.e., time after installation). The results of this study provide valuable information for consumers and building managers to consider when choosing a showerhead meant to reduce microorganisms in shower water.

There are numerous opportunities for nanomaterials and nanotechnology to support circular economy adoption. In this perspective, we present the important role engineered nanomaterials can play in advancing the circularity of bulk composite materials.

Managing drinking water-associated pathogens that can cause infections in immunocompromised individuals is a persistent challenge, particularly for healthcare facilities where occupant exposures carry a substantial health risk.