Trade-offs in ecosystem impacts from nanomaterial versus organic chemical ultraviolet filters in sunscreens.

Both nanoparticulate (nZnO and nTiO) and organic chemical ultraviolet (UV) filters are active ingredients in sunscreen and protect against skin cancer, but limited research exists on the environmental effects of sunscreen release into aquatic systems. To examine the trade-offs of incorporating nanoparticles (NPs) into sunscreens over the past two decades, we targeted endpoints sensitive to the potential risks of different UV filters: solar reactive oxygen production in water and disruption of zebrafish embryo development. First, we developed methodology to extract nanoparticles from sunscreens with organic solvents.

Coupling Light Emitting Diodes with Photocatalyst-Coated Optical Fibers Improves Quantum Yield of Pollutant Oxidation.

A photocatalyst-coated optical fiber was coupled with a 318 nm ultraviolet-A light emitting diode, which activated the photocatalysts by interfacial photon-electron excitation while minimizing photonic energy losses due to conventional photocatalytic barriers. The light delivery mechanism was explored via modeling of evanescent wave energy produced upon total internal reflection and photon refraction into the TiO surface coating. This work explores aqueous phase LED-irradiated optical fibers for treating organic pollutants and for the first time proposes a dual-mechanistic approach to light delivery and photocatalytic performance.

Superfine powdered activated carbon incorporated into electrospun polystyrene fibers preserve adsorption capacity.

A composite material consisted of superfine powdered activated carbon (SPAC) and fibrous polystyrene (PS) was fabricated for the first time by electrospinning. SPAC is produced by pulverizing powdered activated carbon. The diameter of SPAC (100-400nm) is more than one hundred times smaller than conventional powdered activated carbon, but it maintains the internal pore structure based on organic micropollutant adsorption isotherms and specific surface area measurements.

Prospecting nanomaterials in aqueous environments by cloud-point extraction coupled with transmission electron microscopy.

Increasing application of engineered nanomaterials (ENMs) in industry and consumer products inevitably lead to their release into and impact on aquatic environments. To characterize the NMs efficiently in surface water, a fast and simple method is needed to separate and concentrate nanomaterials from the aqueous matrix without altering their shape and size. Applying cloud-point extraction (CPE) using the surfactant Triton 114 to an array of NMs (titanium dioxide, gold, silver, and silicon dioxide) with different sizes or capping agents in nanopure water resulted in extraction efficiency of 83%-107%.

Survey of food-grade silica dioxide nanomaterial occurrence, characterization, human gut impacts and fate across its lifecycle.

There is increasing recognition of the importance of transformations in nanomaterials across their lifecycle, yet few quantitative examples exist. We examined food-grade silicon dioxide (SiO2) nanomaterials from its source (bulk material providers), occurrence in food products, impacts on human gastrointestinal tract during consumption, and fate at wastewater treatment plants. Based upon XRD, XPS and TEM analysis, pure SiO2 present in multiple food-grade stock SiO2 exhibited consistent morphologies as agglomerates, ranging in size from below 100nm to >500nm, with all primary particle size in the range of 9-26nm and were most likely amorphous SiO2 based upon high resolution TEM.

Understanding droplet bridging in ionic liquid-based Pickering emulsions.

We have studied the unique bridging behavior of solid-stabilized oil-in-ionic liquid (IL) and water-in-ionic liquid emulsions with respect to particle concentration, particle size, and droplet phase using a confocal laser scanning microscope. The emulsions exhibited three morphology regimes: (1) single, sparingly covered droplets, (2) bridged clusters of droplets, and (3) fully covered droplets. The degree of bridging was directly proportional to the total potential bridging area which can be determined from the particle size and concentration.