Adsorptive-Photocatalytic Performance for Antibiotic and Personal Care Product Using CuMnFeO.

The amount of antibiotics and personal care products entering local sewage systems and ultimately natural waters is increasing and raising concerns about long-term human health effects. We developed an adsorptive photocatalyst, CuMnFeO nanoparticles, utilizing co-precipitation and calcination with melamine, and quantified its efficacy in removing paraben and oxytetracycline (OTC). During melamine calcination, CuMnFeO recrystallized, improving material crystallinity and purity for the adsorptive-photocatalytic reaction.

Developing a Slow-Release Permanganate Composite for Degrading Aquaculture Antibiotics.

Copious use of antibiotics in aquaculture farming systems has resulted in surface water contamination in some countries. Our objective was to develop a slow-release oxidant that could be used in situ to reduce antibiotic concentrations in discharges from aquaculture lagoons. We accomplished this by generating a slow-release permanganate (SR-MnO) that was composed of a biodegradable wax and a phosphate-based dispersing agent.

Enhanced degradation of herbicides in groundwater using sulfur-containing reductants and spinel zinc ferrite activated persulfate.

A challenge to successfully implementing an injection-based remedial treatment in aquifers is to ensure that the oxidative reaction is efficient and lasts long enough to contact the contaminated plume. Our objective was to determine the efficacy of zinc ferrite nanocomposites (ZnFeO) and sulfur-containing reductants (SCR) (i.e.

Fabrication of Ternary Nanoparticles for Catalytic Ozonation to Treat Parabens: Mechanisms, Efficiency, and Effects on L. and Eker Leiomyoma Tumor-3 Cells.

The use of parabens in personal care products can result in their leakage into water bodies, especially in public swimming pools with insufficient water treatment. We found that ferrite-based nanomaterials could catalytically enhance ozone efficiency through the production of reactive oxygen species. Our objective was to develop a catalytic ozonation system using ternary nanocomposites that could minimize the ozone supply while ensuring the treated water was acceptable for disposal into the environment.

A biological and chemical approach to restoring water quality: A case study in an urban eutrophic pond.

Efforts to improve water quality of eutrophic ponds often involve implementing changes to watershed management practices to reduce external nutrient loads. While this is required for long-term recovery and prevention, eutrophic conditions are often sustained through the recycling of internal nutrients already present within the waterbody. In particular, internal phosphorus bound to organic material and adsorbed to sediment has the potential to delay lake recovery for decades.

Modeling the release and spreading of permanganate from aerated slow-release oxidants in a laboratory flow tank.

Aerated, slow-release oxidants are a relatively new technology for treating contaminated aquifers. A critical need for advancing this technology is developing a reliable method for predicting the radius of influence (ROI) around each drive point. In this work, we report a series of laboratory flow tank experiments and numerical modeling efforts designed to predict the release and spreading of permanganate from aerated oxidant candles (oxidant-wax composites).

Remediating 1,4-dioxane-contaminated water with slow-release persulfate and zerovalent iron.

1,4-dioxane is an emerging contaminant that was used as a corrosion inhibitor with chlorinated solvents. Metal-activated persulfate can degrade dioxane but reaction kinetics have typically been characterized by a rapid decrease during the first 30 min followed by either a slower decrease or no further change (i.e.

A five-year performance review of field-scale, slow-release permanganate candles with recommendations for second-generation improvements.

In 2009, we identified a TCE plume at an abandoned landfill that was located in a low permeable silty-clay aquifer. To treat the TCE, we manufactured slow-release potassium permanganate cylinders (oxidant candles) that had diameters of either 5.1 or 7.

Removing PAHs from urban runoff water by combining ozonation and carbon nano-onions.

Ozone (O3) is a chemical oxidant capable of transforming polycyclic aromatic hydrocarbons (PAHs) in urban runoff within minutes but complete oxidation to CO2 can take days to weeks. We developed and tested a flow-through system that used ozone to quickly transform PAHs in a runoff stream and then removed the ozone-transformed PAHs via adsorption to carbon nano-onions (CNOs). To quantify the efficacy of this approach, (14)C-labeled phenanthrene and benzo(a)pyrene, as well as a mixture of 16 unlabeled PAHs were used as test compounds.

A combined chemical and biological approach to transforming and mineralizing PAHs in runoff water.

The water quality of lakes, rivers and streams associated with metropolitan areas is declining from increased inputs of urban runoff that contain polycyclic aromatic hydrocarbons (PAHs). Our objective was to transform and mineralize PAHs in runoff using a combined chemical and biological approach. Using (14)C-labeled phenanthrene, (14)C-benzo(a)pyrene and a mixture of 16 PAHs, we found that ozone transformed all PAHs in a H2O matrix within minutes but complete mineralization to CO2 took several weeks.

Improving the treatment of non-aqueous phase TCE in low permeability zones with permanganate.

Treating dense non-aqueous phase liquids (DNAPLs) embedded in low permeability zones (LPZs) is a particularly challenging issue for injection-based remedial treatments. Our objective was to improve the sweeping efficiency of permanganate (MnO4(-)) into LPZs to treat high concentrations of TCE. This was accomplished by conducting transport experiments that quantified the penetration of various permanganate flooding solutions into a LPZ that was spiked with non-aqueous phase (14)C-TCE.

Improving the sweeping efficiency of permanganate into low permeable zones to treat TCE: experimental results and model development.

The residual buildup and treatment of dissolved contaminants in low permeable zones (LPZs) is a particularly challenging issue for injection-based remedial treatments. Our objective was to improve the sweeping efficiency of permanganate into LPZs to treat dissolved-phase TCE. This was accomplished by conducting transport experiments that quantified the ability of xanthan-MnO4(-) solutions to penetrate and cover (i.

Using slow-release permanganate candles to remediate PAH-contaminated water.

Surface waters impacted by urban runoff in metropolitan areas are becoming increasingly contaminated with polycyclic aromatic hydrocarbons (PAHs). Slow-release oxidant candles (paraffin-KMnO(4)) are a relatively new technology being used to treat contaminated groundwater and could potentially be used to treat urban runoff. Given that these candles only release permanganate when submerged, the ephemeral nature of runoff events would influence when the permanganate is released for treating PAHs.

Using slow-release permanganate candles to remove TCE from a low permeable aquifer at a former landfill.

Past disposal of industrial solvents into unregulated landfills is a significant source of groundwater contamination. In 2009, we began investigating a former unregulated landfill with known trichloroethene (TCE) contamination. Our objective was to pinpoint the location of the plume and treat the TCE using in situ chemical oxidation (ISCO).

Developing slow-release persulfate candles to treat BTEX contaminated groundwater.

The development of slow-release chemical oxidants for sub-surface remediation is a relatively new technology. Our objective was to develop slow-release persulfate-paraffin candles to treat BTEX-contaminated groundwater. Laboratory-scale candles were prepared by heating and mixing Na(2)S(2)O(8) with paraffin in a 2.

Transformation of hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) by permanganate.

The chemical oxidant permanganate (MnO(4)(-)) has been shown to effectively transform hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) at both the laboratory and field scales. We treated RDX with MnO(4)(-) with the objective of quantifying the effects of pH and temperature on destruction kinetics and determining reaction rates. A nitrogen mass balance and the distribution of reaction products were used to provide insight into reaction mechanisms.

Abiotic transformation of high explosives by freshly precipitated iron minerals in aqueous FeII solutions.

Zerovalent iron barriers have become a viable treatment for field-scale cleanup of various ground water contaminants. While contact with the iron surface is important for contaminant destruction, the interstitial pore water within and near the iron barrier will be laden with aqueous, adsorbed and precipitated Fe(II) phases. These freshly precipitated iron minerals could play an important role in transforming high explosives (HE).

Using gas-phase molecular descriptors to predict dechlorination rates of chloroalkanes by zerovalent iron.

Reductive dehalogenation of chlorinated compounds is the most important process occurring within the zerovalent iron (Fe0) barrier. The relative reaction rates of individual halocarbons with Fe0 can vary considerably. This variability has been the stimulus for using various chemical descriptors for a priori predictions of transformation rates via linear free-energy relationships (LFERs).

Dechlorinating chloroacetanilide herbicides by dithionite-treated aquifer sediment and surface soil.

The prevalent use of chloroacetanilide herbicides has resulted in nonpoint contamination of some groundwater and surface water. We determined the efficacy of dithionite-treated sediment and soils to transform chloroacetanilides. When used alone, dithionite rapidly dechlorinates chloroacetanilides in water, with the following order of reactivity: propachlor > alachlor > acetochlor > metolachlor.

Electron capture detector response and dissociative electron attachment cross sections in chloroalkanes and chloroalkenes.

Electron capture detectors (ECDs) are widely used in gas chromatography to detect electronegative compounds. In this work, we examine the connections between the ECD response and the cross sections for dissociative electron attachment (DEA) determined from low energy electron beam studies in the chloroalkane family, stressing in particular the role of temporary anion state energies. We show that attachment rate coefficients computed from these cross sections are well correlated with ECD response, and that the latter decreases exponentially with increasing energies of the lowest anion states.

Increasing Fe0-mediated HMX destruction in highly contaminated soil with didecyldimethylammonium bromide surfactant.

Mixtures of energetic compounds pose a remediation problem for munitions-contaminated soil. Although treatment with zerovalent iron (Fe0) can be effective, RDX and TNT are more readily destroyed than HMX. Adding didecyldimethylammonium bromide (didecyl) at 2% w/v with 3% (w/v) Fe0 to a 20% slurry of Los Alamos National Laboratory soil containing solid-phase HMX (45 000 mg/kg) resulted in >80% destruction within 6 days.

Green rust and iron oxide formation influences metolachlor dechlorination during zerovalent iron treatment.

Electron transfer from zerovalent iron (Fe0) to targeted contaminants is affected by initial Fe0 composition, the oxides formed during corrosion, and surrounding electrolytes. We previously observed enhanced metolachlor destruction by Fe0 when iron or aluminum salts were present in the aqueous matrix and Eh/pH conditions favored formation of green rusts. To understand these enhanced destruction rates, we characterized changes in Fe0 composition during treatment of metolachlor with and without iron and aluminum salts.

Effects of oxide coating and selected cations on nitrate reduction by iron metal.

Under anoxic conditions, zerovalent iron (Fe(0)) reduces nitrate to ammonium and magnetite (Fe3O4) is produced at near-neutral pH. Nitrate removal was most rapid at low pH (2-4); however, the formation of a black oxide film at pH 5 to 8 temporarily halted or slowed the reaction unless the system was augmented with Fe(2+), Cu(2+), or Al(3+). Bathing the corroding Fe(0) in a Fe(2+) solution greatly enhanced nitrate reduction at near-neutral pH and coincided with the formation of a black precipitate.