Brian J. Teppen

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small amounts of water to soil reduced the sorption of organic compounds relative to the sorption by the In soils, organic matter and minerals are often associated such that dehydrated soil in hexane, and that organic vapor ad-it is unclear how the presence of the former component influences sorption by soil was significantly depressed by increasing the(More)
Nitroaromatic compounds (NACs) are commonly found as soil contaminants in military training sites and manufacturing facilities, and may adversely affect human and ecosystem health. Exchangeable cation effects on p-nitrocyanobenzene (p-NCB) and 1,4-dinitroben-zene (1,4-DNB) sorption by the Webster (fine loamy, mixed, mesic Typic Haplaquoll) soil series A(More)
Smectite clays demonstrate high affinities for nitroaromatics that strongly depend on the exchangeable cation. The K-smectites have high affinities for nitroaromatics, but Ca-smectites do not. Here we evaluate the ability of K-smectite to attenuate the bioavailability and hence toxicity of 2,4-dinitrotoluene (2,4-DNT) to the aquatic plant duckweed. In the(More)
Applications of molecular modeling procedures to adsorption processes at clay mineral surfaces are described. Using a recently developed empirical force field for molecular dynamics (MD) simulations of dioctahedral clays, the interactions of various classes of organic compounds with clay surfaces are being explored, including man-made pollutants,(More)
Sorption of carbaryl (1-naphthyl-N-methyl-carbamate) from aqueous suspension to smectite was studied using Fourier transform infrared (FTIR), high-performance liquid chromatography (HPLC) (for batch sorption), and quantum chemical methods. The amount of carbaryl sorbed was strongly dependent on the surface-charge density of the smectite with more sorption(More)
In aqueous suspension, the affinity of many pesticides for smectites is influenced by the clay properties such as surface area, surface charge density and location, exchangeable cations, and hydration status of exchangeable cations in clay interlayers. The amount and the type of salts present in the aqueous phase influence clay quasicrystal structures and(More)
We investigated the sorption of three triazine herbicides (atrazine, simazine, and metribuzin) by saponite and beidellite clay minerals saturated with K+, Cs+, Na+, and Ca2+. Saponite clay sorbed a larger fraction of each pesticide from aqueous solution than did beidellite clay. The lower cation-exchange capacity in saponite compared to that in beidellite(More)
Sphingomonas wittichii strain RW1 (RW1) is one of the few strains that can grow on dibenzo-p-dioxin (DD). We conducted a transcriptomic study of RW1 using RNA-Seq to outline transcriptional responses to DD, dibenzofuran (DF), and the smectite clay mineral saponite with succinate as carbon source. The ability to grow on DD is rare compared to growth on the(More)
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Nitroaromatic compounds (NACs) are prominent soil and sediment contaminants that are strongly adsorbed by smectites at extents that depend on hydration properties of the exchangeable cation. Potassium smectites adsorb nitroaromatics much more strongly than calcium smectites, so that adjustment of K+ versus Ca2+ occupation on cation exchange sites in(More)