No description available.

This study evaluates the effectiveness of molasses injection for reducing heavy metals and chlorinated solvents in a ground water plume at the Avco-Lycoming Superfund site in Williamsport, Pennsylvania. Molasses injection stimulates the respiration of microorganisms to make a more reducing environment. As the environment?s Redox potential decreases, the rate of chemical reduction increases. The concentrations of heavy metals and chlorinated solvents were monitored to evaluate the effectiveness of the molasses injection. The statistics revealed a decrease in the Oxidation-Reduction Potential in the groundwater and a reduction in hexavalent chromium and TCE concentrations in the groundwater. The Environmental Protection Agency views molasses injection as a viable technique for site remediation. Molasses injection is a form of facilitated natural attenuation. Molasses is injected into a plume to make the environment anaerobic. An anaerobic environment facilitates the microbes that breakdown trichloroethylene (TCE), trans-dichloroethylene (DCE), vinyl chloride (VC) and hexavalent chromium.

No description available.

No description available.

No description available.

No description available.

The purpose of this study was learn how the diffusion, swelling, and crystallization processes are coupled during solvent-induced crystallization of poly(ether ether ketone) (PEEK). Unoriented amorphous PEEK films were immersed in aprotic organic liquids at ambient temperature and bulk properties or characteristics were monitored as a function of immersion time. The sorption behavior, Tg and Tm° suppression, crystallinity, and dynamic mechanical response were correlated as a function of solvent chemistry and immersion time. The saturation time of methylene chloride, 1,3-dichloropropane, tetrahydrofuran, cyclopentanone, chlorobenzene, toluene, diethyl ketone, and ethylbenzene in amorphous PEEK films were found to range from hours to days depending on the level of polymer-solvent interactions. In-situ isochronal DMA spectra show that the Tg of PEEK was suppressed from 150 ° C to below ambient temperature such that crystallization was kinetically feasible during ambient immersion. In addition, an increase in viscoelastic dispersion was attributed to the presence of crystallinity. From dynamic mass uptake and wide-angle x-ray diffraction (WAXD) results, it was found that the bulk sorption rate was equal to the bulk crystallization rate for all solvent systems that promoted SINC and PEEK exhibited diffusion-limited crystallization, irrespective of the nature of the transport mechanism. In addition, the solvent-induced crystals exhibit preferred orientation as supported by photographic WAXD. A distinct sorption front, observed with scanning electron microscopy, further supports the scenario of diffusion-controlled crystallization and one-dimensional diffusion. Isothermal DMA spectra for THF, cyclopentanone, and chlorobenzene, indicate that, as the solvent diffuses into the films, the stiffness of the polymer decreases at short times, begins to increase, and then reaches a relatively time-independent value. It was determined that the initial decrease in the storage modulus was due to the incredible plasticization of the amorphous phase. When the films contained greater than 60 % of the ultimate crystallinity, the storage modulus was observed to increase as a result of the reinforcing effect of the solvent-induced crystals. WAXD and mass uptake results confirm that the plateau in the storage modulus coincides with the completion of bulk crystallization and saturation of the amorphous phase. / Ph. D.

The production of biofuels and biobased products from low-cost abundant renewable non-food lignocellulosic biomass will be vital to sustainable development because it will bring benefits to the environment, the economy, and the national security. The largest technical and economic challenge for emerging biorefineries is cost-effective release of fermentable sugars from recalcitrant structure of lignocellulosic biomass. Cellulose- and organic-solvent-based lignocelluloses fractionation (COSLIF) technology was employed to overcome biomass recalcitrance. Surface response methodology (SRM) showed that optimal COSLIF pretreatment conditions were 85% (w/v) H₃PO₄ and ~50 °C, regardless of moisture contents in biomass from 5-15% (w/w) for common reed. Under these conditions, the pretreated biomass was hydrolyzed fast with high glucan digestibilities at low enzyme loadings (i.e., one FPU of cellulase per gram of glucan). Crystallinity index (CrI) measurements by X-ray diffraction (XRD) and cross polarization/magic angle spinning (CP/MAS) ¹³C nuclear magnetic resonance (NMR), and cellulose accessibility to cellulase (CAC) determinations of COSLIF-pretreated biomass confirmed that highly ordered hydrogen-bonding networks in cellulose fibers of biomass were disrupted through cellulose dissolution in a cellulose solvent. This disruption of hydrogen bonding networks among cellulose chains resulted in a drastic increase in CAC values. Fourier transform infrared (FTIR) analyses on COSLIF-pretreated biomass revealed conformational changes in specific hydrogen bonding among cellulose chains due to COSLIF. While CrI is believed to be a key substrate characteristic that impacts enzymatic cellulose hydrolysis, studies in this thesis showed CrI values varied greatly depending on measurement techniques, calculation approaches, and sample preparation conditions. A correlation between CAC values and glucan digestibility of pretreated biomass showed that substrate accessibility is a key substrate characteristic impacting enzymatic cellulose hydrolysis. In summary, COSLIF can effectively overcome biomass recalcitrance. The resulting pretreated biomass has high CAC values, resulting in fast hydrolysis rates and high enzymatic glucan digestibilities of COSLIF-pretreated biomass at low enzyme usage. / Ph. D.

Biomolecular Modeling is playing an important role in many practical applications such as biotechnology and structure-based drug design. One of the essential requirements of Biomolecular modeling is an accurate description of the solvent (water). The challenge is to make this description computationally facile that is reasonably fast, simple, robust and easy to incorporate into existing software packages. The most rigorous procedure to model the effect of aqueous solvent is to explicitly model every water molecule in the system. For many practical applications, this approach is computationally too intense, as the number of required water atoms is on average one order of magnitude larger than the number of atoms of the molecule of interest. Implicit solvent models, in which solvent molecules are represented by a continuum function, have become a popular alternative to explicit solvent methods as they are computationally more efficient. The Generalized Born (GB) implicit solvent has become quite popular due to its relative simplicity and computational efficiency. However, recent studies showed serious deficiencies of many GB variants when applied to Biomolecular Modeling such as an over- stabilization of alpha helical secondary structures and salt bridges. In this dissertation we present two new GB models aimed at computing solvation properties with a reasonable compromise between accuracy and speed. The first GB model, called NSR6, is based on a numerically surface integration over the standard molecular surface. When applied to a set of small drug-like molecules, NSR6 produced an accuracy, with respect to experiments, that is essentially at the same level as that of the expensive explicit solvent treatment. Furthermore, we developed an analytic GB model, called AR6, based on an approximation of the volume integral over the standard molecular volume. The accuracy of the AR6 model is tested relative to the numerically exact NSR6. Overall AR6 produces a good accuracy and is suitable for Molecular Dynamics simulations which is the main intended application. / Ph. D.

Liquid extraction is a means of separating two or more components of a solution. The process involves mixing the solution with an immiscible solvent, separating the two phases, and recovery of the desired materials and of solvent from the solvent phase, usually by distillation. Separation is accomplished if certain of the solution components are more soluble in the extracting solvent employed than in the feed solution. Liquid extraction is used to concentrate aqueous solutions of acetic acid produced in the esterification of cellulose and in other manufacturing processes because acetic acid and water are not easily separated by direct rectification. Liquid extraction of acetic acid must always be followed by solvent-recovery systems. Then the selection of solvents suitable for extraction of acetic acid must be based not only on the relative affinity of the solvents for acetic acid but also on consideration of heat and other energy requirements of the extraction and solvent recovery systems. The purpose of this investigation was to develop a method of evaluating solvent extraction systems for the recovery of acetic acid from aqueous liquors, by comparisons of selected solvent systems on the basis of: (a) theoretical transfer units required for extraction, (b) in the case of solvents boiling below 100 °C, theoretical plates required for distillation of extracts, and (c) heat required for recovery of pure acetic acid and of solvent. / Master of Science