The small size and high surface-to-volume ratio makes nanoiron attractive for in situ remediation of groundwater contaminants that are susceptible to reductive transformation, e.g. trichloroethylene (TCE). Nanoiron synthesized from borohydride reduction of dissolved iron is the most widely studied. Its reactivity with chlorinated organics such as trichloroethylene (TCE) is unique compared to other nanoiron and to iron filings that are typically used for in situ groundwater remediation, e.g. (1) higher surface-area normalized TCE dechlorination reaction rate constants, (2) the formation of saturated reaction products, and (3) higher reaction rates in the presence of H2. The objectives of this study were to confirm the ability of monometallic Fe(B) to activate and use H2 for TCE hydrodechlorination and to determine how the nanoiron chemical composition and the degree of crystallinity influence nanoiron reactivity with TCE. Fresh (Fe(B)), partially oxidized (Fe(B)ox), and annealed (Fe(B)cr) nanoiron samples made from borohydride reduction of dissolved Fe(II) in a water/methanol solution were characterized by HRTEM, XRD, XPS, and N2-BET. The TCE dechlorination rate and products and the dissolved iron and boron released during reaction with TCE were measured. Fe(B) and Fe(B)ox were poorly ordered and could activate and use H2 to reduce TCE to ethane. Fe(B)cr was crystalline and could not activate and use H2 and reduced TCE to acetylene. The poorly ordered structure rather than the presence of boron (up to 5 wt %) provided the ability of Fe(B) and Fe(B)ox to activate and use H2 for TCE dechlorination. Fe(B) and Fe(B)ox underwent oxidative dissolution during TCE dechlorination, and the Fe0 in the particles was fully accessible. Particle dissolution suggests that normalizing the observed reaction rate constants with the measured specific surface area for comparison with other types of Fe0 may be inappropriate.

A series of y wt % Pt/Ce x Zr1–x O2 catalysts (y = 0.1, 0.5, and 1.0; x = 0.3, 0.5, and 0.7) were synthesized and characterized to investigate the effect of CeO2 doping with Zr4+ and of Pt particle size (Pt/Ce0.5Zr0.5O2) on important mechanistic and kinetic aspects of the water–gas shift (WGS) reaction. These included the concentration (μmol·g–1 or θ (surface coverage based on Pts)) and chemical structure of active reaction intermediates present in the “carbon path” and “hydrogen path” of the WGS reaction in the 200–300 °C range and the prevailing mechanism among “redox” and “associative formate” largely considered in the literature. Toward this goal, steady-state isotopic transient kinetic analysis coupled with in situ DRIFTS and mass spectrometry experiments were performed for the first time using D2O and 13CO isotopic gases. A novel transient isotopic experiment allowed quantification of the initial transient rate of reaction of adsorbed formate (HCOO−) with water and that of adsorbed CO with water under steady-state WGS reaction conditions. On the basis of these results, it was concluded that formate should not be considered as an important intermediate. It was found that on Pt/Ce x Zr1–x O2 catalysts, the WGS reaction mechanism switches from “redox” to a combination of “redox” and “associative formate with −OH group regeneration” mechanisms by increasing the reaction temperature from 200 to 300 °C. The superior WGS activity exhibited by Pt/Ce x Zr1–x O2 (x = 0.3, 0.5, and 0.7) catalysts in comparison with Pt/CeO2 was explained by the fact that the site reactivity of Pt across the metal–support interface was increased as a consequence of the introduction of Zr4+ into the ceria lattice. The concentration of active reaction intermediates was found to strongly depend on reaction temperature, support composition (Ce/Zr ratio), and Pt particle size, parameters that all determine the shape of the light-off CO-conversion curve.

Extractive crystallization was employed for the preparation of deicing compositions of calcium acetate (CA) and magnesium acetate (MA) at room temperature. The design system comprises an aqueous phase as the source of calcium or magnesium ions and an organic phase as the source of acetate ions. The process was designed with the consideration that acetic acid is used in an organic phase as extracted from a fermentation broth. The conditions under which the extractive crystallization method resulted in the formation of single crystals or aggregates of calcium acetate and magnesium acetate were studied. Furthermore, the effect of acetic acid concentration in the organic and aqueous phases on the characteristics of the obtained crystals was investigated. Overall, the extractive crystallization process proved to be feasible at least in the laboratory and resulted in the production of well-formed, nonporous, large single crystals and clusters of either calcium acetate acetic acid hydrate [Ca(CH3COO)2·CH3COOH·H2O] or magnesium acetate tetrahydrate [Mg(CH3COO)2·4H2O, α], depending on the type of salt (CaCO3 or MgCO3) used in each case.

Cu-Ag alloy nanoparticles were synthesized by a novel method and coated over glassy carbon electrode for the detection of a carcinogen, 2-butanone Abstract Spherical shaped silver-copper alloy nanoparticles of 10-15 nm size were synthesized by an aqueous polymer solution method. The synthesized nanoscale Ag-Cu alloy was characterized by UV-Visible spectroscopy, X-ray diffraction spectroscopy, transmission electron microscopy (TEM), high resolution TEM, and energy dispersive spectroscopy. XRD pattern showed high crystallinity and phase formation of nanoparticles. The bimetallic alloy nanoparticles were coated over a well-polished glassy carbon electrode and the designed sensor was applied for the detection of a highly carcinogenic carbonyl compound, 2-butanone. Electrochemical studies revealed that PEI used as a capping agent also enhances the sensing of the modified electrode for the recognition of 2-butanone. The sensor developed from Ag-Cu (1:1) alloy nanoparticles showed the best sensing properties for the detection of 2-butanone as evidenced by electrochemical impedance spectroscopy and 0.1 µM detection limit.