COMPLEX FORMATION AND LIQUID-LIQUID EXTRACTION OF SILVER WITH CYCLIC AND OPEN-CHAIN OXATHIA ALKANES

The complex forming and extraction properties of various open-chain and two cyclic oxathia alkanes towards silver have been studied. The investigations confirm the direct proportionality between extraction constants and related complex stability constants.The extraction of silver by open-chain oxethie alkenee is greeter than by structurally analogoue thicacrown compounds. This fact and the determined stability constants show an absence of a macrocyclic effect during complex formation. The differences of extraction power between the various open-chain compounds can be interpreted on the basic o f the coordinative saturation and stereochemiatry of the silver ion, on the size o f the poesible chelate rings, and on the complexing capability o f the ether oxygen atoms.     

Investigation of a Novel Condensation Aerosol Generator: Solute and Solvent Effects

Part I of this article presents results of an experimental study on gas-phase nucleation for three model solutes and their solvent, propylene glycol (PG), with variables being solute concentration and the nature of the solute substance. A single manifestation of an aerosol generator, which forms condensation aerosols by cooling of hot vapor issuing from an electrically heated, pumped capillary, is described and used for all experiments. The effects of solute concentration and solute type were studied for deoxycorticosterone (DOC), benzil (BZ), and phenyl salicylate (PhS). Suppression of homogeneous nucleation and occurrence of heterogeneous condensation of the solvent was observed at different solute concentrations for BZ, PhS, and DOC. The nature and concentration of the solute dissolved in the solvent was shown to determine the final particle size distribution of the condensed aerosol. In the case of the least volatile solute, DOC, solute aerosol and total aerosol size distributions were identical at low solute concentrations. A transitional concentration region then existed in which a bimodal solute aerosol was formed, followed at high concentrations by increasing separation of the solvent-dominated aerosol size distribution and that of the solute. In Part II of this article, the effect of DOC dissolution in different solvents was studied at fixed solute concentration. The effects of six glycol solvents--i.e., PG, ethylene glycol (EG), dipropylene glycol (DPG), diethylene glycol (DEG), triethylene glycol (TEG), and tetraethylene glycol (TetEG)--and three nonglycol solvents--i.e., dimethyl sulfoxide (DMSO), formamide (FORM), and oleyl alcohol (OA)--were studied, as these affected the resultant aerosol sizes. Suppression of total aerosol mass median aerodynamic diameter (MMAD) was observed on dissolution of 0.5% w/w DOC in each solvent, although suppression occurred to different extents. It was shown that the boiling point or volatility of the solvent used to dissolve the less volatile DOC had an effect on the final particle size distribution of the condensed aerosol and whether the aerodynamic size distributions for the solute and the total aerosol were the same or different.     

Analysis of Aerosols from the World Trade Center Collapse Site,New York,October 2 to October 30, 2001

The collapse of the World Trade Center (WTC) buildings #2 (South Tower), #1 (North Tower), and #7 created an enormous collapse pile which emitted intense plumes of acrid smoke and dust until roughly mid-December, when the last spontaneous surface fire occurred. We collected particles by size (8 modes, ≈12 to 0.09 micrometers diameter) and time (typical resolution of 1 to 3 h) from October 2 until late December at the EML 201 Varick Street site roughly 1.8 km NNE of the collapse site and 50 m above ground level. Here we show some of the 70,000 mass and elemental data from the time period October 2 through October 30. Identification of a WTC collapse pile source for aerosols seen at the receptor site were based upon the simultaneous presence of finely powdered concrete, gypsum, and glass with intense very fine combustion mode mass episodes concurrent with winds from the southwest quadrant. The results, derived from seven independent beam-based analytical techniques, showed that while PM₁₀ and PM_2.5 24 h values rarely, if ever, violated federal air quality standards, WTC-derived plumes swept over lower Manhattan Island, resulting in intense aerosol impacts of duration a few hours at any one site. The WTC plume resembled in many ways those seen from municipal waste incinerators and high temperatures processes in coal-fired power plants. The size fractions above 1 micrometer contained finely powdered concrete, gypsum, and glass, with sootlike coatings and anthropogenic metals, but little asbestos. Composition in the very fine size range (0.26 > D_p > 0.09 μm) was dominated by sulfuric acid and organic matter, including polycyclic aromatic hydrocarbons (PAHs) and their derivatives, and glasslike silicon-containing aerosols. Many metals were seen in this mode, most, but not all, at low concentrations. The concentrations of very fine silicon, sulfur, and many metals, as well as coarse anthropogenic metals, decreased markedly during October, probably in association with the cooling of the collapse piles. Values of very fine elements seen in May, 2002 at the WTC site were only a few percent of October values.     

Designing for Counterpressure Foam Molding

The counterpressure structural foam process, although not new, is generating increasing interest in the structural foam community. Initial development work began as far back as the mid-1950s in Europe. The driving impetus for its development has been the surface enhancement that it provides. While this improvement is important and beneficial, it is not the only benefit of the process. The purpose of this paper is to discuss the effect of the counterpressure process on the mechanical properties and behavior of counterpressure-processed engineering structural foam.     

Observations of Twelve USEPA Priority Polycyclic Aromatic Hydrocarbons in the Aitken Size Range (10–32 nm D p )

Particle size distribution measurements of twelve USEPA priority pollutant polycyclic aromatic hydrocarbons (PAHs)—collected in Riverside, California, down to 10 nm aerodynamic diameter (D_p)—observed on integrated nocturnal samples (7:00 p.m.-6:30 a.m.) revealed that between 46 and 100% of the mass of particles in the Aitken size range was found in the 10–18 nm size bin. Particles in this size range have high alveolar deposition efficiency.     

Particle Mixing and Diffusion in the Turbulent Wake of a Sphere

The mixing and diffusion of monodisperse aerosols from a turbulent free stream into the wake created by a solid sphere were studied experimentally and analytically. Experimental measurements with regard to wake velocity profiles and momentum transport were taken in a tubular flow system by hot-wire anemometry. Particle concentration profiles, measured in the wake by means of a screen collection technique, were used to calculate mixing and diffusion parameters for the aerosols used. Experimental results are presented for the mean velocity and particle concentration profiles, wake centerline velocity and particle concentration, wake velocity and concentration half widths, and momentum and particle diffusivities. It is shown that the experimental results may be reasonably described in terms of two phenomenological theories, i.e., Prandtl's mixing length and constant diffusivity in the radial cross section of the wake. Certain departures from predicted concentration behavior are empirically analyzed resulting in the ability to predict overall particle mixing and diffusion characteristics in a turbulent wake.