Stephen R. Daniel

Identification of persistent anionic surfactant-derived chemicals in sewage effluent and groundwater

Preparative isolation and fractionation procedures coupled with spectrometric analyses were used to identify surfactant-derived contaminants in sewage effluent and sewage-contaminated groundwater from a site located on Cape Cod, Massachusetts. Anionic surfactants and their biodegradation intermediates were isolated from field samples by ion exchange and fractionated by solvent extraction and adsorption chromatography. Fractions were analyzed by 13C nuclear magnetic resonance spectrometry and gas chromatography-mass spectrometry. Carboxylated residues of alkylphenol polyethoxylate surfactants were detected in sewage effluent and contaminated groundwater. Linear alkylbenzenesulfonates (LAS) were identified in sewage effluent and groundwater. Groundwater LAS composition suggested preferential removal of select isomers and homologs due to processes of biodegradation and partitioning. Tetralin and indane sulfonates (DATS), alicyclic analogs of LAS, were also identified in field samples. Although DATS are a minor portion of LAS formulations, equivalent concentrations of LAS and DATS in groundwater suggested persistence of alicyclic contaminant structures over those of linear structure. Sulfophenyl-carboxylated (SPC) LAS biodegradation intermediates were determined in sewage effluent and groundwater. Homolog distributions suggested that SPC containing 3–10 alkyl-chain carbons persist during infiltration and groundwater transport. Surfactant-derived residues detected in well F300-50 groundwater have a minimum residence time in the range of 2.7–4.6 yr. LAS detected in groundwater at 500 m from infiltration has been stable over an estimated 50–500 half lives.

Deposit formation in liquid fuels. 1. Effect of coal-derived Lewis bases on storage stability of Jet A turbine fuel

Abstract The development of reasonably precise techniques for the measurement of storage stability of jet aviation fuel is described. Lewis bases, extracted by ligand-exchange from a coal-derived liquid, are shown to adversely affect storage stability (as determined by an accelerated storage test) when added to Jet A turbine fuel. JFTOT results suggesting slight decreases in thermal stability of fuel ‘spiked’ (i.e. contaminated with a measured quantity of reagent) with extract are reported. Addition to Jet A turbine fuel of individual heterocyclic nitrogen compounds is shown to produce comparable decreases in storage stability.

Deposit formation in liquid fuels. 2. The effect of selected compounds on the storage stability of Jet A turbine fuel

The influence of substituted pyridines, pyrroles, indoles, and quinolines on the storage stability of conventional Jet A turbine fuel is evaluated. Significant increases in the amount of deposit formed in accelerated storage tests are found upon addition of these compounds at levels as low as one ppm nitrogen. While the effect is correlated with basicity of the nitrogen compound within a given compound class, the correlation does not hold between classes (pyridines, quinolines, etc.). Steric hindrance at the nitrogen atom greatly inhibits deposit promotion. The characteristics, but not the elemental composition, of deposits vary with the identity of the added nitrogen compound and with deposition temperature.

Deposit formation in liquid fuels. 3. The effect of selected nitrogen compounds on diesel fuel

The influence of substituted quinolines, pyrroles, indoles, and pyridines on deposit formation in a diesel fuel is evaluated. Significant increases in deposition rate are found which are dependent upon the basicity of the nitrogen compound within a given compound class. These effects correspond closely with those produced in a Jet A fuel. Removal of highly polar fuel components renders the nitrogen compound influence inoperative. These components are therefore participants in deposit-forming reactions.

Deposit formation in liquid fuels: 4. Effect of selected organo-sulphur compounds on the stability of Jet A fuel

The influence of aliphatic sulphides, disulphides, thiols, and thiophenes on deposit formation at 394–408 K in Jet A turbine fuel has been evaluated. Addition of aliphatic sulphides and disulphides at 10–1000 μ g S ml −1 fuel slightly inhibited deposition while similar addition of thiols and thiophenes decreased stability of the fuel. The effect on deposition rate in sulphide- and thiol-spiked fuel was proportional to an experimental estimate of the Lewis basicity of the sulphide or thiol. The inhibition by sulphides is consistent with complexation or diversion of soluble deposit precursors.

ON THE INTERPRETATION OF SCHUBERT PLOT SLOPES FOR METAL-HUMATE SYSTEMS

In this paper we identify an error in the literature pertaining to the interpretation of nonintegral slopes in Schubert plots for metal-humate and metal-fulvate systems, and we derive equations that correctly describe the behavior of these systems.

Complexation of neptunium(V) by salicylate, phthalate and citrate ligands in a pH 7.5 phosphate buffered system

Abstract Conditional stability constants, enthalpies and entropies of complexation at pH 7.5 and ionic strength 0.1 have been determined for neptunium(V) complexes of phosphate, salicylate, phthalate and citrate. Phosphate forms a complex with log β = 2.36 ± 0.42 at 25°C, ΔH°c = − 69.9 kJ/mole and ΔS°c = − 188 J/mole-K. At pH 7.5 salicylate does not form a complex with neptunium(V) due to the low charge density of the NpO2+ ion and incomplete ionization of the salicylate ion. Phthalate forms a complex with log β = 3.43 ± 0.33 at 25°C, ΔH°c = 33.5 kJ/mole and ΔS°c = 182 J/mole-K. Citrate forms a complex with log β = 4.84 ± 0.72 at 25°C, ΔH°c = 14.0 kJ/mole and ΔS°c = 140 J/mole-K. In all cases, only 1:1 complexes were identified.

Colloid particle sizes in the Mississippi River and some of its tributaries, from Minneapolis to below New Orleans

An on-board technique was developed that combined discharge-weighted pumping to a high-speed continuous-flow centrifuge for isolation of the particulate-sized material with ultrafiltration for isolation of colloid-sized material. In order to address whether these processes changed the particle sizes during isolation, samples of particles in suspension were collected at various steps in the isolation process to evaluate changes in particle size. Particle sizes were determined using laser light-scattering photon correlation spectroscopy and indicated no change in size during the colloid isolation process. Mississippi River colloid particle sizes from twelve sites from Minneapolis to below New Orleans were compared with sizes from four tributaries and three seasons, and from predominantly autochthonous sources upstream to more allochthonous sources downstream.

Use of principal component regression to characterize a complex oxidation product mixture

Abstract Analytical data for complex mixtures (e.g., humic substances and hydrocarbon fuel deposits) contain a wealth of information about the components which cannot be interpreted without resolution of the contributions from the various species present. Such resolution can be achieved by separation of components (chromatography, distillation, etc.) prior to analysis or use of selective detectors or methods. Multivariate statistical methods offer an alternative approach; mathematical resolution of the data which does not require painstaking chemical separations and can be applied to mixtures not amenable to conventional separation methods. In this example, acid—base fractionation and complementary instrumental analyses provide the discriminators to select mass spectral features of components from the pyrolysis mass spectrum of the complex mixture of air oxidation products of 1-tetralone.

Quantitative separation of tetralin hydroperoxide from its decomposition products by high performance liquid chromatography

Abstract A method for the separation and analysis of tetralin hydroperoxide and its decomposition products by high pressure liquid chromatography has been developed. Elution with a single, mixed solvent from a μ-Porasil column was employed. Constant response factors (internal standard method) over large concentration ranges and reproducible retention parameters are reported.