Vassilis C. Stamoudis

Determination of biological removal of organic constituents in quench waters from high-BTU coal-gasification pilot plants

Abstract Studies were initiated to assess the efficiency of bench scale, activated-sludge treatment for removal of organic constituents from coal-gasification process effluents. Samples of pilot plant, raw-gas quench waters were obtained from the HYGAS process of the Institute of Gas Technology and from the slagging, fixed-bed (SFB) process of the Grand Forks Energy Technology Center. The types of coal employed were Bituminous Illinois No. 6 for HYGAS and Indian Head lignite for SFB process. These pilot plant quench waters, while not strictly representative of commercial condensates, were considered useful to evaluate the efficiency of biological oxidation for the removal of organics. Biological reactors influent and effluent samples were extracted using a methylene chloride pH-fractionation method into acid, base, and neutral fractions, which were analyzed by capillary-column gas chromatography/mass spectrometry. Influent acid fractions of both HYGAS and SFB condensates showed that nearly 99% of extractable and chromatographable organic material comprised phenol and alkylated phenols. Activated sludge treatment removed these compounds almost completely. Removal efficiency of base-reaction organics was generally good, except for certain alkylated pyridines. Removal of neutral-fraction organics was also good, except for certain alkylated benzenes, certain polycyclic aromatic hydrocarbons, and certain cycloalkanes and cycloalkenes, especially, at low influent concentrations.

Distribution coefficients for chemical components of a coal-oil/water system

Distribution coefficients (KDS) were measured by equilibrating a coal oil comparative reference material (CRM-1) with water and then separating the oil and water phases. Aqueous phase concentrations were determined by direct analysis of this phase, while organic phase concentrations were determined from the original oil composition by difference. The log K o values obtained for acidic and basic components were generally <3, while those for the neutral components ranged from 3 to 6. For aromatic hydrocarbons, strong correlations were observed between log KD and log Sw (water solubility), and between log K o and log Kow (octanol/water partition coefficient). Alkylated benzenes had significantly higher Kos than did unsubstituted aromatics of similar molecular weight. Examination of homologs revealed an increase of 0.307 IOg KD units per additional carbon atom for polynuclear aromatic hydrocarbons having from 10 to 16 carbons. Alkyl substituent effects determined for various sets of homologs ranged from 0.391 to 0.466 log K~ units per --CH 2- group added.

A5–4 PYRIMIDINE‐PYRIMIDONE PHOTOPRODUCT PRODUCED FROM MIXTURES OF THYMINE AND 4‐THIOURIDINE IRRADIATED WITH 334 nm LIGHT

The nucleoside 4‐thiouridine, present in some bacterial tRNA species, is known to be a chromophore and a target for near‐UV light‐induced growth delay and also mediates both photoprotection and near‐UV cell killing in various bacterial strains. To investigate the photoreaction of 4‐thiouridine with DNA or its precursors, we irradiated aqueous mixtures of thymine and 4‐thiouridine with 334 nm light and then separated photoproducts using two or more stages of reversed‐phase high performance liquid chromatography. The two equally abundant major photoproducts were analyzed by UV absorbance spectrophotometry, fast‐atom bombardment and electron‐impact mass spectrometry, and 1H‐ and 13C‐NMR spectroscopy, and have been identified as two diastereomers of 6‐hydroxy‐5‐[1‐(β‐D‐erythro‐pentofuranosyl)‐4′‐pyrimidin‐2′‐one]dihydrothymine (o6hThy[5‐4]Pdo), of molecular weight = 370.32. These two diastereomers, although stable at room temperature or below, are interconvertible by heating (90d̀C for 5 min) in aqueous solution. The possible biological significance of this photoproduct is discussed, and an application as a crosslinker for oligonucleotides to selectively block replication is suggested.

Protection by uridine diphosphoglucuronic acid and DT-diaphorase against the cytotoxicity of polycyclic aromatic hydrocarbons isolated from a complex coal gasification condensate

The cytotoxicities of polycyclic aromatic hydrocarbon (PAH) subclasses isolated from a complex organic mixture (coal gasification condensate) were studied in vitro in Chinese hamster ovary cells, in the presence of rat liver microsomes from animals pretreated with Aroclor. Toxicity was enhanced by microsomal metabolism and was inversely related to aromatic ring number. Rat liver cytosol, semipurified DT-diaphorase, and uridine diphosphoglucuronic acid decreased the cytotoxicity of a variety of PAH mixtures and representative PAH, as well as individual PAH metabolites. The results indicate that the in vitro toxicity of complex PAH mixtures is caused primarily by hydroxy-PAH and quinone metabolites of the predominant, nonmutagenic two- and three-ring PAHs.

Isolation of a highly mutagenic aminophenanthrene from a coal gasification process tar.

A major portion of the mutagenic activity associated with products and by-products of coal conversion can be ascribed to nitrogen-containing bases. We improved the extraction efficiencies for three- to five-ring aromatic bases by extracting them with a mixture of methanol and aqueous HCl, rather than with aqueous HCl alone. A complex mutagenic basic fraction of a coal gasification process tar was successively fractionated using cation exchange and reversed phase high-performance liquid chromatography. The fractions were assayed for mutagenic activity and were chemically analyzed by gas chromatography and gas chromatography-mass spectrometry. Aminophenanthrenes were identified as major contributors to the mutagenicity of the basic fraction. Aminonaphthalenes, aminobiphenyls, and their alkyl homologs were also present but were not detected as principal mutagens.

Isolation and identification of mutagenic polycyclic aromatic hydrocarbons from a coal gasifier condensate

An iterative scheme of short-term bacterial mutagenesis assays and multidimensional liquid chromatographic methods was used to isolate mutagens from a neutral fraction of a complex carcinogenic tar formed as a by-product of coal gasification. Mutagens in the complementary reversed- and normal-phase liquid chromatographic fractions were identified by capillary column gas chromatography and gas chromatography-mass spectrometry. The principal mutagens included a variety of 4- to 6-ring unsubstituted polycyclic aromatic hydrocarbons, their alkylated homologs, and related methylene-bridged compounds. Most of the unsubstituted mutagens were known carcinogens that were qualitatively similar to those detected by carcinogenicity assays of fractions from other types of coal tars and cigarette smoke condensate. The chromatographic approach is generally applicable to complex mixtures and is especially well suited for fractionating mixtures of aromatic compounds and their alkyl homologs.

Rapid characterization of mutagenic aromatic amines in energy-related materials by short column liquid chromatography with electrochemical detection.

A liquid Chromatograph equipped with a short (3 cm) reverse phase column and electrochemical detector was used to characterize aromatic amines in shale oil, synthetic oil, and coal gasification streams. Five major peaks were produced from each sample mixture. The composition of the peaks was determined by high performance liquid chromatography with a long (25 cm) reverse phase column and by gas chromatography/mass spectrometry. Amines in the various peaks included aminonaphthalenes, aminobiphenyls, aminofluorenes, and aminophenanthrenes plus aminoanthracenes. The concentration of aminofluorenes, and aminophenanthrenes plus aminoanthracenes correlated with relative mutagenicity of the base fraction from the oils or tars. The levels of 2- and 3-ringed aromatic amines from shale oil and oil from the Great Plains commercial coal gasification plan were 24 and 184 μg/g tar, respectively, while the respective mutagenicities were 8 and 214 revertants/μg base fraction. This technique has the advantages of high sensitivity and rapid analysis, and could be used to screen for the presence of mutagens in synthetic fuel samples.