Abstract  Densities and relative permittivities at a frequency of 30 kHz for the binary mixtures of 1-alkanols, CnH2n+1OH for n = 1 to 10, + dodecane were measured for the mole fraction range of 1-alkanol between 0 and 0.1 at a temperature of 298.15 K. By using Debye and Frohlich equations, the apparent dipole moments (mu) of 1-alkanols were calculated, and the limiting values (mu(0)) were determined by extrapolating to infinite dilution. The value of mu(0) decreased with increasing hydrocarbon length of the 1-alkanol. The present results were compared with our previous measurements in cyclohexane and heptane. Methanol had the same mu(0) value irrespective of solvent, while mu(0) for 1-alkanols with n >= 2 showed a lower value in dodecane than those found in cyclohexane and heptane. The excess partial molar volumes of 1-alkanols at infinite dilution decreased with increasing n.

Abstract  The enhanced removal of carbon tetrachloride (CCl4), tetrachloroethene (C2Cl4), and trichloroethene (C2HCl3) by chloride green rust (GR(Cl)) in the presence of copper ions was investigated. X-ray powder diffraction (XRPD) and X-ray photoelectron spectroscopy (XPS) were used to characterize the crystallization and chemical speciation, respectively, of the secondary mineral phases produced in the GR(Cl)-Cu(II) system. The addition of Cu(II) to GR(Cl) suspensions resulted in enhanced dechlorination of the chlorinated hydrocarbons examined in this study. The degradation reactions followed pseudo-first-order kinetics and the pseudo-first-order rate constant (k(obs)) for CCl4 (20 microM) removal by GR(CI) at pH 7.2 was 0.0808 h(-1). Addition of 0.5 mM Cu(II) completely dechlorinated CCl4 within 35 min, and the k(obs) was 84 times greater than that in the absence of Cu(II). Chloroform (CHCl3), the major chlorinated product in CCl4 dechlorination, accumulated at a concentration up to 13 microM in the GR(Cl) system alone, but was completely dechlorinated within 9 h in the GR(Cl)-Cu(II) suspension. Also, rapid removal of C2Cl4 and C2HCl3 by GR(Cl) was observed when Cu(II) was added. The k(obs) values for the removal of chlorinated ethenes were 4.7-7 times higher than that obtained in the absence of Cu(II). In addition, the k(obs) for PCE removal increased linearly with respect to Cu(II) concentrations in the range from 0.1 to 1.0 mM. Addition of Cu(II) at a concentration higher than 1.0 mM decreased the k(obs) for the removal of both C2Cl4 and C2HCl3 due to the decrease in structural Fe(II) concentration in GR(Cl) and the changes in redox potentials and pH values. Moreover, the highest removal efficiency and rate of C2Cl4 was obtained at near-neutral pH when Cu(II) was added into the GR(Cl) suspension. XPS and XRPD results showed that the Fe(II) in the GR(Cl) suspension could reduce Cu(II) to both Cu(I) and metallic Cu. These findings are relevant to the better understanding of the role of abiotic removal of chlorinated hydrocarbons during remediation and/or natural attenuation in iron-reducing environments.

Abstract  The extraction of Eu3+ from an aqueous perchlorate medium of constant ionic strength (0.1 M NaClO4) was studied at different temperatures by 8-quinolinol (HQ) in benzene, carbon tetrachloride, and chloroform, and by a mixture of 8-quinolinol and 1,10-phenanthroline (Phen), allowing for elucidation of the thermodynamic parameters and the mechanism of extraction of the species formed. The results indicated that the extraction is enhanced by adduct formation in the organic phase, and that the main extracted species were EuQ(3). 2HQ, EuQ(3). 2HQ . Phen, and EuQ(3). 2HQ . 2Phen.

Abstract  Binary mixtures containing compounds which show cross-association between them are investigated in terms of DISQUAC: namely, systems with two linear monocarboxylic acids, or with one acid and one 1-alkanol. In the former, the interactions between the COOH groups of the acids are represented by dispersive parameters only. Binary systems involving two l-alkanols behave similarly. In the linear monocarboxylic acids + 1-alkanol mixtures, the COOH/OH interactions are represented by structure-dependent dispersive and quasichemical parameters. It is shown that those solutions with methanol and ethanol do not fit into the general scheme followed by the higher members of each homologous series considered here. A similar behaviour is found when mixtures containing methanol and benzene or CCl4 ate compared with those involving higher alkanols in the frameworks of DISQUAC or of the Barker's theory. Vapor-liquid equilibria, VLE, and excess enthalpy, H-E, data are consistently described by DISQUAC. Discrepancies are analysed. The UNIQUAC association model or an equation of state (Carnahan-Starling) with the association built in have been applied in the literature as pure correlation equations of the experimental data for acids + l-alkanols systems. Their results are compared with those reported in this work by DISQUAC. (C) 1997 Elsevier Science B.V.

Abstract  A review of Authors' 16 works covering the integrated stripp-adsorption on active C as applied to sep. 1,1,2-trichloroethane from vinyl chloride wastes, further converted into vinylidene chloride or 1,1,1-trichloroethane, to sep. 1,2,3-trichloropropane which is further converted into 2,3-dichloropropene, 2-chloroallyl aic. and amine, 2-chlorothioallyl alc. or bis(2-chloroaltyl amine). Waste 1.2-dichloropropane from propylene oxide plants is ammonolyzed to 1,2-diaminopropane or used to prep. alpha-methyttaurine. Other compds. are chlorolyzed to yield C2Cl4, CCl4, C2Cl6, C6Cl(6), and hexachloro-1,3-butadiene. Sapon. of chlorohydrin with NaOH, rather than time milk, eliminates waste CaCl2.

Abstract  Comprehensive product yield determinations from the high-temperature, gas-phase pyrolysis of tetrachloroethene (C2Cl4) using two fused-silica tubular flow reactors are reported. The effects of reactor surface area to volume (S/V) ratio were evaluated by conducting detailed product analyses with 0.1-cm i.d. and 1.0-cm i.d. reactors. Under low S/V ratio, initial decomposition was observed at 1123 K with formation of dichloroacetylene (C2Cl2) and hexachlorobenzene (C6Cl6(cy)). Molecular chlorine was also observed as a product at higher temperatures. Under high S/V ratio, C2Cl4 decomposition was initiated at 973 K. Reaction products included Cl-2, carbon tetrachloride (CCl4), hexachlorobutadiene (C4Cl6), and C6Cl6(cy). Product yields under low S/V ratio indicated that yields of C6Cl6(cy) were a factor of 4 larger than observed for high S/V ratios. A previously published detailed pyrolysis mechanism for trichloroethene (C2HCl3) was incorporated into a C2Cl4 pyrolysis model to provide predictions of the high-temperature reaction behavior of C2Cl4. The model predictions are in much better agreement with product distributions obtained using the 1 cm i.d. reactor versus the 0.1 cm i.d. reactor. Minor revisions of the C2HCl3 model significantly improved comparisons with the observed C2Cl4 product distributions without compromising previous agreement with C2HCl3 product distributions. Important radical-molecule addition reactions leading to C6Cl6(cy) are identified using sensitivity analysis and production rate calculations.

Abstract  OBJECTIVE: To investigate capacity of Hyptis suaveolens (H. suaveolens) methanol extract as an antioxidant to protect against carbon tetrachloride (CCl(4))-induced oxidative stress, hepatotoxicity in Albino Wistar rats and cytoprotective effect of hydrogen peroxide (H(2)O(2)) induced cell death in HepG(2) cell line.

METHODS: Two different doses of methanol extract of H. suaveolens were evaluated for the hepatoprotective activity against carbon tetrachloride (CCl(4)) induced hepatotoxicity in rats. Animals in Group I: served as control, group II: H. suaveolens (100 mL/kg b.w), group III: H. suaveolens (50 mL/kg b.w) + CCl(4) (1 mg/kg), group IV: H. suaveolens (100 mL/kg b.w) + CCl(4) (1 mL/kg) and group V: CCl(4) (1 mL/kg). Histopathologic changes of liver were also evaluated. Cytotoxicity was also determined by 3, (4,5-dimethylthiazol-2-yl)2,5-diphenyl-tetrazolium bromide (MTT) assay.

RESULTS: Oral sigle dose treatment of CCl(4) produced a marked elevation in the serum levels of aspartate transaminase (AST), alanine transaminase (ALT), alkaline phosphatase (ALP) and Lactate dehydrogenase (LDH). Histopathological analysis of the liver of CCl(4)-induced rats revealed marked liver cell necrosis with inflammatory collections that were conformed to increase in the levels of SOD, GSH, GST, GR and LPO. Treatment with H(2)O(2) significantly induced death of HepG(2) cell. Pretreatment with H. suaveolens methanol extract inhibited or attenuated H(2)O(2) induced cytotoxicity.

CONCLUSIONS: This study shows that H. suaveolens methanol extract can be proposed to protect the liver against CCl(4)-induced oxidative damage in rats and protect the cells against H(2)O(2)-induced oxidative damage in HepG(2) cells. The hepatoprotective and cytoprotective effects might be correlated with its antioxidant and free radical scavenger effects.

Abstract  Cysteine was studied as a reductant in carbon tetrachloride (CCl4) transformation mediated by vitamin B-12 at room temperature in the pH range of 4-14. The reaction proceeded in two consecutive phases: the initial phase was rapid but lasted only minutes before the slow subsequent phase started as B-12 was inactivated, presumably due to nonreactive alkylcobalamin formation. The reduction of Co(III) to Co(II) was rate-limiting in the fast phase, whereas the decomposition of the alkylcobalamin may control the rate in the slow phase. B-12r was the reduced B-12 species but exhibited little reactivity toward CCl4 in the absence of cysteine; the reactive B-12 species is hypothesized to be the penta coordinated B-12r-cysteinate complex. Most of the CCl4 was transformed to unidentified water-soluble products. The chloroform yield decreased with pH from 20% to nearly zero, whereas the carbon monoxide yield remained constant (3.2 +/- 0.3%) with pH. These findings suggest that (1) the reductant controls both the kinetics and the mechanism of the reaction and should not be viewed simply as an electron donor, and (2) the B-12 species involved in reductive biodehalogenation is likely to be either B-12s Or B-12r-thiolate complexes.

Abstract  The Solubility data of 5-amino salicylic acid in methanol, ethanol, carbon tetrachloride, and tetrahydrofuran (THF) at Various temperatures were measured by gravimetrical method front (293.15 to 313.15) K Under atmospheric pressure, and the solubility data were correlated as a function of temperature. The order of solubility is THF > carbon tetrachloride > ethanol > methanol. Further, some thermodynamic parameters such as enthalpy, Gibb's energy, and entropy have also been evaluated for the dissolution process. It is observed that enthalpy and entropy are positive, whereas the Gibb's energy of activation is negative for all of the four solvents. The negative Gibb's energy Suggests the spontaneous nature of dissolution process, whereas positive enthalpy indicates endothermic dissolution of compounds. The positive entropy is due to favorable dissolution in the Studied solvents.

Abstract  The results and a numerical simulation of studies on dynamics of the adsorption from seven-component aqueous solution of light chlorinated hydrocarbons on activated carbon have been presented. Aqueous solution of 1,2-dichloroethane (12DCE), 1,1,2,2-tetrachloroethane (S-TET), chloroform (CHCl(3)), carbon tetrachloride (CCl(4)), 1,1-dichloroethene (VDC), perchloroethene (PER) and 1,1,2-trichloroethene (TRI) was used. Concentrations of chlorohydrocarbons were similar as in wastewater from vinyl chloride plant. A cell model that incorporates the diffusion through a laminar layer of liquid around a particle was used to describe the experimental results. The applied calculation methods, which take kinetics into account, allows to well describe a phenomenon of dynamic adsorption. Mean relative deviations between the experimental and calculated values amounted 17%. The breakthrough curves become steeper along with an increase of the bed height. A consistency of the experimental results with those calculated indicates for a negligible contribution of the axial diffusion on the dynamic adsorption process of light chlorinated hydrocarbons from aqueous solution under the hydrodynamic conditions corresponding to the Reynolds number equal to 1.3. Determined optimal bed height for waste linear flow rate-15 cm/min is in the range 80-120 cm.

Abstract  Total vapour pressure measurements using a modified static method at 313.15 K are reported for binary mixtures of CCl4 with benzene, toluene, o-xylene, p-xylene, hexane, heptane, octane, nonane and decane. The results were correlated with the generalized Redlich-Kister equation for excess Gibbs energy. A comparison with literature vapour-liquid equilibrium data and excess enthalpy was made. Consistency within homologous series was checked. Predictions made using the UNIFAC method and the Hildebrand-Scatchard equation were compared.

Abstract  Air samples were collected simultaneously at platform, mezzanine and outdoor in five typical stations of subway system in Shanghai, China using stainless steel canisters and analyzed by gas chromatography-mass selective detector (GC-MSD) after cryogenic preconcentration. Benzene, toluene, ethylbenzene and xylenes (BTEX) at the platforms and mezzanines inside the stations averaged (10.3 +/- 2.1), (38.7 +/- 9.0), (19.4 +/- 10.1) and (30.0 +/- 11.1) microg/m3, respectively; while trichloroethylene (TrCE), tetrachloroethylene (TeCE) and para-dichlorobenzene (pDCB), vinyl chloride and carbon tetrachloride were the most abundant chlorinated hydrocarbons inside the stations with average levels of (3.6 +/- 1.3), (1.3 +/- 0.5), (4.1 +/- 1.1), (2.2 +/- 1.1) and (1.2 +/- 0.3) microg/m3, respectively. Mean levels of major aromatic and chlorinated hydrocarbons were higher indoor (platforms and mezzanines) than outdoor with average indoor/outdoor (I/O) ratios of 1.1-9.5, whereas no significant indoor/outdoor differences were found except for benzene and TrCE. The highly significant mutual correlations (p < 0.01) for BTEX between indoor and outdoor and their significant correlation (p < 0.05) with methyl tert-butyl ether (MTBE), a marker of traffic-related emission without other indoor and outdoor sources, indicated that BTEX were introduced into the subway stations from indoor/outdoor air exchange and traffic emission should be their dominant source. TrCE and pDCB were mainly from indoor emission and TeCE might have both indoor emission sources and contribution from outdoor air, especially in the mezzanines.

Abstract  The solubility of pyoluteorin (Plt) in water, dichloromethane, chloroform, and carbon tetrachloride was determined using an analytical method over the temperature range of (278.2 to 333.2) K.. The solubility of Plt in chloroform is much higher than that in water, dichloromethane, and carbon tetrachloride. The solubility of Plt increases with increasing temperature in the four solvents, and all measurements were correlated with the Apelblat equation.

Abstract  To optimize the efficiency of bioremediation, treatability studies are needed to understand the fate of pollutants and environmental conditions under which microorganism growth is promoted and efficient degradation of these pollutants result. This article presents a recommended procedure which may achieve these goals. Results and treatability comparisons for candidate compounds including carbon tetrachloride (CT), methyl-tert-butyl-ether (MTBE) and hexachlorobutadiene (HCBD) are presented and discussed. Culture redox potential (ORP) which is an indicator or free electron activity of a system appeared to have a significant impact on CT biodegradation. Optimum biodegradation of CT by Pseudomonas cepacia was observed between -100 and -200mv. Under the optimum environmental conditions established during the batch-scale biotransformation study, 98 to 99.9% of CT and 70% of MTBE introduced into the continuous fixed-biofilm reactor were degraded. The biphasic model simulating biodegradation of CT and MTBE provided an excellent correlation in the fixed-biofilm study and was simple to apply as compared with other models.

Abstract  BIOSIS COPYRIGHT: BIOL ABS. RRM BOOK CHAPTER LITERATURE REVIEW HUMAN EXPOSURE ASSESSMENT TOXIC CHEMICALS CANCER REPRODUCTIVE EFFECTS VALIDITY

Abstract  The influences of amphiphiles, including humic acid (HA) and various types of surfactants, on dechlorination of carbon tetrachloride (CTC) and chloroform (CF) by the nano-scale Fe particles were investigated. Since the amphiphiles would modify the surface tension between the liquid-liquid and solid-liquid interface, in the presence of amphiphile matrix solution the Fe corrosion rate and the parent compound dechlorination rate would be different from those in the ultrapure water. Among the four amphiphile solutions, Fe corrosion rate was the highest in the anionic surfactant sodium dodecyl sulfate (SDS) solution, presumably due to the existence of chemisorption between the hydrophilic head of SDS and Fe particles. The dechlorination rates of CTC and CF could be described with the pseudo-first order kinetic model. The influences of amphiphiles on the dechlorination reaction rate were related to the species of parent compound and concentration of the matrix solution. The influences of HA on the dechlorination of CTC and CF were the most significant compared to other matrix solutions. At relatively low HA concentration (<0.1 g L(-1)), the HA molecules (serving as electron transfer mediator) would significantly accelerate the dechlorination rate of CF. The two-parameter regression with energy of the lowest unoccupied molecular orbital (E(LUMO)) and HA concentration as the descriptors was developed to predict the specific reduction rate constants of chlorinated methanes in HA solution. The analysis of variance (ANOVA) indicated the existence of significant relationship between the dechlorination rate constants and the two descriptors.

Abstract  Results of activity investigation of a granular catalyst containing Pd (1%) at gamma-Al(2)O(3) carrier in the oxidation process of selected chloroorganic compounds occurring in liquid industrial wastes was analysed. The following compounds were used as substrates: 1,3-dichloro-2-propanol, chloroacetone, 1,1,1-trichloroacetic aldehyde (chloral), tetrachloromethane, 1,1,1-trichloroethane, 1,1,2-trichloroethane and 1,1,2,2-tetrachloroethane. The temperature range was from 250 to 600 degrees C and the contact time was 0.36 s. Gaseous and liquid reaction products were analysed including the content of dioxins (PCDD/Fs) determination in combustion gases. Total oxidation of the substrates in the presence of the catalyst was found in the temperature range of 375 divided by 550 degrees C. The final products of the substrates oxidation were as follows: carbon dioxide, water vapour and dilute hydrochloric acid. Formaldehyde, carbon monoxide and chlorine were the intermediate products of this reaction. Trace presence of several polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofuranes (PCDD/Fs) was determined. The toxicity equivalent of combustion gases sampled in the temperature of 450-550 degrees C was in the range from 0.0087 to 0.0247 ng TEQ/m(3) and was compatible with the admissible values in combustion gases, required by law regulations (0.1 ng TEQ/m(3)). Results of the investigation prove the possibility of the decrease in the temperature to 450 divided by 550 degrees C during the chloroderivates treatment with the application of the palladium catalyst in comparison with a high-temperature process carried out in the temperature of about 1350 degrees C in industrial plants nowadays.

Abstract  By using physiologically based pharmacokinetic (PBPK) modeling coupled with Monte Carlo simulation, the interindividual variability in the concentrations of chemicals in a worker's exhaled breath and urine were estimated and compared with existing biological exposure indices (BEIs). The PBPK model simulated an exposure regimen similar to a typical workday, while exposure concentrations were set to equal the ambient threshold limit values (TLVs) of six industrial solvents (benzene, chloroform, carbon tetrachloride, methylene chloride, methyl chloroform, and trichloroethylene). Based on model predictions incorporating interindividual variability, the percentage of population protected was derived using TLVs as the basis for worker protection. Results showed that current BEIs may not protect the majority or all of the workers in an occupational setting. For instance, current end-expired air indices for benzene and methyl chloroform protect 95% and less than 10% of the worker population, respectively. Urinary metabolite concentrations for benzene, methyl chloroform, and trichloroethylene were also estimated. The current BEI recommendation for phenol metabolite concentration at the end-of-shift sampling interval was estimated to protect 68% of the worker population, while trichloroacetic acid (TCAA) and trichloroethanol (TCOH) concentrations for methyl chloroform exposure were estimated to protect 54% and 97%, respectively. The recommended concentration of TCAA in urine as a determinant of trichloroethylene exposure protects an estimated 84% of the workers. Although many of the existing BEIs considered appear to protect a majority of the worker population, an inconsistent proportion of the population is protected. The information presented in this study may provide a new approach for administrative decisions establishing BEIs and allow uniform application of biological monitoring among different chemicals.

Abstract  This position paper delineates the expert recommendations of the Regulatory Affairs Committee of the American Society for Veterinary Clinical Pathology for the use of preclinical, clinical pathology endpoints in assessment of the potential for drug-induced hepatic injury in animals and humans. Development of these guidelines has been based on current recommendations in the relevant preclinical and human clinical trial literature; they are intended to provide a method for consistent and rigorous interpretation of liver-specific data for the identification of hepatic injury in preclinical studies and potential liability for hepatic injury in human patients.

Abstract  In this experiment, we studied the different changes in activities and protein levels of each subform of hepatic cytochrome P450 and glutathione S-transferase (GST), in chemical-induced liver injury in rats. Rats were administered 1,1-dichloroethylene (DCE), allyl alcohol (AA), bromobenzene (BB) and N,N-dimethylformamide (DMF) p.o. once every two days for 7 times, and decapitated 18 hr after the last administration. DCE and AA showed stronger hepatic toxicity than BB and DMF, as serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) were higher in DCE and AA treated rats than in BB and DMF groups. Anti-cytochrome P450 inhibitable activity of toluene metabolism and/or immunoblot analysis showed that CYP2E1 and CYP2B1/2 were induced by BB and DMF, but not by the other two chemicals; CYP2C11 was greatly decreased by all of the four toxicants; and CYP1A1/2 was slightly reduced by the four treatments. These changes were reflected in testosterone metabolism. Formation of 6 beta- and 7 alpha-hydroxytestosterone from testosterone was enhanced only in DMF-treated rats, whereas that of 2 alpha- and 16 alpha-hydroxytestosterone was reduced by all of the four chemicals. Serum GST activity was increased only in BB and DMF treated rats, but liver cytosolic GST activity was enhanced by all of the four hepatotoxicants, with higher values in BB and DMF groups than in DCE and AA groups. Immunoblot analysis demonstrated that GST Yp was induced by BB and DMF treatments, and Ya and Yc were increased only by BB. GST Yk and Yb1 were not affected by the treatments. The different change patterns of enzymes by a specific toxin and the similar modifying effect on a specific enzyme by different toxins were discussed in relation to the liver damage and to the heterogeneous distribution of enzymes in liver.