Volatile Liquid Hydrocarbons Research Articles

Benzene and leukemia: from scientific evidence to regulations. A historical example.

Background:Benzene is a highly flammable, highly volatile liquid aromatic hydrocarbon. It has been used in many industrial processes as a solvent or a starting material. At the beginning of the twentieth century, it was very widely used in the workplace, especially in printing and in the shoe manufacturing and rubber industries. Although benzene was first recognized to cause aplastic anemia, its association with leukemia has been investigated only since the 1930s. In 1963, Italy was one of the first countries in the world to adopt a law to ban benzene as a solvent in work activities.Objectives:This study analyzed the contribution of the Clinica del Lavoro in Milan, Italy, to studies of the relationship between exposure to benzene and leukemia.Methods:Scientific literature and historical sources on benzene and leukemia in the twentieth century were reviewed, and interviews with a first-hand witness of that period were conducted.Results:By 1928, several scholars had reported anecdotal cases of leukemia among workers exposed to benzene. Enrico Vigliani was the first to collect all of these cases and to try to conduct statistical analysis on these data, in order to support the association between benzene and leukemia. In the 1960s, Vigliani and Alessandra Forni showed that benzene could cause chromosome aberrations in the bone marrow that could produce leukemic clones.Conclusions:As a result of these studies and the subsequent regulations which banned benzene, exposure conditions changed in the workplace in the last few decades. The resulting low concentrations have prompted researchers to investigate new exposure biomarkers and to study any related health problems.

Laser-Driven Calorimetry of Single-Component Liquid Hydrocarbons.

A novel laser-heating technique, referred to as the laser-driven thermal reactor (LDTR), was used to determine sample thermal (exothermic/endothermic) behavior, specific heat release rate, and total specific heat release of three volatile single-component liquid hydrocarbons, i.e., n-decane, n-butylcyclohexane and n-butylbenzene. The objective was to demonstrate measurement repeatability and extend the LDTR model from earlier investigations. The experimental apparatus consists of a copper sphere-shaped reactor mounted within a vacuum chamber, with sample and substrate supported on a thermocouple near the center of the reactor. The reactor is heated from opposing sides by a near-infrared laser to achieve nearly uniform sample temperature. The change in temperature with time (i.e., thermogram) is compared to a previously recorded baseline (no liquid sample) thermogram. A model, based on thermal energy conservation, is used to evaluate the thermograms for the thermochemical characteristics of interest. This study represents a step toward applying this technique to more complex volatile multi-component fuels of unspecified composition. Results for the LDTR were compared with a differential scanning calorimetry/thermal gravimetric analysis (DSC/TGA) instrument. The model analysis was extended to include an estimation of the hydrocarbon mass change with increasing temperature, based on the temporal change in the specific heat release rate. An estimate of the total specific heat release was obtained for these three liquid hydrocarbons and found to be consistent with the literature values when the measurements were carried out under suitable operating conditions.

Determination of genetic damage and urinary metabolites in fuel filling station attendants

Fuel (diesel and petrol) constitutes a complex mixture of volatile flammable liquid hydrocarbons among them benzene (BZ), toluene (TOL), and xylene (XYL) are considered to be the most hazardous, predominantly BZ because of its carcinogenic potency. Exposure to these compounds may have an impact on the health of the exposed subjects. Hence, genotoxicity and quantitative analysis of these compounds was performed in blood and urine samples of 200 workers exposed to fuel in filling stations and compared to controls. The level of genetic damage was determined by micronucleus test (MNT) in buccal epithelial cells (BEC) and chromosomal aberrations (CA) assay in peripheral blood lymphocytes (PBL) of fuel filling station attendants (FFSA) and compared to a matched control group. Urine analysis for BZ and its metabolites, phenol (Ph), trans, trans-Muconic Acid (t, t-MA), and S-Phenyl Mercapturic Acid (S-PMA) was done in all the study subjects. The results of our study revealed that exposure to BTX in petrol vapors induced a statistically significant increase in the frequency of micronuclei (MN) and CA in the exposed subjects than in controls (P < 0.05). There was a significant rise in the levels of urinary BZ, Ph, t, t-MA, and S-PMA in the exposed subjects. Our study highlights the significance of MNT, CA, and urinary metabolites as potential biological exposure indices of genetic damage in FFSA. This study suggests the need for regular monitoring of FFSA for possible exposure to BTX as a precautionary and preventive step to minimize exposure and reduce the associated health risks.

A toxicity risk assessment method for spill incidents involving volatile liquid hydrocarbons and aqueous solutions in enclosed areas

A new method for the assessment of toxicity risk due to spill incidents involving volatile liquid hydrocarbons and aqueous solutions in enclosed areas is proposed. First, mass transfer models coupled with time-varying evaporation and emission rates (source models) are used to estimate the dynamic concentration profiles of potentially toxic gas/vapor pollutants resulting from spills of volatile liquid hydrocarbons as well as aqueous solutions in an enclosed area or indoor environment. Recognizing that toxicity risk depends nonlinearly on exposure duration and concentration, while the latter varies dynamically with time at any receptor position, the use of the aforementioned models to reliably compute toxic loads in the presence of time-varying concentration profiles is pursued explicitly in the present study. In this manner, one effectively overcomes the limitations of more traditional approaches to toxicity risk assessment where toxic loads are estimated under constant (steady state, average or mean) concentration levels of the toxic pollutant. Furthermore, instead of resorting to complex physiologically inspired pharmacokinetic models and the associated formidable multi-parameter estimation problems requiring the availability of large sets of good and reliable data, the proposed method incorporates also the idea of using a simple dynamic description that provides the requisite degree of differentiation between the exposure concentration obtained through the above models and the effective concentration (often associated with dose) that reaches the receptor site as determined by the uptake rate of a toxic vapor/gas. On the basis of the time-varying effective concentration or dose, an effective toxic load that takes into account potential recovery processes is then computed and integrated into a probit methodological framework where the proper quantification of a population response to toxic exposure (effective toxic load) provides the means to assess and characterize toxicity risk. Finally, the proposed method is evaluated through simulation studies in a case study involving a spill episode of ammonia solution in an enclosed area.

A Unified Approach for the Measurement of Individual or Total Volatile Organic Sulfur Compounds in Hydrocarbon Matrices by Dual-Plasma Chemiluminescence Detector and Low Thermal Mass Gas Chromatography

A novel gas chromatographic technique has been developed, offering dual-analytical capability of either speciation or rapid measurement of total volatile sulfur compounds in hydrocarbon matrices using the same hardware. The technique employs a pressurized liquid injection system for the delivery of volatile liquid hydrocarbons, low thermal mass gas chromatography, and a dual-plasma sulfur chemiluminescence detector to enable this dual capability with a high degree of sensitivity and selectivity towards sulfur-containing compounds. Using the technique described, a detection limit in the range of 20 ppb sulfur and less than 30 s analysis is attained. Response is linear over five orders of magnitude, with a high degree of repeatability.

Permeation of Telone C-35 EC™ and chloropicrin through protective gloves

Telone is a potent volatile liquid chlorinated hydrocarbon pesticide based on 1,3-dichloropropene that is applied without dilution for fumigation purposes, and so poses an inhalation and air pollution threat, as proven by past monitoring. 1,3-Dichloropropene also causes allergic skin effects, is absorbed through the skin, and metabolites have been shown to be excreted after skin absorption, so making it a skin exposure threat too, one that may become most important in the situations of adequate respirator protection or cleaning up spills. It is often coformulated with agents like chloropicrin, a chemical warfare agent, to substitute for methyl bromide fumigant. The aim of the study was to assess if nitrile and laminated gloves provided adequate protection against Telone C-35 EC™, using an ASTM-type I-PTC-600 permeation cell containing disposable (Safeskin™) and chemically-resistant (Sol-Vex™) nitrile and laminated (Barrier™ and Silver Shield™) glove materials with hexane liquid collection. Analyses of cis- and trans-1,3-dichloropropene and chloropicrin in the collection fluid at various times were performed on a moderately polar capillary column, using gas chromatography–electron capture detection by the internal and external standards methods. Both nitrile materials were degraded by the formulation and pure chloropicrin, and so were unsuitable for protection. Both laminated glove materials offered some protection with Silver Shield™ the better, since less mass had permeated by 8 h, but the extent of protection was still inadequate, as illustrated by a risk assessment of the skin exposure situation. It is recommended that Viton gloves be worn rather than the laminated ones when Telone C-35 EC™ is handled. Laminated gloves may protect against pure chloropicrin. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 100: 18–25, 2006

Effect of Methods of Modification of Synthetic Mordenite with Respect to Acidity and Catalytic Activity in the Conversion of Methanol

The acid properties of samples of the H-form of decationated and dealuminated synthetic mordenite, prepared respectively from the NH4 form or by treatment of the Na-form of the zeolite with hydrochloric acid solution, were studied by programmed thermodesorption of ammonia. The sample of dealuminated synthetic mordenite had a smaller content of weakly acidic β-centers than the decationated sample, which led to deactivation of the zeolites in methanol conversion. It was established that on this sample, in contrast to a sample of decationated synthetic mordenite, methanol was converted at temperatures above 613 K into C2-C4 volatile and C5-C10 liquid hydrocarbons of the benzene fraction.

Distribution of Volatile Liquid Hydrocarbons in the Vicinity of Power/Desalination Plants in Kuwait

Volatile liquid hydrocarbons (VLHs) represent some 40% of crude oil and are considered to be the most toxic compounds of petroleum other than the carcinogenic polycyclic aromatic hydrocarbons. The distribution of these compounds in Kuwait's coastal waters in the vicinity and at the inlets of power plants was assessed. About 200 samples were collected from selected sampling stations over the four seasons. The VLHs in the samples were concentrated using Grob's closed-loop technique and analyzed by GC using FID and confirmed by GC/MS. The results showed that VLHs were ubiquitous in the coastal water of Kuwait. The detected levels (ranged from 307 to 7882 ng/l in Kuwait Bay and from 331 to 5017 ng/l in the south) were comparable to the levels found in other parts of the world and were not alarming. However, the spotty higher levels encountered gave reason for some concern. Benzenoids (originating from petroleum) predominated, representing roughly 70% of the total VLHs. The levels were relatively low at the intake of the power plant located in the Kuwait Bay (annual average 677 ng/l) while higher levels (annual average 3006 ng/l) were encountered at the intake of the plant located at the south of oil the loading terminals and refineries.

Contribution of power and desalination plants to the levels of volatile liquid hydrocarbons in the nearby coastal areas of Kuwait

The levels and distribution of volatile liquid hydrocarbons (VLHs) were determined in Kuwait's coastal areas in the vicinity of outlets of power and desalination plants. About 230 samples were collected from the selected sampling locations over the 4 seasons. The VLHs in the samples were analyzed using Grob's closed-loop stripping technique and GC with FID and confirmed by GC/MS. The results showed that significant levels of VLHs were present. The levels ranged from 307 to 6500 ng/L and from 2880 to 7811 ng/L in Kuwait Bay and Sulaibekhat Bay, respectively. The annual average for VLHs near Al-Zor power plant ranged from 465 to 4665 ng/L. Benzenoids formed the bulk (about 80%) of the VLHs present. Comparison with the levels in the outlets indicated that Doha West power plant contributed much higher levels of VLHs to the coastal areas than Al-Zor plant.

Distribution of volatile liquid hydrocarbons in the vicinity of power/desalination plants in Kuwait

Volatile liquid hydrocarbons (VLHs) represent some 40% of crude oil and are considered to be the most toxic compounds of petroleum other than the carcinogenic polycyclic aromatic hydrocarbons. The distribution of these compounds in Kuwait's coastal waters in the vicinity and at the inlets of power plants was assessed. About 200 samples were collected from selected sampling stations over the four seasons. The VLHs in the samples were concentrated using Grab's closed-loop technique and analyzed by GC using FID and confirmed by GC/MS. The results showed that VLHs were ubiquitous in the coastal water of Kuwait. The detected levels (ranged from 307 to 7882 ng/l in Kuwait Bay and from 331 to 5017 ng/l in the south) were comparable to the levels found in other parts of the world and were not alarming. However, the spotty higher levels encountered gave reason for some concern. Benzenoids (originating from petroleum) predominated, representing roughly 70% of the total VLHs. The levels were relatively low at the intake of the power plant located in the Kuwait Bay (annual average 677 ng/1) while higher levels (annual average 3006 ng/l) were encountered at the intake of the plant located at the south of oil the loading terminals and refineries.

Contribution of power/desalination plants to the levels of halogenated volatile liquid hydrocarbons in the coastal areas of Kuwait

The levels and distribution of halogenated volatile liquid hydrocarbons (HVLHs) were determined in the vicinity of the inlets and outlets of power/desalination plants in Kuwait. A total of 384 seawater samples were collected from the designated sampling stations. The volatile chlorinated compounds present were removed and concentrated by using Grob's closed-loop stripping technique. The concentrated extract was analyzed by gas chromatography using ECD. The results indicated that chlorinated VLHs were ubiquitous in the coastal waters of Kuwait. The levels of total HVLHs in the seawater were significantly higher in the north in the vicinity of the Al-Zor power plant. The distribution of these compounds indicated that the main contributors were the cooling water discharges from the power/desalination plants. Trihalomethane compounds generally constituted the bulk of the total HVLHs. Among the trihalomethanes, bromoform dominated (about 87% of trihalomethanes). The concentration of HVLHs was significantly higher at the outlets as compared to the inlets. The levels were consistently higher in Sulaibekhat Bay, which receives the cooling waters of the Doha West power plant. Halogenated aromatic compounds were present in low levels in the inlets and slightly higher levels in the outlets of the power plant.

An experimental investigation of air venting of volatile liquid hydrocarbon mixtures from homogeneous and heterogeneous porous media

Experimental results are reported which delineate the vaporization modes of single and binary hydrocarbon liquids held in homogeneous and heterogeneous porous media during air venting. The experiments were performed in a two-dimensional apparatus which allowed visual observation of the evolving geometry of the liquid contaminant pool under various conditions. In homogeneous sand packings, the contaminant pool receded primarily from the upstream edge to the downstream edge during venting. In heterogeneous (dual permeability and packs, the permeability ratio of the high- to low-permeability zones was found to be an important factor on the geometric evolution of the contaminant pool. Different permeability ratios were investigated for a high-permeability layer above a contaminant pool trapped in a low-permeability layer. For permeability ratios below 10:1, the pool geometry evolved in a similar manner as in the homogeneous sand pack because a significant amount of airflow passed through the contaminant in the low-permeability zone. For ratios greater than 100:1 the pool receded downward from the interface of the two layers into the low-permeability zone, and the venting became limited by diffusion of the contaminant vapors from the low-permeability zone to the air flowing in the high-permeability zone. During venting of binary mixtures from dual-permeability sand packs with large permeability ratios, the mass fractions of the two components in the vapor-phase exhibited three distinct stages: (1) an early, rapid decrease in the mass fraction ratio of the more volatile to less volatile compound due to a depletion of the more volatile component at the evaporating surface in the liquid; (2) a period of constant mass fraction ratio resulting from a quasi-steady-state evaporation of the liquid pool which receded into the low-permeability zone; and (3) a long-term gradual decrease in the mass fraction ratio of the more volatile to less volatile compound caused by the diminishing size of the contaminant pool.

Occupational Exposure to Organic Solvents-Reply

In Reply. —As you point out correctly, we meant to use the termbenzineorbenzinrather than the termBenzene. Benzene is a single compound C6H6, a colorless volatile liquid hydrocarbon. Benzine or benzin, on the other hand, is a distillate from petroleum consisting of a mix of hydrocarbons, among them pentanes and hexanes. You are also correct in that benzine is a colorless, clear liquid. The commercial preparation that our patient was using was a clear green liquid, due to the addition of a dye at a concentration of 0.003%.

Initiation of explosive boiling of a droplet with a shock wave

The role of incident shock waves in the initiation of vapor explosions in volatile liquid hydrocarbons has been investigated. Experiments were carried out on single droplets (1–2 mm diameter) immersed in a host fluid and heated to temperatures at or near the limit of superheat. Shocks generated by spark discharge were directed at previously nonevaporating drops as well as at drops boiling stably at high pressure. Explosive boiling is triggered in previously nonevaporating drops only if the drop temperature is above a threshold temperature that is near the superheat limit. Interaction of a shock with a stably boiling drop immediately causes a transition to violent unstable boiling in which fine droplets are torn from the evaporating interface, generating a two-phase flow downstream. On the previously nonevaporating interface between the drop and the host liquid, multiple nucleation sites appear which grow rapidly and coalesce. Overpressures generated in the surrounding fluid during bubble collapse may reach values on the same level as the pressure jump across the shock wave that initiated the explosive boiling. A simple calculation is given, which suggests that shock focusing may influence the location at which unstable boiling is initiated.

Release of volatile liquid hydrocarbons from spilled petroleum.

The extensive shipping of crude oil over the world's oceans has produced increased concern over the effects of the accidental spillage of petroleum on the marine environment. One portion of the petroleum released to the oceans that is of particular interest environmentally are the toxic, volatile liquid hydrocarbons (VLHs). The fate and mode of incorporation of VLHs into the water column during a petroleum spill is important both to the controlling of the spill and in assessing its environmental impact. In this paper, volatile hydrocarbon solution studies were conducted in a 68.5 L, glass rectangular tank with a surface area of 2250 cm/sup 2/. Each experiment was run with 10-L (9 cm dep) of Gulf of Mexico seawater with a salinity of approximately 32 ppt.

Volatile liquid hydrocarbon characterization of underwater hydrocarbon vents and formation waters from offshore production operations

Volatile liquid hydrocarbon characterization of underwater hydrocarbon vents and formation waters from offshore production operations

Volatile liquid hydrocarbons around a production platform in the Northwest Gulf of Mexico.

We have characterized the volatile liquid hydrocarbons in the oil, discharge brine and surface receiving waters from an oil and gas production platform discharging brine into the Gulf of Mexico. The mean VLH concentrations were 450,000 μg/g (oil), 21,600 μg/L (brine) and 1900 ng/L (surface waters). Light aromatic compounds comprised over 80% of VLH in the brine and surface waters, with benzene, toluene, ethylbenzene, m-, p-, and o-xylene being the predominant compounds. VLH concentrations around a control platform 3 km distant were four times lower, indicating rapid dilution. The 2 μg/L concentration of VLH around platform 296-B is twice the concentration that SAUER (1980) suggested could be detrimental to the life processes of many marine organisms. If this value is representative of the complete water column and considering the fact that the Buccaneer field has been discharging brine at this location for over twenty years, with no obvious harm to the biota, the lower limit for VLH to cause detrimental long term effects on marine organisms may have to be reevaluated.

Problems concerning the operation of high productivity biomass fermentations using volatile liquid hydrocarbon feedstocks

AbstractThe possibilities of using liquefied petroleum gas (LPG) heavy ends, predominantly volatile liquid n‐alkanes (a location‐specific hydrocarbon feedstock) for single‐cell protein (SCP) production are examined against criteria established to define potentially attractive SCP production processes. The factors discussed include the use of the heat of vaporization for fermentor cooling, the efficiency of conversion of nalkane vapors, problems of maintaining constant composition substrates when feeding volatile liquid n‐alkane vapors to laboratory fermentors, the possible solvent effect of liquid n‐alkanes, and the possibilities of competitive inhibition. The study confirms that mixed volatile n‐alkane feedstocks will introduce major physical and biological problems for both product and process research and development. Even when the technical problems are solved, the economic question of whether a direct production route using the feedstock as the fermentation substrate or an indirect route involving the conversion of the feedstock, by chemical means, into methanol, which can then be used as the fermentation substrate, needs careful examination.

Volatile liquid hydrocarbons in waters of the Gulf of Mexico and Caribbean Sea1

Concentrations of volatile liquid hydrocarbons (VLH), C6−C14 hydrocarbons, were determined in 1977 in coastal, shelf, and open‐ocean surface waters of the Gulf of Mexico and Caribbean Sea. In open‐ocean, nonpetroleum‐polluted surface water, VLH concentrations were 60 ng·liter−1 while in heavily polluted Louisiana shelf and coastal water values reached ≈500 ng·liter−1. Caribbean surface samples had very low concentrations, ≈30 ng·liter−1. The relationship between anthropogenic gaseous hydrocarbons and VLH was approximately linear. Aromatic VLH accounted for 60–85% of the total VLH in surface waters. Cycloalkane concentrations were &lt;1.0 ng·liter−1 in open ocean water, 60–100 ng·liter−1 in polluted water (20% of total VLH). Alkanes were ≈15 ng·liter−1 in open ocean water, 40 ng·liter−1 in polluted water. The concentrations of five major VLH compounds (aromatics) in water samples—benzenc, toluene, ethylbenzene, m‐, p‐xylenes, and o‐xylene (called BTX)— were sufficient to predict the total VLH. The empirically determined relationship is VLH(ng·liter−1) = 1.42 BTX (ng·liter−1); r = 0.96.Subsurface VLH concentrations in samples of polluted waters collected from depths of 50 in were only 35–40 ng·liter−1 below surface concentrations. Open ocean subsurface samples had concentrations of only ≈30 ng·liter−1 at 30–50‐m depths, comparable to those of Caribbean surface water.

Volatile liquid hydrocarbons in the surface coastal waters of the Gulf of Mexico

Abstract A sampling and analysis procedure has been developed to determine quantitatively volatile liquid C 6 C 14 hydrocarbons, the most immediately toxic components of petroleum hydrocarbons, at the ng/l level characteristically found in marine waters. The method of analysis involves dynamic headspace sampling; continuous stripping of volatile hydrocarbons from heated seawater by an ultrapure inert gas, and trapping of volatile components on a solid polyphenyl ether adsorbent, Tenax-GC. The trapped components are subsequently desorbed from the Tenax-GC by heating to 250°C, with cryogenic (liquid nitrogen) trapping of the volatile hydrocarbons on a SE-30 pre-column. After the cryogenic trapping, the pre-column is then heated rapidly which ‘injects’ the trapped components onto a non-polar GC column for separation. The stripping system is uniquely designed in that the stripping of the volatiles is done in the sample bottle itself. Components are identified by means of GC-MS analyses and GC retention times. The reproducibility based on replicates is ±12%. The use of conventional oceanographic samplers is found to be unsuitable for liquid hydrocarbon sampling at the ng/l level. Distributions of liquid hydrocarbons were determined in coastal surface waters of the Gulf of Mexico. Total volatile n-alkane concentrations range from 7 ng/l to 50 ng/l, whereas total volatile aromatics (benzene, toluene, ethylbenzene and xylenes) range from 20 ng/l to 450 ng/l. At most sample stations, 80–90% of the total liquid hydrocarbons in surface water is aromatic. The contribution in seawater of these volatile hydrocarbons to the total solvent-extractable hydrocarbon budget is a few percent at most. A direct correlation exists between liquid hydrocarbon concentrations and C 1 C 5 hydrocarbon concentrations. Surface-water samples which show high liquid hydrocarbon concentrations (500 ng/l) are also extremely high in methane and ethane relative to open-ocean levels. Samples which are lowest in liquid hydrocarbons (30 ng/l) have concentrations of methane and ethane close to baseline or open-ocean concentrations.