2-hexanone Research Articles

Development of a safety analysis method for volatile organic compounds using 2-phenoxyethanol as solvent

Indoor volatile organic compounds (VOCs) are usually sampled using active carbon samplers and subsequently analyzed using gas chromatography-mass spectrometry (GC-MS) to assess the exposure risk to workers. Therefore, selection of a suitable solvent for VOC extraction is crucial. However, reports on the use of 2-phenoxyethanol—known for its low vapor pressure and low toxicity—as a solvent for extracting VOCs from activated carbon are lacking. Here, we show that 2-phenoxyethanol is a suitable alternative solvent with low toxicity and can extract a wide variety of VOCs without overlapping with target VOCs on the gas chromatogram. The recoveries of 2-phenoxyethanol were 57% (styrene) to 83% (methyl n-butyl ketone), which were higher than those of CS2, acetone, and n-hexane at room temperature. The recoveries improved to 67% (styrene) to 102% (isopentyl acetate) under 50 °C. Optimization of the GC conditions showed that a viscosity delay time of 3 s was required to avoid producing bubbles in the injection syringes. We selected DB-HeavyWAX as a column because it could be heated above the boiling point of 2-phenoxyethanol (247 °C), allowing the removal of 2-phenoxyethanol from the column. This study contributes to the development of analysis methods for VOCs under safe operating conditions.

Kinetic and Mechanistic Investigations of OH-Initiated Atmospheric Degradation of Methyl Butyl Ketone.

Methyl butyl ketone (MBK, 2-hexanone) is a common atmospheric oxygenated volatile organic compound (OVOC) owing to broad industrial applications, but its atmospheric oxidation mechanism remains poorly understood. Herein, the detailed mechanisms and kinetic properties of MBK oxidation initiated by OH radicals and subsequent transformation of the resulting intermediates are performed by employing quantum chemical and kinetic modeling methods. The calculations show that H-abstraction at the C4 position of MBK is more favorable than those at the other positions, with the total rate coefficient of k(T) = 4.13 × 10-14 exp(1576/T) cm3 molecule-1 s-1 at 273-400 K. The dominant pathway of unimolecular degradation of the C-centered alkyl radical is 1,2-acyl group migration. For the isomerization of the peroxy radical RO2, 1,5- and 1,6-H shifts are more favorable than 1,3- and 1,4-H shifts. The multiconformer rate coefficient kMC-TST of the first H-shift of the RO2 radical is estimated to be 1.40 × 10-3 s-1 at room temperature. Compared to the H-shifts of analogous aliphatic RO2 radicals, it can be concluded that the carbonyl group enhances the H-shift rates by as much as 2-4 orders of magnitude. The rate coefficients of the RO2 radical reaction with the HO2 radical exhibit a weakly negative temperature dependence, and the pseudo-first-order rate constant k'HO2 = kHO2[HO2] is calculated to be 3.32-22.10 × 10-3 s-1 at ambient temperature. The bimolecular reaction of the RO2 radical with NO leads to the formation of 3-oxo-butanal as the main product with the formation concentration of 2.2-7.4 μg/m3 in urban areas. The predicted pseudo-first-order rate constant k'NO = kNO[NO] is 2.20-9.98 s-1 at room temperature. By comparing the kMC-TST, k'HO2, and k'NO, it can be concluded that reaction with NO is the dominant removal pathway for the RO2 radical formed from the OH-initiated oxidation of MBK. These findings are expected to deepen our understanding of the photochemical oxidation of ketones under realistic atmospheric conditions.

Optimal design of a high atom utilization and sustainable process for the treatment of crude phenol separation wastewater

The wastewater generated by crude phenol separation (CPS) process contains complex pollutants such as oil, phenolic compounds, and sodium sulfate. The environment will be seriously destroyed if the wastewater is discharged without proper treatment. In order to dispose crude phenol separation process wastewater (CPSW) effectively, this paper proposes an integration system that combines the source exploration of CPS and the optimum design of CPSW treatment. The CPS process is first simulated to obtain the composition of CPSW and then optimized to improve its atomic utilization. A treatment process is then designed after CPS process simulation, which is divided into two parts: the extraction of phenol and the electrolysis of sodium sulfate. A novel phenol extraction process is proposed, in which the wastewater is separated into oil and aqueous phases according to density difference. As phenolic compounds exist in both two phases after separation, pyrazole and methyl n-butyl ketone (MBK) are used to extract phenol from the oil and aqueous phase, respectively. After that, a heat integration is explored for the extraction process to reduce the energy consumption. A control scheme is also established by supplementing necessary controllers. These controllers make the process get back to smooth operation quickly in the face of ±10% disturbances of feed flow, which is verified by dynamic simulation. Finally, the sodium sulfate in CPSW is specifically disposed by electrolysis based on experimental results. The obtained sodium hydroxide and sulfuric acid solutions are recycled to CPS process for the further improvement of atom utilization.

Ternary Liquid–Liquid Equilibrium for Phosphoric Acid Extraction from Aqueous Solutions with 1-Pentanol or Methyl Butyl Ketone at T = (298.2, 308.2, and 318.2) K

The tie-line values of the aqueous mixture (H2O + phosphoric acid + organic solvents) were checked at several temperatures and air pressures. Methyl butyl ketone or 1-pentanol was selected as the organic solvent. Solubility data were specified for an aqueous ternary mixture employing the cloud point measurements. All the ternary mixtures exhibit the type-1 liquid–liquid phase behavior system. Experimental data were determined employing the refractive index method, the Karl–Fischer technique, and acidimetric titration. Binary interaction parameters were predicted employing liquid–liquid equilibrium modeling. The NRTL and UNIQUAC models were employed to define which model is more reliable. The trustworthiness of the experiment outcome was approved by considering the Hand and Othmer-Tobias equations. Selectivity factors and distribution coefficients were derived to determine the solvents’ extraction capacity. The effect of temperature change was checked on the solubility curve and extraction process at different temperatures.

Comprehensive characterization and health assessment of occupational exposures to volatile organic compounds (VOCs) in Xi'an, a major city of northwestern China

The personal exposure to volatile organic compounds (VOCs) was determined in five occupational groups (including printing shop employees, office workers, furniture store employees, bus and taxi drivers) in the capital city of Xi'an in northwest China. The highest personal exposure concentration (258.7 ± 10.0 μg m−3) to the 64 Air Toxics VOCs classified by the United States Environmental Protection Agency (U.S.EPA), as well as associated health risk potential, were seen in the furniture store employees. These could be attributed to off-gassing from brand new furniture and volatiles from cleaning reagents. Aromatic species were the dominant class in the personal exposure samples collected from the groups of printing shop employees, office workers, and bus and taxi drivers, with the concentrations of 49.8–74.4 μg m−3 and mass compositions of 34.8–43.2% of the sum of the 64 Air Toxics for the cases studied. The highest personal exposure to carbonyls (C≥3) of 100.4 ± 25.6 μg m−3 and composition of 38.8% were again seen in the furniture store employees. The unique VOC composition profiles represented potential indoor or in-vehicle sources in each workplace. Moreover, environmental tobacco smoke (ETS) contributed to the personal exposure to many of the Air Toxics species, especially methyl butyl ketone and 1,2-dibromoethane. The cancer risks of Class 1 carcinogens of vinyl chloride, 1,3-butadiene, and benzene, were 1.4, 12, and 5.2 times, respectively, of the threshold of carcinogenicity (1 × 10−6). Acrolein showed the highest non-cancer risk which was ~150 times the acceptable level (1.0). The results could offer a scientific basis for the government to establish the occupational air quality standards to the toxic VOCs in China.

Optimal Design of a Sustainable Extraction Process for the Treatment of Acidic Wastewater

The wastewater from the fluid catalytic cracking refinery is difficult to treat because of its high organic and oil content. A sustainable extraction process is designed to treat the wastewater. In this process, oil is first separated from wastewater to facilitate further removal of phenol from wastewater. The purification process of oil phase makes use of parazole to extract phenol from oil and wastewater to back-extract parazole, while the purification process of water phase makes use of Methyl Butyl Ketone (MBK) to extract phenol from wastewater followed by distillation recycling of MBK. The extraction mechanism is explained by molecular simulation from micro-level. Compared to traditional extraction operations, this treatment process reduces the make-up of extractant greatly and is sustainable. Subsequently, the extraction process is optimised by sensitivity analysis and Heat Integration with Aspen Plus software. The simulation result exhibits high purity of disposed oil and wastewater (up to 99.50 % and 99.99 %) and a great reduction of energy consumption, utility cost, and CO2 emission. Finally, one control scheme is designed for this process after its anti-disturbance ability is verified with Aspen Dynamics software.

Accelerated doping of trans-4-stilbenemethanol into polymer optical fibers by binary non-solvent/solvent mixtures

Abstract Solution-mediated doping of photosensitive molecules into polymer optical fibers (POFs) has been proved to be a feasible way to prepare photoactive POFs. To accelerate the doping process, this study uses binary non-solvent/solvent mixtures rather than pure non-solvents to swell PMMA fibers and to facilitate diffusion of trans-4-stilbenemethanol into fibers. Binary solvent mixtures are composed of methanol and one good solvent of PMMA. Three mixtures containing three different solvents, namely, acetone, methyl butyl ketone and dimethylformamide, are investigated. It is found that addition of these solvents can effectively increase the doping speed. The doping process is faster as more solvents are added, up to 30% in volume ratio of the solution. The time for reaching diffusion equilibrium is reduced from more than 60 h in methanol to about 20 h in the mixture of methanol/acetone in 70/30 v/v. However, the attenuation of solution-processed POFs by binary mixtures significantly increases compared to pristine POFs, and it should be considered when applying the technique to prepare photoactive POFs. Among the three studied solvents, methyl butyl ketone is recommended for real applications since its addition results significant acceleration to the doping process while the attenuation increase is moderate.

Identification of changes in volatile compounds in dry-cured fish during storage using HS-GC-IMS

Changes in the volatile components of dry-cured fish during storage at 4 ℃ and 25 ℃ were investigated by HS-GC-IMS fingerprinting combined with principal component analysis (PCA). Topographic plots were used to establish the fingerprints of flavor substances, and 32 signal peaks were identified that corresponded to 22 compounds, mainly aldehydes, ketones, alcohols and esters. During storage at 4 ℃, 3-methylbutanal, dimethyl ketone and hexanal were the main volatile components, while hexanal, 1-octen-3-ol and 3-methylbutanal were the main compounds of dry-cured fish stored at 25 ℃; butyl methyl ketone was only observed at 25 °C. In the early stage of storage, significant changes in octanal, 3-methylbutanal and ethyl acetate were found in dry-cured fish at both temperatures (P < 0.05) while heptanal, pentanal and butanal changed significantly in the late stage (P < 0.05). PCA clearly distinguished the samples in relation to their storage temperature and time. In addition, heat map clustering analysis further revealed the differences and similarities among different samples, and those results were in accordance with the PCA results.

Sensing the Molecular Structures of Hexan-2-one by Internal Rotation and Microwave Spectroscopy.

Using two molecular jet Fourier transform spectrometers, the microwave spectrum of hexan-2-one, also called methyl n-butyl ketone, was recorded in the frequency range from 2 to 40 GHz. Three conformers were assigned and fine splittings caused by the internal rotations of the two terminal methyl groups were analyzed. For the acetyl methyl group CH3 COC3 H6 CH3 , the torsional barrier is 186.9198(50) cm-1 , 233.5913(97) cm-1 , and 182.2481(25) cm-1 for the three observed conformers, respectively. The value of this parameter could be linked to the structure of the individual conformer, which enabled us to create a rule for predicting the barrier height of the acetyl methyl torsion in ketones. The very small splittings arising from the internal rotation of the butyl methyl group CH3 COC3 H6 CH3 could be resolved as well, yielding the respective torsional barriers of 979.99(88) cm-1 , 1016.30(77) cm-1 , and 961.9(32) cm-1 .

Liquid-liquid equilibrium for methyl butyl ketone + o-, m-, p-cresol + water ternary systems and COSMO-SAC predictions

The liquid–liquid equilibrium (LLE) data for the three ternary systems, methyl butyl ketone (MBK) + o-, m-, p-cresol + water, were measured at 333.2 K and 353.2 K under 101 kPa in this work. Distribution coefficient and selectivity for cresols were calculated from the experimental tie-line data to evaluate the performance of MBK extracting cresols from the aqueous solution. The experimental tie-line data were correlated by the NRTL and UNIQUAC activity coefficient models, and both models showed good agreement with the experimental data. The COSMO-SAC model (conductor-like screening model for segment activity coefficient) was employed to predict LLE phase diagrams for the studied systems with root mean square deviations less than 3%.

Liquid-Liquid Equilibrium for the Ternary Systems of Solvent+ m/o/p-Cresol+Water: Thermodynamic Modeling

In this study, NRTL and UNIQUAC thermodynamic models were used to predict the composition of ternary mixtures of solvents+ m/o/p-cresol+ water in organic and aqueous phases. Various solvents are used for the separation of cresols from water. In this study, methyl propyl ketone, methyl isopropyl ketone, methyl butyl ketone, and methyl isobutyl ketone solvents were investigated. Intermolecular interaction parameters were considered to be a function of temperature. The binary interaction parameters of water and cresols (m, o, or p) in the presence of each type of solvent were considered to be the same. Also, regardless of the type of cresol (m, o, or p), the parameters of binary interaction between water and each solvents were considered to be the same. The results proved the accuracy of the presented models, though the parameters of binary interaction parameters were considered to be the same. The root mean square deviation for NRTL and UNIQUAC models was 0.0086 and 0.0089, respectively.

Experimental Determination and Correlation of Liquid–Liquid Equilibria for Methyl Isopropyl Ketone + Phenol + Water Mixtures at 298.15, 313.15, and 323.15 K

Liquid–liquid equilibria (LLE) data for the ternary system, methyl isopropyl ketone (MIPK) + phenol + water, were measured at 298.15 K, 313.15 and 323.15 K under atmospheric pressure by gas chromatography. Distribution coefficients and separation factors were calculated to evaluate the extracting performance of methyl isopropyl ketone, which was proven to be a very efficient solvent to extract phenol from aqueous solution, with distribution coefficients for phenol even higher than those of methyl isobutyl ketone (MIBK) or methyl butyl ketone (MBK). The nonrandom two-liquid (NRTL) and universal quasi-chemical activity coefficient (UNIQUAC) models were used to correlate the experimental data to yield binary interaction parameters for phenol extraction process design or optimization.

Ternary and Quaternary Liquid–Liquid Equilibria for Systems of Methyl Butyl Ketone + Water + Hydroquinone + Phenol at 313.2 K and Atmospheric Pressure

Liquid–liquid equilibria (LLE) data of the quaternary system {methyl butyl ketone + phenol + hydroquinone + water} and two relevant ternary systems, {methyl butyl ketone + phenol + water} and {methyl butyl ketone + hydroquinone + water}, were measured at T = 313.2 K and p = 101.3 kPa. The experimental data were correlated with the nonrandom two-liquid (NRTL) and universal quasichemical (UNIQUAC) models. The root-mean-square deviation of the NRTL and UNIQUAC models were 0.144 and 0.0476%, respectively. Good agreement was found between experimental LLE data and those calculated from the NRTL or UNIQUAC equations for all systems studied in this work.

Liquid–liquid equilibria in the ternary systems water + cresols + methyl butyl ketone at 298.2 and 313.2 K: Experimental data and correlation

Liquid–liquid equilibrium data for ternary systems (water+o-, m- or p-cresol+methyl butyl ketone) were measured at 298.2 and 313.2K under atmospheric pressure by gas chromatography. Distribution coefficients and separation factors were calculated to evaluate the extracting performance of methyl butyl ketone. For each system, the Hand and Othmer–Tobias equations were used to assess the quality of LLE data. These data were also correlated using NRTL and UNIQUAC models to yield binary interaction parameters for designing or optimizing cresols extracting process.

Liquid–Liquid Equilibria for Ternary Systems: Methyl Butyl Ketone + Phenol + Water and Methyl Butyl Ketone + Hydroquinone + Water at 298.15 K and 323.15 K

Liquid–liquid equilibria (LLE) data for two ternary systems: methyl butyl ketone (MBK) + phenol + water and methyl butyl ketone + hydroquinone + water have been measured at 298.15 K and 323.15 K under atmospheric pressure. The reliability of experimental tie-line data was checked by Hand and Bachman equations. The distribution coefficient and selectivity were used to evaluate the extraction performance of methyl butyl ketone. In addition, NRTL (nonrandom two-liquid) and UNIQUAC (universal quasi-chemical activity coefficient) models were used to correlate experimental data, which yielded corresponding binary interaction parameters. Results from both models agree with each other well. NRTL model presents a stronger predictive power than UNIQUAC model.

Compensation for occupational neurological and mental disorders.

Standards for the recognition of occupational diseases (ODs) in Korea were established in 1954 and have been amended several times. In 2013, there was a significant change in these standards. On the basis of scientific evidence and causality, the International Labour Organization list, European Commission schedule, and compensated cases in Korea were reviewed to revise the previous standards for the recognition of ODs in Korea. A disease-based approach using the International Classification of Diseases (10th version) was added on the previous standards, which were agent-specific approaches. The amended compensable occupational neurological disorders and occupational mental disorders (OMDs) in Korea are acute and chronic central nervous system (CNS) disorders, toxic neuropathy, peripheral neuropathy, manganese-related disorders, and post-traumatic stress disorder. Several agents including trichloroethylene (TCE), benzene, vinyl chloride, organotin, methyl bromide, and carbon monoxide (CO) were newly included as acute CNS disorders. TCE, lead, and mercury were newly included as chronic CNS disorders. Mercury, TCE, methyl n-butyl ketone, acrylamide, and arsenic were newly included in peripheral neuropathy. Post-traumatic stress disorders were newly included as the first OMD. This amendment makes the standard more comprehensive and practical. However, this amendment does not perfectly reflect the recent scientific progress and social concerns. Ongoing effort, research, and expert consensus are needed to improve the standard.

Animal Models of Peripheral Neuropathy Due to Environmental Toxicants

Despite the progress in our understanding of pathogeneses and the identification of etiologies of peripheral neuropathy, idiopathic neuropathy remains common. Typically, attention to peripheral neuropathies resulting from exposure to environmental agents is limited relative to more commonly diagnosed causes of peripheral neuropathy (diabetes and chemotherapeutic agents). Given that there are more than 80,000 chemicals in commerce registered with the Environmental Protection Agency and that at least 1000 chemicals are known to have neurotoxic potential, very few chemicals have been established to affect the peripheral nervous system (mainly after occupational exposures). A wide spectrum of exposures, including pesticides, metals, solvents, nutritional sources, and pharmaceutical agents, has been related, both historically and recently, to environmental toxicant-induced peripheral neuropathy. A review of the literature shows that the toxicity and pathogeneses of chemicals adversely affecting the peripheral nervous system have been studied using animal models. This article includes an overview of five prototypical environmental agents known to cause peripheral neuropathy--namely, organophosphates, carbon disulfide, pyridoxine (Vitamin B6), acrylamide, and hexacarbons (mainly n-hexane, 2,5-hexanedione, methyl n-butyl ketone). Also included is a brief introduction to the structural components of the peripheral nervous system and pointers on common methodologies for histopathologic evaluation of the peripheral nerves.

Urinary 2,5-hexanedione excretion in cryptogenic polyneuropathy compared to the general Swedish population

Background2,5-hexanedione (2,5-HD) is the main neurotoxic metabolite of methyl-n-butyl ketone (MBK) and n-hexane, and known to cause polyneuropathy. The aim of our study was to compare the urinary levels of 2,5-HD between cases with cryptogenic polyneuropathy and the general Swedish population, and to elucidate the role of certain external factors.MethodsMorning urine samples were collected from 114 cases with cryptogenic polyneuropathy (77 men and 37 women) and 227 referents (110 men and 117 women) randomly selected from the population registry. None had any current occupational exposure to n-hexane or MBK. The urine samples were analysed by a gas chromatographic method based on acidic hydrolysis.ResultsCases had statistically higher urinary levels of 2,5-HD (0.48 mg/L) than the general population (0.41 mg/L) and men higher excretion than women (0.48 mg/L and 0.38 mg/L, respectively). There was no difference in 2,5-HD levels between current smokers and non-smokers. Occupational exposure to xylene, alcohol consumption and ever exposed to general anaesthesia were associated with lower excretion in men while for occupational exposure to nitrous oxide in women higher excretion was seen. Higher excretion of 2,5 HD was inversely related to increasing age.ConclusionsSignificantly higher levels of urinary 2,5-HD were seen in men and cryptogenic polyneuropathy cases seemingly unexposed to n-hexane. Hypothetically, this might be due to either differences in metabolic patterns or some concealed exposure. The difference in means between cases and the general population is small and can therefore not allow any firm conclusions of the causality, however.

Dependence of volume expansion on alkyl chain length and the existence of branched methyl group of CO 2-expanded ketone systems at 40 °C

We measured the density and liquid-phase CO 2 mole fraction of CO 2-expanded ketones (acetone, methyl ethyl ketone, methyl propyl ketone, methyl butyl ketone, methyl i-propyl ketone, and t-methyl butyl ketone) at 40 °C and evaluated the expansion coefficient on the basis of the experimental results. Volume expansion was slow in the region of a low carbon dioxide mole fraction (<0.7) but rapid in the region of a high carbon dioxide mole fraction (>0.7). The dependence of the expansion coefficient on the carbon dioxide mole fraction could be attributed to the number of molecules in a certain volume. These phenomena were inferred from the partial molar volume estimated using the Peng–Robinson equation of state (PR-EOS).

Mothball Mayhem: Relapsing Toxic Leukoencephalopathy due to p-Dichlorobenzene Neurotoxicity

Letters3 March 2009Mothball Mayhem: Relapsing Toxic Leukoencephalopathy due to p-Dichlorobenzene NeurotoxicityNeeraj Kumar, MD, Lowell C. Dale, MD, and Eelco F.M. Wijdicks, MDNeeraj Kumar, MDFrom Mayo Clinic, Rochester, MN 55905.Search for more papers by this author, Lowell C. Dale, MDFrom Mayo Clinic, Rochester, MN 55905.Search for more papers by this author, and Eelco F.M. Wijdicks, MDFrom Mayo Clinic, Rochester, MN 55905.Search for more papers by this authorAuthor, Article, and Disclosure Informationhttps://doi.org/10.7326/0003-4819-150-5-200903030-00025 SectionsAboutFull TextPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissions ShareFacebookTwitterLinkedInRedditEmail Background: Aromatic hydrocarbons (such as toluene, n-hexane, and methyl butyl ketone) are volatile, lipid-soluble compounds found in various household and commercial products, such as aerosols, cleaning fluids, paints, and fuels. These substances are not identified as recreational drugs, but they are readily available and are commonly abused by sniffing (nasal inhalation) or huffing (oral inhalation). Symptoms due to inhalant abuse are similar to those resulting from central nervous system depressants, such as alcohol.Because of its much lesser toxicity, p-dichlorobenzene (PDB) has replaced naphthalene as the primary component of mothballs. Both compounds have abuse potential. Inhalation and dermal absorptions are ...