Showing papers on "Xylene published in 2010"
TL;DR: The first fabrication of the MOF-coated capillary column for high-resolution GC separation is shown, featuring MIL-101 as the stationary phase and xylene isomers and ethylbenzene (EB) as the targets for separation.
Abstract: Metal–organic frameworks (MOFs) have received great attention because of their fascinating structures and intriguing applications in hydrogen storage, gas separation, catalysis, chiral separation, sensing, and imaging. Recently, MOFs such as MOF-508, MIL-47, and MIL53 have been shown to be promising as stationary phases for gas chromatography (GC) and liquid chromatography. 11] All these pioneering works on the utilization of MOFs as stationary phases in chromatography were performed on packed columns. However, packed columns usually result in low resolution as a result of peak broadening, which impairs the separation efficiency of MOFs. Moreover, gram-scale MOFs are needed for packed columns, leading to high-cost applications of MOFs as stationary phases in chromatographic separation. In contrast, capillary columns, either wall-coated open tubular (WCOT) columns or porous layer open tube (PLOT) columns, involve a thin film of MOFs coated on their inner walls, and thus improve the resolving power of MOFs and reduce the amount of MOFs required for GC applications. However, to the best of our knowledge, no work on the utilization of MOFs as stationary phases for high-resolution capillary GC separation has been reported so far. Herein we show the first fabrication of the MOF-coated capillary column for high-resolution GC separation. For a proof-of-concept demonstration, we choose MIL-101 as the stationary phase and xylene isomers and ethylbenzene (EB) as the targets for separation. Xylene isomers and EB are important raw chemicals in industry; in particular, p-xylene is used in the manufacture of terephthalic acid for the polyester industry. The separation and detection of individual xylene isomers and EB are also of environmental concern, and of great practical interest in air monitoring and blood analysis. For these reasons, numerous stationary phases have been developed for GC separation of xylene isomers and EB, for example, 7,8benzoquinoline, tetrachlorophthalate, 1,8-diaminonaphthalene, modified organo-clays Bentone-34, liquid-crystalline compounds, b-cyclodextrin derivatives, poly(ethylene glycol), and MIL-47. However, long analysis time (27–90 min) or temperature programming is often needed. MIL-101 is a chromium terephthalate MOF with coordinatively unsaturated sites (CUS). We utilized MIL-101 as the stationary phase because of its high surface area, large pores (2.9–3.4 nm), accessible CUS, and excellent chemical and thermal stability, which make it an attractive candidate for isomer separation. However, MIL-101 has never been explored as the stationary phase for chromatographic separation before, even though the tiny crystal size characteristic of MIL-101 is beneficial to the fabrication of MIL-101 coated capillary columns by a dynamic coating method. In this work, we prepared the MIL-101 coated capillary column and achieved a baseline separation of p-xylene, oxylene, m-xylene, and EB on the fabricated MOF coated capillary column by GC within 1.6 min without the need for temperature programming (Figure 1).
400 citations
TL;DR: In this article, mesoporous activated carbons were obtained by chemical activation of kraft lignin with H 3 PO 4 and used as supports for the preparation of carbon-based Pd catalysts with low palladium content (0.5%).
Abstract: Mesoporous activated carbons were obtained by chemical activation of kraft lignin with H 3 PO 4 and used as supports for the preparation of carbon-based Pd catalysts with low palladium content (0.5%). The catalytic properties of the carbon-based Pd samples were evaluated in the catalytic oxidation of toluene. The effect that a thermal treatment at 900 °C in inert atmosphere carried out before and after the Pd-deposition produced on the structure and activity of the catalysts was analyzed. The catalysts obtained show high external surface areas and mesopore volumes. The chemical activation with H 3 PO 4 yielded carbon supports with a significant amount of surface phosphorus, in form of C O PO 3 , C PO 3 and C 3 PO groups. These phosphorus groups act like physical barrier, increasing the oxidation resistance of the catalysts and avoiding the burn-off of the carbon substrate during the oxidation of the VOCs. TEM analysis confirmed the presence of well-dispersed Pd particles, with sizes between 5 and 12 nm. A kinetic study of the catalytic oxidation of toluene was performed. The reaction seems to proceed through a Langmuir–Hinshelwood mechanism, whose rate-limiting step is the surface reaction between adsorbed toluene and oxygen adsorbed dissociatively, with an activation energy value of 83 kJ mol −1 . Toluene and xylene were oxidized to CO 2 and H 2 O in the temperature range of 150–400 °C at a space velocity of 19,000 h −1 .
177 citations
TL;DR: In this paper, the adsorption and separation of xylene isomers and ethylbenzene (EB) on two Zn−terephthalate MOFs (MOF-5 and MOF-monoclinic) were studied by means of pulse gas chromatography.
Abstract: Metal−organic frameworks (MOFs) with metal-containing secondary building units and organic linkers have great potential for the separation of isomers. In this work, the adsorption and separation of xylene isomers and ethylbenzene (EB) on two Zn−terephthalate MOFs (MOF-5 and MOF-monoclinic) were studied by means of pulse gas chromatography, static vapor-phase adsorption, and breakthrough adsorption. The two studied Zn−terephthalate MOFs showed different selectivity and efficiency for the separation of xylene isomers and EB. On MOF-5, EB eluted first, while other isomers eluted at the same time. MOF-monoclinic showed a preferable adsorption of p-xylene over other isomers. The adsorption and separation of xylene isomers and EB were equilibrium-constant-controlled on MOF-5 and diffusion-dominated on MOF-monoclinic. On the basis of the measured McReynolds constants, MOF-5 was characterized as a stationary phase of nonpolarity, whereas MOF-monoclinic as a stationary phase of intermediate polarity for gas chroma...
162 citations
TL;DR: A novel on-line sequential injection (SI) dispersive liquid-liquid microextraction (DLLME) system coupled to electrothermal atomic absorption spectrometry (ETAAS) was developed for metal preconcentration in micro-scale, eliminating the laborious and time consuming procedure of phase separation with centrifugation.
132 citations
TL;DR: A novel 3D metal-organic framework with 2D rhombic channels was synthesized for selective adsorption of p-xylene from xylene isomers by acting as a molecular sieve.
98 citations
TL;DR: In this article, a fraction of mixed plastic wastes was pyrolyzed in a bench-scale plant equipped with a fluidized-bed reactor and a char removal system to find out the optimum reaction temperature for a high yield of benzene, toluene, and xylene (BTX) aromatics.
Abstract: Mixed plastic wastes are very difficult to mechanically recycle into new products because of their nonhomogeneity. Therefore, pyrolysis and gasification seem to be very effective in the extraction of energy from mixed plastic wastes in the form of oil and gas. In this study, a fraction of mixed plastic wastes was pyrolyzed in a bench-scale plant equipped with a fluidized-bed reactor and a char removal system. This study has two aims. The first is to find out the optimum reaction temperature for a high yield of benzene, toluene, and xylene (BTX) aromatics. The second is to find out the best additive for chlorine removal. To find out the optimum reaction temperature for the maximum BTX content, experiments at a temperature range of 660−780 °C were carried out. The pyrolysis oils that were obtained from the experiments were composed of aliphatics and mono- and polyaromatic compounds. The reaction temperature had a positive effect on the BTX aromatics yield. The maximum BTX aromatics yield was obtained at 719...
87 citations
TL;DR: It is proposed that mostly ozone and OH radicals are responsible for the degradation of organic molecules in the plasma air purifier.
82 citations
TL;DR: With the combination of bake-out exhaust, biological treatment was applied to deal with volatile organic compounds (VOCs) and four bacterial strains were isolated from the biotrickling filter and were identified according to physiological and biochemical tests as well as bacterial fatty acids.
82 citations
TL;DR: In this article, a natural zeolite was modified by two cationic surfactants (i.e., hexadecyltrimethyl ammonium chloride (HDTMA-Cl), and N-cetylpyridinium bromide (CPB)) and the prepared adsorbents were then characterized, and their adsorptive capabilities for BTEX examined at different experimental conditions.
Abstract: Monoaromatic hydrocarbons including benzene, toluene, ethylbenzene and xylene isomers (BTEX) are a very important category of water pollutants. These volatile compounds are very hazardous because of their fast migration in soil and water bodies and their acute and chronic toxicities when inhaled or ingested, especially benzene which is a known carcinogenic molecule. In this study, a natural zeolite (i. e., clinoptilolite-rich tuffs) was modified by two cationic surfactants (i. e., hexadecyltrimethyl ammonium chloride (HDTMA-Cl), and N-cetylpyridinium bromide (CPB)). The prepared adsorbents were then characterized, and their adsorptive capabilities for BTEX examined at different experimental conditions. The results of adsorption tests at 24 h revealed that the adsorption capacity of the modified zeolites improved by increasing the surfactant loading (i. e., less than the critical micelle concentration (CMC), to higher than the CMC), which caused an increase in sorption capacity from 60 to 70% for HDTMA-modified samples, and from 47 to 99% for CPB-modified zeolite. Adsorption kinetic tests showed the optimum contact time was 48 h with an average BTEX removal of 90 and 93% for HDTMA-modified and CPB-modified zeolite, respectively. Results showed that by increasing of pH from 3 to 11, the sorption capacity of the adsorbent decreased markedly from 97 to 75%. Analyzing the influence of temperature showed that the adsorption efficiency of adsorbents for benzene reduced from 93% at 20°C to 10% at 4°C. However, the influence of temperature on other compounds was not remarkable. Overall, CPB-modified zeolite exhibited higher selectivity toward BTEX compounds at optimum experimental conditions. Although commercial powder activated carbon (PAC) showed a higher capacity for all BTEX compounds and faster adsorption kinetics, the adsorption capacity of the CPB-modified zeolite at optimized conditions was competitive with PAC results.
81 citations
TL;DR: In this paper, mixed SnO2 nanoparticles with 1 ¼wt.% MWCNTs were fabricated on micro-platforms to detect NO2, NH3, and xylene gases.
Abstract: Using mixed SnO2 nanoparticles with 1 wt.% MWCNTs sensing materials, NO2, NH3, and xylene gas sensors were fabricated on micro-platforms. A micro-platform consists of micro-sensing electrode and micro-heater on 2 μm thick SiNx membrane. The fabricated gas sensors were characterized to NO2, NH3, and xylene gases, respectively, as a function of concentration at 300 °C and temperature from 180 °C to 380 °C at constant concentration. The measured highest sensitivities for the NO2, NH3, and xylene were 1.06 at 1.2 ppm and 220 °C, 0.19 at 60 ppm, and 220 °C, and 0.15 at 3.6 ppm and 220 °C, respectively. So, it was found that 220 °C was the optimum temperature to have the best sensitivities. From these results, mixed SnO2 nanoparticles with 1 wt.% MWCNTs showed good sensitivity and selectivity at low power operation below 30 mW. Fabricated micro-gas sensors could be used for ubiquitous sensor network applications to monitor environmental pollutants in the air.
78 citations
TL;DR: A working hypothesis that toluene and/or xylene in a mixture containing benzene affect benzene induced toxicity in a non-target organism, Drosophila melanogaster is tested and antagonistic effect of xylene and toLUene on benzene toxicity and additive/synergistic effectof xylene on toluenes induced toxicity is suggested.
TL;DR: The SCGE assay results showed that these three pollutants could significantly induce DNA damage in earthworms and the clear dose-dependent relationships were displayed, indicating potential genotoxic effects of toluene, ethylbenzene, and xylene on E. fetida.
Abstract: Superoxide dismutase (SOD), guaiacol peroxidase (POD), catalase (CAT), and the comet assay (SCGE) were used as biomarkers to evaluate the oxidative stress and genotoxicity of toluene, ethylbenzene and xylene in earthworms (Eisenia fetida). The results indicated that the exposure of the three pollutants caused a stress response of the three enzymes, an approximate bell-shaped change (a tendency of inducement firstly and then inhibition with increasing concentrations of the pollutants) was mostly found. The three enzymes tested differed in their sensitivity to different pollutants. While the activity of POD was not significantly changed within the concentration range, the concentration thresholds for significant (P < 0.05) responses to toluene based on SOD and CAT were 5 mg kg−1, respectively. Similarly, the concentration thresholds for significant (P < 0.05) responses to ethylbenzene based on CAT and POD were 10 and 5 mg kg−1, respectively, while the activity of SOD was not significantly changed within the concentration range. Significant responses to xylene based on CAT and POD were 5 mg kg−1, respectively, while the activity of SOD was significantly (P < 0.05) induced at 10 mg kg−1. The SCGE assay results showed that these three pollutants could significantly (P < 0.01) induce DNA damage in earthworms and the clear dose-dependent relationships were displayed, indicating potential genotoxic effects of toluene, ethylbenzene, and xylene on E. fetida. The inducement of DNA damage may be attributed to the oxidative attack of toluene, ethylbenzene, and xylene. Toluene seemed to be more genotoxic as it could induce the higher extent of DNA damage than ethylbenzene and xylene. The results suggest that the SCGE assay of earthworms is simple and efficient for diagnosing the genotoxicity of pollutants in terrestrial environment.
TL;DR: EH831 was able to degrade many recalcitrant hydrocarbons at higher degradation rates compared with previous well-known degraders, and primarily suggested the aerobic biodegradation pathway, which may provide valuable information for researchers and engineers working in the field of environmental engineering.
Abstract: Hexane, a representative VOC, is used as a solvent for extraction and as an ingredient in gasoline. The degradation of hexane by bacteria is relatively slow due to its low solubility. Moreover, the biodegradation pathway of hexane under aerobic conditions remains to be investigated; therefore, a study relating to aerobic biodegradation mechanisms is required. Consequently, in this study, an effective hexane degrader was isolated and the biodegradation pathway examined for the first time. In addition, the degradation characteristics of a variety of recalcitrant hydrocarbons were qualitatively and quantitatively investigated using the isolate. A hexane-degrading bacterium was isolated from an enrichment culture using petroleum-contaminated soil as an inoculum with hexane as the sole carbon and energy source. The bacterium was also identified using the partial 16S rRNA gene sequence. To test the hexane-degrading capacity of the isolate, 10 ml of an EH831 cell suspension was inoculated into a 600-ml serum bottle with hexane (7.6–75.8 μmol) injected as the sole carbon source. The rates of hexane degradation were determined by analyzing the concentrations of hexane using headspace gas chromatography. In addition, the hexane biodegradation pathway under aerobic conditions was investigated by identifying the metabolites using gas chromatography–mass spectrometry with solid-phase microextraction. 14C-hexane was used to check if EH831 could mineralize hexane in the same experimental system. The degradabilities of other hydrocarbons were examined using EH831 with methanol, ethanol, acetone, cyclohexane, methyl tert-butyl ether (MTBE), dichloromethane (DCM), trichloroethylene, tetrachloroethylene, benzene, toluene, ethylbenzene, xylene (BTEX), pyrene, diesel, lubricant oil, and crude oil as sole carbon sources. A bacterium, EH831, was isolated from the enriched hexane-degrading consortium, which was able to degrade hexane and various hydrocarbons, including alcohols, chlorinated hydrocarbons, cyclic alkanes, ethers, ketones, monoaromatic and polyaromatic hydrocarbons, and petroleum hydrocarbons. The maximum hexane degradation rate (V
max) of EH831 was 290 μmol g dry cell weight−1 h−1, and the saturation constant (K
s) was 15 mM. Using 14C-hexane, EH831 was confirmed to mineralize approximately 49% of the hexane into CO2 and, converted approximately, 46% into biomass; the rest (1.7%) remained as extracellular metabolites in the liquid phase. The degradation pathway was assessed through the qualitative analysis of the hexane intermediates due to EH831, which were 2-hexanol, 2-hexanone, 5-hexen-2-one and 2,5-hexanedione, in that order, followed by 4-methyl-2-pentanone, 3-methly-1-butanol, 3-methyl-1-butanone and butanal, and finally, CO2. EH831 could degrade methanol, ethanol, acetone, cyclohexane, MTBE, DCM, BTEX, pyrene, diesel, and lubricant oil. EH831 was able to degrade many recalcitrant hydrocarbons at higher degradation rates compared with previous well-known degraders. Furthermore, this study primarily suggested the aerobic biodegradation pathway, which may provide valuable information for researchers and engineers working in the field of environmental engineering. Rhodococcus sp. EH831 is a promising bioresource for removing hexane and other recalcitrant hydrocarbons from a variety of environments. Moreover, the aerobic biodegradation pathway is reported for the first time in this study, which offers valuable information for understanding the microbial degradation of hexane. The utility of the strain isolated in this study needs to be proved by its application to biological process systems, such as biofilters and bioreactors, etc., for the degradation of hexane and many other recalcitrant hydrocarbons. Detailed investigations will also be needed to clarify the enzymatic characteristics relating the degradation of both recalcitrant hydrocarbons and hexane.
TL;DR: In this paper, a series of Mn-Ce oxides were prepared using a redox-precipitation method and the complete catalytic oxidation of o -xylene was examined.
TL;DR: In this article, the results showed that with increasing dielectric constant of the diluent, the extraction percent decreased while the separation factors did not change considerably while the values of the equilibrium constants and the separation factor were calculated.
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24 Feb 2010TL;DR: In this article, the cycloaddition of ethylene to DMF provides an alternative route to para-xylene, and the starting material for the processes may be synthesized from carbohydrates (e.g., glucose or fructose), thereby providing a pathway that relies at least partly, if not completely, on renewable feedstocks.
Abstract: Catalytic processes for the conversion of 2,5-dimethyl furan (DMF) to para-xylene are described. Para-xylene is a key product that is currently obtained commercially from petroleum sources. However, it has now been determined that the cycloaddition of ethylene to DMF provides an alternative route to para-xylene. Advantageously, the DMF starting material for the processes may be synthesized from carbohydrates (e.g., glucose or fructose), thereby providing a pathway that relies at least partly, if not completely, on renewable feedstocks.
TL;DR: Irrespective of the RH, the introduction of MnO(x)/Al(2)O(3) catalyst significantly promotes BTX conversion and improves the energy efficiency and CPC under 30% RH shows the best performance towards CO(x) formation during BTX oxidation processes.
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20 Dec 2010TL;DR: In this paper, a process for producing xylene by transalkylation of a C9+ aromatic hydrocarbon feedstock with a C6 and/or C7 aromatic hydrocarbons is described.
Abstract: In a process for producing xylene by transalkylation of a C9+ aromatic hydrocarbon feedstock with a C6 and/or C7 aromatic hydrocarbon, the C9+ aromatic hydrocarbon feedstock, at least one C6 and/or C7 aromatic hydrocarbon and hydrogen are contacted with a first catalyst comprising (i) a first molecular sieve having a Constraint Index in the range of about 3 to about 12 and (ii) at least first and second different metals or compounds thereof of Groups 6 to 12 of the Periodic Table of the Elements. Contacting with the first catalyst is conducted under conditions effective to dealkylate aromatic hydrocarbons in the feedstock containing C2+ alkyl groups and to saturate C2+ olefins formed so as to produce a first effluent. At least a portion of the first effluent is then contacted with a second catalyst comprising a second molecular sieve having a Constraint Index less than 3 under conditions effective to transalkylate C9+ aromatic hydrocarbons with said at least one C6-C7 aromatic hydrocarbon to form a second effluent comprising xylene.
TL;DR: Biodegradation rates and patterns were measured using an in situ microcosm in a crude-oil contaminated aquifer near Bemidji, Minnesota and isomer-specific degradation patterns were compared to observations from a multi-year study conducted using data collected from monitoring wells along a flowpath in the contaminant plume.
TL;DR: Advanced oxidation of benzene, toluene, ethylbenzene, and o-, m-, and p-xylene (BTEX) by the extracellular hydroxyl radicals (*OH) generated by the white-rot fungus Trametes versicolor is for the first time demonstrated.
TL;DR: In this paper, the physicico-chemical properties of the catalysts in the spent and chemically treated states were analyzed by using nitrogen adsorption-desorption isotherm and elemental analysis (EDX).
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09 Sep 2010TL;DR: In this paper, the use of a mixture of a solid hydrocarbonaceous material and a heterogeneous pyrolytic catalyst component is proposed to improve the yield and/or selectivity of certain products.
Abstract: This invention relates to compositions and methods for fluid hydrocarbon product, and more specifically, to compositions and methods for fluid hydrocarbon product via catalytic pyrolysis. Some embodiments relate to methods for the production of specific aromatic products (e.g., benzene, toluene, naphthalene, xylene, etc.) via catalytic pyrolysis. Some such methods may involve the use of a composition comprising a mixture of a solid hydrocarbonaceous material and a heterogeneous pyrolytic catalyst component. In some embodiments, an olefin compound may be co-fed to the reactor and/or separated from a product stream and recycled to the reactor to improve yield and/or selectivity of certain products. The methods described herein may also involve the use of specialized catalysts. For example, in some cases, zeolite catalysts may be used. In some instances, the catalysts are characterized by particle sizes in certain identified ranges that can lead to improve yield and/or selectivity of certain products.
TL;DR: In this article, the authors showed that the catalytic conversion of methanol, ethanol, dimethyl ether and diethyl ether to aromatic hydrocarbons (especially benzene, toluene, and xylene) can be achieved over 0.8%Zn/0.6%La/HZSM-5 with a BTX selectivity as high as over 50% at reaction conditions of 710 K, WHSV 0. 8−h−1.
TL;DR: In this article, the effect of Si/Al ratio in Zeolite Beta was evaluated and it was found that transalkylation activity and xylene yields increase with decreasing Si/al ratio.
Abstract: Zeolites Beta, mordenite and Y were evaluated for their activity in transalkylation reaction of toluene with trimethylbenzenes. Zeolite Beta was found to possess the highest conversion in toluene–trimethylbenzene transalkylation as well as a higher stability in time-on-stream compared with mordenite and zeolite Y. The effect of Si/Al ratio in zeolite Beta was evaluated and it was found that transalkylation activity and xylene yields increase with decreasing Si/Al ratio. Zeolite Beta with the lowest Si/Al ratio of 12.5 (the highest concentration of active sites) exhibited the highest 1,2,4-trimethylbenzene (124TMB) conversion and maximum xylene yield. The highest xylene yield was obtained at optimum equimolar ratio (1:1) of 124TMB to toluene. With increasing 124TMB concentration in the feed, the conversion of 124TMB and xylene yield decreased while toluene conversion simultaneously increased. The increase in the concentration of toluene in the feed resulted in the increase in the conversion of 124TMB. However, addition of higher concentrations of toluene led to a significant decrease in xylene yield.
TL;DR: In this paper, the authors analyzed the chemical kinetics of the catalytic chemical vapor deposition (CCVD) process and showed that the addition of acetylene significantly increases the decomposition rate of xylene and decreases the benzene concentration in the effluent gas, as well as improving the quality of the CNTs obtained.
TL;DR: The results showed that the capability for BTEX removal decreases in the order of benzene, toluene, p-xylene, ethylbenzene for both added-Nitrogen and no-added-nitrogen under BTEX concentrations at 30 mg l−1.
Abstract: To remediate benzene, toluene, ethylbenzene and xylene (BTEX) -contaminated groundwater, a biotreatment process including biostimulation and bioaugmentation was simulated using oxygen-releasing reactive barriers (ORRB) and water with added BTEX in a lab-scale system. The results showed that the capability for BTEX removal decreases in the order of benzene, toluene, p-xylene, ethylbenzene for both added-nitrogen and no-added-nitrogen under BTEX concentrations at 30 mg l(-1). The removal efficiencies in ORRB systems were higher in the nitrogen-added condition for biostimulation compared with the no-nitrogen-added condition; moreover, an increased pattern for removal was observed during the bioaugmentation process. The oxygen content was found to be inversely proportional to the distance from the ORRB, as evidenced by observing that the average bacteria densities were two orders higher when located at 15 cm compared with 30 cm from the ORRB. The microbial community structure was similar in both cases of added-nitrogen and the no-added-nitrogen conditions.
TL;DR: The method developed is satisfactorily applied to the analysis of aqueous samples obtained from wastewater treatment plants and shows that repeatability and recoveries with the NT device are equivalent to those obtained using solid-phase microextraction with a carboxen/ PDMS (CAR/PDMS) coating.
Abstract: A needle trap (NT) device filled with Carbopack X as a sorbent material is evaluated for the static headspace analysis of benzene, toluene, ethylbenzene, and xylene (BTEX) compounds in aqueous samples. Injection parameters used with the NT device (e.g. volume of carrier gas and time to open the split valve) are evaluated to determine the mechanism involved during the desorption and transferring of the target compounds into the GC column. Furthermore, different parameters affecting the adsorption capacity of the sorbent are studied (e.g. sampling time and temperature, headspace/sample volume ratio, salting-out, and stirring). The evaluation of the method with aqueous samples shows that repeatability and recoveries with the NT device are equivalent to those obtained using solid-phase microextraction with a carboxen/PDMS (CAR/PDMS) coating. LODs obtained with flame ionization detection are in the range of 10-25 μg/L, and in the range of hundredths of μg/L with MS detection. The method developed is satisfactorily applied to the analysis of aqueous samples obtained from wastewater treatment plants.
TL;DR: In this article, a xylene decomposition system that combines a process of adsorption with decomposition by nonthermal plasma with gas circulation is investigated for treating volatile organic compounds exhaust from indoor small-scale sources.
Abstract: A xylene decomposition system that combines a process of adsorption with a process of decomposition by nonthermal plasma with gas circulation is investigated for treating volatile organic compounds exhaust from indoor small-scale sources An ac 60-Hz neon transformer and an inverter-type neon transformer are used for the generation of the nonthermal plasma After p-xylene or a xylene mixture consisting of o-, m -, and p-xylene is adsorbed by an adsorbent, nonthermal plasma is generated with gas circulation, and adsorbed xylene is decomposed The performance of this system is evaluated in terms of the conversion ratio of adsorbed xylene to CO and CO2 and the energy efficiency of the xylene decomposition process The energy efficiency of the xylene decomposition process carried out using the inverter-type neon transformer is found to be better than that of the process carried out using the ac 60-Hz neon transformer However, the stable operation of the plasma reactor is difficult, and a large amount of NOx is generated as a byproduct when the inverter-type neon transformer is used Thus, the results obtained in this research suggest that the ac 60-Hz neon transformer is suitable for this system
TL;DR: In particular, the solubility of hydrocarbons in both ionic liquids increases with the temperature in the order n -heptane, n -hexane, m -xylene, p-xylene and o -xene as discussed by the authors.
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14 Jun 2010TL;DR: In this paper, a complex emulsion is made by mixing an acid aqueous phase with an external micro-emulsion to give an initial product, where the acid annealing phase is an external phase and the microemulsion is an internal phase.
Abstract: Using a complex emulsion for treating a subterranean formation, such as to dissolve minerals therein (e.g. carbonates, scales, and/or filter cake) to improve permeability, substantially improves post treatment fluid clean-up for improved hydrocarbon production. The complex emulsion is made by mixing an acid aqueous phase with an oil external microemulsion to give an initial product, where the acid aqueous phase is an external phase and the microemulsion is an internal phase. Then the initial product is mixed with a second oil (e.g. xylene, diesel, toluene, kerosene, other aromatics, refined hydrocarbons and the like) containing an emulsifier to make a complex emulsion.