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A Poly (3,4-ethylenedioxothiophene) (PEDOT)/UiO-66 composite was electrodeposited on an etched stainless-steel wire as head-space solid-phase microextraction (HS-SPME) coating. A robust, well controlled thickness, and uniform coating of metal organic framework composites can be realized by the electrodeposited strategy. The incorporated UiO-66 not only enhanced the uniformity and stability of the composite coating, but also effectively decreased the stacking phenomenon of PEDOT and improved its extraction efficiency, which was over 100 times higher than that of the PEDOT coating without UiO-66. The composite coating was used to enrich seven types of volatile organic compounds (VOCs) in ion-exchange resins, including methyl cyclohexane, benzene, toluene, ortho-xylene, styrene, para-xylene and divinyl-benzene. The results of adsorption isotherm analysis showed that π stacking effect played dominant role between the composite coating and VOCs in the extraction process. The composite coating was characterized by scanning electron microscopy, X-ray diffraction, Fourier transform infrared and thermogravimetric analysis, respectively. A determination method for seven kinds of VOCs was established by HS-SPME coupled with gas chromatography-flame ionization detection (GC-FID). Under the optimal experimental conditions, the detection linear range (LRs) was 0.09-100 ng mL -1 , and the detection limit (LODs) was 0.03-0.06 ng mL -1 (S/N = 3). The method was applied for the migration detection of VOCs in four types of ion-exchange resin, which showed satisfactory recovery (84.5-117.2%)., Competing Interests: Declaration of Competing Interest The authors declare no conflict of interest., (Copyright © 2020 Elsevier B.V. All rights reserved.)

A deep eutectic solvent functionalized graphene oxide composite adsorbent (DFG) was synthesized through reversible-addition fragmentation chain-transfer polymerization. The synthesized DFG had multiple adsorption interactions after covalent modification with a deep eutectic solvent (allyltriethylammonium bromide/ethylene glycol). Adsorption isotherms and kinetics studies of DFG indicate that the adsorption of hippuric acid (HA) and methylhippuric acid (MHA) was monolayer chemical adsorption. The comparison of DFG with commercial adsorbents demonstrates that the adsorption ability of DFG was superior. This was due to the multiple adsorption interactions of DFG for the three analytes (mainly π-interaction, hydrogen bonding, electrostatic adsorption, and hydrophobic interaction). The DFG adsorbent was applied to miniaturized pipette-tip solid-phase extraction (MPT-SPE), followed by high-performance liquid chromatography (HPLC) to determine biomarkers in urine for toluene and xylene exposure. The DFG-MPT-SPE-HPLC method required only 2.00 mg of DFG as adsorbent, 0.50 mL of washing solvent, and 0.40 mL of elution solvent to achieve a wide linear range (0.200-200 μg mL -1 ), high recoveries (90.9-99.1%), and high precision (RSD ≤ 6.3%). The proposed method was applied to determine HA and MHA in urine samples from occupational workers. Graphical abstract Deep eutectic solvent functionalized graphene oxide composite adsorbent for miniaturized pipette-tip solid-phase extraction of toluene and xylene exposure biomarkers in urine prior to their determination with HPLC-UV.

Spray paint exhaust gas contains recalcitrant volatile organic compounds (VOCs), such as benzene, toluene and xylene (BTX). Treating BTX with a biofilter often achieves unsatisfactory results because the biofilter lacks efficient microbial community. In this work, three strains for BTX degradation were isolated and identified as Pseudomonas putida, Bacillus cereus and Bacillus subtilis by using 16S rRNA sequencing technology. A consortium of highly efficient microbial community was then constructed on a stable biofilm to treat BTX in a biofilter. A relatively suitable ratio of P. putida, B. cereus and B. subtilis was obtained. An efficiency of over 90% was achieved in the biofilter with VOC concentration of 1000 mg/m 3 through inoculation with the microbial community after only 10 days of operation. Thus, fast start-up of the biofilter was realised. Analysis of intermediate products by gas chromatography-mass spectrometry indicated that BTX was degraded into short-chain aldehydes or acids via ring opening reactions.

In its crystalline state, a dinuclear Cu-based metallocycle discriminates between the three isomers of xylene with liquid-phase selectivity in the order p -xylene ≫ m -xylene ≫ o -xylene. This selectivity holds over a wide concentration range, with p -xylene concentrations as low as 5%. Single-crystal X-ray diffraction and gas chromatography further indicate that the metallocyclic host extracts trace amounts of p -xylene from commercially pure o -xylene (≥99%); using NMR spectroscopy, we show that the metallocycle exhibits exclusive selectivity for p -xylene. Crystallographic studies show that the selectivity is based on the size and shape of the guest in combination with the flexibility of the host.

Particulate matter and volatile organic compounds have emerged as a prime environmental concern with increasing air pollution in metropolitan cities leading to lung and heart-related issues. This paper describes a facile and novel method for fabrication of polyester based air filter via surface coating with Sericin for imparting effective removal of particulate matter and volatile organic compounds. A simple dip-coating method followed by thermal fixation has been adopted to coat Sericin on the polyester fiber. The developed changes in surface functionality and morphology of the polyester fiber were confirmed by Attenuated total reflection Fourier-transform infrared spectroscopy and Field emission scanning electron microscopy analysis. The fabricated air filter was tested for removal of particulate matter (generated burning incense stick) and volatile organic compounds (generated vaporizing gasoline), in an indoor chamber. The Sericin coated filter was able to remove the PM 2.5 and PM 10 (from 1000 μg/m 3 level to 5 μg/m 3 in a 6.28 m 3 chamber) within 27 and 23 min of operation, respectively. The fabricated filter very effectively removed particulate matter for 2160 cycles with intermittent washing. The Sericin-coated air filter also proved very effective for removal of volatile organic compounds (Benzene, Toluene, Ethylbenzene and Xylene) from an indoor chamber at a varying initial concentration of 100-1000 μg/m 3 . The adsorption behavior was described by Langmuir-Freundlich (sips) isotherm and pseudo-first order kinetics with minimal error. The maximum adsorption capacity (mg/g) obtained with Sips Isotherm fitting followed the order Xylene (6.97)>Ethyl Benzene (5.68)> Toluene (5.35) >Benzene (4.78)., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

A needle-to-post ionization source was designed for high-field asymmetric waveform ion mobility spectrometry (FAIMS). The needle-to-post ion source includes asymmetric electrode comprised of a copper post with a diameter of 2 mm and a stainless-steel needle with 200-μm tip radius and length of 28 mm. With the discharge voltage of -5.6 kV and N2 gas flow, glow discharge was realized at atmospheric pressure. The mass spectra of ionized ions about acetone, ethanol and ethyl acetate were gotten by Thermo Scientific LTQ XL ion trap mass spectrometer (MS). The MS experimental results show that the main ions are protonated and dimer ions. The needle-to-post ion source was mounted on the FAIMS system and FAIMS spectra are gotten successfully. Separation of p-xylene, o-xylene and m-xylene was realized. It shows that the needle-to-post electrode could be used as the ion source in a FAIMS system., Competing Interests: The authors have declared that no competing interests exist.

Constructed wetlands (CWs) are well-established wastewater treatment technologies and applied for bioremediation of contaminated water. Despite the optimal performance of CWs, the understanding of the bacterial processes in the rhizosphere, where mainly microbial degradation processes take place, is still limited. In the present study, laboratory-scale CWs planted with Juncus effusus and running under controlled conditions were studied in order to evaluate removal efficiency of dimethylphenols (DMPs), also in comparison to an unplanted bed. Next to removal rates, the bacterial community structure, diversity, and distribution, their correlation with physiochemical parameters, and abundance of the phenol hydroxylase gene were determined. As a result, better removal performance of DMP isomers (3,4-, 3,5-, and 2,6-DMP added as singles compounds or in mixtures) and ammonium loads, together with a higher diversity index, bacterial number, and phenol hydroxylase gene abundance in Juncus effusus CW in comparison with the non-planted CW, indicates a clear rhizosphere effect in the experimental CWs. An enhancement in the DMP removal and the recovery of the phenol hydroxylase gene were found during the fed with the DMP mixture. In addition, the shift of bacterial community in CWs was found to be DMP isomer dependent. Positive correlations were found between the bacteria harboring the phenol hydroxylase gene and communities present with 3,4-DMP and 3,5-DMP isomers, but not with the community developed with 2,6-DMP. These results indicate that CWs are highly dynamic ecosystems with rapid changes in bacterial communities harboring functional catabolic genes.

Online coupling of Lab-In-Syringe automated headspace extraction to gas chromatography has been studied. The developed methodology was successfully applied to surface water analysis using benzene, toluene, ethylbenzene, and xylenes as model analytes. The extraction system consisted of an automatic syringe pump with a 5 mL syringe into which all solutions and air for headspace formation were aspirated. The syringe piston featured a longitudinal channel, which allowed connecting the syringe void directly to a gas chromatograph with flame ionization detector via a transfer capillary. Gas injection was achieved via opening a computer-controlled pinch valve and compressing the headspace, upon which separation was initialized. Extractions were performed at room temperature; yet sensitivity comparable to previous work was obtained by high headspace to sample ratio V HS /V Sample of 1.6:1 and injection of about 77% of the headspace. Assistance by in-syringe magnetic stirring yielded an about threefold increase in extraction efficiency. Interferences were compensated by using chlorobenzene as an internal standard. Syringe cleaning and extraction lasting over 10 min was carried out in parallel to the chromatographic run enabling a time of analysis of <19 min. Excellent peak area repeatabilities with RSD of <4% when omitting and <2% RSD when using internal standard corrections on 100 μg L -1 level were achieved. An average recovery of 97.7% and limit of detection of 1-2 μg L -1 were obtained in analyses of surface water., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Purification of the C 8 alkylaromatics o-xylene, m-xylene, p-xylene, and ethylbenzene remains among the most challenging industrial separations, due to the similar shapes, boiling points, and polarities of these molecules. Herein, we report the evaluation of the metal-organic frameworks Co 2 (dobdc) (dobdc 4- = 2,5-dioxido-1,4-benzenedicarboxylate) and Co 2 ( m-dobdc) ( m-dobdc 4- = 4,6-dioxido-1,3-benzenedicarboxylate) for the separation of xylene isomers using single-component adsorption isotherms and multicomponent breakthrough measurements. Remarkably, Co 2 (dobdc) distinguishes among all four molecules, with binding affinities that follow the trend o-xylene > ethylbenzene > m-xylene > p-xylene. Multicomponent liquid-phase adsorption measurements further demonstrate that Co 2 (dobdc) maintains this selectivity over a wide range of concentrations. Structural characterization by single-crystal X-ray diffraction reveals that both frameworks facilitate the separation through the extent of interaction between each C 8 guest molecule with two adjacent cobalt(II) centers, as well as the ability of each isomer to pack within the framework pores. Moreover, counter to the presumed rigidity of the M 2 (dobdc) structure, Co 2 (dobdc) exhibits an unexpected structural distortion in the presence of either o-xylene or ethylbenzene that enables the accommodation of additional guest molecules.

A low-cost, sensitive and reliable reduced-pressure headspace solid-phase microextraction (HS-SPME) setup was developed and evaluated for direct extraction of residual solvents in commercial antibiotics, followed by determination by gas chromatography with flame ionization detection (GC-FID). A stainless steel narrow wire was made porous and adhesive by platinization by a modified electrophoretic deposition method and coated with a polyaniline/multiwalled carbon nanotube nanocomposite. All experimental variables affecting the extraction efficiency were investigated for both atmospheric-pressure and reduced-pressure conditions. Comparison of the optimal experimental conditions and the results demonstrated that the reduced-pressure strategy leads to a remarkable increase in the extraction efficiency and reduction of the extraction time and temperature (10 min, 25 °Ϲ vs 20 min, 40 °Ϲ). Additionally, the reduced-pressure strategy showed better analytical performances compared with those obtained by the conventional HS-SPME-GC-FID method. Limit of detections, linear dynamic ranges, and relative standard deviations of the reduced-pressure HS-SPME procedure for benzene, toluene, ethylbenzene, and xylene (BTEX) in injectable solid drugs were obtained over the ranges of 20-100 pg g -1 , 0.02-40 μg g -1 , and 2.8-10.2%, respectively. The procedure developed was successful for the analysis of BTEX in commercial containers of penicillin, ampicillin, ceftriaxone, and cefazolin. Graphical abstract Schematic representation of the developed RP-HS-SPME setup.

Water-insoluble β-cyclodextrin polymer was synthesized by chemical cross-linking using epichlorohydrin (EPI) as a cross-linker agent. The produced water-insoluble polymer was used as a sorbent for the micro-solid phase extraction (μ-SPE) of benzene, toluene, ethylbenzene and xylenes (BTEX) from water samples. The μ-SPE device consisted of a sealed tea bag envelope containing 15mg of sorbent. For the evaluation of the extraction efficiency, parameters such as extraction and desorption time, desorption solvent and salt concentration were investigated. At an extraction time of 30min in the course of the extraction process, analytes were extracted from a 10mL aqueous sample solution. The analytes were desorbed by ultrasonication in 200μL of acetonitrile for 20min. Analysis of the analytes was done by a gas chromatography-flame ionization detector (GC-FID) system. The enrichment factor (EF) was found to be in the range 23.0-45.4 (EF max =50.0). The method provided linearity ranges of between 0.5 and 500.0ng/mL (depending on the analytes), with good coefficients of determination (r 2 ) ranging between 0.997 and 0.999 under optimized conditions. Detection limits for BTEX were in the range of between 0.15 and 0.60ng/mL, while corresponding recoveries were in the range of 46.0-90.0%. The relative standard deviation of the method for the analytes at 100.0ng/mL concentration level ranged from 5.5 to 11.2% (n=5). The proposed method was concluded to be a cost effective and environmentally-friendly extraction technique with ease of operation and minimal usage of organic solvent., (Copyright © 2017 Elsevier B.V. All rights reserved.)

This study focused on a haloduric BTEX-degrading microbial consortium EC20 enriched from Bohai Sea sediment. EC20 degraded 87% of BTEX at 435 mg L -1 initial concentration (benzene, toluene, ethylbenzene, and xylenes in equal proportions) in the presence of 3.4% NaCl. 16S rRNA gene-based PCR-DGGE profiles revealed that the dominant bacteria in EC20 were Proteobacteria, Actinobacteria, Bacteroidetes, and Firmicutes at the phylum level, and Pseudomonas, Mesorhizobium, Achromobacter, Stenotrophomonas, and Halomonas at the genus level. PCR detection of genes coding the key enzymes which participated in BTEX degradation pathways showed that the enriched consortium EC20 contained TOL pathway and TOD pathway to initiate biodegradation of BTEX.

This study reports a new composite based on ZSM-5 zeolite decorated with iron oxide magnetic nanoparticles as a valuable sorbent for magnetic solid-phase extraction (MSPE). A proposal is made to determine benzene, toluene, ethylbenzene and xylenes (BTEX) as model analytes in water samples using gas chromatography-mass spectrometry. A two-step multivariate optimization strategy, using Plackett⬜Burman and circumscribed central composite designs, was employed to optimize experimental parameters affecting MSPE. The method was evaluated under optimized extraction conditions (i.e., amount of sorbent, 138mg; extraction time, 11min; sample pH, pH of water (i.e., 5.5⬜6.5); eluent solvent volume, 0.5mL; and elution time, 5min), obtaining a linear response from 1 to 100μgL(↙1) for benzene; from 10 to 100μgL(↙1) for toluene, ethylbenzene and o-xylene; and from 10 to 75μgL(↙1) for m,p-xylene. The repeatability of the proposed method was evaluated at a 40μgL(↙1) spiking level and coefficients of variation ranged between 8 and 11% (n=5). Limits of detection were found to be 0.3μgL(↙1) for benzene and 3μgL(↙1) for the other analytes. These values satisfy the current normative of the Environmental Protection Agency and European Union for BTEX content in waters for human consumption. Finally, drinking water, wastewater and river water were selected as real water samples to assess the applicability of the method. Relative recoveries varied between 85% and 114% showing negligible matrix effects., (Copyright © 2016 Elsevier B.V. All rights reserved.)

Eight in situ solidification/stabilization (ISS) amendments were tested to promote in situ chemical oxidation (ISCO) with activated persulfate (PS) in a contaminated soil. A 3% (by weight) dose of all ISS amendments selected for this study completely activated a 1.5% dose of PS within 3 h by raising temperatures above 30 °C (heat activation) and/or increasing pH above 10.5 (alkaline activation). Heat is released by the reaction of CaO with water, and pH increases because this reaction produces Ca(OH)2. Heat activation is preferred because it generates 2 mol of oxidizing radicals per mole of PS, whereas alkaline activation releases only 1. The relative contribution of heat vs. alkaline activation increased with CaO content of the ISS amendment, which was reflected by enhanced contaminant oxidation with increasing CaO content, and was confirmed by comparing to controls promoting purely heat or alkaline (NaOH) activation. The test soil was contaminated with benzene, toluene, ethylbenzene, and xylenes (BTEX) and polycyclic aromatic hydrocarbons (PAH), particularly naphthalene (NAP). ISS-activated PS oxidized between 47% and 84% of the BTEX & NAP, and between 13% and 33% of the higher molecular weight PAH. ISS-activated PS reduced the leachability of BTEX & NAP by 76%-91% and of the 17 PAH by 83%-96%. Combined ISCO/ISS reduced contaminant leachability far than ISCO or ISS treatments alone, demonstrating the synergy that is possible with combined remedies., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

This study aims at developing a method for the determination of 9 synthetic musk compounds in seafood products by combining the quick, easy, cheap, effective, rugged, and safe (QuEChERS) method and determination by gas chromatography mass spectrometry (GC-EI-MS). Method detection limits (MDL) ranging between 0.001 and 1.94 ng g(-1) were obtained. The linearity is higher than 0.9899 in the range MDL - 100 ng g(-1) with precision below 18% and recoveries between 46% and 120% were obtained. The method was applied to quantify musk compounds in seafood products from the European southwest coast (oysters, mussels, salmon organs, glass eels). Galaxolide and Tonalide exhibited the highest concentration levels ranging between MDL - 96.4 ng g(-1) and MDL - 6.85 ng g(-1), respectively. Contamination levels observed for the two nitro musks (musk xylene and musk ketone) are significantly lower ranging between MDL - 0.6 ng g(-1) and MDL - 0.09 ng g(-1), respectively. Analysis of different organs of salmons showed higher concentrations in liver and gonad than in muscle tissues., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

The application of ostrich bone waste-loaded a cationic surfactant (OBW-OH-CTABr) bioadsorbent for benzene, toluene, ethylbenzene and p-xylene (BTEX) removal from the synthetic and real waters have been studied, and the prepared biomaterials were studied by Fourier transform infrared (FTIR), X-ray diffraction (XRD), surface area measurements (BET), scanning electron microscopy (SEM), Energy-dispersive X-ray spectroscopy (EDX) and point of zero (pH(PZC)). The immobilization of CTABr molecules on the framework of modified OBW showed good tendency to adsorb BTEX from aqueous solution. The exposure time to obtain equilibrium for maximum removal of BTEX was observed to be 60 min. The removal kinetics of BTEX has been evaluated in terms of pseudo-first- and -second-order kinetics, and the Freundlich and Langmuir isotherm models have also been utilized to the equilibrium removal data. The removal process was spontaneous and endothermic in nature and followed pseudo-second-order kinetic model. The immobilized CTABr showed high reusability because of its high adsorption efficiency after 12th cycles. The proposed low-cost bioadsorbent could also be utilized to adsorb BTEX from the real water (Anzali lagoon water). The OBW-OH-CTABr composite is indeed an attractive biomaterial for drinking water-based pollutants and act as an adsorbent for BTEX and oil spills especially in third world due to its low-cost preparation and regeneration and clean processing of the biomaterial with no byproducts after utilize., (Copyright © 2015 Elsevier Inc. All rights reserved.)

Residential proximity to industrial sites has been associated with adverse effects on human health. Children are more susceptible to airborne environmental exposure because their immune and respiratory systems are still developing. This study aimed to investigate whether living close to an oil terminal in Genoa where there is higher VOCs exposure is associated with an increased rate of school absenteeism because of disease in primary school children. Five schools were chosen for the recruitment of children and students residing in the industrial site (A) were compared to those living in residential sites (B). Sixty-six of the 407 students involved in the project were also selected for VOC monitoring. Source apportionment was carried out by comparing profiles of VOCs; principal component analysis was performed to study the correlation between profiles, and Kriging interpolation model was used to extend profiles to all participants. The concentration means of total VOCs were significantly higher in the industrial areas compared to controls. Adjusting for potential confounders, children who lived in area A had a significantly higher risk of being absent from school due to sore throat, cough, and cold compared to controls. o-Xylene, which is dispersed during the industrial activity, showed clear evidence of a significant association with respiratory symptoms.

The simultaneous aerobic removal of a mixture of benzene, toluene, ethylbenzene, and o,m,p-xylene (BTEX); cis-dichloroethylene (cis-DCE); and trichloroethylene (TCE) from the artificially contaminated water using an indigenous bacterial isolate identified as Pseudomonas plecoglossicida immobilized on waste scrap tyres was investigated. Suspended and immobilized conditions were compared for the removal of these volatile organic compounds. For the immobilized system, toluene, benzene, and ethylbenzene were completely removed, while the highest removal efficiencies of 99.0 ± 0.1, 96.8 ± 0.3, 73.6 ± 2.5, and 61.6 ± 0.9% were obtained for o-xylene, m,p-xylene, TCE, and cis-DCE, respectively. The sorption kinetics of contaminants towards tyre surface was also evaluated, and the sorption capacity generally followed the order of toluene > benzene > m,p-xylene > o-xylene > ethylbenzene > TCE > cis-DCE. Scrap tyres showed a good capability for the simultaneous sorption and bioremoval of BTEX/cis-DCE/TCE mixture, implying a promising waste material for the removal of contaminant mixture from industrial wastewater or contaminated groundwater.

The present study focuses on the comparison of two materials, compost from municipal solid waste and natural zeolite for the simultaneous removal of petroleum hydrocarbons (benzene, toluene, ethylbenzene, xylenes - BTEX) and toxic metals from groundwater. First, batch experiments were conducted to identify the optimal removal conditions. All of the kinetic experiments were fitted to the pseudo-second-order kinetic model; equilibrium was reached within approximately 8 h for the zeolite and 12 h for the compost. An increase in the adsorbent dose and the pH value as well as a decrease in the initial concentration enhanced the pollutants' removal. The removal selectivity of both materials with slight differences follows the order Cd > Zn & toluene > ethylbenzene > m- & p-xylene > o-xylene > benzene. According, to the results derived from the continuous flow experiments the maximum adsorption capacity of the compost (90%) referred to Cd (0.88 mmol/g) whereas the minimum refers to benzene (65%) with a capacity up to 0.065 mmol/g. Zeolite had lower efficiencies for the studied pollutants with a higher performance corresponding to Cd (0.26 mmol/g), whereas the minimum zeolite capacity (63%) corresponds to toluene (0.045 mmol/g). Thus, this paper provides evidence that compost, a low cost material produced from waste, is capable for the simultaneous removal of both organic and inorganic pollutants from wastewater, and its performance is superior to zeolite., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

A new and simple method for benzene, toluene, ethylbenzene and o-xylene (BTEX) quantification in vehicle exhaust was developed based on diffusion-controlled extraction onto a retracted solid-phase microextraction (SPME) fiber coating. The rationale was to develop a method based on existing and proven SPME technology that is feasible for field adaptation in developing countries. Passive sampling with SPME fiber retracted into the needle extracted nearly two orders of magnitude less mass (n) compared with exposed fiber (outside of needle) and sampling was in a time weighted-averaging (TWA) mode. Both the sampling time (t) and fiber retraction depth (Z) were adjusted to quantify a wider range of Cgas. Extraction and quantification is conducted in a non-equilibrium mode. Effects of Cgas, t, Z and T were tested. In addition, contribution of n extracted by metallic surfaces of needle assembly without SPME coating was studied. Effects of sample storage time on n loss was studied. Retracted TWA-SPME extractions followed the theoretical model. Extracted n of BTEX was proportional to Cgas, t, Dg, T and inversely proportional to Z. Method detection limits were 1.8, 2.7, 2.1 and 5.2 mg m(-3) (0.51, 0.83, 0.66 and 1.62 ppm) for BTEX, respectively. The contribution of extraction onto metallic surfaces was reproducible and influenced by Cgas and t and less so by T and by the Z. The new method was applied to measure BTEX in the exhaust gas of a Ford Crown Victoria 1995 and compared with a whole gas and direct injection method., (Copyright © 2015 Elsevier B.V. All rights reserved.)

The paper presents the results of a two-stage pilot plant for the removal of benzene, toluene, ethylbenzene and xylene (BTEX) from a waste air stream of a refinery wastewater treatment plant (WWTP). The pilot plant consisted of a water scrubber followed by a biotrickling filter (BTF). The exhausted air was drawn from the main works of the WWTP in order to prevent the free migration to the atmosphere of these volatile hazardous contaminants. Concentrations were detected at average values of 12.4 mg Nm(-3) for benzene, 11.1 mg Nm(-3) for toluene, 2.7 mg Nm(-3) for ethylbenzene and 9.5 mg Nm(-3) for xylene, with considerable fluctuation mainly for benzene and toluene (peak concentrations of 56.8 and 55.0 mg Nm(-3), respectively). The two treatment stages proved to play an effective complementary task: the water scrubber demonstrated the ability to remove the concentration peaks, whereas the BTF was effective as a polishing stage. The overall average removal efficiency achieved was 94.8% while the scrubber and BTF elimination capacity were 37.8 and 15.6 g BTEX d(-1) m(-3), respectively. This result has led to outlet average concentrations of 1.02, 0.25, 0.32 and 0.26 mg Nm(-3) for benzene, toluene, ethylbenzene and xylene, respectively. The paper also compares these final concentrations with toxic and odour threshold concentrations.

Isobutanol is being considered as a fuel additive; however, the effect of this chemical on gasoline degradation (following a spill) has yet to be fully explored. To address this, the current study investigated the effect of isobutanol on benzene, toluene, ethylbenzene and p-xylene (BTEX) degradation in 14 sets of experiments in saturated soils. This involved four hydrocarbons for three soils (12 experiments) and two extra experiments with a lower level of isobutanol (for toluene only). Each soil and hydrocarbon combination involved four abiotic control microcosms and 12 sample microcosms (six with and six without isobutanol). The time for complete degradation of each hydrocarbon varied between treatments. Both toluene and ethylbenzene were rapidly degraded (5-13 days for toluene and 3-13 days for ethylbenzene). In contrast, the time for complete degradation for benzene ranged from 5 to 47 days. The hydrocarbon p-xylene was the most recalcitrant chemical (time for removal ranged from 14 to 86 days) and, in several microcosms, no p-xylene degradation was observed. The effect of isobutanol on hydrocarbon degradation was determined by comparing degradation lag times with and without isobutanol addition. From the 14 treatments, isobutanol only affected degradation lag times in three cases. In two cases (benzene and p-xylene), an enhancement of degradation (reduced lag times) was observed in the presence of isobutanol. In contrast, toluene degradation in one soil was inhibited (increased lag time). These results indicate that co-contamination with isobutanol should not inhibit aerobic BTEX degradation rates.

In this study, multi-walled carbon nanotubes (MWNTs) were employed to remove benzene, toluene, ethylbenzene, and xylenes (BTEX) from low and high salinity water pre-equilibrated with crude oil. The treatment endpoint of crude oil-contaminated water is often controlled by BTEX compounds owing to their higher aqueous solubility and human-health toxicity compared to other hydrocarbons. The MWNT sorbent was extensively characterized and the depletion of the organic sorbate from the produced water was monitored by gas chromatography-mass spectrometry (GC-MS) and total organic carbon (TOC) analyses. The equilibrium sorptive removal of BTEX followed the order: ethylbenzene/o-xylene > m-xylene > toluene > benzene in the presence of other competing organics in produced water. Sorption mechanisms were explored through the application of a variety of kinetics and equilibrium models. Pseudo 2(nd) order kinetics and Freundlich equilibrium models were the best at describing BTEX removal from produced water. Hydrophobic interactions between the MWNTs and BTEX, as well as the physical characteristics of the sorbate molecules, were regarded as primary factors responsible for regulating competitive adsorption. Salinity played a critical role in limiting sorptive removal, with BTEX and total organic carbon (TOC) removal falling by 27% and 25%, respectively, upon the introduction of saline conditions. Results suggest that MWNTs are effective in removing risk-driving BTEX compounds from low-salinity oilfield produced water.

This paper describes a new extraction technique with needles and a sorbent based on carbon nanotubes to analyze trace amounts of three isomers of xylenes in aqueous samples. In this research, results have been compared with one commercial sorbent. The synthesized sorbent was prepared using sol-gel technology and was packed into 20 gauge needles, and the same size needle was used for packing the commercial sorbent. In the extraction process, a purge and trap sampling methodology is developed, so purging and trapping cycles were performed by a sampling pump. Optimized conditions for standard xylene samples have been obtained, and eight urine samples from workers that were exposed to xylene in the workplace were collected and analyzed. Experimental parameters such as limits of detection and quantification were investigated, and these two parameters were <1 μg/L., (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

This study is dedicated to the investigation of the potential of volatile organic compounds (VOC) adsorption over low cost natural minerals (bentonite and diatomite). The performances of these solids, in terms of adsorption/desorption properties, were compared to commercial adsorbents, such as silica, alumina and titanium dioxide. The solids were first characterized by different physico-chemical methods and di-methyl benzene (dMB) was selected as model VOC pollutant for the investigation of adsorptive characteristics. The experiments were carried out with a fixed bed reactor under dynamic conditions using Fourier Transform InfraRed spectrometer to measure the evolution of dMB concentrations in the gaseous stream at the outlet of the reactor. The measured breakthrough curves yields to adsorbed amounts at saturation that has been used to obtain adsorption isotherms. The latters were used for determination of the heat involved in the adsorption process and estimation of its values using the isosteric method. Furthermore, the performances of the studied materials were compared considering the adsorption efficiency/cost ratio., (Copyright © 2013 Elsevier B.V. All rights reserved.)

In this study, performance evaluation for the gas-phase o-xylene removal using a xylene-acclimated biotrickling filter (BTF) was conducted. Substrate interactions during aerobic biodegradation of three poorly soluble compounds, both individually and in paired mixtures (namely, o-xylene and ethyl acetate, o-xylene and dichloromethane, which are common solvents used by pharmaceutical industry), were also investigated. Experimental results indicate that a maximum elimination capacity of 99.3 g x m(-3) x h(-1) (70% removal) was obtained at an o-xylene loading rate of 143.0 g x m(-3) x h(-1), while the top packing layer (one-third height of the three packing layers) only contributed about 13% to the total elimination capacity. Kinetic constants for o-xylene biodegradation and the pattern of o-xylene removal performance along the height of the BTF were obtained through the modified Michaelis-Menten kinetics and convection-diffusion reaction model, respectively. A reduction of removal efficiency in o-xylene (83.2-74.5% removal at a loading rate of 40.3 g x m(-3) x h(-1) for the total volatile organic compound (VOC) loading rate of 79 g x m(-3) x h(-1)) in the presence of ethyl acetate (100% removal) was observed, while enhanced o-xylene removal efficiency (71.6-78.6% removal at a loading rate of 45.1 g x m(-3) x h(-1) for the total VOC loading rate of 90 g x m(-3) x h(-1)) was achieved in the presence of dichloromethane (35.6% removal). This work shows that a BTF with xylene-acclimated microbial consortia has the ability to remove several poorly soluble compounds, which would advance the knowledge on the treatment of pharmaceutical VOC emissions.

In the present work, a laboratory scale corn-cob based biofilter inoculated with Bacillus sphaericus (MTCC 8103) was used for degradation of BTEX for a period of 86 days. The overall performance of a biofilter evaluated in terms of its elimination capacity by using 3-D mesh technique. Maximum removal efficiency was found more than 96.43% for all four compounds in each phase of experiments. A maximum elimination capacity (EC) of 60.89 gm(-3)h(-1) of the biofilter was obtained at inlet BTEX load of 63.14 gm(-3)h(-1). The follow-up of carbon dioxide concentration profile through the biofilter revealed that the mass ratio of carbon dioxide produced to the BTEX removed was approximately 2.2, which confirms complete degradation of BTEX. Moreover, BTEX concentration profile along the biofilter depth bed also determined by convection-diffusion reactor (CDR) model., (Copyright © 2013 Elsevier Ltd. All rights reserved.)

The pre-acclimated microbial consortium and the activated sludge were used as start inoculums of a bench-scale biotrickling filter (BTF). The performance of the biotrickling filter on the removal of BTEX mixture was evaluated, and the changes in the bacterial community structure of the BTF were analyzed by PCR-DGGE technique. The results showed that the BTF could be acclimated within a short time, the biomass that adhered to the surface of packing materials increased rapidly from 5.7 mg x g(-1) at 10th day to 112 mg x g(-1) at 30th day. BTF could simultaneously remove all components of the BTEX mixture efficiently. The maximum removal capacity of the BTF was 216.6 g x (m3 x h)(-1), which was achieved with an inlet loading rate of 269.7 g x (m3 x h)(-1) and an empty bed retention time (EBRT) of 39 s. DGGE analysis indicated that the dominant microorganisms may be derived from the pre-acclimated microbial consortiums rather than the activated sludge. Although the bacterial community changed with run time, the spatial distribution was very uniform.

Two new prenylated para-xylenes, named caulerprenylols A (1) and B (2), were isolated from the green alga Caulerpa racemosa, collected from the Zhanjiang coastline, China. The structures of the two metabolites were elucidated on the basis of detailed spectroscopic analysis. This is the first report of prenylated para-xylenes from marine algae and from marine organisms as well. Moreover, caulerprenylol B (2) is also characterized by an uncommon indane ring system. In in vitro bioassays, the new compounds exhibited a broad spectrum of antifungal activity against Candida glabrata (537), Trichophyton rubrum (Cmccftla), and Cryptococcus neoformans (32609) with MIC80 values between 4 and 64 μg/mL when compared to amphotericin B (MIC80 values of 2.0, 1.0, and 4.0 μg/mL, respectively) as a positive control and showed no growth inhibition activity against the tumor cells HL60 and A549., (Copyright © 2013 Elsevier Ltd. All rights reserved.)

In this work the development and validation of a new procedure for the simultaneous determination of 9 nitro and polycyclic musk compounds: musk ambrette (MA), musk ketone (MK), musk mosken (MM), celestolide (ADBI), phantolide (AHMI), tonalide (AHTN), traseolide (ATII), cashmeran (DPMI) and galaxolide (HHCB) in environmental water samples (estuarine and wastewater) using microextraction by packed sorbent (MEPS) followed by large volume injection-gas chromatography-mass spectrometry (LVI-GC-MS) was carried out. Apart from the optimization of the different variables affecting MEPS (i.e., nature of the sorbent, nature of the solvent elution, sample load, and elution/injection volume) extraction recovery was also evaluated, not only for water samples but also for environmental water matrices such as estuarine and waste water. The use of two deuterated analogs ([(2)H3]-AHTN and [(2)H15]-MX) was successfully evaluated in order to correct matrix effect in complex environmental matrices such as influent samples from wastewater treatment plants. Method detection limits (MDLs) ranged from 5 to 25 ng L(-1), 7 to 39 ng L(-1) and 8 to 84 ng L(-1) for influent, effluent and estuarine samples, respectively. Apparent recoveries were higher than 75% for all target compounds in all the matrices studied (estuarine water and wastewater) and the precision of the method, calculated as relative standard deviation (RSD), was below 13.2% at 200 ng L(-1) concentration level and below 14.9% at low level (20 ng L(-1) for all the target analytes, except for AHTN which was set at 40 ng L(-1) and HHCB at 90 ng L(-1), due to the higher MDL values presented by those target compounds). Finally, this MEPS procedure was applied to the determination of the target analytes in water samples, including estuarine and wastewater, from two estuaries, Urdaibai (Spain) and Adour (France) and an established stir-bar sorptive extraction-liquid desorption/large volume injection-gas chromatography-mass spectrometry (SBSE-LD/LVI-GC-MS) method was performed in parallel for comparison. Results were in good agreement for all the analytes determined, except for DPMI., (Copyright © 2013 Elsevier B.V. All rights reserved.)

Biofiltration of BTEX with corn-cob packing material have been performed for a period of 68 days in five distinct phases. The overall performance of a biofilter has been evaluated in terms of its elimination capacity by using 3-D mesh techniques. Maximum removal efficiency was found more than 99.85% of all four compounds at an EBRT of 3.06 min in phase I for an inlet BTEX concentration of 0.0970, 0.0978, 0.0971 and 0.0968 g m(-3), respectively. Nearly 100% removal achieved at average BTEX loadings of 20.257 g m(-3) h(-1) to biofilter. A maximum elimination capacity (EC) of 20.239 g m(-3) h(-1) of the biofilter was obtained at inlet BTEX load of 20.391 g m(-3) h(-1). Moreover, using convection-diffusion reaction (CDR) model for biofilter depth shows good agreement with the experimental values for benzene, toluene and ethyl benzene, but for o-xylene the model results deviated from the experimental., (Copyright © 2013 Elsevier Ltd. All rights reserved.)

A novel rotating biological contactor (RBC) bioreactor immobilized with microorganisms was designed to remove volatile organic compounds (VOC), such as benzene and xylene from emissions, and its performance was investigated. Gas-phase VOCs stripped by air injection were 98 % removed in the RBC when the superficial air flow rate was 375 ml/h (1,193 and 1,226 mg/l of benzene and xylene, respectively). The maximum removal rate was observed to be 1,007 and 1,872 mg/m(3)/day for benzene and xylene, respectively. The concentration profile of benzene and xylene along the RBC was dependent on the air flow rate and the degree of microbial adaptation. Air flow rate and residence time were found to be the most important operational parameters for the RBC reactor. By manipulating these operational parameters, the removal efficiency and capacity of the bioreactor could be enhanced. The kinetic constant K (s) demonstrated a linear relationship that indicated the maximum removal of benzene and xylene in RBC reactor. The phylogenic profile shows the presence of bacterium like Pseudomonas sp., Bacillus sp., and Enterococcus sp., which belonged to the phylum Firmicutes, and Proteobacteria that were responsible for the 98 % organic removal in the RBC.

A novel dielectric barrier discharge (DBD) reactor was made for the abatement of xylene. This reactor has a photocatalytic electrode prepared by a modified anodic oxidation method which was proposed in this work. The photocatalytic electrode has nano-TiO(2) deposited on sintered metal fiber (SMF). The reactor using the nano-TiO(2)/SMF electrode shows much better performance in abating xylene compared with reactors using other electrodes such as resistance wire or SMF. The conversion ratio of xylene reaches 92.7% in the novel reactor at a relatively voltage (23.6 kV). This ratio is much higher than the conversion ratios of xylene in the traditional reactors with resistance wire or SMF electrodes, which are ~64.7%. The selectivity of CO(2) of the reactor using the nano-TiO(2)/SMF electrode (300 pps, 23.6 kV) was observed to be 86.6%, which is about twice as large as that of a traditional reactor using a resistance wire electrode. If a traditional DBD reactor is replaced by the novel reactor, at the same specific input energy, the energy yield can increase from 0.391 to 0.556 mg/kJ. Finally, the xylene decomposition mechanism with the nano-TiO(2)/SMF electrode was also briefly discussed., (Copyright © 2012 Elsevier B.V. All rights reserved.)

The effect of relative humidity (RH: 30% to >95%) of a gas-phase mixture composed of benzene, toluene, ethylbenzene and para-, meta- and ortho-xylenes (BTEX), inlet concentrations (0.2-12.6 g m(-3)), and empty bed residence times (EBRTs) (48-144 s) was tested in a fungi-dominant biofilter. A maximum elimination capacity (EC(max)) of 244.2 gBTEX m(-3) h(-1) was achieved at a total inlet loading rate (ILR(T)) of 371.2 gBTEXm(-3) h(-1) (RH: 65%). The transient-state response was tested by increasing the ILR(T), in two steps, from ~50 to 850 gm(-3) h(-1) and from ~50 to 320 g m(-3) h(-1), at a constant EBRT of 41.7s. Increasing the ILR(T) reduced the total BTEX removal efficiency (RE(T)) from >97% to 35%, and from >90% to 60% during medium and high shock-load, respectively. When subjected to short (4d) and long-term (7d) shut-down periods, the biofilter was able to recover high EC(max) of, respectively, 200 and 72 gBTEX m(-)3 h(-1) after resuming operation., (Copyright © 2012 Elsevier Ltd. All rights reserved.)

The defensive secretion of the ground beetle Chlaenius cordicollis is predominantly 3-methylphenol. Adult C. cordicollis were collected in Pennsylvania and Manitoba and induced to discharge defensive secretion in a vial. The headspace was sampled by solid phase microextraction, and samples were analyzed by gas chromatography-mass spectrometry. Five alkylphenolic compounds were detected: all beetles secreted 3-methlyphenol, 2,5-dimethylphenol, and 3-ethylphenol, and most beetles from each locality secreted detectable amounts of 2,3-dimethlyphenol and 3,4-dimethylphenol. In about 80% of beetles, we detected small amounts of the alkoxyphenolic compounds 2-methoxy-4-methylphenol and 2-methoxy-5-methylphenol. Multivariate compositional analysis of relative peak areas of alkylphenolic compounds revealed geographic variation and sexual dimorphism in defensive secretions. Compared with samples from Manitoba, relative peak areas of samples from Pennsylvania were lower for 2,3-dimethylphenol and higher for 3-methylphenol. Sexual dimorphism was detected only in Manitoba where, compared with samples from males, relative peak areas for samples from females were higher for 2,5-dimethylphenol and lower for 3-ethylphenol. This is the first report of geographic variation in defensive secretions of carabid beetles, and it demonstrates the need for knowledge of patterns of variation before characterizing the defensive secretions of a species as a whole.

ZnO nanorod array coating is a novel kind of solid-phase microextraction (SPME) fiber coating which shows good extraction capability due to the nanostructure. To prepare the composite coating is a good way to improve the extraction capability. In this paper, the ZnO nanorod array polydimethylsiloxane (PDMS) composite SPME fiber coating has been prepared and its extraction capability for volatile organic compounds (VOCs) has been studied by headspace sampling the typical volatile mixed standard solution of benzene, toluene, ethylbenzene and xylene (BTEX). Improved detection limit and good linear ranges have been achieved for this composite SPME fiber coating. Also, it is found that the composite SPME fiber coating shows good extraction selectivity to the VOCs with alkane radicals.

Metal-organic framework MIL-53(Al) was explored as the stationary phase for high-performance liquid chromatographic separation of position isomers using a binary and/or polar mobile phase. Baseline separations of xylene, dichlorobenzene, chlorotoluene and nitrophenol isomers were achieved on the slurry-packed MIL-53(Al) column with high resolution and good precision. The effects of mobile phase composition, injected sample mass and temperature were investigated. The separation of xylene, dichlorobenzene, chlorotoluene and nitrophenol isomers on MIL-53(Al) were controlled by entropy change., (This journal is © The Royal Society of Chemistry 2012)

Two new secondary metabolites, named 7-dehydroxyl-zinniol (1) and 20-hydroxyl-ergosta-4,6,8(14),22-tetraen-3-one (2), were isolated from the culture of Alternaria solani, an endophytic fungal strain residing in the roots of Aconitum transsectum. Their structures were elucidated on the basis of comprehensive spectroscopic analyses including IR, ESI-MS, HR-ESI-MS, 1D and 2D NMR. Biological activity tests indicated that compound 1 showed moderate anti-HBV activity.

In wastewater treatment facilities, air quality is not only affected by conventional unpleasant odour compounds; toxic volatile organic compounds (VOCs) are also found. In this study, the adsorptive capacity of Chilean natural zeolite toward VOC removal was evaluated. Moreover, the influence of zeolite chemical surface properties on VOC elimination was also investigated. Three modified zeolite samples were prepared from a natural Chilean zeolite (53% clinoptilolite, 40% mordenite and 7% quartz). Natural and modified zeolite samples were characterised by nitrogen adsorption at 77 K, elemental analyses and X-ray fluorescence (XRF). Chemical modifications of natural zeolite showed the important role of Brønsted acid sites on the abatement of VOCs. The presence of humidity has a negative effect on zeolite adsorption capacity. Natural zeolites could be an interesting option for benzene, toluene and xylene vapour emission abatement.

This report compares the performance of polymer and carbon nanotube-polymer composite membranes on a quartz crystal microbalance (QCM) sensor for the detection of aromatic hydrocarbons (benzene, toluene, ethylbenzene, p-xylene and naphthalene) in aqueous solutions. Several different polymers (polystyrene, polystyrene-co-butadiene, polyisobutylene and polybutadiene) and types of functionalized carbon nanotubes (multi-walled and single-walled carbon nanotubes) were investigated at varying carbon nanotube (CNT) loading levels and film thicknesses. In a majority of instances, the difference in response between membranes comprising pure polymer and membranes containing 10% (w/w) carbon nanotubes were not statistically significant. However, a notable exception is the decreasing sensitivity towards p-xylene with increasing carbon nanotube content in a polybutadiene film. This variation in sensitivity can be attributed to a change in the sorption mechanism from absorption into the polymer phase to adsorption onto the carbon nanotube sidewalls. With much thicker coatings of 10% (w/w) carbon nanotube in polybutadiene, the sensitivity towards toluene was higher compared to the pure polymer. The increased toluene sensitivity may be partially attributed to an increase in the sorption capacity of a carbon nanotube polymer composite film relative to its corresponding pure polymer film. Attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) measurements were performed to understand the mechanism of sorption and these studies showed that the addition of functionalized CNT to the polymer increases the absorption of certain types of hydrocarbons. This study demonstrates that carbon nanotubes can be incorporated into a polymer-coated QCM sensor and that composite films may be used to modify the QCM response and selectivity during the analysis of complex hydrocarbon mixtures., (Crown Copyright © 2011. Published by Elsevier B.V. All rights reserved.)

The diverse structures and pore topologies, accessible cages and tunnels, and high surface areas make metal-organic frameworks attractive as novel media in separation sciences. Here we report the slurry-packed MIL-101(Cr) column for high-performance liquid chromatographic separation of substituted aromatics. The MIL-101(Cr) packed column (5 cm long × 4.6 mm i.d.) offered high-resolution separation of ethylbenzene (EB) and xylene, dichlorobenzene and chlorotoluene isomers, and EB and styrene. The typical impurities of toluene and o-xylene in EB and styrene mixtures were also efficiently separated on the MIL-101(Cr) packed column. The column efficiencies for EB, m-dichlorobenzene, and m-chlorotoluene are 20000, 13000, and 10000 plates m(-1), respectively. The relative standard deviation for five replicate separations of the substituted aromatics was 0.2-0.7%, 0.9-2.9%, 0.5-2.1%, and 0.6-2.7% for the retention time, peak area, peak height, and half peak width, respectively. The MIL-101(Cr) offered high affinity for the ortho-isomer, allowing fast and selective separation of the ortho-isomer from the other isomers within 3 min using dichloromethane as the mobile phase. The effects of the mobile phase composition, injected sample mass, and temperature were investigated. The separation of xylene, dichlorobenzene, and chlorotoluene on MIL-101(Cr) was controlled by entropy change, while the separation of EB and styrene on MIL-101(Cr) was governed by enthalpy change.

This study is to apply ultrasound to remove m-xylene, a volatile compound from aqueous solutions which causes environmental damage. High frequency ultrasound was used to investigate the effect of different operational parameters, such as m-xylene initial concentration, ultrasonic frequency and ultrasonic power. The degradation rate of m-xylene was increased with decreasing initial concentration of m-xylene and increasing frequency and power. Optimal conditions include 26.07 mg/L, 806.3 kHz and 70±1 W, in which MnO(2), Cu(2+), Fe(2+), and H(2)O(2) had little or no effect on the degradation. Moreover, the effect of radical scavengers such as Na(2)CO(3) and t-butyl was not obvious, which indicates that direct pyrolysis inside the collapsing bubbles has an important role in m-xylene ultrasonic removal. In addition, the degradation of m-xylene was observed to behave under pseudo-first-order kinetics with different experimental conditions tested in the present work., (Copyright © 2011 Elsevier B.V. All rights reserved.)

Interactions of toluene and p-xylene in air treatment biofilters packed with an inert filter media were studied. The effect of the inlet load of toluene, p-xylene and mixtures of both compounds on the biodegradation rate was analyzed in three lab-scale biofilters. A maximum elimination capacity (EC) of 26.5 and 40.3 gCm(-3)h(-1) for an inlet load (IL) of 65.6 and 57.8 gCm(-3)h(-1) was obtained for p-xylene and toluene biofilters, respectively. Inhibition of p-xylene biodegradation by the presence of toluene took place when the mixture was treated, whereas the presence of p-xylene had an enhancing effect on the toluene removal efficiency. Specific growth rates (μ) from 0.019 to 0.068 h(-1) were calculated in the mixed biofilter, where the highest values were similar to mixtures with lower p-xylene levels (IL(p-Xyl) 8.84 ± 0.29 gCm(-3)h(-1)). Michaelis-Menten and Haldane type models were fitted to experimental EC for p-xylene and toluene biofilters, respectively., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

In this study, poly(ethylene glycol) (PEG) grafted onto multi-walled carbon nanotubes (PEG-g-MWCNTs) were synthesized by the covalent functionalization of MWCNTs with hydroxyl-terminated PEG chains. For the first time, functionalized product of PEG-g-MWCNTs was used as selective stationary phase to prepare the sol-gel solid-phase microextraction (SPME) fiber in combination with gas chromatography-flame ionization detector (GC-FID) for the determination of ultra-trace levels of benzene, toluene, ethylbenzene and o-xylene (BTEX) in real water samples. The PEG-g-MWCNTs were characterized by Fourier transform infrared spectra and also thermo-gravimetric analysis, which verified that PEG chains were grafted onto the surface of the MWCNTs. The scanning electron micrographs of the fiber surface revealed a highly porous structure which greatly increases the surface area for PEG-g-MWCNTs sol-gel coating. This fiber demonstrated many inherent advantages, the main being the strong anchoring of the coating to the fused silica resulting from chemical bonding with the silanol groups on the fused-silica fiber surface. The new PEG-g-MWCNTs sol-gel fiber is simple to prepare, robust, with high thermal stability and long lifetime, up to 200 extractions. Important parameters influencing the extraction efficiency such as desorption temperature and time, extraction temperature, extraction time, stirring speed and salt effect were investigated and optimized. Under the optimal conditions, the method detection limits (S/N=3) were in the range of 0.6-3 pg mL(-1) and the limits of quantification (S/N=10) between 2 and 10 pg mL(-1). The relative standard deviations (RSDs) for one fiber (repeatability) (n=5) were obtained from 4.40 up to 5.75% and between fibers or batch to batch (n=3) (reproducibility) in the range of 4.31-6.55%. The developed method was successfully applied to real water samples while the relative recovery percentages obtained for the spiked water samples at 20 pg mL(-1) were from 90.21 to 101.90%., (Copyright © 2011 Elsevier B.V. All rights reserved.)

An industrial coating site in activity located on a chalky plateau, contaminated by BTEX (mainly xylenes, no benzene), is currently remediated by in situ chemical oxidation (ISCO). We present the bench scale study that was conducted to select the most appropriate oxidant. Ozone and catalyzed hydrogen peroxide (Fenton's reaction) were discarded since they were incompatible with plant activity. Permanganate, activated percarbonate and activated persulfate were tested. Batch experiments were run with groundwater and groundwater-chalk slurries with these three oxidants. Total BTEX degradation in groundwater was reached with all the oxidants. The molar ratios [oxidant]:[Fe(2+)]:[BTEX] were 100:0:1 with permanganate, 100:100:1 with persulfate and 25:100:1 with percarbonate. Precipitation of either manganese dioxide or iron carbonate (siderite) occurred. The best results with chalk slurries were obtained with permanganate at the molar ratio 110:0:1 and activated persulfate at the molar ratio 110:110:1. To avoid precipitation, persulfate was also used without activation at the molar ratio 140:1. Natural Oxidant Demand measured with both oxidants was lower than 5% of initial oxidant contents. Activated percarbonate was not appropriate because of radical scavenging by carbonated media. Permanganate and persulfate were both effective at oxidant concentrations of ca 1 g kg(-1) with permanganate and 1.8 g kg(-1) with persulfate and adapted to site conditions. Activation of persulfate was not mandatory. This bench scale study proved that ISCO remediation of a chalky aquifer contaminated by mainly xylenes was possible with permanganate and activated or unactivated persulfate., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

A molecularly imprinted polymer (MIP) was synthesized using toluene as template, and was implemented in a fluorescence optosensor (λ(exc)=260 nm, λ(em)=284 nm) for the screening of TEXs (toluene, ethylbenzene and xylenes) in drinking water. All the parameters which can affect the sensitivity and selectivity of the optical sensing phase, were carefully optimized. The screening test runs without the need for any pre-concentration step, thus rendering it suitable for routine use in water-quality-control laboratories. The test recognizes contaminated samples rapidly (81 s) and inexpensively with a cut-off level of 700 μg L(-1) ethylbenzene which corresponds with the maximum contaminant level (MCL) established by US Environmental Protection Agency (EPA) in drinking water. The threshold value of the screening test for the cut-off level was 8.27±0.57 a.u. (95% confidence level, n=10). The reliability of the screening test was 32% false positives and 0% false negatives for 50 samples, and its applicability has been demonstrated by analyzing 15 samples of mineral, tap and river waters obtaining 0% false negatives., (Copyright © 2011 Elsevier B.V. All rights reserved.)

The performance of a polyurethane (PU) biofilter was evaluated using different operating modes (unidirectional flow (UF) and flow-directional switching (FDS) operations) under transient loading conditions (intermittent and shutdown). Gas mixtures containing benzene, toluene and xylene (BTX) were employed as model gases. Quantitative real-time PCR methods were used for targeting the tmoA gene responsible for BTX degradation and estimating density of the BTX-degraders in the PU filter bed. Although the overall BTX Removal efficiencies at the outlet (50 h(-1) of space velocity) were similar between the UF and FDS biofilters, the removability of BTX in the FDS biofilter was higher than that in the UF biofilter until the 3rd sampling position (68 h(-1) of space velocity). The BTX removal potentials and tmoA gene copy numbers of the FDS biofilter remained constant, irrespective of the distances from the inlet, but those of the UF biofilter increased with increasing distance from the inlet position. These results indicate that an even distribution of BTX degraders in the FDS filter bed contributed to better BTX removal performance. After a 10 day-shutdown, the performances of the UF and SDF biofilters were rapidly restored within 1 day.

Microbes bound to a wheat bran/red wood powder/diatomaceous earth carrier were used as inoculants for a biotrickling filter (BTF) for treating gases contaminated with a mixture of benzene, toluene, and o-xylene (BTo-X). An overall removal efficiency of more than 87.9% was achieved after a start-up period of as low as 4days. At BTo-X loading rates (LRs) below 60.0g/m(3)h, the BTF's performance was similar for EBRTs of 90, 60, 45 and 30s with an elimination capacity (EC) almost approaching the LR; stable REs above 91.3% for benzene and toluene and above 82.8% for o-xylene were achieved. A maximum EC of 97.7g/m(3)h was obtained at inlet load of 146.4g/m(3)h. The mass ratio of carbon dioxide produced to the BTo-X removed was approximately 2.62, which confirmed complete degradation of BTo-X. The results demonstrate that microbes bound to a solid carrier can be an alternative to traditional liquid inoculums applied in BTFs and highlight their potential applicability to BTF technologies., (Copyright 2010 Elsevier Ltd. All rights reserved.)