Extraction Of Chlorobenzenes Research Articles

Lotus-like Ni@NiO nanoparticles embedded porous carbon derived from MOF-74/cellulose nanocrystal hybrids as solid phase microextraction coating for ultrasensitive determination of chlorobenzenes from water

Lotus-like Ni@NiO embedded porous carbons (Ni@NiO/PCs) were fabricated by pyrolysis of MOF-74/cellulose nanocrystal hybrids, and used as a solid phase microextraction (SPME) coating for ultrasensitive determination of chlorobenzenes (CBs) from water combined with gas chromatography-mass spectrometry. Owing to its abundant chemical groups, high porosity, and excellent thermal stability, the as-prepared Ni@NiO/PCs presented superior extraction performance compared to commercial SPME coatings. Notably, Ni@NiO/PCs derived from MOF-74/CNC hybrids presented higher extraction efficiencies towards CBs than that derived from pristine CNC and MOF-74 due to the formation of micro/mesopores and more abundant oxygen-containing groups. Under the optimum extraction conditions, the proposed analytical method presented wide linearity range (0.5–1500 ng L−1), ultra-low detection of limit (0.005–0.049 ng L−1), and excellent precision with relative standard deviations of 4.7–9.2% for a single fiber and 8.8–10.9% for 5 fibers, and long lifetime (≥160 times). The proposed analytical method was finally applied for determination of CBs from real water samples, and the recoveries were in the range of 93.2–116.8% towards eight CBs. This study delivered a novel and efficient sorbent as SPME coating to extraction and determination of CBs from water.

Extraction of Chlorobenzenes and PCBs from Water by ZnO Nanoparticles

Metal oxide nanoparticles have great potential for selective adsorption and catalytic degradation of contaminants from aqueous solutions. In this study, we employ mass spectrometry and molecular dynamics simulations to better understand the chemical and physical mechanisms determining the affinity of chlorobenzenes and polychlorinated biphenyls (PCBs) for zinc oxide nanoparticles (ZnO NPs). The experiments and simulations both demonstrate that the adsorption coefficients for chlorobenzenes increase steadily with the number of chlorine atoms, while, for PCBs, the relation is more complex. The simulations link this complexity to chlorine atoms at ortho positions hindering coplanar conformations. For a given number of chlorine atoms, the simulations predict decreasing adsorption affinity with increasing numbers of ortho substitutions. Consequently, the simulations predict that some of the highest adsorption affinities for ZnO NPs are exhibited by dioxin-like PCBs, suggesting the possibility of selective sequestration of these most acutely toxic PCBs. Remarkably, the experiments show that the PCB adsorption coefficients of ZnO NPs with diameters ≤ 80 nm exceed those of a soil sample by 5–7 orders of magnitude, meaning that a single gram of ZnO NPs could sequester low levels of PCB contamination from as much as a ton of soil.

Evaluation of prepared natural polymers in the extraction of chlorobenzenes from environmental samples: Sol–gel–based cellulose acetate-phenyltriethoxysilane fibers

In this research, three fibers including cellulose acetate (CA), CA–phenyltriethoxysilane (PTES) prepared via sol–gel electrospinning and sol–gel–based CA fibers immersed in PTES solution (dipped–CA–PTES) were prepared. The composition and morphology of the prepared fibers were evaluated by energy dispersive X-ray spectroscopy and field emission scanning electron microscopy. The prepared fibers were implemented in a home–made needle trap device, followed by thermal desorption of the selected chlorobenzenes (CBs) to a gas chromatography–flame ionization detector. Finally, parameters affecting the extraction methodology such as the amount of sorbent, extraction time and temperature, desorption time and temperature and the ionic strength were investigated. Among the fabricated extractive phases, the hybrid CA–PTES fibers exhibited higher extraction efficiency. Under the optimal condition, the limits of detection were lower than 0.42 μg L−1 and the relative standard deviations for intra– and inter–day precision for a single needle were in the range of 3–5% and 5–10%, respectively. In addition, the needle–to–needle reproducibility was from 9 to 12% (n = 3). Finally, the method was applied to the analysis of samples from river water, sediment and sludge samples. Relative recoveries were in the range of 94–105%.

Nanoporous silica aerogel modified by triethylchlorosilane as a new sorbent for the needle‐trap extraction

AbstractIn this work, nanoporous silica aerogel modified by triethylchlorosilane is used as a new sorbent for headspace needle‐trap extraction of chlorobenzenes from aqueous samples. The needle trap extraction is derived from solid‐phase microextraction, and the sorbent is in the inside a needle. The thermal stability and functional groups of the sorbent were studied by thermal gravimetric/differential thermal analyses and FTIR spectroscopy, respectively. The modified silica aerogel characterized by field‐emission scanning electron microscopy shows a 3D network containing homogeneous pore structure with pore sizes of a few tens of nm and a nanoporous structure. The influential parameters on the extraction efficiency, including the extraction temperature, ionic strength and extraction time, were optimized. Under optimized conditions, the detection limit and quantification limit were obtained in the range of 0.3–1 and 1–3 ng/L, respectively. The relative standard deviation values for water spiked with the chlorobenzenes at 100 ng/L under optimum conditions were 3–9%. The dynamic linear range of method was investigated in the range of 3–3000 ng/L. Finally, the current method for the analysis of real water samples containing spiked chlorobenzenes was applied and the relative recovery values were found to be in the range of 96–101%.

Wireless electrochemical preparation of gradient nanoclusters consisting of copper(II), stearic acid and montmorillonite on a copper wire for headspace in-tube microextraction of chlorobenzenes.

This work introduces a new gradient fiber coating for microextraction of chlorobenzenes. Nanoclusters of organoclay-Cu(II) on a copper wire were fabricated by wireless electrofunctionalization. The resultant gradient coatings are more robust, and thermally and mechanically stable. Wireless electrofunctionalization was carried out in a bipolar cell under a constant deposition potential and using an ethanolic electrolyte solution containing stearic acid and montmorillonite. Stearic acid acts as an inexpensive and green coating while montmorillonite acts as a modifier to impart thermal stability. The gradient morphology of the nanoclusters was investigated by scanning electron microscopy, thermogravimetric analysis and energy dispersive X-ray spectroscopy. The coated wire was placed in a hollow needle and used for headspace in-tube microextraction (HS-ITME) of chlorobenzenes (CBs). Effects of various parameters affecting synthesis and extraction were optimized. Following extraction, the needles were directly inserted into the GC injector, and the CBs (chlorobenzene, 1,4-dichlorobenzene, 1,2-dichlorobenzene, 1,2,4-trichlorobenzene, 1,2,3,4-tetrachlorobenzene) were quantified by GC-MS. The limits of detection under optimized conditions range from 0.5 to 10ng.L-1. The intra- and inter-day relative standard deviations (RSDs) (for n = 10, 5 respectively) using a single fiber are 6-10 and 10-15%, respectively. The fiber-to-fiber RSDs (for n = 3) is between 17 and 24%. The method was successfully applied to the extraction of CBs from real water samples, and relative recoveries are between 91 and 110%. Graphical abstract A gradient coating of organoclay-Cu nanoclusters was fabricated on a copper wire by wireless electrofunctionalization. The oxidation of copper takes place at the anodic pole (red) while dissolved oxygen in ethanol solution is reduced at the cathodic pole (blue).

Further investigation of array capillary in-tube solid-phase microextraction of trace organic pollutants in water samples

Array capillary in-tube solid-phase microextraction (ACIT-SPME) was demonstrated to be a fast, reproducible and convenient extraction method for trace organic pollutants in water samples. In order to improve the extraction efficiency per unit of extraction time, ACIT-SPME cartridges with capillary tubes of different inner diameters (I.D.), from 0.1 mm to 0.5 mm I.D., were fabricated and compared systematically for the extraction of chlorobenzenes (CBs) and nitrochlorobenzenes (NCBs). The results indicated that the ACIT-SPME cartridges with the largest bore diameter were more suitable for rapid extraction of analytes in abundant water samples, while the ACIT-SPME with the smallest bore diameter resulted in the highest absolute recovery. Thus, ACIT-SPME capillary tubes of 0.5 mm I.D. were applied in the rapid extraction of CBs and NCBs from environmental water. Parameters such as sample volume, extraction time, ionic strength, and thermal desorption conditions were investigated to obtain the optimal operation conditions. The extraction was completed in 1.5 min under gravity using 250 mL of water sample. The desorbed analytes were analyzed by gas chromatography (GC) coupled with electron capture detection (ECD). A linear relationship between the peak areas and the concentrations of the analytes covered 2 orders of magnitude with correlation coefficients higher than 0.9961 for all the compounds being studied. The detection limits were between 0.00041 and 0.047 μg L−1 with a relative standard deviation (RSD) of between 1.4% and 4.8%. The proposed method was applied in the extraction and determination of CBs and NCBs in real water samples. Relative recoveries and RSDs for the analysis of real water samples were 87.1–116% and 1.8–9.4%, respectively. These results further proved that ACIT-SPME could be applied as a routine sample preparation method for water analysis both in the field and in the lab .

Ultrasonic-assisted water extraction and solvent bar microextraction followed by gas chromatography–ion trap mass spectrometry for determination of chlorobenzenes in soil samples

A novel and simple analytical method for the determination of chlorobenzenes (CBs) in soil samples was developed using ultrasonic-assisted water extraction (UAWE) coupled with solvent bar microextraction (SBME). Four chlorobenzenes, 1,2,3-trichlorobenzene (1,2,3-TCB), 1,2,3,4-tetrachlorobenzene (1,2,3,4-TeCB), hexachlorobenzene (HCB), and 1-chloro-4-nitrobenzene (1-C-4-NB), were used as model compounds to investigate the extraction performance. Parameters affecting the extraction efficiency were investigated in detail. UAWE was used for the extraction of CBs from 1.0g of sediment using 10mL of ultrapure water at 100W for 30min at 30–35°C. The extract was subsequently subjected to a single step SBME cleanup and enrichment procedure. Both ends of the solvent bar with about 4μL of 1-octanol were sealed by a sealing machine, and it was placed in the soil slurry for extraction. After extraction, analysis was carried out by gas chromatography–ion trap mass spectrometry (GC–ITMS) detection. The relative recoveries from the spiked soil sample varied between 93 and 105% for CBs, and exceeded levels achieved for conventional Soxhlet extraction. The method linearities were 10–150, 40–600, and 100–1500ngg−1 for different CBs. The limits of detection (LODs) and the limits of quantification (LOQs) were in the range of 0.7–27.3ngg−1 and 2.2–90.9ngg−1, respectively. Good reproducibilities were obtained with relative standard deviation (RSD) values below 6.8%. The analytical potential of the method was demonstrated by applying the method to spiked soil sample.

Trace analysis of chlorobenzenes in water samples using headspace solvent microextraction and gas chromatography/electron capture detection

In the present work, a rapid method for the extraction and determination of chlorobenzenes (CBs) such as monochlorobenzene, 1,2-dichlorobenzene, 1,3-dichlorobenzene, 1,4-dichlorobenzene, 1,2,3-trichlorobenzene and 1,2,4-trichlorobenzene in water samples using the headspace solvent microextraction (HSME) and gas chromatography/electron capture detector (ECD) has been described. A microdrop of the dodecane containing monobromobenzene (internal standard) was used as extracting solvent in this investigation. The analytes were extracted by suspending a 2.5 μl extraction drop directly from the tip of a microsyringe fixed above an extraction vial with a septum in a way that the needle passed through the septum and the needle tip appeared above the surface of the solution. After the extraction was finished, the drop was retracted back into the needle and injected directly into a GC column. Optimization of experimental conditions such as nature of the extracting solvent, microdrop and sample temperatures, stirring rate, microdrop and sample volumes, the ionic strength and extraction time were investigated. The optimized conditions were as follows: dodecane as the extracting solvent, the extraction temperature, 45 °C; the sodium chloride concentration, 2 M; the extraction time, 5.0 min; the stirring rate, 500 rpm; the drop volume, 2.5 μl; the sample volume, 7 ml; the microsyringe needle temperature, 0.0 °C. The limit of detection (LOD) ranged from 0.1 μg/l (for 1,3-dichlorobenzene) to 3.0 μg/l (for 1,4-dichlorobenzene) and linear range of 0.5–3.0 μg/l for 1,2-dichlorobenzene, 1,3-dichlorobenzene and from 5.0 to 20.0 μg/l for monochlorobenzene and from 5.0 to 30 μg/l for 1,4-dichlorobenzene. The relative standard deviations (R.S.D.) for most of CBs at the 5 μg/l level were below 10%. The optimized procedure was successfully applied to the extraction and determination of CBs in different water samples.