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 10 ng.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).
A new dioxomolybdenum (VI) complex with tridentate hydrazone Schiff base ligand (H2L) derived from 2‐hydroxy‐5‐nitrobenzaldehyde and benzhydrazide was synthesized and designated as [MoO2L (DMF)]·2H2O. The Fe3O4@SiO2‐CPS‐L‐MoO2 (EtOH) nanocatalyst was successfully prepared by grafting H2L ligand on modified Fe3O4 nanoparticles followed by reacting with MoO2 (acac)2. The complex and nanocatalyst were characterized by various techniques such as elemental analysis, mass, FT‐IR, UV–Vis, 1H NMR, 13C{1H}‐NMR, TGA, XRD, XPS, TEM, SEM and VSM. The catalytic activity of [MoO2L (DMF)]2H2O and Fe3O4@SiO2‐CPS‐L‐MoO2 (EtOH) were evaluated for the oxidation of various alkenes (cyclooctene, norbornene, cyclohexene, styrene and α‐methyl styrene) in the presence of tert‐butylhydroperoxide as oxidant. The results revealed that the catalysts were especially efficient for oxidation of cyclooctene and norbornene with 100% selectivity towards corresponding epoxide product. Fe3O4@SiO2‐CPS‐L‐MoO2 (EtOH) showed higher catalytic activity, shorter reaction time and higher turnover number (TON) compared with homogeneous complex [MoO2L (DMF)]·2H2O. Moreover, simple magnetic recovery from the reaction mixture and reuse for several times with no significant loss in activity were other advantages of the nanocatalyst. 相似文献
Acoustical Physics - The results of the evaluation on the spatial and temporal changes of the underwater sound speed in the southern abyssal zone of the Caspian Sea are investigated. Experimental... 相似文献
The polar diagram of a set of points in a plane and its extracted dual EDPD were recently introduced for static and dynamic cases. In this paper, the near-pole polar diagram NPPD for a set of points is presented. This new diagram can be considered as a generalization of the polar diagram and has applications in several communication systems and robotics problems. After reviewing the NPPD of points, we solve the problem for a set of line segments and simple polygons in optimal time Θ(n log n), where n is the number of line segments or polygon vertices. We introduce duality for the NPPD of points and identify some applications. 相似文献
Pyridine-2,6-dicarboxylic acid (dipic) was used for the synthesis of a co-crystal with 1,10-phenanthroline-5,6-dione (phen-dione)
and a nickel(II) complex. The co-crystal dipic·phen-dione·4H2O (1) has been synthesized and studied by X-ray crystallography. The structure is stabilized with hydrogen bonds between dipic,
H2O and phen-dione. It is surprising that there is no direct hydrogen bonding between phen-dione and dipic and yet the molecules
co-crystallize in aqueous solution. A new complex of nickel(II), [Ni(phen)(dipic)(H2O)]·4H2O (2), (where phen = 1,10-phenanthroline) has been synthesized and characterized by elemental and thermogravimetric analyses,
FT-IR, UV–Vis and 1H-NMR spectroscopy. The structure of (2) has been studied by X-ray crystallography. The coordination around Ni(II) is a distorted octahedron. The crystal packing
shows that the dimensionality of (2) is enlarged to 3D, through hydrogen bonds and π–π interactions. Cyclic voltammetry of (2) shows that the Ni(II/I) couple is irreversible. 相似文献
Let a be an ideal of a commutative Noetherian ring R and M a finitely generated R-module. We explore the behavior of the two notions fa(M), the finiteness dimension of M with respect to a, and, its dual notion qa(M), the Artinianness dimension of M with respect to a. When (R,m) is local and r?fa(M) is less than , the m-finiteness dimension of M relative to a, we prove that is not Artinian, and so the filter depth of a on M does not exceed fa(M). Also, we show that if M has finite dimension and is Artinian for all i>t, where t is a given positive integer, then is Artinian. This immediately implies that if q?qa(M)>0, then is not finitely generated, and so fa(M)≤qa(M). 相似文献