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41.
The purpose of this review is to provide a short overview of electrochemical reduction processes for oxidized contaminants in water. The major parameters affecting the electroreduction mechanisms and the impact of electrode choice are discussed with reference to both inorganic and organic pollutants that are either regulated or emerging (e.g., nonmetal oxyanions, perfluoroalkyl and polyfluoroalkyl substances). To conclude, a discussion is presented on the future directions and challenges that must be addressed to develop these electrochemical reduction processes at a larger, commercialized scale. 相似文献
42.
Hsin-Chang Chen 《Talanta》2009,79(2):442-445
This paper describes the analysis of perchlorate (ClO4−) in surface water samples by a rapid and reliable ion-pair hollow-fiber liquid-phase microextraction (HF-LPME) method coupled with flow-injection electrospray ionization tandem mass spectrometry (ESI-MS-MS) technique. The effects of the type and concentration of ion-pairing reagents, extraction time, temperature and pH value on the quantitative extraction of perchlorate by ion-pair HF-LPME were investigated and optimized. Di-n-hexyl ammonium acetate (DHAA) was employed to form an extractable ion-pair complex with aqueous perchlorate. The characteristic ions [ClO4-ClO4-DHA]− at m/z 384.6 and 386.7 were observed in the ESI negative-ionization mode. The predominant product ions [ClO4]− at m/z 99 and 101 were used for quantitation and to maximize the detection selectivity and sensitivity. The limit of detection (LOD) was 0.5 μg/L. The reliability and precision of the standard addition method of ion-pair HF-LPME for the determination of trace levels of perchlorate in surface water were demonstrated. 相似文献
43.
Some unusual oligonuclear copper(II) complexes with a bis(tridentate) pyrazolate‐based ligand that is composed of two diethylentriame‐type coordination compartments have been structurally characterized. In [(LCu2)2(CO3)(H2O)2(ClO4)](ClO4)3 ( 1 ), CO2 has been taken up and two {LCu2} subunits are spanned by both a μ3‐μ3‐κO:κO′:κO″‐bridging carbonate as well as by a μ3‐κO:κO′:κO″‐bridging perchlorate. The latter is a rare structural motif in coordination chemistry. In one experiment, a different complex [(LCu2(OH))2Cu2(OH)4](BF4)4 ( 2 ) has been serendipitiously obtained. One Cu atom of each {LCu2} subunit of 2 together with two further copper ions forms a pyrazolate‐appanded {Cu4(OH)4} cube. 相似文献
44.
Perchlorate (ClO(4) (+)) and other chlorine oxide anions were observed to complex weakly with hexamethonium (1,6-bis-(trimethylammonium)-hexane) in both aqueous and polar nonaqueous solvents. The resultant positively charged complexes were resolved by NACE using 2-propanol/acetone electrolytes prior to mass spectrometric detection using an Agilent(3D)CE system coupled to a Bruker Esquire 3000+ quadrupole IT mass detector. Using electrokinetic injection, the method detection limit for perchlorate in nonaqueous media was 10 microg/L. The isotope patterns due to the presence of (35)Cl and (37)Cl in complex mass spectra allowed for unambiguous identification of perchlorate, chlorate (ClO(3) (+)), chlorite (ClO(2) (+)), and chloride (Cl(+)) in photoreaction samples. 相似文献
45.
吭氯酸盐电解电流效率的化学分析过程复杂、费时。本文通过改变电解槽结构,提出一种气体分析方法,即采用氧阴极或使用一张钠离子交换膜改变电极槽结构,通过测定电解槽产气量,得到电解电流效率。与传统分析方法相比,气体分析方法既简单又方便。这种方法特别适用于实验室研究使用和评价阳极材料的电化学性能。此外,使用氧阴极代替铁阴极,可以电解电压和节约电能。 相似文献
46.
Summary Perchlorate is a groundwater contaminant originating from facilities that manufacture and test solid rocket fuel. A new technology,
capillary electrophoresis, has the potential to measure perchlorate rapidly and inexpensively in water samples. With its speed
and simplicity, this method would complement existing methods. The perchlorate anion is routinely detected in water samples
using high performance ion exchange chromatography, a very sensitive yet time consuming and expensive method. In this work,
the parameters for detection of perchlorate are optimized to permit detection of 0.400 mgL−1 perchlorate in a standard solution. The usefulness of this technology is demonstrated for measuring perchlorate in several
ground-water samples from the Western United States. The results demonstrate that CE can be used to rapidly screen environmental
samples for perchlorate at intermediate to high levels (greater than 0.400 mgL−1). This technique allows faster, easier screening of potential contamination sites and could complement the use of ion exchange
chromatography for groundwater testing. 相似文献
47.
A simple and sensitive single step electro membrane extraction (EME) procedure was demonstrated for biological organic anions with determination by ion chromatography (IC). Nitrite, adipate, oxalate, iodide, fumarate, thiocyanate and perchlorate were extracted from aqueous donor solutions, across a supported liquid membrane (SLM) consisting of methanol impregnated in the walls of a porous polypropylene membrane bag and into an alkaline aqueous acceptor solution in the lumen of the propylene envelope by the application of potential of 12 V applied across the SLM. The acceptor solution was analyzed by IC. Parameters affecting the extraction performance such as type of SLM, extraction time, pH of the donor and acceptor solution, and extraction voltage were studied. The most favorable EME conditions were methanol as the SLM, extraction time of 5 min, pH of acceptor and sample solutions of 12 and 4, respectively, and a voltage of 12 V. Portable 12 V batteries were used in the study. Under these optimized conditions, all anions had enrichment factors ranging from 3.6 to 36.2 with relative standard deviations (n = 3) of between 6.6 and 17.5%. Good linearity ranging from 0.1 to 10 μg mL−1 with coefficients of correlation (r) of between 0.9981 and 0.9996 were obtained. The limits of detection of the EME-IC method were from 0.01 to 0.14 μg mL−1. The developed methodology was applied to amniotic fluid samples to evaluate the feasibility of the method for real applications. 相似文献
48.
《Journal of Coordination Chemistry》2012,65(16-18):2905-2912
AbstractDuring an effort to synthesize the trans-III-copper(II) complex with 1,4,8,11-tetramethyl-pyro-phosphonate-1,4,8,11-tetra-aza-cyclo-tetradecane, using only perchlorate salts, it was noted that the perchlorate is reduced to chloride. Analysis of the reactions leading to this surprising result points out that Cu(H2O)42+ catalyzes the reduction of perchlorate by H2 and by CH2O. These reactions are slow at room temperature and ambient pressures. A plausible mechanism, supported by DFT calculations, is proposed pointing out that the role of CuH+ under mild conditions cannot be ignored. 相似文献
49.
《Journal of Coordination Chemistry》2012,65(2):113-124
The reactions of ciprofloxacin (CIP) and norfloxacin (NOR) with iron(II) and iron(III) perchlorate have been investigated. The optical spectra support the formation of four complexes for each oxidation state with 1 : 1, 1 : 2, 1 : 3 and 1 : 4 metal to ligand molar ratios. The electrical conductivity and magnetic susceptibility measurements show that the isolated complexes are high spin and the Fe(ClO 4 ) 2 and Fe(ClO 4 ) 3 complexes behave as 1 : 2 and 1 : 3 electrolytes, respectively. The IR spectra indicate that CIP and NOR bind to the iron ion as bidentate ligands through the carbonyl oxygen atom and one of the oxygen atoms of the carboxylate group. 相似文献
50.
《Journal of Coordination Chemistry》2012,65(4):363-369
A lead(II) complex containing 2,2′-bipyridine (bpy), acetate and perchlorate ligands, [Pb(bpy)(CH3COO)(ClO4)] has been synthesized and characterized by elemental analysis, IR-, 1H NMR-, 13C NMR spectroscopy. Single crystal X-ray data show the complex is two dimensional polymeric as a result of an unusual perchlorate bi- and unidentate bridging with repeating dimeric {[Pb(bpy)(µ-OAc)]2(µ-O2ClO2)(µ-OClO2O)}n units. The Pb atom has an unsymmetrical eight-coordinate geometry with a coordination gap around the Pb(II) ion, possibly occupied possibly by a stereo-active lone pair of electrons on lead(II). 相似文献