共查询到20条相似文献,搜索用时 46 毫秒
1.
UV/H2O2/micro-aeration is a newly developed process based on UV/H2O2. Halogenated pesticide 2,4-dichlorophenoxyacetic acid (2,4-D) photochemical degradation in aqueous solution was studied under
various solution conditions. The UV intensity, initial 2,4-D concentrations and solution temperature varied from 183.6 to
1048.7 μW·cm−2, from 59.2 to 300.0 μg·L−1 and from 15 to 30°C, respectively. The concentration of hydrogen peroxide (H2O2) and pH ranged from 0 to 50 mg·L−1 and 5 to 9, and different water quality solutions (tap water, distilled water and deionized water) were examined in this
study. With initial concentration of about 100 μg·L−1, more than 95.6% of 2,4-D can be removed in 90 min at intensity of UV radiation of 843.9 μW·cm−2, H2O2 dosage of 20 mg·L−1, pH 7 and room temperature. The removal efficiency of 2,4-D by UV/H2O2/micro-aeration process is better than UV/H2O2 process. The photodecomposition of 2,4-D in aqueous solution follows pseudo-first-order kinetics. 2,4-D is greatly affected
by UV irradation intensity, H2O2 dosage, initial 2,4-D concentration and water quality solutions, but it appears to be slightly influenced by pH and temperature.
There is a linear relationship between rate constant k and UV intensity and initial H2O2 concentration, which indicates that higher removal capacity can be achieved by the improvement of these factors. Finally,
a preliminary cost analysis reveals that UV/H2O2/micro-aeration process is more cost-effective than the UV/H2O2 process in the removal of 2,4-D from drinking water. 相似文献
2.
Jiankun Xie Qinyan Yue Hui Yu Wenwen Yue Renbo Li Shengxiao Zhang Xiaona Wang 《Frontiers of Chemistry in China》2008,3(1):33-40
Activated carbon was prepared from the sewage sludge of municipal wastewater treatment plant by chemical activation (activation
reagent is ZnCl2) and was used for the adsorption of dye (reactive brilliant red K-2BP). The impact of adsorbent amount, adsorption time and
pH value on adsorption effect, the adsorption kinetics, and the adsorption thermodynamics were discussed according to batch
adsorption tests. The results indicated that the activated carbon developed from sewage sludge (ACSS), which was mesoporous,
possessed opened porous structures. The iodine number of the ACSS was 326 mg·g−1. The rate of achievement was 51.31%. The BET surface area was 298 m2·g−1 and the contents of heavy metals in the leachate didn’t exceed the contents limit. The adsorption kinetics of reactive brilliant
red K-2BP on the ACSS was accorded with the two-step kinetics rate equation and pseudo-second-order kinetics equation. Compared
to the Freundlich isotherm equation, the Langmuir isotherm equation showed better applicability for the adsorption. The adsorption
which was favorable was an endothermic (enthalpy ΔH > 0) and spontaneous (free energy ΔG < 0) process and was accompanied by an increase in entropy (ΔS > 0).
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Translated from Journal of Shandong University (Natural Science), 2007, 42(3): 64–70 [译自: 山东大学学报(理学版)] 相似文献
3.
Dazhang Zhu Shilong Wang Xiaoyu Sun Yaming Ni Side Yao 《Frontiers of Chemistry in China》2007,2(4):354-358
The reaction mechanism between isoquinoline and ·OH radical in aqueous dilute solutions under different conditions was studied
by pulse radiolysis. The main characteristic peaks in these transient absorption spectra were attributed and the growth-decay
trends of several transient species were investigated. Under neutral or alkaline conditions, the reaction of ·OH radical and
isoquinoline produces OH-adducts with respective rate constants of 3.4 × 109 and 6.6 × 109 mol−1 · dm3 · s−1 while under acidic conditions, the isoquinoline was firstly protonated and then ·OH added to the benzene ring and produced
protonated isoquinoline OH-adducts with a rate constant of 3.9 × 109 mol−1 · dm3 · s−1. With a better understanding on radiolysis of isoquinoline, this study is of help for its degradation and for environmental
protection.
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Translated from Journal of Fudan University (Natural Science), 2006, 45(6): 774–778 [8BD1;81EA: 590D;65E6;5B66;62A5;(自然科学版)] 相似文献
4.
Chun Yang Gongfeng Xu Bin Liu Qinglun Wang Daizheng Liao 《Frontiers of Chemistry in China》2008,3(3):294-297
The bimetallic complex of Ni2Co(TTHA)·12H2O (TTHA = triethylene tetraminehexaacetic acid) was synthesized and characterized structurally and magnetically. The title
complex crystallizes in the triclinic space group P ī with a = 0.7316(2), b = 0.8624(2), c = 1.5041(4) nm; α = 73.38(2), β = 83.97(2), γ = 70.50(2)°. The crystal structure is built up of [Ni2(TTHA)(H2O)2]2−, Co(H2O)62+ and water molecules. The variable magnetic measurement shows that there is strong antiferromagnetic interaction between two
Ni(II) ions in [Ni2(TTHA) (H2O)2]2− with J
Ni−Ni = −141.64 cm−1, g
Ni = 2.21 and that the constant of spin-orbit coupling of Co(II) ion is −134.8 cm−1.
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Translated from Acta Scientiarum Naturalium Universitatis Nankaiensis, 2007, 40(1): 6–10 [译自: 南开大学学报(自然科学版)] 相似文献
5.
A new tripodal rhodamine B derivative 2 was designed and synthesized by tripodal trialdehyde and rhodamine B hydrazide for
the first time. This derivative could be used as a fluorescent chemosensor for the selective and sensitive determination of
copper(II) in Tris-HCl buffer and ethanol aqueous mixed media. Under the optimum conditions described herein, fluorescence
enhancement at 557/577 nm was linearly related to the concentration of copper(II) in the range of 0.10 to 10.00×10−5 mol·L−1, with a correlation coefficient of R
2=0.9964 (n=15) and a detection limit of 1.129×10−7 mol·L−1 (the relative standard deviation for five repeated measurements at 4.00×10−5 mol·L−1 Cu(II) was 2.2%). The absorbance measurements at 557 nm were linearly related to the concentration of Cu(II) in the range
of 0.50 to 25.00×10−5 mol·L−1, with a correlation coefficient of R
2=0.9948 (n=13) and a detection limit of 3.338×10−7mol·L−1.
Supported by the Foundation of the Governor of Guizhou Province, China (Grant No. 200617) and the Talented Person Foundation
of Guizhou University (Grant No. 2007039) 相似文献
6.
Chunhai Yang Shenghui Zhang Yingxuan Liu Wensheng Huang 《Frontiers of Chemistry in China》2008,3(3):353-358
A multi-wall carbon nanotubes (MWNTs)-Nafion film-coated glassy carbon electrode (GCE) was fabricated and the electrochemical
behavior of ofloxacin on the MWNTs-Nafion film-coated GCE were investigated by cyclic voltammetry (CV), linear sweep voltammetry
(LSV) and electrochemical impedance spectroscopy (EIS). The oxidation peak current of ofloxacin increased significantly on
the MWNTs-Nafion film modified GCE compared with that using a bare GCE. This nano-structured film electrode exhibited excellent
enhancement effects on the electrochemical oxidation of ofloxacin. A well-defined oxidation peak attributed to ofloxacin was
observed at 0.97 V and was applied to the determination of ofloxacin. The oxidation peak current was proportional to ofloxacin concentration
in the ranges 1.0 × 10−8 to 1.0 × 10−6 mol/L and 1.0 × 10−6 to 2.0 × 10−5 mol/L. A detection limit of 8.0 × 10−9 mol/L was obtained for 400 s accumulation at open circuit (S/N = 3). This method for the detection of ofloxacin in human
urine was satisfactory.
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Translated from Chinese Journal of Applied Chemistry, 2007, 24(5): 540–545 [译自: 应用化学] 相似文献
7.
Victoria F. Samanidou Emmanouil D. Tsochatzis Ioannis N. Papadoyannis 《Mikrochimica acta》2008,160(4):471-475
An HPLC method was developed and validated for the determination of the cephalosporins cefotaxime and cephalexine in skimmed
bovine milk. The analytical column, Kromasil C18 (250 mm × 4.0 mm, 5 μm) was operated at ambient temperature. Mobile phase consisted of CH3OH-acetate buffer (pH = 4.0) and it was delivered isocratically at a flow rate of 1.0 mL · min−1. Total analysis time was less than 5 min. Caffeine was used as internal standard (5 ng · μL−1). UV detection was performed at 265 nm. Method validation was performed by means of intra-day (n = 5) and inter-day accuracy and precision (n = 8), sensitivity and linearity. Limits of detection (LOD) and limits of quantification (LOQ) were 0.1 and 0.3 ng · μL−1, respectively. The method was applied to the analysis of a veterinary drug (CEPOREX) containing cephalexine. The results
were quite accurate with the relative error varying from −8.0 to −3.5%. Solid-phase extraction was applied to remove all matrix
interference from milk samples. High extraction recoveries (average 84–121%) were achieved by using Abselut NEXUS cartridges
with acetonitrile as eluent and a rinsing step with water and n-butanol. A pre-concentration step was necessary in a 1/10
level to reach the EU MRL concentration level (100 μg · kg−1). RSD values were less than 7% for both cephalosporins.
Correspondence: Ioannis N. Papadoyannis, Laboratory of Analytical Chemistry, Department of Chemistry, Aristotle University
of Thessaloniki, GR-54124 Thessaloniki, Greece 相似文献
8.
A simple spectrophotometric method is presented for the determination of tetrakis [methylene (3,5-di-tert-butyl-4-hydroxyhyrocinnamate)] methane (Irganox 1010) in polymeric samples. To a solution of Irganox 1010 in acetone is added
concentrated sodium hydroxide solution and then it is shaken for a short time. The 2-phase system produced in the upper phase
(acetone) is yellow colored. Absorbance of the colored phase is recorded in a quartz cell at 440 nm. Different parameters
such as temperature, time after mixing solutions of Irganox 1010 and sodium hydroxide, and concentration of sodium hydroxide
are studied. The linear dynamic range, limit of detection and correlation coefficient (r) are 25–1000 mg·L−1, 10 mg·L−1 and 0.996, respectively. The repeatability of this method is good (n = 6, C = 250 mg·L−1, RSD = 3.26%).
Correspondence: Mir Ali Farajzadeh, Department of Analytical Chemistry, Faculty of Chemistry, Tabriz University, Tabriz, Iran 相似文献
9.
Peng Ping Wenshou Wang Peibiao Zhang Xuesi Chen Xiabin Jing 《Frontiers of Chemistry in China》2007,2(4):331-336
A series of segmented poly(L-lactide)-polyurethanes (PLA-PUs) were synthesized by a two-step method, with oligo-poly(L-lactide) (PLA) as the soft segments and the reaction product of 2,4-toluene diisocyanate (TDI) and ethylene glycol (EG) as
the hard segments. The shape-memory properties and biocompatibility of PLA-PUs were examined. The 50% compressed PLA-PUs could
recover almost 100% to their original shape within 10°C from the lowest recovery temperature (22°C–37°C). In the recovery
process the PLA-PU showed a maximum contracting stress in the range of 1.5–4 MPa. Cell incubation experiments show that PLA-PU
has biocompatibility comparable to that of pure PLA. Therefore, this kind of polyurethane can be used for implanted medical
devices with shape memory requirements.
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Translated from Chemical Journal of Chinese Universities, 2007, 28(2): 371–375 [译自: 高等学校化学学报] 相似文献
10.
Controlled/living photopolymerization of methyl methacrylate (MMA) in miniemulsion mediated by 4-hydroxy-2,2,6,6-tetramethyl-piperidinyloxy
(HTEMPO) was carried out at ambient temperatures. MMA miniemulsion was prepared by using an anionic surfactant with cetylalcohol
as a co-stabilizer. The photopolymerization led to stable lattices and they were obtained with no coagulation during synthesis
and no destabilization over time. It was found that the obtained MMA homopolymers exhibited relatively narrow molecular weight
distribution (PDI = 1.27 − 1.36) which was characterized by GPC. The plots of number-average molecular weight in (M
n) vs. conversion and ln([M0]/[M]) vs. time both were linear indicating that the reaction was a controlled/living free radical polymerization.
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Translated from Chemical Journal of Chinese Universities, 2007, 28(4): 774–778 [译自: 高等学校化学学报] 相似文献
11.
Jinzhang Gao Dongyu Lv Wu Yang Xiaoxia Wei Jie Qu Hua Chen Hongxia Dai Jie Ren 《Central European Journal of Chemistry》2007,5(2):581-589
A convenient and sensitive method for determination of sulfanilamide (SNA) was described based on the Mn(II)-catalyzed oscillating
chemical reaction. Under optimum conditions, a linear relationship existed between the changes of oscillating period or amplitude
and the negative of logarithm of SNA concentration in the range of 4.27 × 10−8 mol ·L−1 ∼ 7.41 × 10−6 mol ·L−1 (RSD, 0.85%) and 9.33 × 10−8 mol ·L−1 ∼ 3.02 × 10−6 mol ·L−1 (RSD, 1.08%), respectively. The lower limit of detection was found to be 2.69 × 10−8 mol ·L−1 and 6.03 × 10−8 mol ·L−1, respectively.
相似文献
12.
Jorge L. Guzmán Mar Leticia López Martínez Pedro L. López de Alba Jesús E. Castrejón Durán Víctor Cerdà Martín 《Mikrochimica acta》2006,153(3-4):139-144
1-Naphthylamine (NPA) is one of the main degradation products of pesticides derived from naphthalene, and a well-known bladder
carcinogen in men. The Griess assay is used for NPA determination because of its high sensitivity and selectivity. The azo
dye 4-(sulphophenylazo)-1-naphthylamine is formed, which shows a peak maximum at 540 nm. After optimizing multisyringe flow
injection analysis (MSFIA) parameters, the analytical characteristics of the method were obtained, with a working linear range
of 0.5 to 14 mg L−1, according to the equation A = 0.0738±0.0019 [NPA] + 0.0028 ± 0.0042, r = 0.9997. Values for RSD (%) and Erel (%) were calculated for the concentration levels of 0.5, 6 and 12 mg L−1; values obtained were 1.1, 0.4 and 0.3% for RSD and 0.8, 0.3 and 0.2% for Erel, respectively. LD was 0.01 mg L−1 and LQ was 0.04 mg L−1 NPA. The MSFIA procedure for the determination of NPA was applied to different water samples (well water, tap water, seawater,
and wastewater from the EDAR-1, Palma de Mallorca water treatment plant), with satisfactory results and a throughput of 90
samples per hour. 相似文献
13.
Summary A capillary electrophoretic method for the determination of Cu(II) and Co(III) chelates with ethylenediamine in electroless
copper plating baths has been developed. The influence of carrier electrolyte parameters such as nature of counter-ion and
pH were studied and discussed. The optimised separations were carried out in a fused silica capillary (57 cm × 75 μm I.D.)
filled with an ethylenediamine sulfate electrolyte (20 mol L−1 ethylendiamine, pH7.0 with H2SO4; applied voltage, +25 kV) using direct UV detection at 214 nm. The detection limits for a signalto-noise ratio of 3 and 10s
hydrodynamic injection were 5×10−6 mol L−1 for Cu(II) and 1×10−6 mol L−1 for Co(III). The relative standard deviations of the peak areas for Cu(II) and Co(III) were found to be 1.5% and 2.4%, respectively,
with five consecutive injections of standard solution containing 5×10−5 mol L−1 of each metal ion. Application of the method to the speciation of Cu(II) and Co(III) complexes in copper plating bath samples
is also demonstrated. 相似文献
14.
A new Schiff-base ligand [N, N′, N″-Tri- (2,4-dihydroxyacetophenone) – triaminotriethylamine (TDATA)] with a tripodal structure
was synthesized. Its fluorescence intensity with the europium(III) complex was increased about 178-fold in the presence of
sodium acetate (NaAc) and about 126-fold in the presence of sodium phosphate (Na3PO4) solution. After adding the organic solvent dimethylsulfoxide (DMSO) to the above system, which leads to Eu3+ the fluorescence was further enhanced about 12-fold. Spectrofluorimetric determination of trace amounts of Eu3+ based on the phenomenon was performed. The excitation and emission wavelength is 365 nm and 615 nm, respectively. Under optimum
conditions, the fluorescence intensities vary linearly with the concentration of Eu3+ in the range of 4.9 × 10−12–3.2 × 10−6 mol · L−1 with a detection limit of 4.5 × 10−12 mol · L−1 (for the TDATA-NaAc-DMSO system) or 6.2 × 10−11–8.6 × 10−6 mol · L−1 with a detection limit of 6.0 × 10−11 mol · L−1 (for the TDATA-Na3PO4-DMSO system). Interferences of some rare earth metals and other inorganic ions are described. The method is a selective,
sensitive, rapid and simple analytical procedure for the determination of europium(III) in a high purity yttrium oxide and
synthetic sample. The mechanism for the fluorescence enhancement is also discussed. 相似文献
15.
Jie Gong Yang Liu Lili Wang Jinghai Yang Zhanguo Zong 《Frontiers of Chemistry in China》2008,3(2):157-160
Hexagonal close-packed Ni nanoparticles were synthesized using a heat-treating technique with the precursors prepared by the
sol-gel method. The synthesis condition, structure, and morphology of the samples were characterized and analysed by thermogravimetric
analysis (TG), differential thermal analysis (DTA), X-ray diffraction (XRD) and transmission electron microscopy (TEM). Results
indicate that the hexagonal close packed Ni nanoparticles were synthesized at a heat-treating temperature of 300°C. The cell
constants are calculated at a = 0.2652 nm and c = 0.4334 nm. The average grain size of the hexagonal close-packed Ni particles evaluated by Scherrer equation is about 12
nm. The phase transformation from a hexagonal close-packed Ni to a face-centered cubic Ni structure occurred when the heat-treating
temperature was increased.
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Translated from Chemical Journal of Chinese Universities, 2007, 28(7): 1232–1234 [译自: 高等学校化学学报] 相似文献
16.
The degradation of 4-chlorophenol (4-CP) by using gamma rays generated by a 60Co source in the presence of O3 was investigated. The radiolysis of 4-CP and the kinetics of 4-CP mineralization were analyzed based on the determination
of total organic carbon (TOC). The influence of initial 4-CP concentration and the free radicals scavengers (such as NaHCO3 and t-butanol) on the 4-CP degradation was also studied. The results showed that when the radiation rate was 336 Gy·min−1, 4-chlorophenol at concentration of 10 mg·L−1 could be completely degraded at the radiation dose of 2 kGy. The degradation of 4-chlorophenol could be described by a first-order
reaction model, the rate constant of 4-CP degradation by combined ozonation and radiation was 0.1016 min−1, which was 2.4 times higher than the sum of radiation (0.0294 min−1) and ozonation (0.0137 min−1). It revealed that the combination of radiation and ozonation resulted in synergistic effect, which can remarkably increase
the degradation efficiency of 4-CP. 相似文献
17.
The electrochemical behavior of ciprofloxacin (CFX) and its interaction with the natural calf thymus DNA (ctDNA) is studied
by using pulse difference voltammetry on a carbon electrode. CFX shows a well-defined oxidative peak at + 0.88 V. As a result
of reaction with ctDNA,the oxidative peak of CFX decreased markedly. According to the electrochemical equation deduced in
this paper, the binding constant of 1.36 × 105 (mol/L)−1 and the binding size of 1.94 (base pairs) of CFX with ctDNA were obtained by nonlinear fit analysis of the electrochemical
data. The mechanism of the interaction was explored.
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Translated from Journal of Zhejiang University (Science Edition), 2007, 34(3): 330–334 [译自: 浙江大学学报(自然科学版)] 相似文献
18.
This contribution describes use of a separation method based on on-line coupling of a multisyringe flow system with a chromatographic
monolithic column for simultaneous determination of hydrochlorothiazide and losartan potassium in tablets. The system comprised
a multisyringe module, three low-pressure solenoid valves, a monolithic C18 column (25 mm × 4.6 mm i.d.), and a diode-array detector. The mobile phase was 10 mmol L−1 potassium dihydrogen phosphate (pH 3.1)-acetonitrile-methanol (65:33:2 v/v/v) at a flow rate 0.8 mL min−1. UV detection was carried out at 226 nm. The multi-syringe chromatographic (MSC) method with UV spectrophotometric detection
was optimized and validated. Results from validation were very good. The analysis time was about 400 s. The method was found
to be applicable to routine analysis of both compounds in tablets. The coupling of the monolithic columns with a multi-syringe
flow-injection analysis manifold provides an excellent and inexpensive tool to solve the separation problems without use of
HPLC instrumentation. 相似文献
19.
Xiaofeng Zhang Shen Lin Xinqing Chen Jiebo Chen Liuyi Yang Minghong Luo 《Frontiers of Chemistry in China》2007,2(4):419-421
Mesoporous aluminophosphate was prepared by using G4.0 poly(amido amine)dendrimer as a template and characterized by Fourier
transform infrared spectrometer (FTIR), X-ray diffraction (XRD), transmission electron microscopy (TEM) and N2 adsorption/desorption methods. Results show that the title compound exhibits a typical mesoporous structure with the average
pore size from 5 to 8 nm. The formation mechanism of the nanoporous structure using dendrimer as a template was also discussed.
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Translated from Journal of Fujian Normal University (Natural Science Edition), 2007, 23(2): 67–70 [译自: 福建师范大学学报 (自然科学版)] 相似文献
20.
Pyrene-tetramethylpiperidinyl (Pyr-Tempo) as a spin label fluorescent probe for iron(II) was synthesized. It exhibited weak
fluorescence (λexc/λem = 346/399 nm) in aqueous solution due to an intramolecular quenching pathway. A method for determination of iron(II) was
proposed based on the fluorescence enhancement of the probe in the presence of iron(II) in acidic medium. Under optimum conditions,
the fluorescence enhancement of Pyr-Tempo is linearly proportional to the iron(II) concentration range of 6.0 × 10−8 to 9.6 × 10−6 mol L−1 with a detection limit of 8.0 × 10−9 mol L−1. The relative standard deviation (RSD) of six replicate measurements is 1.95% for 3.0 × 10−7 mol L−1 iron(II). The developed spin label fluorescence probe is found to be rapidly and sensitively responsive to iron(II) with
high selectivity compared to existing fluorescence methods. The proposed method was successfully applied to iron(II) detection
in five real samples with satisfactory results obtained by manual UV/Vis spectrophotometry (standard method) with 1,10-phenanthroline. 相似文献