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1.
Photocatalytic decolorization of methyl orange solution with potassium peroxydisulfate 总被引:1,自引:0,他引:1
Zhong Junbo Ma Di Zhao Hong Lian An Li Min Jiao Huang Shengtian Li Jianzhang 《Central European Journal of Chemistry》2008,6(2):245-252
Increasing environmental pollution caused by toxic dyes due to their hazardous nature is a matter of great concern. It has
been generally agreed that methyl orange (MO) can be effectively degraded in aerated K2S2O8 homogeneous reaction system using near-UV irradiation. In this paper photocatalytic degradation of MO solutions with K2S2O8 was investigated, with particular attention on the possible underlying mechanisms. This report has shown decolorization efficiency
of MO increases with the increasing of the dosage of the catalyst. There is no optimal amount of catalyst in our case, where
special attention was paid on the nature of the photocatalyst itself. The current research revealed that the decolorization
reaction is a pseudo first-order reaction when the concentration of MO is below 20 mg L−1 and the decolorization reaction is zero-order reaction when the concentration of MO is above 100 mg L−1, but the Langmuir-Hinshewood kinetic model does not describe this. The influence of IO4−, BrO3− and H2O2 were investigated in detailed. Several observations indicate that the mechanism is not involved in hydroxyl radical attacks
in MO degradation with K2S2O8 by UV irradiation. The possible underlying mechanisms are direct oxidation of the MO by S2O82− and hydrogen attraction by SO4•−.
相似文献
2.
Yuxi Ren Zhen Chen Riyao Chen Xi Zheng Yamin Geng 《Central European Journal of Chemistry》2007,5(1):177-190
The preparation of SAMS-CMC-CS bipolar membrane grafted onto CMC by SAMS was reported. The cross-section view of SAMS-CMC-CS
BM were studied by SEM. FT-IR spectrum indicated that SAMS-CMC-CS BM contained-SO
3
−
,-COO− and −N=CHR functional groups. Compared with CMC-CS BM, SAMS-CMC-CS BM appears to have better mechanical strength and chemical
stability in alkali solution at [OH−]≥9.5 mol/L, with a swelling of 55 %. The electrochemical properties of SAMS-CMC-CS BM were also studied. SAMS-CS-CMC BM not
only effectively prevented FeO
4
2−
from diffusing into the cathode chamber, but also played an important role in the supply of OH− consumed during the electro-generated FeO
4
2−
process.
相似文献
3.
Halil Turgut Şahin 《Central European Journal of Chemistry》2007,5(3):824-834
Attempts were made to plasma deposit an oriented π-conjugated polymer of pyrrole (Py) on paper surfaces in order to produce
electrically conductive layers. The N/C atomic ratio of 0.13–0.24 was observed for all treatment conditions. This implies
the nature of the deposition formed on the paper surface via pulsed plasma is different from that of pyrrole monomer. An increase
in conductivity of all pyrrole-plasma treated papers was observed. The 50 W RF-power with 5 min plasma exposed paper sample
shows 8.15 × 10−9 S·cm−1 conductivity. The conductivity measurements indicated a plasma-enhanced ring-opening reaction mechanism of pyrrole.
相似文献
4.
Zholt Kormosh Iryna Hunka Yaroslav Bazel Andriy Laganovsky Iryna Mazurenko Nataliya Kormosh 《Central European Journal of Chemistry》2007,5(3):813-823
The potentiometric response characteristics of a diclofenac selective electrode, based on ion association in different plasticizers,
were compared. The sensitivity, working range, detection limit and selectivity of membrane sensors demonstrated significant
dependence on the type of plasticizers. The potentiometric unit presented a linear response toward diclofenac concentrations
between 1 × 10−5 − 5 × 10−2 mol L−1, with slopes of approximately 60 mV dec−1, and exhibited a response time of 3 s. The potentiometric analysis of sodium diclofenac in pharmaceutical formulations was
perfomed by the membrane electrode proposed and compared with the results of potentiometric titration given by the Pharmacopoeia
of Ukraine.
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5.
Ksenija R. Kumrić Tatjana M. Trtić-Petrović Ljubiša M. Ignjatović Jožef J. Čomor 《Central European Journal of Chemistry》2008,6(1):65-69
Lutetium has been determined by differential pulse anodic stripping voltammetry in an acidic solution containing Zn-EDTA.
Lutetium (III) ions liberated zinc (II), which was preconcentrated on a hanging mercury drop electrode and stripped anodically,
resulting in peak current linearly dependent on lutetium (III) concentration. Less than 0.4 ng mL−1 lutetium could be detected after a 2 min deposition.
相似文献
6.
Li-Wen Xu Ming-Song Yang Jian-Xiong Jiang Hua-Yu Qiu Guo-Qiao Lai 《Central European Journal of Chemistry》2007,5(4):1073-1083
Ionic liquid-functionalized mesoporous materials exhibited high catalytic activity in versatile organic reactions, such as
cycloaddition of carbon dioxide (CO2) with epoxide, aza-Michael addition of amines to α, β-unsaturated carbonyl compounds, and the Biginelli reaction of aldehyde, ethyl acetoacetate and urea. Recycling of the catalyst
in these reactions could be carried out and the catalyst used at least five times without significant loss in activity.
相似文献
7.
Jaromíra Chýlková Renáta Šelešovská-Fadrná Jaroslava Machalíková 《Central European Journal of Chemistry》2007,5(2):479-495
The optimal process of pre-treatment and activation of gold rotating disc electrode (AuRDE) before voltammetric determination
of mercury is proposed. This treatment encompasses polishing of the electrode surface, electrochemical cycling, and activation.
This procedure both increases determination sensitivity as well as improves determination reproducibility. The detection limit
on the working electrode achieved using this approach amounted to 8.26·10−10 mol L−1for direct mercury determination in water solution (applying 200 s running accumulation). The procedure of the quantitative
mercury isolation from complicated sample matrix was developed as well. It provides better selectivity and significant increase
of sensitivity of mercury determination. In case of mercury isolation from one liter of water the detection limit is 6.23·10−11 mol L−1 (analyzing a greater sample volume the determined concentration could be lower).
相似文献
8.
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
9.
Voltammetric and potentiometric studies of some sulpha drug-Schiff base compounds and their metal complexes 总被引:1,自引:0,他引:1
M. M. Ghoneim E. M. Mabrouk A. M. Hassanein M. A. El-Attar E. A. Hesham 《Central European Journal of Chemistry》2007,5(3):898-911
The electrochemical behavior of some sulpha drug-Schiff bases at a mercury electrode was examined in the Britton-Robinson
universal buffer of various pH values (2.5–11.7) containing 20% v/v) of ethanol using DC-polarography, cyclic voltammetry
and controlled-potential electrolysis. The DC-polarograms and cyclic voltammograms of the examined compounds exhibited a single,
2-electron, irreversible, diffusion-controlled cathodic step within the entire pH range which is attributed to the reduction
of the azomethine group-CH=N- to -CH2-NH-. The symmetry transfer coefficient (α) of the electrode reaction and the diffusion coefficient (D
0) of the reactant species were determined. The electrode reaction pathway of the compounds at the mercury electrode was suggested
to follow the sequence: H+, e−, e−, H+. The dissociation constant of the sulpha drug-Schiff bases, the stability constant and stoichiometry of their complexes with
various divalent transition metal ions (Mn2+, Co2+, Ni2+, Cu2+ and Zn2+) were determined potentiometrically at room temperature.
相似文献
10.
Borjana V. Donkova Katja I. Milenova Dimitar R. Mehandjiev 《Central European Journal of Chemistry》2008,6(1):115-124
The precursors with a low manganese content ≤ 0.07% Mn were synthesized by spontaneous crystallization from Zn2+, Mn2+ and C2O4
2−-containing solutions. The initial ratio Zn2+:C2O4
2− = 1:1 and 1:2 influences the morphology and prevailing orientations of the crystallites in the oxalate samples. The presence
of such small Mn content in the samples does not change the morphology or size of the crystals. The ZnO and Mn/ZnO oxides
with manganese content from 0.51×10−2 to 15.1×10−2 Wt % are obtained after thermal decomposition of the oxalates. The oxides preserved the morphology of the precursors. The
catalytic tests show that the pure ZnO has a poor activity for CO oxidation reaction. Its doping with Mn promotes the catalytic
activity (up from twice to five times) in spite of the very low contents of the dopants. The observed increase of the activity
depends on both dopant concentration and Zn2+:C2O4
2− ratio, probably due to the different mechanism of the manganese inclusion and different morphology of the oxides. The catalysts
of the 1:2 series are more active in CO oxidation reaction.
相似文献
11.
Nitin A. Mirgane Sandip B. Kotwal Anil V. Karnik 《Central European Journal of Chemistry》2010,8(2):356-360
Ionic liquids (IL) are gaining importance as green solvents. Imidazolium ionic liquid [bmim]+[Cl]−, an environmentally benign solvent, was found to promote the Diels-Alder reaction between anthrone and maleimides at room
temperature with excellent yields. The ionic liquid played a dual role as solvent and catalyst.
相似文献
12.
Radina Kralchevska Maria Milanova Mirjana Bistan Albin Pintar Dimitar Todorovsky 《Central European Journal of Chemistry》2012,10(4):1137-1148
Commercial product Degussa TiO2 P25, sol-gel produced TiO2 and TiO2 modified by carbon nanotubes addition (5% of the TiO2 mass) are tested as photocatalysts for the degradation of endocrine disrupting compound 17α-ethynylestradiol (1 μM aqueous solution). The molecular and crystal structure, phase composition, crystallite size, specific surface area, pore average diameter, their area and volume distribution, morphology, IR and UV/Vis spectra of the catalysts are characterized. HPLC is used for estrogen analysis. The sorption ability and photocatalytic activity (measured by degradation rate constant and percentage of the pollutant conversion) of the catalysts under UV (17 W, emission maximum at 254 nm) irradiation is determined. Full destruction of the pollutant is reached after 30 min irradiation in presence of Degussa P25. The performance of some of the catalysts is compared with literature data for their activity under 365 nm-illumination. 相似文献
13.
The performance of a ground level reactive cell, filled with Fe0, designed for the treatment of water contaminated by chlorinated solvents, having a total input concentration of approximately
2 mg 1−1 of the principal contaminants trichloroethene and perchloroethene, was tested at the Milovice site in the Czech Republic.
A residence time of 1.62 days in the box was sufficient to reduce concentrations to a fraction less than 0.015 of the initial
concentration. However, incomplete degradation of cis-1,2-DCE was observed. Reactions approximated first-order kinetics. The
principal changes of concentrations of inorganic dissolved species in the reactive cell occurred for Ca2+, HCO
3
−
, NO
3
−
(decreased) and for Fe (initially increased, then decreased). Changes for Ca2+ and HCO
3
−
were caused by the precipitation of secondary carbonate mineral phases such as aragonite and siderite with the minor presence
of green rust-CO3. Concentration changes were gradual, along the complete length of the cell with a maximum at the inlet zone. The observations
were attributed to minor increases of pH and slow kinetics of precipitation in the carbonate-buffered system. The average
porosity loss was estimated to be approximately 2.7 % of the initial porosity per year, suggesting the long-term function
of the permeable reactive barrier.
相似文献
14.
Radina Kralchevska Maria Milanova Petya Kovacheva Jovo Kolev Georgi Avdeev Dimitar Todorovsky 《Central European Journal of Chemistry》2011,9(6):1027-1038
Microcomposites consisting of TiO2 (or Ce-doped TiO2) and ThO2 (0.5–2% of the TiO2 mass) are produced by sol-gel synthesis of TiO2 in presence of ThO2. X-ray diffraction study reveals the effects of ThO2 (compared to the ThO2-free TiO2, obtained by the same method) on the anatase interplanar distances, crystallites size and phase composition. The photocatalytic
tests in presence of the composites under UV irradiation reveal an increase of the Malachite Green degradation rate constant.
The effect depends on the Th relative content, temperature of annealing of the catalyst and addition of other doping agent.
The highest photocatalytic activity is observed for TiO2 obtained at 550°C and containing 1% ThO2. The composite exhibits activity in dark, also. The presence of Ce4+ ions is not an obligatory requirement for the realization of the ThO2 effect. The reported results suggest that the radioactivity of the Th and/or its decay products is one of the main factors
responsible for the increased photocatalytic activity of TiO2.
相似文献
15.
Jinzhang Gao Yingying Zhang Jie Ren Ming Li Wu Yang 《Central European Journal of Chemistry》2010,8(3):602-606
A sensitive and convenient method for the determination of trace europium ions using an oscillating chemical reaction involving
Ce(IV) - KBrO3 - acetone - oxalic acid - H2SO4 was proposed. The results indicated that the changes in oscillating period (T) was linearly proportional to the negative
logarithmic concentration of Eu3+ (-log C) in the range of 1.41 × 10−8 ˜ 1.41 × 10−4 mol L−1 (r = 0.9982) with a detection limit of 1.04 × 10−9 mol L−1. The recoveries were limited to the range of 99.5% to 100.8%. Under the same conditions, other rare earth ions did not interfere
with the determination of Eu3+. In addition, a perturbation mechanism was also discussed briefly.
相似文献
16.
The nanocatalyst-assisted sonodegradation of Basic Blue 41 (BB41) dye in aqueous medium was modeled and optimized using response
surface method (RSM) based on Box-Behnken design. The studied variables included pH, initial dye concentration, H2O2 concentration and sonolysis time while each factor varied at three levels: Low level (−1), Medium level (0) and High level
(+1). The ultrasound -assisted degradation was well described by developing quadratic model with correlation value squared
(R2) of 0.9114. Factor effects along with interaction effects were evaluated. The graphical optimization step was conducted to
achieve the best experimental condition in dye removal. pH, H2O2 concentration and initial dye concentration of the reaction were investigated. It was recognized that at lower pH values
the dye removal rate decreased. However, dye removal rate increased (82.5%) by increasing the concentration of H2O2 and by lowering the initial dye concentration.
相似文献
17.
Violeta D. Mitic Snezana D. Nikolic Vesna P. Stankov-Jovanovic 《Central European Journal of Chemistry》2010,8(3):559-565
A kinetic spectrophotometric method for hydrazine determination in the range of 9.36×10−7 to 4.37×10−5 mol dm−3, based on the inhibitory effect of hydrazine on the oxidation of Victoria Blue 4- R by KBrO3, was developed and validated. Kinetic parameters are reported for both the indicating and the inhibiting reaction. The detection
limit was established as 9.98×10−8 mol dm−3. The selectivity of the proposed method was tested considering the influence of different ions that may be present in real
samples. The method was successfully applied for hydrazine determination in various samples (very pure water from the water-steam
system of a power plant and Isoniazid tablets, a pharmaceutical product).
相似文献
18.
In this study, a series of new 5-phenylazo-6-aminouracil dyes were prepared by linking m-,p-nitroaniline, m-,p-chloroaniline,
m-,p-anisidine, m-,p-toluidine, m-,p-cyanoaniline, p-ethoxyaniline, p-phenoxyaniline, p-ethylaniline, p-acetamidoaniline,
p-acetylaniline, p-carboxyaniline and aniline to 6-aminouracil. The prepared dyes were characterized by UV-vis, FT-IR, 1H NMR spectroscopic techniques and elemental analysis. The effect of acid and base upon the UV-vis spectra of these dyes were
investigated. In addition, the solvatochromic behaviors and substituent effects in various solvents were evaluated.
相似文献
19.
Mónica Díaz-Pérez Manuel Aboal-Somoza Pilar Bermejo-Barrera Adela Bermejo-Barrera 《Central European Journal of Chemistry》2008,6(4):520-525
Preliminary results of development of a direct and fast method of determination of antimony in samples of tap water using
GFAAS are presented. The found levels of antimony were lower than permitted for human consumption. A mixture of Pd and Mg(NO3)2 (concentrations in the injected solution: 8.6 μg mL−1 and 5.8 μg mL−1 respectively) was used as the chemical modifier. The pyrolysis and atomization temperatures were 1000 and 1700°C, respectively
and the mean analytical recovery 98.2%.
相似文献
20.
Abdülhadi Baykal Nermin Kasapoğlu Yüksel Köseoğlu Ali Cemil Başaran Hüseyin Kavas Muhammet S. Toprak 《Central European Journal of Chemistry》2008,6(1):125-130
A series of Ni-doped cobalt ferrites NixCo1−xFe2O4 (x = 0.0, 0.4, 0.6, 0.8, and 1.0) were prepared using microwave-induced combustion. Nickel, cobalt, and ferric nitrates were
used as starting materials and glycine as fuel. The influence of Ni content on the lattice parameter, stretching vibrations,
and magnetization was studied. XRD, FTIR, and SEM were used for structure, composition, and morphology investigation. A porous
network structure was observed with average particle size 60–67 nm. All samples had a cubic spinel structure. The unit cell
parameter “a” decreases linearly with nickel concentration due to the smaller ionic radius of nickel. Magnetization measurements
showed that coercivity decreased as Ni content increased; it increased with decreasing temperature.
相似文献