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11.
Zhen Jun WANG* Zheng Hua SONG Department of Chemistry Northwest University Xian 《中国化学快报》2003,14(3):283-286
Benzoicacidisacommonadditiveusedwidelyasfoodpreservativeandplasticizer.Itcouldpromoteseverereactiontoallergicpopulationevenatlowconcentrationlevel1.Routinemethodsfortheassayofbenzoicacidincludeschromatographic2-6,spectrophotometry7,8,capillaryelectrophoresis9-13andelectrochemicaltitration14.Stokes15etal.monitoredairbornebenzoicacidbasedonsurface-enhancedRamanscatteringtechniques.Thereisalsoreportonamicrobialsensorusingpseudomonasforbenzoicacidandtheirderivativesinaqua16.Interestofusinglumines… 相似文献
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Summary Due to the carcinogenity and ubiquity of polycyclic aromatic hydrocarbons in the environment they are of ongoing interest
to analytical chemistry. In this study, a comparison of the classic Soxhlet extraction and, fluidized-bed extraction, has
been conducted. The extraction of polycyclic aromatic hydrocarbons by this technique has been optimized considering as experimental
variables the variation of the number of extraction cycles and the holding time after reaching the heating temperature by
means of a surface response design. The significance of the operational parameters of the fluidized-bed extraction on the
performance characteristics has been investigated. For the determination of the analytes a selective clean-up of the extracts
followed by a fast gas chromatography method with mass spectrometric detection was used, resulting in low limits of detection
(0.2 pg μL−1). The accuracy of the complete analytical method was established by extraction and analysis of reference materials. 相似文献
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16.
建立了耐硫甲烷化循环式反应器的拟均相一维模型,考察了床层直径,循环比,入口气体温度及压力和温度范围对反应器操作的影响,结果表明:循环比和温度操作范围是反应器操作的决定因素,对日产5万标准立方煤气的反应器进行了优化设计分析。 相似文献
17.
聚乙烯塑料在连续超临界水反应器中的油化研究 总被引:1,自引:1,他引:1
在连续超临界水(SCW)反应器中考察了反应温度、停留时间和反应压力对聚乙烯(PE)降解油化的影响。实验结果表明,在120s、25MPa下,从500℃提高到550℃,液体收率呈现先升后降的趋势,在530℃达到最大值(79%);在520℃、25MPa下,随停留时间的延长,PE裂解程度加深,产物轻质化程度提高,导致液体收率降低,停留240s时,气体收率达到43%;反应压力对产物收率的影响较小,气、液产物中烯/烷比随反应压力的增加而增大。 相似文献
18.
Pulverized coal plasma gasification 总被引:11,自引:0,他引:11
R. A. Kalinenko A. P. Kuznetsov A. A. Levitsky V. E. Messerle Yu. A. Mirokhin L. S. Polak Z. B. Sakipov A. B. Ustimenko 《Plasma Chemistry and Plasma Processing》1993,13(1):141-167
A number of experiments on the plasma-vapor gasification of brown coals of three types have been carried out using an experimental plant with an electric-arc reactor of the combined type. On the basis of the material and heat balances, process parameters have been obtained: the degree of carbon gasification (c), the level of sulfur conversion into the gas phase (s), the synthesis gas concentration (CO+Hz) in the gaseous products, and the specific power consumption for the gasification process. The degree of gasification was 90.5-95.0%, the concentration of the synthesis gas amounted to 84.7–85.7%, and the level of sulfur conversion into the gas phase was 94.3–96.7%. Numerical study of the process of plasma gasification of coals was carried out using a mathematical model of motion, heating, and gasification of polydisperse coal particles in an electric-arc reactor of the combined type with an internal heat source (arc). The initial conditions for a conjugate system of nonlinear differential equations of the gas dynamics and kinetics of a pulverized coal stream interacting with the electric arc and oxidizer (water vapor) agree with the initial conditions of the experiments. The computation results satisfactorily correlate with the experimental data. The mathematical model can be used for the determination of reagent residence time and geometrical dimensions of the plasma reactor for the gasification of coals.Nomenclature
c
i
volume concentration of components (kmol m–3)
-
x
longitudinal coordinate (m)
-
f
i
source members, determined by variation of the ith component due to chemical reactions in unit volume in unit time (kmol m–3s–1)
-
velocity (m s–1)
-
M
s
ash mass in one particle (kg)
-
C
D
particle drag coefficient
-
3.14
-
r
s
particle radius (m)
-
d
particle diameter (m)
-
density (kg m–3)
-
C
p
heat capacity of components (J molt– K–1)
-
Q
j
thermal effect of reaction (J kmol–1)
- Ej
activation energy of reaction
-
N
l
volume concentration of particles of thelth fraction (m–3)
-
T
temperature (K)
-
emissivity factor of coal particles
-
5.67 × 10–8, blackbody emissivity coefficient (W m–2 K–4)
-
P
pressure (Pa)
-
S
reactor cross section (m2)
-
D
reactor diameter (m)
-
V
reactor volume (m3)
-
L
R
reactor length (m)
-
F
W
friction force on the wall (N)
-
f
g
friction coefficient
-
residence time (s)
- Nu
Nusselt number
- Re
Reynolds number
- Pr
Prandtl number
-
thermal conductivity of gas (J m– s–1 K–1)
-
R
8.3 × 103, universal gas constant (J kmol K–1)
- µ
i
molecular mass of component (kg kmol–1)
-
dynamic viscosity coefficient of gas (kg m–1 s–1)
-
thermal efficiency of plasma reactor
- qarc
specific heat flow from arc (W m–3)
-
P
1
heat supplied in vapor at T = 405 K (W)
-
P
2
heat loss to wall (W)
-
P
3
heat loss in the gas and slag separator chamber (W)
-
P
4
heat loss in the synthesis gas oxidation chamber (W)
-
P
5
heat loss in the slag catcher (W)
-
P
6
heat carried away in the off-gas (W)
- P
heat input of arc (W)
-
P
arc
electric power of arc (W)
- Qsp
specific power consumption (kw Hr kg–1)
-
d
w
specific heat flow to wall (W m–2)
-
c
degree of carbon gasification (%)
-
s
level of sulfur conversion into gas phase (%) 相似文献
19.
20.
Z. P. Lu L. Stachowicz P. Kong J. Heberlein E. Pfender 《Plasma Chemistry and Plasma Processing》1991,11(3):387-394
Diamond crystals and films have been success full y synthesized by DC thermal plasma jet CVD at a pressure of I atrn. A novel triple torch plasma reactor has been used to generate a convergent plasma volume to entrain the participating gases. Three coalescing plasma jets produces! by this reactor direct the dissociated and ionized gaseous species onto ( 100) silicon wafer substrates where the diamond grows. In a typical 10-min run, depending on the method of .substrate preparation, either microcrystals with sizes up to 8 m or continuous films with thicknesses of 1–2 m have been obtained. X-ray diffraction, scanning electron microscopy, and Raman spectroscopy have been used for the characterization of the crystals and of the films. 相似文献