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121.
Chemical modification of silica surface by immobilization of functional groups for extractive concentration of metal ions 总被引:11,自引:0,他引:11
Increased utilization of mechanically stable synthetic matrices particularly silica gel as a solid support and its surface modification either by impregnation of organic ligands directly or covalent grafting through spacer unit for extractive concentration of trace elements are highlighted in the present article. Experimental evidences for existence of surface silanol and its chemical nature have explored the idea of silica surface modification. Recent methods of development in functionalized silica synthesis by attachment of various ligands or organic reagents to the silica surface and techniques of characterization of the modified surface have been reported. Analytical applications of various modified silica surfaces, in particular, adsorption of trace elements taking separation and preconcentration into account from complex synthetic mixture as well as natural water is presented. 相似文献
122.
Metal (M) oxide (M: Ir, Os, Pd, Pt, Rh, Ru) together with MaO2 and MnO2 alone, were coated on SnO2 films and the anode behavior was examined in 1.0 N H2SO4, 1.0 N NaOH and 1.0, N NaCl aqueous solutions at 25°. The results are compared with those of DSA and of metallic Pt. 相似文献
123.
A need for an elaboration of the methods for synthesis and characterization of activated carbons with a requisite porous structure has existed for a long time. One of the methods giving possibility for creating controlled mesopore and micropore structures deals with the steam gasification of various carbon materials. In this work the effects of calcium catalyst on the catalytic steam gasification of active carbons from plum stones and porous polymers are presented. Determination of micropores capacity and specific adsorption in mesopores have been performed by means of the
s
method, but adsorption on the heterogeneous solids was described by the integral equation with various local isotherms. This equation has been solved by the regularization method. Based on this method the changes in structural parameters of active carbons depending on the amount of calcium catalyst were estimated.Nomenclature
d
width of slit-like micropore
-
F(x)
distribution function of the half-width
-
p
vapor pressure of sorbate
-
p/p
N
relative pressure
- PSAC
Plum Stone Active Carbon
-
average pore radius, nm
-
S
1
relative limit of the validity of experimental point on the adsorption isotherm in the computations by means of regularization method
- SAC
Synthetic Active Carbon
-
S
BET
specific surface area calculated by means of BET method, m2/g
-
S
mes
mesopore surface area, m2/g
-
S
mic
micropore surface area, m2/g
-
T
absolute temperature, K
-
V
mes
sorption capacity of mesopores, cm3/g
-
V
mic
sorption capacity of micropores, cm3/g
-
V
p
sorption capacity of pores, cm3/g
- w/w
weight in weight concentration
-
x
half-width of slit-like micropore, nm
-
x
1
maximum of half-width of micropore slit, nm
-
average half-width of slit-like micropore, nm
-
X
min-X
max
integration limits of thex
Greek Letters Greek Letters
variance of average half-width of slit-like micropore, nm2
-
local relative filling of micropores
-
total relative filling of micropores 相似文献
124.
Wolfgang?Gutleben Verena?Unterholzner Dietmar?Volgger Andreas?ZemannEmail author 《Mikrochimica acta》2004,146(2):111-117
In the course of this investigation, a method for the characterization and differentiation of paper pulps was developed. After hydrolyzation of the papers and the respective raw pulps with trifluoroacetic acid, the hydrolyzates were analyzed with respect to their carbohydrate composition using ion exchange chromatography. The variations in carbohydrate composition mainly arise from the various hemicelluloses of the papers and pulps. The chromatographic results were then further processed using principal component analysis which allows correlating the various papers to different pulp materials. 相似文献
125.
Fabrication of high performance thin films from metal fluorocomplex aqueous solution by the liquid phase deposition 总被引:1,自引:0,他引:1
Hnin Yu Yu Ko Minoru Mizuhata Akihiko Kajinami Shigehito Deki 《Journal of fluorine chemistry》2003,120(2):157-163
The hetro-structured oxide thin films from metal fluorocomplex solution have been prepared by the liquid phase deposition (LPD) method. The Pt/Nb2O5 and Au/Nb2O5 composite films can be prepared from a mixed solution of niobium source, H3BO3, Pt(NH3)4Cl2 and HAuCl4 aqueous solutions under the ambient temperature and atmosphere. In the case of Au/SiO2 composite film, (NH4)2SiF6 solution is used as a mother solution. The Pt and Au ionic species are deposited in Nb2O5 and SiO2 matrices. They are reduced to their metallic state after treatment above 200 °C. The size of dispersed particles can be controlled by heat treatment temperature. It is also clear that, gold nanoparticles are also found to interact with SiO2, although the interaction is smaller than that with Nb2O5 showing the size of Au nanoparticles remain smaller in Nb2O5 that in SiO2. 相似文献
126.
127.
用原子吸收法或极谱法测定了对例慢性肾炎病人(A组)和24例慢性肾衰病人(B组)及40名健康人(对照组,C组)全血中的Fe、Zn、Cu、Mn、Se、Pb和Ga含量。结果表明,A组与C组比较.血中Fe的含量A组明显低于C组(P<0.05),Zn、Mn和Se的含量A组均非常明显低于C组(P<0.01),Pb含量A组非常明显高于C组(P<0.01),Cu和Ca含量两组间均无明显差异(P>0.05);B组与C组比较,Fe含量B组明显低于C组(P<0.06),Se含量则B组明显高于C组(P<0.05);Zn、Mn、Cu、Ga含量B组均非常明显低于C组(P<0.01),而Pb含量则B组非常明显高于C组(P<0.01)。 相似文献
128.
简要总结了我们在C=C及C=O双键低温加氢双金属催化剂方面的最新研究成果. 首先, 我们以环己烯加氢为探针反应, 证明了平行使用多种研究手段的重要性, 包括单晶表面的基础研究与DFT计算, 多晶表面的合成与表征, 负载型催化剂的制备与性能测试等. 其次, 总结了双金属催化剂在其他加氢反应, 如丙烯醛C=O双键的选择性加氢, 苯的低温加氢, 以及乙炔的选择性加氢等反应中的应用. 最后, 讨论了利用金属碳化物代替贵金属Pt以减少双金属催化剂中Pt用量的可能性. 相似文献
129.
130.
常压气相氧化羰基化合成碳酸二乙酯 总被引:3,自引:0,他引:3
碳酸二乙酯是一种重要的有机化工原料,可广泛用于合成农药如脱叶灵,医药如喹啉酮衍生物,中间体3-氧硫代羧酸酯,还可用于电子管阴极的镀层[1-3]。生产碳酸二乙酯的传统方法为:无水乙醇与光气反应生成氯甲酸乙酯,氯甲酸乙酯继续与乙醇反应生成碳酸二乙酯后经水洗蒸馏制成。使用光气为原料对设备的要求较高。我们在常压下气相羰基化合成碳酸二乙酯[4]:2NO+C2H5OH+0.5O2→2C2H5ONO+H2O(1)CO+2C2H5ONO→(C2H5O)2CO+2NO(2)产生的一氧化氮可与氧气和乙醇进行反应再生为亚硝酸乙酯,符合原子经济反应且几乎不放出对… 相似文献