SYNTHESIS AND CRYSTAL-STRUCTURE OF HETEROPOLY MOLYBDOSILICIC LANTHANIDE K10H3[PR(SIMO11O39)2].18H2O

The intensity data of the title complex were collected at a low temperature of -90-degrees-C. The compound crystallizes in the monoclinic space group P2(1)/n, a = 17.504(2), b = 27.323 (5), c = 21.616(4) angstrom, beta = 104.49 (2)degrees, Z = 4. The structure was solved by Patterson and Fourier techniques and refined by least-squares to an R = 0.088 for 8320 independent reflections. The central Pr ion is bonded to eight oxygen atoms from two molybdosilicic heteropoly ligands to form a square antiprism. The Pr-O average distance is 2.44 (2) angstrom. Both molybdosilicic heteropoly ligands are of a defective alpha-Keggin structure.

INVESTIGATION OF CETYLPYRIDINIUM BROMIDE ADSORPTION AT A GLASSY-CARBON ELECTRODE SURFACE BY SPECTROELECTROCHEMISTRY WITH A LONG OPTICAL-PATH LENGTH THIN-LAYER CELL

The adsorption of cationic surfactant cetylpyridinium bromide (CPB) on a glassy carbon (GC) electrode surface has been studied by spectroelectrochemistry with a long optical path length thin-layer cell (LOPTLC) for the first time. A fine adsorption isotherm of CPB molecules from an aqueous solution containing 0.10 M KBr has been obtained over the range of (1.00-8.00) x 10(-5) M. From theoretical calculation and experimental data, adsorption of CPB on the GC electrode surface shows four distinct orientations and three large orientation transitions. Compared with the ordinary isotherm, the differential isotherm is more characteristic and would be suitable for the study of orientation transitions of organic compounds. With a theoretical treatment of the adsorption isotherm, four orientations of adsorbed CPB on a GC electrode surface coincide with the Frumkin-Langmuir type. From adsorption parameters the Frumkin-Langmuir equations, the adsorption free energy and, therefore, the equilibrium constants of orientation transitions of the CPB molecule can be obtained.

A NEW KIND OF CONDUCTING POLYMER POLYPYRROLE (PPY) BR- ION CHEMICAL SENSOR

The modification of conducting polymer polypyrrole(PPy) on glassy carbon(GC)by electrcchemical technique, and the study on doping effect of Br anion and electrochemical behavior of PPy film electrode were reported.A new kind of Br~- ion selective electrode has been prepared successfully.The mechanism of the electrode potential response is based on the doping effect of anion in the conducting polymer.Effect of polymerization conditions on the potential response characteristic is investigated in dtail.The PPy...

化学修饰电极的研究在电化学聚合的钴原卟啉薄膜电极上氧还原反应的电催化和动力学

用循环伏安法(CV),旋转圆盘和环盘电极(RDE和RRDE)研究了电化学聚合的钴原卟啉二甲酯薄膜玻碳电极〔聚(CoPP)/GC〕对氧还原反应的电催化和动力学。在不同pH缓冲溶液中,在聚(CoPP)/GC电极上氧的还原反应主要为二电子还原为H_2O_2的过程。实验表明,当聚(CoPP)薄膜在玻碳(GC)表面的覆盖度(Γ)大于6×10~(10)mol/cm~2时,催化反应受聚(CoPP)薄膜内电荷传输过程控制;当Γ值小于6×10~(-10)mol/cm~2时,受聚(CoPP)与氧分子间的催化反应速率控制。随电位负移,i_k,ΚΓ,n和K值均增加;随Γ值或溶液pH增加,i_k,ΚΓ和K值减小,而n值略有增加。

松花江水系有机污染的现状

本文介绍了GC、GC/MS、HPLC方法在分析松花江水系有机污染物中的应用。GC/MS、HPLC所用水样在现场处理,而TLC、GC样品在实验室处理。冬夏两次取样,共检出152种有机化合物,其中主要有机污染物55种,PAH_3占19％,氯化物占14％,芳烃占13％,其它占54％。

新型导电聚合物——聚吡咯溴离子化学传感器

本文用电化学方法把导电聚合物聚吡咯(PPy)修饰在玻碳(GC)电极上,研究了Br~-离子的掺杂效应和薄膜电极的电化学行为,研制一种新型Br~-离子选择电极,电极的响应机制是基于导电聚合物中阴离子的掺杂效应,详细研究了聚合条件对电极电位响应性能的影响,电极具有内阻小、响应快、抗毒化能力强、制备简便等优点,电极对1×10~(-1)—1×10~(-4)MBr~-呈能斯特响应,检测下限7×10~(-5)M,斜率61mV/PBr~-。本文结果是化学修饰电极技术在化学传感器方面应用的有意义的尝试。薄膜的良好导电性质使之更易于制备离子敏感电子学器件和生物电子学器件。

TRANSPORT OF ELECTROACTIVE SPECIES FE-2+ THROUGH THIN-FILMS OF VANADIUM HEXACYANOFERRATE

It is demonstrated that the electroactive species Fe~(2+) ion can transport easily through the thin films of vanadium hexacyanoferrate (VHF) to the underlaying glassy carbon (GC)electrode surface to be oxidized directly at less positive potential and that it can also be oxidized at the film at more positive potential through the media- tion of redox sites in the film. These two processes yield sequentially clearly distinguished first and second wave in stationary current-potential curves resulting...

INVESTIGATION OF MICROSTRUCTURE AT IRON TETRAPHENYLPORPHYRIN MODIFIED CLASSY CARBON ELECTRODE BY XPS

Microstructure of the glassy carbon surface modified with iron tetraphenyfporphyrin (FeTPP) by heat treatment has been studied by XPS,, DTA and TG. XPS spectra of Fe 2P_3\2 level in FeTPP and iron tetraphenylporphyriu/glassy carbon (FeTPP/GC) have shown that a bond can be formed between the glassy carbon surface and both the central metal iron ion and the macrocyclic, ligand, which loses its four phenyl groups during the beat treatment. The relationship between the surface mierostructure of FeTPP/GC and the...

气提浓缩仪分析水中痕量挥发性有机物研究

本文描述了气提浓缩仪的设计及操作程序用于对水中痕量挥发性有机物的测定。分析物被气提吸附于TenaxGC柱上,然后直接脱附到毛细管气相色谱柱上进行分析,并用FID或MS鉴定。本文除对色谱条件进行优化外,对气提时间和脱附温度等分析操作条件也进行了研究。检测下限为0.01-0.30PPb,峰面积检测精度优于6.9％,对16种化合物的回收率优于74％。