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Studies on Determination of Ge in Au Alloys by Potassium Iodate potentiometric titration Method

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贵金属 2012年第A1期33卷 298-304页

作者： ZHU Liya ZHOU Yu TAN Yanshan LIU Wen LI Yong HAN Shouli TAN Wenjin HE Xiaotan WU Xilong XIE Hongchao CHEN Liangwei State Key Laboratory of Advanced Technologies for Comprehensive Utilization of Platinum Metals Sino-Platinum Metals Resources(Yimen)Co.Ltd.Kunming 650106China Yunnan Copper Co.Ltd. Dali 675600YunnanChina School of Materials Science and Engineering Kunming University of Science and TechnologyKunming 650093China

The paper presents a new method of determining Ge in gold alloys by potassium iodate potentiometric titration rather than by traditional distillation separation. The influences of conditions such as the reduction acidity, dosage of sodium hypophosphite and reduction time on the determination of Ge were studied. Comparison was made between the influences of end-point indication for potential method and starch method on accruracy and precision of the analysed results, stability and sensitivity of end-point, selectivity of method and so on. The possibility of reaction in an electrochemical way was discussed. Ge in the alloys such as AuGe 12 , AuGeNi 12 2 , AuAgGe 18.8 12.5 and AuAgGeNi 43.8 6 0.2 was measured, respectively, with the relative standard deviation of 0.10%~0.31% and the recoveries of added standard Ge in sample of 99.40%～100.40% when the reduction acidity was 0.40~0.80 mol/L HCl and 3.3 mol/L H 3 PO 4, 15 g sodium hypophosphite and reduction time 40 min. The new method presented is high accuracy and precision in results, good stability and sensibility in end point, easy operation and strong selectivity of determination. When it is applied to analyse actual samples, satisfactory results are achieved.

关键词： analytical chemistry germanium gold alloy potentiometric titration

Determination of Formation Constants of Co￣(2+), Ni￣(2+),Cu￣(2+) and Zn￣(2+) Complexes with Humic and Fulvic Acidsby potentiometric titration Method

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Pedosphere 1994年第4期4卷 289-296页

作者： DUJIN－ZHOU LUCHANG－QING 等 DepartmentofModernPhysics LanzhouUniversityLanzhou73000China InstituteofSoilScience ChineseAcademyo

The formation constants of Co￣(2+), Ni￣(2+), Cu￣(2+) and Zn￣(2+) complexes with humic acid (HA) and fulvicacid (FA) in red soil were determined by the potentiometric titration method. The constants as a functionof composition of the complexation solutions were obtained by two graphical approaches respectively Theformation constants decreased with increasing concentration of metal in the solution. The results provideunambiguous evidence for the heterogeneity of the function groups of humic substances. The formationconstants of FA were much smaller than those of HA, and the formation constants of Cu￣(2+) were muchgreater than those of Co￣(2+) , Ni￣(2+) and Zn￣(2+) . The potentiometric titration method for determining formationconstants are also discussed in the article.

关键词： formation constants of complexes humic and fulvic acids potentiometric titration red soil

Determination of Sulfides in FCC Gasoline by Using the potentiometric titration of Lead Tetraacetate

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Chinese Journal of Chemical Engineering 2004年第3期12卷 448-450页

作者：罗立文夏道宏 College of Chemistry and Chemical Engineering State Key Laboratory of Heavy Oil Processing University of Petroleum(East China) Dongying 257061 China College of Chemistry and Chemical Engineering State Key Laboratory of Heavy Oil Processing University of Petroleum(East China) Dongying 257061 Chinaompared with conventional method of violet spectrum determination of the content of sulfides in fluid catalytic cracking (FCC) gasoline by using the potentiometric titration of lead tetraacetate has some advantages such as clear potentiometric abrupt change at the stoichiometric point stable potentiometric value exact and credible results and simple operation. The content of sulfides in FCC gasoline of Shenghua refinery is 0.136% by this method. The standard deviation about this method is less than 0.01% and the relative standard deviation is less than 2.42%.

Compared with conventional method of violet spectrum, determination of the content of sulfides in fluid catalytic cracking (FCC) gasoline by using the potentiometric titration of lead tetraacetate has some advantages such as clear potentiometric abrupt change at the stoichiometric point, stable potentiometric value, exact and credible results, and simple operation. The content of sulfides in FCC gasoline of Shenghua refinery is 0.136% by this method. The standard deviation about this method is less than 0.01% and the relative standard deviation is less than 2.42%.

关键词： sulfide gasoline lead tetraacetate potentiometric titration

Counterion Binding in Aqueous Solutions of Poly(vinylpyridines) as Assessed by potentiometric titration

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Advances in Materials Physics and Chemistry 2016年第9期6卷 249-261页

作者： Jim D. Roach Mandy M. Bondaruk Abdulaziz Al-Abdulghani Zaid Shahrori Pre-Medical Education Unit Weill Cornell Medicine-Qatar Doha Qatar

The extent to which counterions bind to polyelectrolytes influences a variety of polymer-based applications, including polyelectrolyte enhanced ultrafiltration and forward osmosis using polyelectrolytes as draw agents. potentiometric titrations of poly (2-vinylpyridine) (P2VP), poly (3-vinylpyridine) (P3VP), and poly (4-vinylpydine) (P4VP) were performed using HBr, HCl, HNO3, and HClO4 in both the presence and absence of added NaCl. Because of the systematic differences among the three polyelectrolytes, titration results provide insight into the role of polymer structure in the relative extents to which various counterions bind. titration data reveal that ionization properties vary as functions of polymer investigated, titrant used, degree of protonation, and added salt concentration. Acid dissociation constants of the pyridinium moieties were found to generally increase with increasing degree of protonation, though appreciable differences were exhibited among the three polymers investigated. For all three polymers, Cl- demonstrated the lowest affinity for the charged pyridinium residues, while the affinities associated with Br- and NO-3 were nearly identical to each other. The relative extent of binding for CIO-4 varied across the polymers investigated, and was greatest for P4VP.

关键词： Poly(vinylpyridine) Counterion Binding potentiometric titration Perchlorate

The Amines and Phenols Existing in RFCC Gasoline Affect the Accuracy of potentiometric titration

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The Amines and Phenols Existing in RFCC Gasoline Affect the ...

Formation Equilibria of Ternary Metal Complexes with Citric Acid and Glutamine (Alanine) in Aqueous Solution

甘肃省化学会成立六十周年学术报告会暨二十三届年会

作者： Xingguo Cheng~(1,2), Luning Huang~3, Peixun Li~3, Zhide Hu~1, Lei Cao~2 (1 Department of Chemistry, Lanzhou University, Lanzhou 730000, PR. China 2 Lanzhou lube oil R(?)D institute of Petrochina, Lanzhou 730060. P.R. China 3 Department of Material science, Lanzhou University, Lanzhou 730000, P.R. China)

This paper described that there were two or more endpoints in the curve when potentiometeric titration was used to determine the contents of mercaptan sulfur in residue fluidized catalytic cracking (RFCC) gasoline. Comparing with the one endpoint of a mixture solution of C-SH to C-SH determined under the same conditions, we found some components in RFCC gasoline affected the result of titration. A facile method washing the gasoline with 2% HCl solution was brought out to eliminate the interfering components from the RFCC gasoline. After being treated with this method, all RFCC gasoline that contained 14 to 27 ug/mL mercaptan sulfur (SRSH) met the quality specification (SRSH shall not exceed 10ug/mL. The analysis of gas chromatography mass spectrometry (GC-MS) and gas chromatography infrared spectrometer (GC-IR) verified that the interfering components were aniline, phenol and their alkyl-substituted derivatives.

关键词： RFCC gasoline mercaptan potentiometric titration GC-MS GC-IR

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Journal of Rare Earths 2004年第1期22卷 183-186页

作者：王进平牛春吉杨魁跃倪嘉缵 Key Laboratory of Rare Earth Chemistry and Physics

The species and their formation constants in the ternary systems were obtained by the Scogs2 software from potentiometric titration data. The Comics software was used to calculate the distribution of species in the ternary systems. MLXH, MLXH 2 and MLXH 3 are the common species in these systems. The coordination behaviors of the rare earths are very similar and their stability is closely matched. The ternary rare earth complexes are more stable than the corresponding ternary complexes of calcium. The ternary zinc complex with glutamine as the secondary ligand is more stable than the corresponding complexes of rare earths, but the ternary complex with alanine as the secondary ligand shows an inverse trend. The distributions of species in the ternary systems vary with pH changing. A prediction can be made that exogenous rare earths can affect the species of Ca and Zn in human body.

关键词： physiology calcium zinc speciation potentiometric titration rare earths

Study on electric property at interface of positive sol of magnesium aluminum hydroxide

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Chinese Journal of Chemistry 1997年第4期15卷 304-312页

作者： Han, SH Xu, SP Hou, WG Sun, DJ Zhang, CG Wang, GT Institute of Colloid and Interface Chemistry Shandong University Jinan Shandong 250100 China

The isoelectric point (IEP) and zero point of charge (ZPC) of magnesium aluminum hydroxide were studied by electrophoresis method, potentiometric titration method, and elemental analysis. Results showed that the charge of magnesium aluminum hydroxide was composed of variable charge and permanent positive charge. Because of the permanent positive charge, the IEP and ZPC obtained were higher than calculated. The LEP decreased and ZPC increased as X increased.

关键词： magnesium aluminum hydroxide isoelectric point zero point of charge potentiometric titration

Physical Studies of Some Hydrazinobenzoic Acid Complexes

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Journal of Materials Science & Technology 2005年第1期21卷 140-144页

作者： M.G.Abd El Wahed S.Abd El Wanees M.El Gamel S.Abd El Haleem Faculty of Science Zagazig University Zagazig EgyptFaculty of Science Zagazig University Zagazig EgyptFaculty of Science Zagazig University Zagazig EgyptFaculty of Science Zagazig University Zagazig Egypt

The stability constants of complexes of 2-hydrazinobenzoic acid and 4-hydrazinobenzoic acid with Ni (Ⅱ), Cu (Ⅱ), Zn (Ⅱ), Cd (Ⅱ), and Hg (Ⅱ) were determined potentiometricaIly at different temperatures. The thermodynamic parameters, △G0, △H0, and △S0 were calculated and proved that the complexation process is spontaneous and endothermic. The thermodynamic functions were analyzed in terms of electrostatic and non-electrostatic components and the results reveal that ionic bonds are formed between the studied ligands and metal ions. Conductometric titration was shown that the stoichiometry of the formed complexes are M:L and M:2L. The structure of the prepared solid complexes was characterized using IR, 1H NMR, 13C NMR spectroscopies as well as X-ray diffraction technique. Finally electrical conductivity of the ligands and their copper complexes was measured and shown that the ligands have a semiconductor behaviour.

关键词： potentiometric titration Stability constants Thermodynamic parameters Structure of metal complexes

Some Interface Electrochemical Properties of Kaolinite

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Chinese Journal of Chemistry 2007年第6期25卷 756-764页

作者：焦燕妮侯万国 Key Laboratory for Colloid & Interface Chemistry of Education Ministry Shandong University Jinan Shandong 250100 China Environment Research Institute Shandong University Jinan Shandong 250100 China

The interface electrochemical properties of clay were theoretically analyzed to obtain some relationships among point of zero net charge （PZNC）, point of zero net proton charge （PZNPC）, intrinsic surface reaction equilibrium constants （K in 1-pK model, Ka1^int and Ka2^int in 2-pK model, ＊KNa^int and ＊KNO3^int in inert electrolyte chemical binding model） and structural negative charge density （σst） of clay, and some interface electrochemical parameters of kaolinite were measured. The following main conclusions were obtained. For clay possessing structural negative charges, the PZNC independent of electrolyte concentration （c） should exist just as amphoteric solid without structural charges such as oxides or hydroxides. A common intersection point （CIP） should appear among the potentiometric （or acid-base） titration curves at different c and the pH at the CIP should be PHPZNC. A CIP among potentiometric titration curves at different c for kaolinite was observed, and the value of PHPZNC of kaolinite was 2.16. The values of pHPZNPC were decreased with increasing c, which arises from the presence of structural negative charges of kaolinite. In addition, it was observed that a good linear relationship existed between pHPZNPC and 1g c. According to the values of PHPZNC and σst measured, the intrinsic surface reaction equilibrium constants, pK and pKa1^int and pKa2^int of 1-pK and 2-pK models could be directly calculated for clay, and the values of pK, pKa1^int and pKa2^int for kaolinite were 2.93, 1.90 and 3.97, respectively. These experimental values of pKa1^int and pKa2^int for kaolinite are obviously lower than those optimized with fitting programs in literatures, which maybe arises from the introduction of a type of permanent negatively charged sites in the models of literatures. An interesting result obtained in this study is that the inert electrolyte chemical binding does not exist for kaolinite, which also arises from the presence of structural negative charges.

关键词： clay kaolinite interface electrical property surface complexation potentiometric titration