作者机构：
[冯泳兰; 匡云飞; 许金生] Department of Chemistry and Materials Science, Hengyang Normal University, Hengyang 421008, China;[余润兰] School of Minerals Processing and Bioengineering, Central South University, Changsha 410083, China
通讯机构：
Department of Chemistry and Materials Science, Hengyang Normal University, China
作者机构：
[Zeng, RY] Hengyang Normal Univ, Dept Chem & Mat Sci, Hengyang 421008, Peoples R China.;Guangxi Normal Univ, Dept Chem, Guilin 541004, Peoples R China.
通讯机构：
[Zeng, RY] H;Hengyang Normal Univ, Dept Chem & Mat Sci, Hengyang 421008, Peoples R China.
关键词：
lanthanum;ytterbium;amino acid;solution calorimetry;standard enthalpy of formation
摘要：
In order to obtain the standard molar enthalpies of formation of Rare-Earth amino acid coordination compounds, precise isothermal solution-reaction calorimetric method was used. The value of Δ<sub>r</sub>H<sub>m</sub><sup> [circled minus] </sup> of two coordination reactions was determined at T = 298.2 K. From the experimental results and other auxiliary values, the standard molar enthalpies of formation of Ln(Gly)<sub>5/2</sub>(Ala)<sub>3/2</sub>(ClO<sub>4</sub>)<sub>3</sub> ·H<sub>2</sub>O(s) [Ln = La, Yb] at T = 298.2K were obtained. The values of them is to be Δ<sub>r</sub>H<sub>m</sub><sup> [circled minus] </sup> [ La(Gly)<sub>5/2</sub>(Ala)<sub>3/2</sub>(ClO<sub>4</sub>)<sub>3</sub> ·H<sub>2</sub>O(s)] = -3545.45 kJ/mol and Δ<sub>r</sub>H<sub>m</sub><sup> [circled minus] </sup> [ Yb(Gly)<sub>5/2</sub>(Ala)<sub>3/2</sub>(ClO<sub>4</sub>)<sub>3</sub> ·H<sub>2</sub>O(s)] = -3793.81 kJ/mol, respectively.
摘要：
The corrosive electrochemistry of jamesonite was studied by cyclic voltammetry. Every peak in voltammograms was identified through thermodynamic calculation. The results show an irreversible electrode process by the strong adsorption of oxidation elemental sulfur on jamesonite. A deficient-metal and sulfur-rich compound is formed under the potential of 80 mV at pH 6.86. The passive action by elemental sulfur occurs from 80 to 470 mV and S2O23- , SO24- are produced at potential over 470 mV. The anodic peak producing SO24- is inhibited due to the deposition of PbSO4 at higher potential in Na2SO4 solution. The corrosive action of jamesonite becomes strong and the redox characterization similar to PbS, FeS and Sb2 S3 appears at pH 9.18.
作者机构：
[胡岳华; 邱冠周; Qin, Wen-Qing; 余润兰] Sch. of Resource Processing, Central South Univ., Changsha 410083, China;Dept. of Chem. and Mat. Sci., Hengyang Normal Univ., Hengyang 421008, China
通讯机构：
Sch. of Resource Processing, Central South Univ., China
摘要：
A novel method was described for the determination of ultra trace amount of scandium based on the cathodic adsorptive voltammetry of the mix-polynuclear complex of scandium-calcium-alizarin red S at a carbon paste electrode (CPE). The 2nd-order derivative linear scan voltammograms of the adsorbed complex were recorded by model JP - 303 polarographic analyzer from 0.0 to -1.0 V (vs. SCE). The experimental conditions of the working procedure were optimized. The results show that the complex can be adsorbed on the Surface of the CPE, yielding one peak at - 0.61 V, corresponding to the reduction of the alizarin red S in the mix-polynuclear complex at the electrode. The detection limit of Sc3+ is 1.0 x 10(-10) mol center dot L-1 for 3 min of accumulation time. The procedure was successfully applied to the determination of trace amount of scandium in the sample ores.
摘要：
The corrosive electrochemistry of jamesonite (Pb4 FeSb6 S14) was studied by the electrochemical methods of cyclic voltammetry, polarization, and AC impedance. The electrochemical processes of jamesonite were controlled by the corrosive reactions, growth of the metal-deficient and sulfur-riched layer, passivation and breakdown of elemental sulfur film on the electrode surface. The corrosive potential(ψcorr) moves negatively, its corrosive current increases, and hydroxyl action becomes stronger with the rising pH value. The charge transfer resistance increases and the capacitance decreases due to the gradual growth of the metal-deficient and sulfur-riched layer on the mineral surface from -378 to 122 mV (vs SHE). Element sulfur layer is formed at the potential of 122 mV. The charge transfer resistance increases and its capacitance rises slowly due to the gradual breakdown of sulfur film at voltage from 222 mV to 422 mV. S2O2-3 and SO2-4 ions occur when the electrode potential is over 422 mV. Under basic condition, the hydrophobic hydroxyl precipitate occurs on jamesonite surface, so that its collectorless floatability is poor. Under the condition of pH 6.86, it can be deduced that the potential range of collectorless floatability of jamesonite is from 22 to 422 mV due to the passive action of the hydrophilic sulfur on jamesonite surface, and its optimum range of floatable potential is between 122 and 322 mV.
作者机构：
[张复兴] Department of Chemistry, Hengyang Teachers' College, 421008 Hengyang, China;Hunan Normal University, China;Chemistry Department, Hengyang Teachers' College, China;Chinese Chemical Society, China;[邝代治] Department of Chemistry, Hengyang Teachers' College, 421008 Hengyang, China, Hunan Normal University, China, Chemistry Department, Hengyang Teachers' College, China, Chinese Chemical Society, China
通讯机构：
[Kuang, D.] D;Department of Chemistry, Hengyang Teachers' College, China
