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Separation and Determination of Sulfur with Different Valance in Polysulfide Mixture

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Journal of Central South University 2000年第3期12卷 149-151页

作者： ZHOU Ji-hong chen qi-yuan ZHANG Ping-min YIN Zhou-lan College of Chemistry and Chemical Engineering Central South UniversityChangsha 410083China

A new process of separating sulfur with different valance from polysulfide mixtures was developed. Sulfide, sulfite and sulfur were separated by adding acetic acid in one step. The polysulfide mixture, sulfite solution and sulfur were oxidized to sulfate by hydrogen peroxide. The products were measured by X ray Fluorescence Spectrometer(XRF) using filter method preparative specimen. The measurement needs only one set of standard *** effects of temperature and pH values on the separation were discussed. The results show that the recoveries range from 98.0% to 101.3% of sulfidic sulfur S( II), 97.0% to 103.0% for sulfite S(IV) and 98.4% to 100.4% for polysulfidic sulfur S(0).

关键词： polysulfide separation determination X ray fluorescence spectrum valance

Kinetic study of LiMn2O4 in process of lithium intercalation

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Journal of Central South University of Technology 2005年第z1期12卷 72-75页

作者： XU Ming-fei LI Xing-hai chen qi-yuan School of Metallurgical Science and Engineering Central South University Changsha 410083China School of Chemistry and Chemical Engineering Central South University Changsha 410083China School of Metallurgical Science and Engineering Central South University Changsha 410083China School of Chemistry and Chemical Engineering Central South University Changsha 410083China

Exchange current density of spinel LiMn2 O4 was studied by linear polarization. The relationship of the kinetic property with the structure of spinel LiMn2 O4 was investigated by studying the effect of the doping and surface coating on the kinetic properties of electrode material. The results show that the exchange current density of spinel LiMn2 O4 electrode increases with the increase of the amount for lithium intercalation at first, and then decreases. The maximal exchange current density appeares at the 80%-90% lithium intercalation. The similar phenomenon was observed on the doped spinel LiMn2 O4 electrode. Doping can enhance the exchange current density of spinel LiMn2 O4 material. However, the degree of the doping effect varies with the doped element varying. Surface coating can also enhance the exchange current density of spinel material, and the increment of value is higher than that of doped ones.

关键词： kinetic exchange current density spinel LiMr2O4 doping surface coating

Thermal behaviors of deactivation catalysts for synthesizing 2, 3, 5-trimethylhydroquinone

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Journal of Central South University of Technology 2005年第z1期12卷 65-67页

作者： qiAN Dong SHI Ai-hua chen qi-yuan LIU Zhi-jian School of Chemistry and Chemical Engineering Central South University Changsha 410083 China State Key Laboratory of Powder Metallurgy Central South University Changsha 410083 China Sinopec Changling Catalyst Division Yueyang 414012 China School of Chemistry and Chemical Engineering Central South University Changsha 410083 China School of Chemistry and Chemical Engineering Central South University Changsha 410083 China State Key Laboratory of Powder Metallurgy Central South University Changsha 410083 China

The thermal behaviors of the deposits on supported noble metal catalysts for synthesizing 2, 3, 5-trimethylhydroquinone by DSC were studied. The results show that the supported Pd catalysts have two exothermic peaks at around 312 ℃ and 435 ℃ in the DSC thermograms, respectively, while the supported Pt catalysts have one exothermic peak at approximately 345 ℃. Therefore, it is supposed that the adsorptive states of deposits on supported Pt catalysts and supported Pd catalysts are different, which may be one reason leading to the stability difference between supported Pt catalysts and supported Pd catalysts.

关键词： deposit supported Pd catalysts supported Pt catalysts DSC

Leaching kinetics of low-grade copper ore with high-alkality gangues in ammonia-ammonium sulphate solution

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Journal of Central South University 2012年第1期19卷 77-84页

作者： LIU Zhi-xiong YIN Zhou-lan HU Hui-ping chen qi-yuan School of Chemistry and Chemical Engineering Central South UniversityChangsha 410083China College of Chemistry and Chemical Engineering Jishou UniversityJishou 416000China

The leaching kinetics of low-grade copper ore with high-alkality gangues was studied in ammonia-ammonium sulphate *** main parameters,such as ammonia and ammonium sulphate concentrations,particle size,solid-to-liquid ratio and reaction temperature,were chosen in the *** results show that the increase of temperature,concentrations of ammonia and ammonium sulphate is propitious to the leaching rate of copper *** leaching rate increases with the decrease of particle size and solid-to-liquid *** leaching rate is controlled by the diffusion through the ash layer and the activation energy is determined to be 25.54 kJ/mol.A semi-empirical equation was proposed to describe the leaching kinetics.

关键词： leaching kinetics ammonia-ammonium sulphate solution low-grade copper ore high-alkality gangues

Synthesis and characterization of arsenate antimonic acid AAAc(1 : 1)

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Journal of Central South University of Technology 2005年第z1期12卷 76-81页

作者： WANG Xue-wen chen qi-yuan YIN Zhou-lan ZHANG Ping-min WANG Yu-wen School of Metallurgical Science and Engineering Central South University Changsha 410083 China School of Chemistry and Chemical Engineering Central South University Changsha 410083 China School of Chemistry and Chemical Engineering Central South University Changsha 410083 China School of Chemistry and Chemical Engineering Central South University Changsha 410083 China Chemistry Department Jinggangshan Normal College Ji''an 343009 China

The AAAc(1 : 1) was synthesized in water by As2O3 and Sb2O3 with molar ratio of 1 : 1: AAAc(1 : 1)was characterized by Raman, IR, TG/DTG, DSC, XPS and XRD. The results show that there are four peaks to vsof As-OH, As-O-Sb, Sb-OH and Sb-O-Sb in Raman spectra of AAAc(1 : 1) at 100 - 1 000 cm-1. The solution of AAAc(1 : 1) was also titrated with KOH solution. The titration results show that AAAc(1 : 1) is a hexabasic acid with dissociation constants of k1 = 3.62 × 10-2 , k2 = 3.05 × 10-3 , k3 = 6. 43 × 10-6 , k4 = 9. 78 × 10-8 ,k5 = 1.32 × 10-11 , k6 =3.87 × 10-12. AAAc(1 : 1) has a good solubility and stability in water, its solid obtained by free volatilizing water from its solution under air at ambient temperature is amorphous. Chemical and thermal analyture of AsO ( OH )2-OH-Sb ( OH )4-O-Sb ( OH )4-OH-AsO ( OH )2 or As ( OH )3-O-Sb(OH)4-O-Sb(OH)4-O-As(OH)3 (isomerism) through experimental determination and geometry optimization.

关键词： arsenic acid antimonic acid arsenate antimonic acid

Synthesis and Thermal Stability of Antimony Tris (Thioethyl Stearate) for PVC

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Journal of Central South University 2000年第3期12卷 146-148页

作者： LIU You nian,WANG Chun jiang,SHU Wan gen,ZENG Dong ming,chen qi yuan (College of Chemistry and Chemical Engineering, Central South University, Changsha 410083, China) 1. College of Chemistry and Chemical Engineering Central South University 410083 Changsha China

A novel type of thermal stabilizer-antimony tris (thioethyl stearate) (ATS) was synthsized. Its thermal stability was measured by heat-aging oven test when incorporated into PVC. ATS was synthesized from stearic acid, antimony trioxide and 2-mercaptoethanol in two steps. The reaction conditions of synthesis were optimized through orthogonal test. Experimental results show that the molar ratio of stearic acid and antimony tris (2-hydroxyethylthiolate) was 1.2, adding 0.6%tetra-n-butyl titanate as catalyst and xylene as azeotropic solvent, heating and refluxing for about 4 h, and the yield of ATS is 83.9%. The thermal stability time is about 40 min(at 200 °C) when added 2phr(per hundred resin) in PVC. The thermal stability of ATS is better than that of Ca-Zn complex and basic lead stabilizers, and equal to that of dibutyltin dilaurate.

关键词： thermal stabilizer antimony thiolate synthesis thermal stability

Negative effect of dissolved organic compounds on settling behavior of synthetic monominerals in red mud

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Journal of Central South University 2016年第7期23卷 1591-1602页

作者：王梦胡慧萍刘锦伟陈启元 School of Chemistry and Chemical Engineering Central South University

Hydration grossular and hematite monominerals were synthesized. The effects of dissolved organic compounds(including sodium formate, sodium acetate, sodium oxalate, sodium salicylate or disodium phthalate) on the settling performance of hydration grossular or hematite slurries were studied. The settling of the slurries was also investigated with the addition of sodium polyacrylate(PAAS) or hydroxamated polyacrylamide flocculant(HCPAM). The adsorption mechanism of organic compounds on monominerals surfaces was studied by FT-IR and XPS, respectively. A deterioration in settling is observed in order of disodium phthalate>sodium salicylate>sodium oxalate>sodium formate(or sodium acetate). Moreover, PAAS can efficiently eliminate the negative effects of organic compounds on the settling performance of the hydration grossular slurry. HCPAM can efficiently eliminate the negative effects of sodium formate, sodium acetate and sodium oxalate on the settling performance of the hematite slurry, but it only partially improves the settling performance of hematite slurry containing sodium salicylate or disodium phthalate. FT-IR and XPS results show that organic compounds are physically adsorbed on hydration grossular surface, and chemisorptions of organic compounds occur on hematite surface with a bidentate chelating complex.

关键词： hydration grossular hematite dissolved organic compounds settling performance simulated bayer digestion

Synthesis of modified polyacrylamide with high content of hydroxamate groups and settling performance of red mud

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Journal of Central South University 2015年第6期22卷 2073-2080页

作者：刘锦伟胡慧萍王梦陈湘攀陈启元丁治英 College of Chemistry and Chemical Engineering Central South University

Hydroxamated polyacrylamide（HPAM） was synthesized from polyacrylamide（PAM） with high relative molecular mass under the optimum reaction conditions（p H 12 and a molar ratio of hydroxylamine to amide groups of 1.5 at 50 ℃for 12 h）. The hydroxamate groups of HPAM were verified by Fourier transform infrared spectrum（FT-IR）. 46%（molar fration） hydroxamate groups and 23%（molar fraction） carbonyl groups on HPAM were determined by conductometric titration combined with Kjeldahl＇s microanalysis method. The settling performance achieved at different flocculant dosages was investigated with high goethite-containing red mud slurry of simulated Bayer process synthesized in laboratory. It turns out that the settling performance of high goethite-containing red mud was better with HPAM. The average settling rate of red mud in the first 5 min and the turbidity of supernatant after settling for 30 min are 2.36 m/h and 507 NTU, respectively, at a flocculant dosage of 120 g/t, which is similar to that achieved with Hx-600.

关键词： hydroxamated polyacrylamide symhesis red mud settling performance

Effects of Polymeric Flocculants on Settlement of Bayer Red Mud Generated from Chinese Diaspore Bauxite

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过程工程学报 2008年第2期8卷 267-273页

作者：张琨瑜胡慧萍张丽娟陈启元 College of Chemistry and Chemical Engineering Central South University Changsha Hunan 410083 China

A systematic investigation on the interaction between Bayer red mud particles generated from Chinese diaspore bauxite and commercial sodium polyacrylate(SPA) or polyacrylamide(PAM) was performed by red mud settling tests,conductivity-pH titration and Ubbelodhe viscosimetric *** results indicate that the treatment with red mud by SPA gives a lower red mud settling rate and lower supernatant turbidity than the treatment with red mud by *** is an optimum polymer dosage of 300 g/t(based on the weight of dry red mud) when red mud slurry is treated by SPA or PAM,so 'bridging' adsorption is one of the main interactions between red mud and SPA or *** the increase of NaOH concentration,the hydrolysis degree of PAM dissolved in NaOH solution increases and its molecular weight almost does not change,but the settling rate of red mud treated by it drops *** settling rate of red mud treated by PAM dissolved in 10 g/L NaOH solution is 0.61 m/h while by PAM dissolved in distilled water it is 1.31 m/h,because the adsorption ability of the hydrolyzed PAM onto red mud surface declines primarily due to the formation of-CONH2～-COO-～-CONH2 intramolecular hydrogen bond。

关键词：高分子絮凝剂水铝石矾土中国赤泥净化聚落氧化铝