摘要：
Magnetite concentrate was recovered from ferrous sulphate by co-precipitation and magnetic separation. In co-precipitation process, the effects of reaction conditions on iron recovery were studied, and the optimal reaction parameters are proposed as follows: n(CaO)/n(Fe~(2+)) 1.4:1, reaction temperature 80 °C, ferrous ion concentration 0.4 mol/L, and the final mole ratio of Fe~(3+) to Fe~(2+) in the reaction solution 1.9-2.1. In magnetic separation process, the effects of milling time and magnetic induction intensity on iron recovery were investigated. Wet milling played an important part in breaking the encapsulated magnetic phases. The results showed that the mixed product was wet-milled for 20 min before magnetic separation, the grade and recovery rate of iron in magnetite concentrate were increased from 51.41% and 84.15% to 62.05% and 85.35%, respectively.
摘要：
Proper utilization of the FeSO_4·7H_2O waste slag generated from TiO_2 industry is an urgent need, and Fe_3O_4 particles are currently being widely used in the wastewater flocculation field. In this work, magnetite was recovered from ferrous sulphate by a novel co-precipitation method with calcium hydroxide as the precipitant. Under optimum conditions, the obtained spherical magnetite particles are well crystallized with a Fe_3O_4 purity of 88.78%, but apt to aggregate with a median particle size of 1.83 μm. Magnetic measurement reveals the obtained Fe_3O_4 particles are soft magnetic with a saturation magnetization of 81.73 A·m~2/kg. In addition, a highly crystallized gypsum co-product is obtained in blocky or irregular shape. Predictably, this study would provide additional opportunities for future application of low-cost Fe_3O_4 particles in water treatment field.
期刊：
高分子材料科学与工程,2017年33(8):85-89 and 95 ISSN：1000-7555
通讯作者：
You, Yilan(hanbinzixuan@163.com)
作者机构：
[游一兰; 刘士军] College of Chemistry and Chemical Engineering, Central South University, Changsha;410083, China;[贺国文] College of Chemistry and Environmental Engineering, Hunan City University, Yiyang;413000, China;[李笃信] State Key Laboratory of Powder Metallurgy, Central South University, Changsha
通讯机构：
[You, Y.] C;College of Chemistry and Chemical Engineering, Central South University, Changsha, China
关键词：
聚酰胺6;混杂改性;摩擦磨损;力学性能
摘要：
采用石墨(Gr)、聚四氟乙烯(PTFE)和玻璃纤维(GF)改性聚酰胺6(PA6),以提高PA6的摩擦磨损性能和力学性能。重点研究了填料组合、配比、载荷和转速对复合材料摩擦磨损性能的影响,通过磨损表面形貌分析探讨了摩擦磨损机理。结果表明:Gr/PTFE/GF混杂改性PA6能明显降低摩擦系数并提高耐磨性,PA6/Gr/PTFE/GF质量比为70/5/10/15时摩擦系数和磨损率最低,且在高转速(40 N, 1500 r/min)下摩擦磨损性能更好,摩擦系数为0.08,比PA6降低了27%,磨损率为5.5×10~(-6) mm~3/(N·m),比PA6降低了1个数量级,且该复合材料的拉伸强度、冲击强度、储能模量和损耗模量都高于PA6。
作者机构：
[彭映林] School of Chemistry and Environmental Engineering, Hunan City University, Yiyang, 413000, China;[张福元] Henan Province Key Laboratory of Gold Resource Utilization, Henan Zhongyuan Gold Smelter Co., Ltd., Sanmenxia, 472000, China;[马亚赟; 郑雅杰] School of Metallurgical and Environmental, Central South University, Changsha, 410083, China
通讯机构：
School of Metallurgical and Environmental, Central South University, Changsha, China
作者机构：
[王锋; 胡拥军; Zeng, Yonglin] College of Chemical and Environmental Engineering, Hunan City University, Yiyang;Hunan;413000, China;[杨运泉] College of Chemical Engineering, Xiangtan University, Xiangtan;411105, China
作者机构：
[孟维; 许峰; 莫红兵; 欧恩才; 周伟; 徐伟箭] College of Chemistry and Chemical Engineering, Hunan University, Changsha, 410082, China;[孟维] Department of Materials &, Chemistry Engineering, Hunan City University, Yiyang, 413000, China
通讯机构：
College of Chemistry and Chemical Engineering, Hunan University, Changsha, China
作者机构：
[周小梅; 李必才; 董萌; 库文珍; 蒋道松] College of Chemistry and Environment Engineering, Hunan City University, Yiyang, Hunan, 413000, China;[赵运林] College of Environmental Science and Engineering, Central South University of Forestry and Technology, Changsha, 410018, China
作者机构：
College of Environmental Science and Engineering, Hunan University, Changsha, 410082, China;Key Laboratory of Environmental Biology and Pollution Control, (Hunan University), Ministry of Education, Changsha, 410082, China;College of Chemistry and Environment Engineering, Hunan City University, Yiyang, 413000, China;[张洁] College of Resources and Environment, Hunan Agricultural University, Changsha, 410128, China;[谭雪斌; 陈耀宁; 黄静霞; 张洁; 黄爱知; Zeng G.; 马騻] College of Environmental Science and Engineering, Hunan University, Changsha, 410082, China, Key Laboratory of Environmental Biology and Pollution Control, (Hunan University), Ministry of Education, Changsha, 410082, China
通讯机构：
[Chen, Y.] C;College of Environmental Science and Engineering, Hunan University, Changsha, China
摘要：
The present study was conducted to elucidate the influence of impurities in waste ferrous sulfate on its recovery of magnetite. Ferrous sulfate solution was purified by the addition of NaOH solution to precipitate impurities, and magnetite was recovered from ferrous sulfate solution without and with purification pretreatment. Calcium hydroxide was added to the solution of ferrous sulfate as a precipitator. A mixed product of magnetite and gypsum was subsequently obtained by air oxidation and heating. Wet-milling was performed prior to magnetic separation to recover magnetite from the mixed products. The results show that with the purification pretreatment, the grade of iron in magnetite concentrate increased from 62.05% to 65.58% and the recovery rate of iron decreased from 85.35% to 80.35%. The purification pretreatment reduced the conglutination between magnetite and gypsum, which favors their subsequent magnetic separation. In summary, a higher-grade magnetite with a better crystallinity and a larger particle size of 2.35 μm was obtained with the purification pretreatment.
摘要：
Electrochemical performances of LiCoO2 as a candidate material for supercapacitor are systematically investigated. LiCoO2 nanomaterials are synthesized via hydrothermal reaction with consequent calcination process. And the particle size increases as the calcination temperature rises.LCO-650 sample with the largest particle size displays the maximum capacitances of 817.5 Fg-1with the most outstanding capacity retention rate of 96.8% after 2000 cycles. It is shown that large particle size is beneficial to the electrochemical and structural stability of Li CoO2 materials. We speculate that the micron-sized waste LiCoO2 materials have great potential for supercapacitor application. It may provide a novel recovered approach for spent LIBs and effectively relieve the burdens on the resource waste and environment pollution.
摘要：
Objective To investigate the flexibility and mobility of the Bacillus thuringiensis toxin Cry1 Aa. Methods The graph theory-based program Constraint Network Analysis and normal mode-based program NMsim were used to analyze the global and local flexibility indices as well as the fluctuation of individual residues in detail. Results The decrease in Cry1 Aa network rigidity with the increase of temperature was evident. Two phase transition points in which the Cry1 Aa structure lost rigidity during the thermal simulation were identified. Two rigid clusters were found in domains I and II. Weak spots were found in C-terminal domain III. Several flexible regions were found in all three domains; the largest residue fluctuation was present in the apical loop2 of domain II. Conclusion Although several flexible regions could be found in all the three domains, the most flexible regions were in the apical loops of domain II.
作者机构：
[He Guo-wen; Li Fen-fang] Cent S Univ, Sch Chem & Chem Engn, Changsha 410083, Peoples R China.;[He Guo-wen; Wen Jie-bin] Hunan City Univ, Coll Chem & Environm Engn, Yiyang 413000, Peoples R China.;[Wen Jie-bin] Cent S Univ, Sch Mat Sci & Engn, Changsha 410083, Peoples R China.
通讯机构：
[Li Fen-fang] C;Cent S Univ, Sch Chem & Chem Engn, Changsha 410083, Peoples R China.
关键词：
N, N-dimethylacetamide (DMAc);sliver nanoparticles;polyvinyl pyrrolidone (PVP);preparation
摘要：
A silver nanoparticle（Ag NP） with good monodispersity was produced by a convenient method for reducing of Ag NO3 with N, N-dimethylacetamide in the presence of polyvinyl pyrrolidone（PVP） as the surface modification agent. The shape and size of the Ag NP with reaction time were taken as variables. The surface plasmon band transition was monitored with reaction mixture time at different temperatures. The Ag NP crystallinity increases with the reaction time, and the reduction efficiency is very low when Ag NP solution is dealt at room temperature even after two days, while it is greatly improved at 160 °C only for 25 min. Ag NP modified by the as-synthesized PVP has a face-centered cubic crystalline structure, in which Ag NP could develop into a spherical morphology with a very narrow size distribution of 2-11 nm. The preparation provides a new reducing agent to form Ag NP with simpler operation and shorter time.
