Fe^3＋掺杂钛酸铅陶瓷的制备及性能研究

采用溶胶凝胶（sol-gel）法制备Fe^3＋掺杂钛酸铅超细粉体，并烧结成陶瓷。讨论了影响铁掺杂PbTiO3凝胶的不同因素，确定了制备陶瓷的最佳工艺条件。利用XRD对钛酸铅粉体进行物相分析，采用SEM对烧结成的陶瓷进行微观结构分析，并测试其介电性能。研究发现，在pH=4～5范围内，pH值越低，成胶时间越长，胶体的质量越好，Fe^3＋在不同掺杂量均能形成透明的凝胶。通过XRD对Fe^3＋掺杂钛酸铅陶瓷进行物相分析可知，在掺杂PbTiO3陶瓷中只得到纯相的PbTiO3衍射峰，但掺杂PbTiO3陶瓷的晶胞参数改变，证明铁已被掺入PbTiO3体系中。通过SEM观察发现，Fe^3＋掺杂PbTiO3陶瓷晶粒结晶良好完整。介电性能的测试表明，Fe^3＋掺杂钛酸铅陶瓷能改变钛酸铅陶瓷的介电性能，并随掺杂量和频率而变。     

Cu^2＋对Fe^2＋在T．f菌修饰粉末微电极上氧化行为的影响

Fe^2 的氧化在细菌浸矿过程中具有重要作用，细菌浸铜过程中，Cu^2 的存在对T．f菌的生长代谢和其氧化Fe^ 的能力有一定影响。制备了T．f菌修饰碳粉粉末微电极，研究了Cu^2 存在下Fe^2 在T．f菌修饰粉末微电极上氧化的电化学反应机理，并测定了相应的电极过程动力学参数。循环伏安研究表明，Cu^2 的存在不影响Fe^2 在T．f菌修饰粉末微电极上的氧化反应的可逆性。对电极稳态及暂态过程研究表明，当Cu^2 浓度在12mmo1/L以下时，Cu^2 的存在不会抑制Fe^2 在T．f菌修饰粉末微电极上的氧化，适量Cu^2 加强T．f菌氧化Fe^2 的作用是在于其加快了电荷传递速率。     

Fe^3＋／Ce^3＋掺杂纳米TiO2的制备及光催化性能研究

采用溶胶-凝胶法制备了不同粒径的纯纳米TiO2和掺杂Fe^3＋和Ce^3＋的纳米TiO2。样品的X射线衍射（XRD）和透射电镜（TEM）表征说明：在相同的制备条件下，掺杂可以减小粒子粒径，掺Fe^3＋和Ce^3＋可以抑制晶相转变。光催化降解NO2的结果表明，在相同的制备方法和掺杂量的条件下合成的光催化剂对亚硝酸盐的降解率由高到低的顺序为：掺铁TiO2〉掺铈TiO2〉TiO2。     

化学清洗中对碳钢产生点蚀的Fe3+临界浓度及消除方法研究

锅炉化学清洗过程中产生的Fe^3 会大大加速碳钢的腐蚀速度。更危险的是,当清洗剂中的[Fe^3 ]达到一定数值(临界值)时,碳钢发生点蚀的可能性就很大。为消除Fe^3 带来的不良影响,可以用还原剂将其还原成Fe^2 ,也可以用掩蔽剂将Fe^3 包络起来。实验中,首先用失重法确定了对碳钢产生明显点蚀的Fe^3 浓度临界值,最后比较了在清洗液中加入不同添加剂消除Fe^3 影响的效果。     

Fe2+对嗜铁钩端螺旋菌L. ferriphilum生长活性的影响

以分离于江西某铜矿的嗜铁钩端螺旋菌（L.ferriphilum YSK）菌株为研究对象,报道不同Fe^2＋浓度对L.ferriphilum生长活性的影响。结果表明,YSK菌株生长最适宜的Fe^2＋浓度约为0.1 mol/L。当初始Fe^2＋浓度为0.4 mol/L时,进入对数生长期前很明显需要一个较长的延迟期,表明该Fe^2＋浓度对细胞的生长产生较强的抑制作用;当初始Fe^2＋浓度为0.6 mol/L时,YSK菌株的生长完全受到抑制。尽管高浓度的Fe^2＋抑制细胞的生长,但受到抑制而不生长繁殖的YSK细胞仍然具有氧化Fe^2＋的能力。     

Fe^2＋对碳钢的微生物腐蚀作用的影响

硫酸盐还原菌（ＳＲＢ）对碳钢的腐蚀与其腐蚀产物ＦｅＳ膜的状态有关。实验表明,当介质中的Ｆｅ＾２离子浓度低于５０ｍｇ／Ｌ时,ＳＲＢ的存在对碳钢起保护作用,其腐蚀产物膜致密,阻碍了介质与铁的作用,而且生物膜（ｂｉｏｆｉｌｍ）＾［１］中的细菌数当于介质中的菌量;当介质中Ｆｅ＾２浓度高于５０ｍｇ／Ｌ时,ＳＢＲ的腐蚀产物膜厚且疏松,ＦｅＳ成为腐蚀微电池的阴极,对碳钢的腐蚀起促进作用,生物膜的存在影响了杀菌剂     

Wagner极化法对熔渣电子电导的研究

利用Wagner极化法对CaO-SiO2-Al2O3-FeOx熔渣体系的电子电导进行了测定,研究表明,熔渣的电子电导包含自由电子电导和电子空穴电导两部分,它们分别由渣相中的Fe^3 及Fe^2＋浓度所确定,随着渣相的温度升高,Fe^3＋转变为Fe^2＋,自由电子电导逐渐减小,而电子空电导逐渐增大,实验还发现,在特定的温度下,不同渣系的电子电导在某一Fe^3＋浓度含量存在一个最大值,在本文实验条件下,电子电导率的大小处于10^-4-10^-2S.cm^-1之间。     

采用中温菌和常温菌浸出含砷金精矿

考察了不同矿浆浓度和接种量对细菌浸出含砷金精矿的影响。结果表明：中度嗜热嗜酸铁氧化菌MLY和嗜酸氧化亚铁硫杆菌（Acidthiobacillus ferrooxidans,At.f）的浸矿效果不同。MLY和At.f对含砷金精矿的浸出机理也不同;接种MLY的矿浆中,可能主要是溶液中的细菌将Fe^2＋氧化为Fe^3＋,再由Fe^3＋氧化溶解矿物,即以间接浸出作用为主;而接种At.f可能首先是At.f被吸附到矿物表面,通过细菌与矿物之间的某种界面作用引起矿物溶解,矿物溶解产生的Fe^2＋被游离菌氧化成为Fe^3＋,从而溶解矿物,即At.f浸出可能包括直接作用和间接作用的共同效应。     

磷酸锂中铁含量的测定

试样以盐酸溶解,用盐酸羟胺将Fe^3＋还原为Fe^2＋,在pH=3．5加热条件下,邻二氮菲生成红色络合物,于分光光度计波长510 nm处测定吸光度。     

A3钢在含Fe^3＋的盐酸溶液中的脆机理

应用原子氢渗透速率测量传感器测定了在５％ＨＣｌ溶液中添加不同含量的Ｆｅ＾３＋时体系渗氢水平（渗氢电流）的变化；采用慢应变速率拉伸（ＳＳＲＴ）试验研究了Ａ３钢在５％ＨＣｌ＋Ｆｅ＾３＋溶液中于阴、阳极极化电位下的脆断敏感性及其断裂机制。结果表明，随着溶液中Ｆｅ＾３＋含量的增加，渗氢水平逐渐下降；Ａ３钢在溶液中的脆性系数（Ｆ％）随Ｆｅ＾３＋含量变化曲线上出现一个极小值；在含０．０１％Ｆｅ＾３＋的盐酸溶液     

Characterization and photocatalytic activity for methylene blue degradation of iron-deposited TiO2 photocatalyst

Iron-deposited TiO2 was prepared by photo-reducing ferric ions. The photocatalytic activity of methylene blue degradation was enhanced after TiO2 was deposited with iron, and the optimum n(Fe)/n(Ti) is 0. 25%. TiO2 and iron-deposited TiO2 are anatase and rutile, and anatase is the dominant crystalline phase. In all samples, theXRD patterns indicate that there are no characteristic peaks of iron to be detected. XPS confirms that Fe^3 and Fe^2 are present on the surface of 0.5% iron-deposited TiO2, however they are not susceptible to XRD detection. The thermodynamics analysis shows that the alternative possibility of reduction from the Fe^3 /Fe^2 couple seems plausible, but Fe^2 can not be reduced to Fe. The fluorescence intensity weakens after iron is deposited on TiO2, because iron deposited traps photo-generated electrons and holes. The fluorescence intensity order of TiO2 and iron-deposited TiO2, from strong to weak, is in good agreement with that of photocatalytic reactiveness TiO2 and iron-deposited TiO2, from low to high.     

Fe^3＋/TiO2复合纳米粒子的制备及可见光响应性能

在钛酸四丁酯(TBOT)的溶胶－凝胶过程中,掺杂Fe3+并加入表面活性剂十六烷基三甲基溴化铵(CTAB),得到的Fe3+/TiO2复合粒子在吸收曲线的530 nm处产生了宽的强吸收峰,并对Rhodamine B具有一定的光催化降解活性.应用TEM,XRD,TG-DTA和UV-Vis等手段对复合粒子进行了表征.结果表明,掺杂的Fe3+进入纳米TiO2的品格,产生新的带宽(Eg=1.37 eV),从而改变了TiO2的光谱响应范围.     

NaH2PO2与H3PO3对Ni^2＋与Fe^2＋电化学行为的影响

极谱法研究表明：ＮａＨ２ＰＯ２，Ｈ３ＰＯ３的存在能抑制Ｆｅ＾２＋的析出，并导致Ｎｉ－Ｆｅ合金电沉积中的共沉积转为正常共沉积现象。欲提高沉积层中Ｆｅ的含量，需通过提高镀液中Ｆｅ＾２＋浓度或增大Ｎｉ＾２＋的阴极极化来实现。     

硫化矿对浸矿细菌(Fe2+)氧化活性的影响

研究了闪锌矿、黄铜矿、黄铁矿、方铅矿、元素硫和石英在矿浆密度分别为0．25％，0．50％，0．75％，1．0％(固液比)时氧化亚铁硫杆菌(Fe^2 )的氧化活性。结果表明：在矿浆密度为0．25％时，石英对细菌(Fe^2 )的氧化活性没有影响;而闪锌矿、黄铜矿、黄铁矿、方铅矿以及元素硫对浸矿细菌(Fe^2 )的氧化活性都有一定的抑制作用，且随着硫化矿矿浆密度升高，对细菌氧化活性的抑制作用加剧。     

Preparation and photocatalytic activity of nano-TiO2 codoped with fluorine and ferric

Nano-F /Fe^3＋/TiO2 particles were prepared by hydrolysis of tetrabutyl titanate in a mixed CF3COOH-Fe（NO3）3-H2O solution. The photocatalytic decomposition of methylene blue in aqueous solution was used as a probe to evaluate their photocatalytic activities. The powders were characterized by X-ray diffraction （XRD）, energy dispersion X-ray spectrum （EDS） and Brunauer-Emmett-Teller （BET） surface area analysis. The results show that F- and Fe^3＋ are doped into TiO2. The F^- and Fe^3＋ doping can help to enhance the nano-TiO2 photocatalytic activity greatly. The appropriate codoping conditions for F-Fe are n（F）/n（TiO2）=2%, n（Fe）/n（TiO2）=0.05%, and the degradation rate of methylene blue at l h is improved from 73.2% to 87.5%. The codoped nano-F /Fe^3＋/TiO2 particles have higher BET specific surface area, smaller crystallite size and higher photocatalytic activity than those of undoped TiO2 particles.     

金属阳离子在锂辉石浮选中的活化行为及作用机理

在油酸浮选锂辉石体系中分别加入Ca^2+、Al^3+、Fe^3+离子,通过单矿物浮选试验、金属离子吸附量检测、金属离子水解组份浓度计算、矿物表面动电位测试、红外光谱检测以及量子化学模拟计算研究Ca^2+、Al^3+、Fe^3+离子对锂辉石浮选的活化行为和作用机理。结果表明:Ca^2+离子的最佳活化区间为pH大于12的强碱性条件,Al^3+离子的最佳活化pH为6.47,而Fe^3+离子的最佳活化pH为7.25;在这些pH区间内,锂辉石浮选回收率和金属离子吸附量均达到最大值。在锂辉石浮选过程中起活化作用的有效组份为它们分别对应的氢氧化物沉淀。Ca^2+、Al^3+、Fe^3+离子可使锂辉石表面动电位向正值方向显著偏移;Ca^2+离子在锂辉石表面双电层的外层发生静电吸附,Al^3+和Fe^3+离子在锂辉石表面双电层的内层发生特性吸附。钙原子与锂辉石矿物表面吸附后形成的Ca—O键的键强较小,以离子键为主;铁原子与矿物表面形成Fe—O化学键的键强较大,含有一定的共价键组份;而铝原子与矿物表面吸附后形成的Al—O键的键长、键强等参数介于钙、铁的参数之间。油酸在Ca^2+活化后的锂辉石表面发生了化学吸附和少量的物理吸附,而在Al^3+、Fe^3+活化后的锂辉石表面发生了较为强烈的化学吸附。     

Effects of citric acid on separation of sillimanite from quartz

Quartz is the main gangue mineral of sillimanite.The results show that Al^3 and Fe^3 ion can activate the floatation of quartz and make the separation of quartz and sillimanite difficult when anion collector is used,and citric acid can inhibit the quartz activated by metallic ion and have slight influence on the sillimanite.X-ray photoelectronic energy spectrum analysis indicates that there are obvious electronic energy peaks on the surface of the quartz before citric acid is added into the ore pulp in presence of Al^3 and Fe^3 ,and after citric acid is added,the energy peak vanished.So citric acid can make Al^3 and Fe^3 on the surface of quartz solve and decrease the active points on the surface of quartz which can adsorb anion collector.     

EPS-contact-leaching mechanism of chalcopyrite concentrates by A. ferrooxidans

The effect of extracelluar polymeric substances（EPS） on the bioleaching chalcopyrite concentrates in the presence of ironand sulphur-oxidizing bacteria （A. ferrooxidans） was studied. The bacterial number, pH, redox potential, and the concentrations of Fe^2＋ and Cu^2＋ ions were investigated. The leached residues were analyzed by the X-ray diffraction and FT-IR. The results indicate that the EPS makes the bacteria adhere to the chalcopyrite surface easily and it is helpful for bacteria in disadvantageous environment At the same time, EPS film layer with Fe^3＋ deposits on the surface of chalcopyrite and becomes a barrier of oxygen transfer to chalcopyrite to passivate chalcopyrite, and creates the high redox potential space through concentrating Fe^3＋ ions to accelerate bioleaching pyrite in chalcopyrite concentrates. The results suggest that EPS formation promotes bioleaching pyrite and inhibits bioleaching chalcopyrite, especially under high potential condition.     

Jarosite-type precipitates mediated by YN22, Sulfobacillus thermosulfidooxidans, and their influences on strain

To have a better understanding on the properties of the jarosite-type precipitate synthesized by Sulfobacillus thermosulfidooxidans, the evolution of the S. thermosulfidooxidans-mediated precipitation and the influence of the precipitate on this species, a newly isolated strain （YN22） ofS. thermosulfidooxidans was cultured in a medium containing Fe^2＋ as energy source under optimal conditions （pH 1.5, 53 ℃, 0.2 g/L yeast extract, 30 g/L Fe2SO4·7H2O and 170 r/min）, added with or without glass beads. Remarkable differences were found in the oxidation rate of Fe^2＋, the precipitate yield ofjarosite-type compounds and the population density between the two groups of cultures. The group with glass beads has a 6 h faster Fe^2＋ oxidation, 6 h earlier precipitation, 78% higher precipitate yield and much lower population density than those without glass beads. XRD, EDS, FTIR and SEM analysis reveals that the precipitates originated from both groups are a mixture of potassium jarosite and ammoniojarosite, with morphological features similar to the latter. The results of the test referring to influence of the precipitates on YN22 show that the precipitate from the group without glass beads has no apparent influence on Fe^2＋ oxidation rate of YN22 and only a limited influence on growth of the strain, whereas that from the group with glass beads remarkably inhibits the growth and Fe^2＋ oxidation ability of YN22 when a precipitate content over 4 g/L is used.