Cooperative effect of chalcopyrite and bornite interactions during bioleaching by mixed moderately thermophilic culture

The cooperative interactions between chalcopyrite and bornite during bioleaching by mixed moderately thermophilic culture were investigated mainly by bioleaching experiments and electrochemical experiments. Bioleaching results showed that a cooperative effect existed between chalcopyrite and bornite. When the mass ratio of chalcopyrite to bornite was 3:1, an extremely high copper extraction of more than 88% was achieved after bioleaching for 27 days. One of the major reasons for the cooperative effect was that a certain redox potential range (370–450 mV vs. Ag/AgCl) could be maintained for a long period of time during bioleaching due to the mixture of chalcopyrite and bornite. Electrochemical measurements revealed that chalcopyrite was much easier to be reduced than oxidized, while bornite was prone to be directly oxidized. Hence, galvanic effect between chalcopyrite and bornite enhanced the reduction of chalcopyrite to secondary copper-iron species and promoted the oxidative dissolution of bornite. Therefore, redox potential controlling and galvanic effect both contributed to the cooperative bioleaching of chalcopyrite and bornite.     

Electronic and thermal properties of compounds bearing diimide,azomethine and triphenylamine units

New triphenylamine containing azomethine diimides and two kinds of poly(azomethine imide)s, i.e., linear and branched were synthesized. These compounds were prepared from two diamines, that is, N,N′-bis(4-amino-2,3,5,6-tetramethylphenyl)phtalene-1,2,4,5-dicarboximide (DAPhDI), N,N′-bis(5-aminonaphtalen)naphthalene-1,4,5,8-dicarboxyimide (DANDI-2) and 4-formyltriphenylamine, 4,4′-diformyltriphenylamine and 4,4′,4″-triformyltriphenylamine. The structures of the compounds were characterized by means of FTIR, ¹H NMR spectroscopy and elemental analysis; the results show an agreement with the proposed structure. Thermal properties of prepared azomethine diimides and polymers were evaluated by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). Obtained compounds exhibited high thermal stability with 5% weight-loss temperatures above 390 °C. Azomethine diimides exhibited glass-forming properties with high glass-transition temperatures 216 and 308 °C. Optical properties of the prepared compounds were investigated by UV–vis and photoluminescence (PL) measurements. All compounds emitted blue light in NMP solution and in solid state as blend with PMMA. The electrochemical properties, that is, orbital energies and resulting energy gap were estimated based on cyclic voltammetry (CV). All synthesized material showed reversible reduction process, furthermore AzPhDI and AzNDI showed partially reversible oxidation process. Electrochemical band gap was found in the range 1.23–1.70 eV. Low molecular weight model compounds were tested as bipolar host materials in blue phosphorescent organic light emitting diodes (OLEDs). The devices exhibited turn-on voltages of about 5.5 V and maximum brightness of 40–220 cd/m².     

New method in synthesis of nano uranyl(VI) Schiff base complexes: Characterization and electrochemical studies

This study presents a new method in synthesis of nano uranyl Schiff base complexes. In this method slow addition of dilute uranyl(VI) acetate solution to dilute Schiff base solution following the reflux for about 24 h, yields nano uranyl(VI) Schiff base complexes. Characterization of Schiff base ligands and nano uranyl complexes has been done using ¹H NMR, IR, UV–vis spectroscopy, elemental analysis. Schiff base ligands were synthesized by the condensation of one mole 3,4-diaminobenzophenone and two moles salicylaldehyde or substituted salicylaldehyde (3-OMe, 4-OMe, 5-OMe, 5-Br, 5-Cl). The electrochemical properties of the uranyl(IV) complexes were investigated by cyclic voltammetry. A good correlation was observed between the oxidation potentials and the electron withdrawing character of the substituents on the Schiff base ligands, according to the following trend: 5-MeO < H < 5-Br ≈ 5-Cl. Also the effect of the position of the substituted groups of Schiff base on the anodic potentials is as follows: 5-OMe < 3-OMe < 4-OMe.     

Electrochemical Performance of PrBaCo2O5+δ and Sm0.5Sr0.5CoO3−δ Infiltrated Ce0.9Gd0.1O1.95 Cathodes

Cathodes with PrBaCo₂O_5+δ (PBC) and Sm_0.5Sr_0.5CoO_3−δ (SSC) infiltrated on Ce_0.9Gd_0.1O_1.95 (CGO) backbones are prepared using metal nitrates as precursors and ethanol as wetting agent. Electrochemical impedance spectra (EIS) are measured from cathode/CGO/cathode symmetrical cells in 400–650 °C under humidified air. The results indicate that interfacial area specific resistance (ASR) value decreases and then increases with infiltrate loading and minimum values occur at 50 wt.% loading (relative to sum of infiltrate and backbone) for both PBC and SSC infiltrates. ASR values of PBC infiltrated cathodes are lower than that of corresponding SSC infiltrated cathodes in general, and in particular ASR values as low as 1.36 × 10⁻² and 2.27 × 10⁻² Ω cm² are obtained at 650 °C in air for 50 wt.% PBC and 50 wt.% SSC infiltrated cathodes, respectively. Conductivity values of CGO electrolyte increase with infiltrate loading and agree with the reported values when the loading reaches 50 wt.%.     

Catalytic mechanism of manganese ions and visible light on chalcopyrite bioleaching in the presence of Acidithiobacillus ferrooxidans

The bioleaching of chalcopyrite is low cost and environmentally friendly,but the leaching rate is low.To explore the mechanism of chalcopyrite bioleaching and improve its leaching rate,the effect and mechanism of manganese ions(Mn²⁺) and visible light on chalcopyrite mediated by Acidithiobacillus ferrooxidans(A.ferrooxidans) were discussed.Bioleaching experiments showed that when both Mn²⁺ and visible light were present,the copper extraction was 14.38% higher than that of t...     

Electrodeposited iodide ions imprinted polypyrrole@bismuth oxyiodide film for an electrochemically switched renewable extractor towards iodide ions

Effective extraction and regeneration of radioactive iodide is one of urgent concerns for the safe utilization of nuclear energy. As a novel environmentally benign ion separation technique, electrochemically switched ion extraction(ESIE) process can be applied for effective capture and recovery of iodide ions(I^-). Herein, a novel kelp seaweed-like core/shell I^-imprinted polypyrrole@bismuth oxyiodide(PPy/I^-@BiOI) composite film is successfully prepared for the sel...     

压水堆核电厂一回路首次钝化工艺研究

压水堆核电厂热态功能试验中的一回路首次钝化对核电厂一回路材料腐蚀控制和减少腐蚀产物等方面具有重要作用。本文结合理论研究与工程实际情况,提出了在热态功能试验过程中钝化膜的生成包含电化学反应和化学反应的观点,阐述了双层膜的生长机理,解释了用电化学测试方法分析钝化工艺过程的合理性,推导出钝化温度与钝化膜反应速率的函数关系式,钝化温度升高,反应速率升高,钝化时间缩短;明确了钝化工艺温度的理论限值应不低于260℃。      

不锈钢电化学着色工艺及着色膜的XPS研究

介绍了不锈钢电化学着色工艺,采用正交试验的方法对不锈钢电化学着色的试验方案进行了优化,得出最佳试验方案;用X射线光电子能谱(XPS)对不锈钢着色膜的元素组成和元素价态进行了分析,这对着色膜层的进一步开发和应用有十分重要的作用.     

邻硝基氯苯在Fe-Fe电极上的电化学行为研究

邻硝基氯苯是持久性有毒污染物,实验采用强制电化学的方法进行降解处理,对电角液进行液相色谱分析和COD检测。研究表明,在适当条件下电解邻硝基氯苯能达到较好的处理效果,电解产生的Fe（OH）3对邻硝基氯苯没有絮凝沉淀作用,降解的邻硝基氯苯转化其他形式的有机物仍存在于水溶液中,电解后废水的可生化性提高。     

Control of local friction of metal/ceramic contacts in aqueous solutions with an electrochemical method

Ball-on-plate sliding friction experiments were designed and performed to show the possibility of local friction control by electrochemical methods. By partitioning a metal plate into charged and uncharged zones, the friction coefficient in these zones can be differential when an external voltage is applied during rubbing. It is also possible to achieve differential friction at different locations of contact by arranging the position of the auxiliary electrode on which the range of electrochemical effects on friction depends. The morphological differences in the worn surfaces between the different zones are given, together with a discussion on the principles of the electrochemical control of friction.