Online Monitoring of Electrochemical Carbon Corrosion in Alkaline Electrolytes by Differential Electrochemical Mass Spectrometry

Carbon corrosion at high anodic potentials is a major source of instability, especially in acidic electrolytes and impairs the long‐term functionality of electrodes. In‐depth investigation of carbon corrosion in alkaline environment by means of differential electrochemical mass spectrometry (DEMS) is prevented by the conversion of CO₂ into CO₃^2?. We report the adaptation of a DEMS system for online CO₂ detection as the product of carbon corrosion in alkaline electrolytes. A new cell design allows for in situ acidification of the electrolyte to release initially dissolved CO₃^2? as CO₂ in front of the DEMS membrane and its subsequent detection by mass spectrometry. DEMS studies of a carbon‐supported nickel boride (Ni_xB/C) catalyst and Vulcan XC 72 at high anodic potentials suggest protection of carbon in the presence of highly active oxygen evolution electrocatalysts. Most importantly, carbon corrosion is decreased in alkaline solution.     

Q235钢焊缝在亚硫酸铵介质中的耐蚀性研究

研究以J420焊条焊接Q235钢,其焊缝于亚硫酸铵介质中的腐蚀行为.电化学方法和金相分析表明,Q235钢用J420焊条焊接后,焊缝的组织特点决定了它的耐蚀性低于母材.提高温度,增加亚硫酸铵浓度,均会促使焊缝的腐蚀速率加快.     

3D X-ray Micro-CT Analysis of Rebar Corrosion in Reinforced Concrete Subjected to a Chloride-Induced Environment

The paper presents experimental investigations of the concrete covers’ protective ability to counteract rebar corrosion in reinforced concrete cubes. The concrete sample was subjected to a chloride-induced environment to get corroded and combined with an un-corroded sample. The chloride-accelerated technique can induce a high degree of corrosion within a controlled time. Moreover, detailed and thorough experimental measurements and analyses of reinforcement loss due to corrosion and its influence on concrete microstructure, were studied through 3D X-ray micro-computed tomography. The rebar outside the concrete was heavily corroded due to the chloride-accelerated test, whereas, only local surface corrosion products appeared inside the concrete. It turned out that the concrete cover showed protective ability to counteract the reinforcing-steel corrosion mechanism despite the accelerated corrosion environment. Moreover, the bond strength between the reinforcement rebar and concrete was not visibly affected since the failure force in the pull-out test and failure mechanisms, observed by 3D X-ray micro-CT, were similar for corroded and un-corroded samples. The failure occurred due to radial cracks with a maximum width equal to approximately 0.25 mm.     

电解液中有机添加剂对锌电极性能的影响

本文通过恒电位计时电流、恒电位阶跃以及线性扫描等电化学方法考察了电解液中加入有机添加剂对锌电极电化学性能的影响。结果表明,在电解液中添加1∶1的NMP TCX型添加剂能有效的抑制锌电极在碱液中枝晶的生长并具有较好的缓蚀作用。     

2-十二烷基二硫代-4-苯基-1,3,4-噻二唑-5-硫酮的合成及其对铜的缓蚀性能

合成了2-十二烷基二硫代-4-苯基-1,3,4-噻二唑-5-硫酮(DPTT),用元素分析、IR1、H NMR等技术对化合物进行了结构表征.采用动态旋转挂片法考察了DPTT和苯并三唑(BTA)复配时对铜的缓蚀作用.结果表明,单一DPTT在浓度为3.0 mg/L时缓蚀效果最佳;DPTT与BTA复配使用时显示出较好的协同效应,1.0 mg/L DPTT和1.0 mg/L BTA复配时缓蚀效果最好.     

反应条件对钌基氨合成催化剂性能的影响

用氨合成催化剂性能评价装置,研究了反应温度、压力、空速和氢氮比对以活性炭为载体的钌基氨合成催化剂活性的影响。研究表明,低于400℃时,随着反应温度降低,催化剂的活性急剧降低。随着压力升高,催化剂活性增大。但钌催化剂具有较高的低压活性,适宜低压合成氨。随着空速的降低,催化剂的活性明显提高。在空速和压力一定的条件下,最佳氢氮比随反应温度而异,并且当空速较高或反应温度较低时,氢氮比的变化对催化剂活性的影响更加明显。     

Pt/C和Pt/CNTs电极的电化学稳定性研究

采用恒电位氧化法研究了Pt/C和Pt/CNTs电极的电化学稳定性. 相同条件下, Pt/C电极的氧化电流大约为Pt/CNTs电极的2倍; 120 h氧化后, Pt/C电极Pt的电化学表面积下降了21.3%, 而Pt/CNTs电极仅下降了7.6%, 表明Pt/CNTs电极性能衰减较慢. X射线光电子能谱(XPS)分析表明, Pt/C的载体碳黑表面氧增加量大于Pt/CNTs中碳纳米管(CNTs)表面氧的增加量, 说明碳黑的被氧化程度较高, 电化学稳定性差; Pt的表面化学状态没有发生变化; 碳纳米管本身的抗电化学氧化性也大于碳黑. 所以, 载体的被氧化程度不同是两种电极性能衰减不同的主要原因之一, 并且排除了Pt表面状态的影响.     

高效液相色谱法测定原油脱钙工艺排水体系中NS-3缓蚀剂浓度

将反相高效液相色谱法用于原油脱钙工艺排水体系中缓蚀剂浓度测定研究,建立了缓蚀剂的快速分离检测方法.使用C18柱,以乙腈∶二氯甲烷=9∶1(V/V)混合溶剂为流动相,采用紫外检测器在300 nm处对排水体系中的缓蚀剂进行测定,外标法进行定性定量分析.测定结果表明缓蚀剂浓度在100~900 mg/kg时其峰面积与相应的质量浓度有良好的线性关系,其线性相关系数为0.999 9,相对标准偏差(RSD)和相对误差(RD%)都小于2.0%.用二氯甲烷为萃取剂对排水体系中的缓蚀剂进行萃取,其平均回收率为100%±2%.最低检测线为0.75mg/kg.该方法具有测定结果准确可靠,操作简便快速,重现性好等特点.     

Investigation of ammonia stripping with a hydrodynamic cavitation reactor

Ammonia is a commonly used compound in the domestic and industrial fields. If ammonia found in wastewater after use is not treated, even at low concentrations it may cause toxic effects in the receiving environment. In this study, a hydrodynamic cavitation reactor (HDC) was designed with the aim of removing ammonia. The effect of parameters like different cavitation numbers, airflow, temperature and initial concentration on NH₃ removal was researched. The potential of hydrodynamic cavitation for removal of volatile gases, like NH₃, was assessed with the aid of two film theory mathematical equations. Experimental studies were performed at fixed pH = 11. Under the conditions of 0.12 cavitation number, 25 L/min airflow, 30 °C temperature and 2500 mg/L initial concentration, in 24 h 98.4% NH₃ removal efficiency was achieved. With the same experimental conditions without any air, the HDC reactor provided 89.5% NH₃ removal at the end of 24 h.The HDC reactor is very effective for the removal of volatile gases from wastewater and it was concluded that even in the absence of aeration, the desired NH₃ removal efficiency was provided.     

Electrodeposition and characterization Zn-Co alloy

The present work details optimization of a stable acid chloride bath for electroplating of bright Zn-Co alloy on mild steel using gelatin and glycine as additives. It was found that the addition of gelatin along with glycine changed the deposition pattern markedly. A suitable bath has been formulated using conventional Hull cell experiments. The bath under plating conditions were found to exhibit anomalous codeposition with preferential deposition of less noble (zinc) over more noble (cobalt) as characterized by Zn-Fe group metal alloys. Investigation revealed that the current density (c.d.), temperature, and pH of the bath have strong effect on the composition of the deposit. Influence of bath constituents and operating parameters on appearance and composition of deposits were studied as measure of their performance against corrosion. A variety of deposits were obtained and their corrosion resistances were measured by Tafel method with/without chrome passivation. Experimental results demonstrated the fact that the corrosion resistances of Zn-Co alloys increased with percent of Co in the deposit except at very high c.d. This is due to the fact at very high c.d. the deposit becomes very porous and thick as evidenced by SEM image. The formation of Zn-Co alloy is confirmed by EDAX analysis. A stable chloride bath for Zn-Co alloy deposition has been proposed and discussed. The formation of passive film on chromatization is indicated by almost same E _corr value of all Zn-Co electroplates irrespective of the current densities at which they have been deposited. Published in Russian in Elektrokhimiya, 2009, Vol. 45, No. 7, pp. 811–816. The text is published in the original.