Wood液态合金在NaOH溶液中的电化学反应及表面张力变化行为

通过改变液体金属在NaOH溶液中所处的环境介质,利用石墨电极对其施加电场,研究了液态金属的表面张力、界面电化学反应、氧化膜的产生、溶液中电润湿等动态过程。实验发现Wood合金液滴在阳极发生电化学反应产生的氧化膜会迅速减小表面张力并发生铺展,在阴极发生还原反应会使带氧化膜的金属在3 s内恢复到原状,电毛细作用力使氧化膜破裂,各氧化物与NaOH反应产生Sn(OH)_6~(2-)、SnO_3~(2-)、SnO_2~(2-)、PbO_3~(2-)、Cd(OH)_4~(2-)使溶液的颜色发生改变,溶液中生成Bi2O3-Bi(OH)3白色共聚物。薄膜电介质层润湿和溶液中电润湿机理在本质上相同,表面张力随着电压的增大而减小并发生明显的电润湿铺展过程,但由于金属液滴通过电化学反应所能吸附的OH-数量有限,润湿角存在饱和性。     

离子电解质电化学还原CO_2行为研究

本文通过简单的亲核加成制备出一种新型的离子电解质—1-二乙二醇甲醚基-3-甲基咪唑甘氨酸盐,并对其电化学CO2转化为CO行为进行了研究。研究结果表明,样品可以在较低过电位下实现CO2到CO的转化,并且样品可以重复使用,电化学还原性能不会明显降低。     

硫酸溶液中铬酸钾在不锈钢表面的电化学还原行为

在硫酸溶液中对不锈钢进行阳极极化曲线的测定表明，铬酸钾在不锈钢表面的还原反应受铬酸根离子在溶液中的扩散步骤所控制，且在不锈钢致钝的电位区间内达到了极限扩散。对不锈钢进行电位滴定的实验结果也证实了铬酸根离子的这一还原行为。     

Fe-Ni合金在0.5 mol/L NaOH溶液中的电化学腐蚀行为研究

通过机械合金化法制备出纳米晶Fe-Ni合金,并与粉末冶金法制备的常规尺寸Fe-Ni合金作对比,探究两种合金在0.5mol/LNaOH溶液中电化学的腐蚀行为。利用三电极体系和电化学工作站,通过测量两种不同晶粒尺寸的Fe-Ni合金的E-t曲线、动电位极化曲线和电化学交流阻抗谱,发现两种合金均有活性溶解现象,交流阻抗谱均由单容抗弧组成。且常规尺寸Fe-Ni合金的腐蚀电流密度高于纳米晶Fe-Ni合金,纳米晶Fe-Ni合金的电荷传递电阻大,说明纳米晶Fe-Ni合金耐腐蚀性较好。     

酸性溶液中钨钼离子的电化学行为

为加大钨钼电化学性质的差异实现钨钼分离,使钨钼形成钨磷、钼磷杂多酸,采用循环伏安法研究酸性条件下含钨钼溶液及钨磷、钼磷杂多酸的电化学行为,获得多种溶液体系的循环伏安曲线. 结果表明,研究体系中钨的还原电位较钼高,但二者电位差小于0.1 V,无法利用电化学性质差异高效分离;而将钨和钼形成杂多酸体系后,钼磷杂多酸还原峰电位为0.401 V,钨磷杂多酸为0.1949 V,加入磷酸增大了钨钼离子电位差,可优先将钼还原.     

不锈钢在硫酸-磷酸溶液中的电化学抛光行为

利用电化学方法采用线性伏安扫描、循环伏安和电化学阻抗测试研究了HR-1不锈钢在硫酸-磷酸溶液中的电化学抛光行为。实验结果表明,实验所得阳极极化曲线与理论阳极极化曲线吻合较好,证明了在抛光过程中钝化膜的存在,钝化膜形成的电压为0.75~1.25V,最佳的抛光电压区域为1.25~1.75V。通过分析研究,对优化电化学抛光参数,更好的将电化学抛光技术应用于实际生产具有指导意义。     

离子液体在蛋白质电化学中的应用研究

综述了离子液体作为黏合剂、支持电解质和修饰材料这三种功用在氧化还原蛋白质直接电化学中的研究现状,并提出了目前研究存在的问题及此种生物传感器应用前景的展望。     

利用不同氢源及氮源电化学合成氨研究进展与挑战

氨是基本有机化学工业及化肥生产的主要原料。工业上利用哈伯法合成氨,该工艺不仅耗能大且转化率仅有10%~15%。相比传统合成氨工艺,电化学合成氨有着清洁环保、反应条件温和等优点。本文综述了氮气、硝酸盐及一氧化氮作为氮源时电化学合成氨的特点与优势,并依据不同氮源的特点,剖析了电化学合成氨的反应机制。文中针对不同的氮源,分析总结了多种氢源方案与氢化机理,系统地概述了反应催化剂的研究进展。分别讨论了氮气在水中溶解度较差、硝酸盐在反应过程中元素价态跨度大而生成诸多中间产物、氮氧化物体系不稳定、电解体系中存在析氢竞争反应等问题,提出了通过改变氢源的组成或结构抑制析氢反应、开发新型高活性位点及氧空位的催化剂体系强化反应选择性、研制非水电解质体系提高反应速率及合成效率等解决思路。     

铜铝双金属复合离子液体的电化学行为及电沉积铜机理

铜铝双金属复合离子液体是新型碳四烷基化技术所用的绿色催化剂,电化学处理是回收工业应用过程外排复合离子液体中金属铜的有效途径之一,为此需要深入研究其电化学行为和电沉积铜机理。循环伏安研究发现,铜铝双金属复合离子液体在Pt盘电极、W盘电极和玻碳电极上的还原过程均包括铜的欠电势沉积、Cu(Ⅰ)的还原和铜的超电势沉积,氧化过程均包括Cu→Cu(Ⅰ)、Cu(Ⅰ)→Cu(Ⅱ)。计时安培研究表明,铜的成核方式为三维瞬时成核。长周期实验结果显示Cu(Ⅰ)的浓度随着时间下降的趋势变缓,表明电沉积铜速率逐步下降。电沉积电势对沉积产物的形貌影响较大,-2.60 V下的产物形貌更平整致密。XRD结果表明在-1.20~-2.60 V电势下阴极电沉积只生成金属铜。     

铜铝双金属复合离子液体的电化学行为及电沉积铜机理

铜铝双金属复合离子液体是新型碳四烷基化技术所用的绿色催化剂,电化学处理是回收工业应用过程外排复合离子液体中金属铜的有效途径之一,为此需要深入研究其电化学行为和电沉积铜机理。循环伏安研究发现,铜铝双金属复合离子液体在Pt盘电极、W盘电极和玻碳电极上的还原过程均包括铜的欠电势沉积、Cu(Ⅰ)的还原和铜的超电势沉积,氧化过程均包括Cu→Cu(Ⅰ)、Cu(Ⅰ)→Cu(Ⅱ)。计时安培研究表明,铜的成核方式为三维瞬时成核。长周期实验结果显示Cu(Ⅰ)的浓度随着时间下降的趋势变缓,表明电沉积铜速率逐步下降。电沉积电势对沉积产物的形貌影响较大,-2.60 V下的产物形貌更平整致密。XRD结果表明在-1.20~-2.60 V电势下阴极电沉积只生成金属铜。     

表(界)面张力测定方法的研究进展

综述了表(界)面张力的测量原理和方法;详细分析了适合高温、高压、不同气氛影响以及动态表面张力的测量方法、表面张力仪器建立时需要注意的问题和影响测量结果准确度的因素以及其发展趋势;指出了在煤液化工艺和石油加氢工艺中考察气氛对表面张力影响时最好采用最大气泡法和悬滴法。     

硫化氢恶臭气体吸收液的电化学氧化处理过程

利用单槽无隔膜电化学反应器,研究了硫化氢恶臭气体碱性吸收液在圆形平板钌钛DSA电极上的电化学氧化处理过程,考察了电流密度、初始料液浓度、辅助电解质以及pH值对S2?电解去除效果的影响。结果表明：在电流密度25 mA/cm2、S2?初始浓度23 mmol/L时,S2?去除率可达95%以上;S2?的氧化产物主要为SO42?,约占总反应产物的95%,而硫单质占2%～3%,同时生成少量SO32?、S2O32?;S2?去除速率受到S2?浓度的较大影响,电流密度越高去除速率越快;pH值影响Sx2?的形成,强碱条件可避免阳极钝化;与NaCl等辅助电解质相比,NaOH最有利于提高电解氧化的速度和深度,S2?去除率达90%时,可缩短处理时间近40%。     

表面张力对传质过程的影响

表面张力对传质过程的影响主要是影响传质界面积,当物系为正物系时,对板式塔有较小较稳定的汽泡,对填料塔和湿壁塔,有较稳定的液膜,结果使二者均有较大的传质界面积,传质效果较好;负物系的情况相反。当液体混合物的平均表面张力较小时,也有利于形成较小较稳定的汽泡,从而有利于传质。表面张力对传质过程的影响机理相当复杂,这方面的研究工作有待深入开展。     

Penicillin G extraction by amberlite LA-2—a study of interfacial reaction kinetics by interfacial tension measurements

The concentration of reactants at an interface cannot be determined directly. The concentration at the interface has been estimated by measuring the interfacial tension at the interface between two immiscible solutions. An aqueous phase, de-ionised water containing penicillin G, and an organic phase containing amberlite LA-2 were used as a typical system to study the kinetics of interfacial reaction. The interfacial tension was measured by a spinning-drop tensiometer at 25 ± 0·1°C. The interfacial tension was found to correlate well with the concentrations of penicillin G, Amberlite, LA-2 and proton in each respective phase.     

Viscosity and surface tension of p-xylene-ethylacetate liquid mixtures

Experimental density, viscosity and surface tension data are reported for p-xylene-ethylacetate mixtures at 20°. 30° and 40°C. over the entire composition range. The presence of interactions has been studied in the light of excess properties.     

Al-Mg-Li三元合金表面张力的估算

运用表面张力计算公式Butler方程,与过剩吉布斯自由能结合,计算了973 K温度下Al?Mg, Al?Li和Mg?Li二元体系的表面张力。结果表明,在铝熔体中分别加入金属镁或锂,合金表面张力随其含量增加而降低;在镁熔体中加入金属锂,合金表面张力随锂含量增加而降低。以此为基础,利用Chou模型计算得Al?Mg?Li三元合金的表面张力为0.326?0.851 N/m,随铝或镁含量增加表面张力增大,随锂含量增加表面张力减小。     

Electrochemical behaviour of cadmium in NaOH solution

The electrochemical behaviour of cadmium in 1 M NaOH solution was studied. Different electrochemical methods such as potentiodynamic measurements, polarization techniques and electrochemical impedance spectroscopy (EIS) were used. During the course of polarization, several characteristic features were observed, including prepassivation and a relatively wide passive range extending over 1.4 V. Equivalent circuit models for the electrode–electrolyte interface under different applied potentials were proposed. The impedance data measured at steady state were fitted to calculated data according to proposed equivalent circuits. The relevance of the proposed equivalent circuits to the different phenomena occurring at the electrode–solution interface was discussed. The passive film formed on Cd is composed of two layers: a barrier layer in contact with metal and a deposit on the barrier layer. The barrier layer appears to form directly from the metal through a solid state reaction, rather than by a dissolution–precipitation mechanism. For an applied potential >+0.7 V the relative passive film thickness and resistance decrease to lower values indicating transpassive dissolution at this potential.     

Novel surfactants for ultralow interfacial tension in a wide range of surfactant concentration and temperature

This work investigates the possibility of injecting dilute aqueous solutions of novel surfactants into the Yibal field (Sultanate of Oman). This was accomplished through an experimental protocol based on the following criteria: (i) compatibility of the surfactants with the high-saline reservoir water (∼200 g/L); (ii) low interfacial tension (IFT) between crude oil and reservoir water (less than 10⁻² mN m⁻¹); and (iii) maintaining the low IFT behaviour during the entire surfactant flooding. Novel surfactants selected in this study consist of a series of ether sulfonates (AES-205, AES-128, AES-506, and 7–58) and an amphoteric surfactant (6–105). These surfactants were found to be compatible with reservoir water up to 0.1% surfactant concentration, whereas 6–105 and 7–58 showed compatibility within the full range of surfactant concentration investigated (0.001–0.5%). All surfactant systems displayed dynamic IFT behavior, in which ultralow transient minima were observed in the range 10⁻⁴–10⁻³ mN m⁻¹, followed by an increase in the IFT to equilibrium values in the range 10⁻³–10⁻¹ mN m⁻¹. The results also showed that with respect to concentration (0.05–0.5%) and temperature (45–80°C), AES-205 and 7–58 surfactants exhibit a wide range of applicability, with the IFT remaining below 10⁻² mN m⁻¹, as required for substantial residual oil recovery. In addition, ultralow IFT were obtained at surfactant concentrations as low as 0.001%, making the use of these surfactants in enhanced oil recovery extremely cost-effective.