硫脲在铜电极表面的吸附及对电结晶结构的影响

用线性电位扫描法研究了在CuSO4-H2SO4电解液中电解铜时硫脲在铜阴极表面的吸附行为。结果表明,在硫脲浓度较低（＜10（－5））时,在铜电极表面的吸附遵守Temkin等温式;当硫脲浓度较高（＞10（－5））时,在铜电极表面的吸附遵守Frumkin等温式。利用X射线衍射方法测试了吸附"转型"对阴极铜结晶结构的影响。     

丙烯基硫脲对低磷化学镀镍沉积过程的影响

通过电化学测量技术研究了丙烯基硫脲对低磷化学镀镍过程的影响,结果表明, 丙烯基硫脲在低浓度时,通过电子转移机理加速了Ｎｉ＾２＋的还原过程,表现出明显的加速作用; 在高浓度时,由于电极表面较厚吸附层的存在,阻碍Ｈ２ＰＯ２＾－在催化表面的氧化反应,表现为 对沉积反应换抑制作用。     

硫酸中硫脲在纯铁上的吸附

一、引言有机物在电极表面上的吸附过程,可提供吸附分子之间以及它们和电极表面相互作用的有用信息。实践上,它与腐蚀抑制、化学电源、电镀、有机电合成等直接相关。汞电极表面上的吸附行为已有大量报道。固体电极上的研究困难较多,文献报道只涉及为数不多的一些体系。本工作研究20～60℃温度区间,0.5～2.0mol·dm~(-3)H_2SO_4中硫脲(TU)在纯铁上的吸附行为,通过对实验结果的分析找出相应的吸附等温式,确定有关的热力学参数。     

水溶液中自组装膜对银的缓蚀作用及吸附机理分析

采用不同的分散剂将十八烷基硫醇(ODT)分散在水溶液中,并以其在银表面制备了自组装膜(SAMs)。用极化曲线、交流阻抗、循环伏安等电化学方法研究了ODTSAMs对银的缓蚀作用及吸附行为。结果表明:ODT分子能够在银表面形成稳定、致密的SAMs,有效抑制了银的阴极氧去极化过程和阳极硫化过程,改变了电极表面的双电层结构,对银有良好的缓蚀作用。ODT在银表面的吸附行为符合Langmuir吸附等温式,吸附机理是典型的化学吸附。     

硫酸溶液中硫脲对铁缓蚀作用的电化学和SERS研究

用表面增强拉曼散射（ＳＥＲＳ）光谱技术和电化学手段研究硫脲在硫酸体系中对铁的缓蚀作用,结果表明,硫脲对铁的缓蚀作用具有浓度极值现象。低２的硫脲通过活性点吸 抑制铁的阳极溶解,高２的硫脲参与铁伯最极溶解反应,奠定Ｌａｎｇｍｕｉｒ吸附等温式,动力学参数为ＶＴＵ＝１,ｂａ＝１１８ｍＶ,低浓度硫脲主要以平行吸附为主,高２硫脲则倾向于垂直吸附。     

N-丙基-N′-乙氧羰基硫脲对黄铜矿和黄铁矿的浮选及其电化学行为（英文）

通过浮选试验,比较N-丙基-N′-乙氧羰基硫脲(PECTU)和丁基黄药(BX)对黄铜矿和黄铁矿浮选行为的影响,并利用动电位测试和电化学方法研究乙氧羰基硫脲与黄铜矿和黄铁矿的作用机理。浮选试验结果表明,相对于丁基黄药,乙氧羰基硫脲表现出对黄铜矿更强的捕收能力以及更好的选择性。与PECTU作用后,黄铜矿表面zeta电位向正方向移动,证明PECTU在黄铜矿表面发生了吸附。循环伏安曲线和塔菲尔测试结果表明,PECTU与黄铜矿表面相互作用后,吸附在黄铜矿电极表面的PECTU阻碍了黄铜矿自身的氧化和腐蚀。动电位和电化学测试结果表明,在弱碱性条件下,PECTU与黄铁矿几乎无相互作用。     

氯代十六烷基吡啶在铝电极上电化学和SERS研究

用电化学和SERS谱研究了氯代十六烷基吡啶在铝电极上的吸附,发现氯代十六烷基吡啶是一种阴阳极混合抑制型几何覆盖缓蚀剂,平卧吸附在电极表面上.     

Pt和Sb、S吸附原子修饰的Pt电极上1,3-丁二醇吸附和氧化过程

应用电化学循环伏安和石英晶体微天平（EQCM）研究了1，3－丁二醇（1，3－BDL）在Pt电极和以Sb,S吸附原子修饰的Pt(Pt/Sbad和Pt/Sad)电极上的吸附和氧化过程，从电极表面质量变化的结果分析，可认为1，3－丁二醇的氧化与电极表面氧物种有着极其密切的关系。Pt电极表面Sb吸附原子能在较低的电位下吸附氧，可显著提高1，3－丁二醇电催化氧化活性，与Pt电极相比较，饱和吸附Sb原子的Pt电极，1，3－丁二醇氧化的峰电位负移了0．25V，峰电流增加了近1倍，相反，Pt电极表面S吸附原子的氧化会消耗表面氧物种，饱和吸附S原子的Pt电极上1，3－丁二醇的电氧化受到抑制，本文从表面质量变化提供了吸附原子电催化作用的新数据。     

缓蚀剂研究报告(Ⅱ)——用动态极化曲线法研究硫脲及其衍生物对低碳钢的缓蚀机理

本文采用动态极化曲线法,测定了低碳钢在酸中的极化曲线,以及硫脲系衍生物、系统温度对极化曲线的影响.通过动力学参数的讨论,指出同种缓蚀剂蚀缓作用因温度而异、系电极表面吸附、成膜或脱附的结果.从而把动力学参数与吸附理论、成膜理论联系起来,为快速筛选新型缓蚀剂提供手段和理论依据.     

铜在3.5%NaCl中阳极溶解过程的研究

采用伏安法研究了铜在3.5%NaCl溶液中的阳极溶解过程,并采用SEM和EDS对表面产物进行了分析.结果表明,铜电极阳极溶解的产物为CuCl;在阳极溶解过程中可生成吸附态的CuClads,电极反应受扩散过程控制,同时电荷传递也影响电极反应的速度;在静态电极和高电位扫描速度条件下,线性电势扫描曲线上出现第二个阳极峰,并且此阳极过程受扩散控制.     

Corrosion and corrosion inhibition of Cu-20%Fe alloy in sodium chloride solution

The electrochemical behavior of copper (Cu), iron (Fe) and Cu-20%Fe alloy was investigated in 1.0 M sodium chloride solution of pH 2. The effect of thiourea (TU) addition on the corrosion rate of the Cu-20%Fe electrode was also studied. Open-circuit potential measurements (OCP), polarization and electrochemical impedance spectroscopy (EIS) were used. The results showed that the corrosion rates of the three electrodes follow the sequence: Cu < Cu-20%Fe < Fe. Potentiostatic polarization of the Cu-20%Fe electrode in the range −0.70 V to −0.45 V (SCE), showed that iron dissolves selectively from the Cu-20%Fe electrode surface and the rate of the selective dissolution reaction depends on the applied potential. At anodic potential of −0.45 V, thiourea molecules adsorb at the alloy surface according to the Langmuir adsorption isotherm. Increasing thiourea concentration (up to 5 mM), decreases the selective dissolution reaction and the inhibition efficiency η reach 91%. At [TU] > 5 mM, the dissolution rate of the Cu-20%Fe electrode increases due to formation of soluble thiourea complexes. At cathodic (−0.6 V), the inhibition efficiency of thiourea decreases markedly owing to a decrease of the rate of the selective dissolution reaction and/or desorption of thiourea molecules. The results indicated that thiourea acts mainly as inhibitor of the selective dissolution reaction of the Cu-20%Fe electrode in chloride solution.     

吡唑的缓蚀作用及协同作用的研究

利用循环伏安法和旋转圆盘电极研究了NaHCO3溶液中吡唑对紫铜的缓蚀作用,并对其与BTA,MBT之间的协同效应进行了初探.结果表明在0.05 mol/L NaHCO3溶液中吡唑在紫铜表面有着强烈的化学吸附作用,吡唑与BTA之间有着协同作用,而与MBT的协同作用不明显.      

LEACHING OF PRECIOUS METALS FROM COMPLEX SULPHIDE ORES——2.DIRECT LEACHING OF Cu SULFIDE CONCENTRATE BY ACIDIC THIOUREA SOLUTIONS

Recovery of gold and silver from a sulphide concentrate by thiourea leaching was investigat-ed.The effects of various parameters on the process,such as oxidants,the initial concentrationof thiourea and acidity in solutions as well as reaction temperature,were systematically exam-ined.From the results it was confirmed that(a)oxidants had no significant influence on the dis-solution of gold and silver at a fixed initial concentration of thiourea;(b)the initial concentra-tion of thiourea and acidity affected the dissolution rate only in the earliest period of leaching;(c)the rate of the process was controlled by reagent diffusion.The optimum operations wereworked out for the thiourea leaching process of the concentrate.     

Additive Behavior in Copper Electrorefining

This paper reports on the mode of action of two different organic additives—gelatine and thiourea—during the electrorefining of copper from acid copper sulfate solutions. Gelatine increases the cathode current efficiency and produces smoother deposits up to a certain level of concentration, beyond which, however, these effects are diminished by the steric hinderance of bulky molecular entities adsorbed to the electrode surface. Thiourea decreases the cathode current efficiency when present at concentrations around 5 mg/1. Nonetheless, it improves deposit quality. In higher concentrations, thiourea increases the cathodic current efficiency but also promotes nodule formation and rough deposits. The degradation and/or hydrolysis of both additives and the various interactions with the electrode surface and with cupric ions in solution are also examined.     

硫脲对 304 不锈钢镀镍层抗腐蚀性能的影响

目的研究硫脲对电镀镍层形貌、晶型、晶粒尺寸以及抗腐蚀性能的影响。方法在添加和不添加硫脲两种条件下,对304不锈钢进行电镀镍。通过XRD和SEM对比镀层的晶相结构、晶粒尺寸和微观形貌,通过Tafel曲线和EIS电化学阻抗谱对比分析样品的抗腐蚀性能。结果添加硫脲前后,镍镀层的择优生长方向从200晶面转变为111晶面,晶粒平均尺寸从60.2 nm减小为20.7 nm。由于硫脲吸附在金属表面,阻滞了溶液中金属离子放电,从而提高了阴极极化作用;同时,硫脲分子吸附在晶体生长的活性点上,有效抑制了晶体生长;因此,镍晶粒得到细化。关于腐蚀性能,镀镍304不锈钢的耐腐蚀性能最好,其次是304不锈钢基体,最差的是含硫镀镍304不锈钢。结论硫脲能够改变镍镀层晶体的择优取向,并且细化晶粒。硫脲影响电镀镍层抗腐蚀性能的机理是:阴极吸附的硫脲通过电化学还原产生H2S,进一步与Ni2+反应生成Ni S,Ni S再与富集的Ni反应生成Ni3S2。随着电镀的进行,Ni3S2被更多地沉积在镍镀层的表面,降低了镍层表面钝化膜的致密性;而且,Ni3S2与镍层存在电势差,故易发生原电池腐蚀。此外,晶粒细化导致晶界和晶面的缺陷增加,也使得腐蚀加速。故镀液中加入硫脲,镀层的耐腐蚀性能大大降低。     

电沉积Ni-S合金作碱液电解活性阴极的研究进展

电沉积Ni-S合金作为碱液电解阴极材料,具有很高的析氢反应活性,能够降低析氢反应的过电位.基于文献调研并结合作者的工作,归纳了Ni-S合金的制备、晶体结构、析氢反应活性及其析氢反应机理等方面的研究状况.     

H2SO4中硫脲作用于纯铁电极的腐蚀电化学特征

用缓蚀剂对电极过程的作用系数分析了硫脲对Fe在H2SO4中腐蚀作用的影响。结果表明,在硫脲浓度极稀时,腐蚀控制由阴极和阳极作用系数共同决定,腐蚀电流随缓蚀剂浓度的升高而增大。在主要的抑制浓度区里,硫脲对Fe的腐蚀控制是由对阴极的作用系数决定的。     

DISSOLUTION THEORY OF GOLD IN ALKALINE THIOUREA SOLUTION(I) Anodic Behavior on Gold in Alkaline Thiourea Solution Containing Na2SO3

Anodic polarization behaviors of gold and its associated elements, e.g., silver, copper, nickel and iron, in the alkaline thiourea solution with and without Na2SO3 were examined. The results showed gold is hardly dissolved in the solution with Na2SO3 because of the passivation of elemental sulfur produced by irreversible decomposition of alkaline thiourea; however, the additive Na2SO3 improves the stability of thiourea in alkaline media, greatly increases anodic current of gold and accelerates the selective dissolution of gold in the alkaline thiourea solution, without changing the passivation states of the associated elements of gold. Also the factors affecting the polarization of gold anode were investigated in detail, and it was found that, the Na2SO3obviously decreases polarization potential of gold and the apparent activation energy of gold dissolution, and the controlling step of the dissolution of gold anode in the alkaline thiourea solution is changed from the anode dissolution reaction to the solute diffusion. The mechanism for accelerated dissolution of gold in the alkaline thiourea solution with Na2SO3 was considered as electrochemical reduction and catalysis, over the Na2SO3 concentration of 0.01 ～0.5 mol/L, at the potential of 0.34～0.44 V.     

天然海水中高效缓蚀剂对碳钢缓蚀作用的研究

以锌盐、葡萄糖酸盐为主要缓蚀成分复配的适用于天然海水中碳钢的高效缓蚀剂，用失重法测定其缓蚀效率，并用电化学方法分析其缓蚀作用机理．结果表明：未预膜时缓蚀剂的临界浓度是280mg／L．此时对碳钢的缓蚀率为93．8％，试样表面光亮如初，没有局部腐蚀；预膜后缓蚀剂的临界浓度降为210mg／L，此时对碳钢的缓蚀率为93．1％．通过极化曲线分析可知该缓蚀剂是一种抑制阳极过程为主的混合型缓蚀剂．据交流阻抗谱图分析得到该缓蚀剂成膜反应分3个阶段：反应初期，缓蚀剂在电极表面初步吸附；反应中期，至浸泡48h时第一层缓蚀膜形成；反应后期，缓蚀膜向多层发展．