Current State of the Theory of Metal Corrosion Inhibition

The general regularities of the action of metal corrosion inhibitors are analyzed. It is noted that the creation of inhibitors is a big scientific problem, requiring that achievements of many fields of physical chemistry be used. The limitations involved in application of adsorption inhibitors, whose theory of action has been developed most thoroughly, are considered. The importance and theoretical aspects of the development of composite materials and inhibiting hydrophilic monomers, that undergo polymerization following adsorption on metal surface, are discussed. The search for ways to manage the polymerization of inhibitors in thin adsorption layers can become a new efficient direction of corrosion inhibition. Special cases of inhibition, which cannot be rationalized in terms of the adsorption theory and which require that complexation be taken into account, are discussed. As the theory of corrosion inhibition develops, the scope of inhibitors expands. Besides the combination of cathodic protection with corrosion inhibitors, the latter are used more and more widely in conversion coatings and in water-borne paints. The strict technological and environmental requirements that are applied to inhibitors in this case do not prevent the progress of this scientific direction and do not diminish its prospects.     

On Reasons for the Catalytic and Inhibitive Effects of Cyclic Polyethers on the Electrodeposition of Cadmium from Perchlorate Water–Acetonitrile Electrolytes

It was found that the inhibition effect of crown ethers on cadmium electrodeposition from water–acetonitrile mixtures is predominantly due to competitive adsorption of their molecules at the electrode. The factors that facilitate the involvement of the same molecules in complexation with metal in solution (e.g., an increase in the ligand concentration, the transsolvation of ions, or the desorbing effect of the components of a solution) decrease the inhibition effect of crown ethers or even cause them to become catalysts of the process.     

Corrosion Inhibition of Galvanized Steel in NaCI Solution by Tolytriazole

Corrosion inhibition of tolytriazole for galvanized steel was studied in 5 mM NaCl by using potentiodynamic polarization and electrochemical impedance spectroscopy (EIS), scanning vibrating electrode technique (SVET). The results of EIS and polarization tests indicate that tolytriazole is effective in corrosion inhibition of galvanized steel. As the concentration of tolytriazole is increased to 0.01 M, the inhibiting efficiency reaches above 98%. The low values of anodic and cathodic current density in SVET maps suggest that the complex of tolytriazole with galvanized steel inhibits the anodic and cathodic reactions of corrosion of zinc. The adsorption behaviour of tolytriazole is found to conform to Langmuir adsorption isotherm, which is typical chemical adsorption.     

Corrosion Inhibition of Galvanized Steel in NaCl Solution by Tolytriazole

Corrosion inhibition of tolytriazole for galvanized steel was studied in 5 mM NaCl by using potentiodynamic polarization and electrochemical impedance spectroscopy(EIS), scanning vibrating electrode technique(SVET). The results of EIS and polarization tests indicate that tolytriazole is effective in corrosion inhibition of galvanized steel. As the concentration of tolytriazole is increased to 0.01 M, the inhibiting efficiency reaches above 98%. The low values of anodie and cathodic current density in SVET maps suggest that the complex of tolytriazole with galvanized steel inhibits the anodic and cathodie reactions of corrosion of zinc. The adsorption behaviour of tolytriazole is found to conform to Langmuir adsorption isotherm, which is typical chemical adsorption.     

Inhibition of the Corrosion of Grey Cast Iron in Ethanediol/Water Solutions by Benzoate/Benzotriazole Mixture: A Synergistic Effect

Abstract

The synergistic effects of sodium benzoate and benzotriazole in inhibiting the corrosion of grey cast iron in 50% ethanediol/water solutions are described. Good inhibition can be obtained in the presence of both inhibitors at concentrations of eachwhich are ineffective when either inhibitor is present alone. The results also showthat the inhibitors are effective on both ‘as-cast’ and machined surfaces. Limited information is presented to demonstrate a similar synergistic effect for the inhibition of corrosion of an aluminium alloy. Some possible adsorption mechanisms to explain these effects are considered briefly.     

Investigation on the corrosion inhibitive effect of 2H-pyrazole-triazole derivatives in acidic solution

Four research methods, such as weight loss test, electrochemical techniques, adsorption isotherm, and quantum chemical calculation, were employed in this paper to study the inhibition efficiency (IE) and inhibition mechanism of three 2H-pyrazole-triazole derivatives, BHOT, FHOT, and CHOT in 1 M HCl solution for mild steel. Using the electrochemical technique, three inhibitors were proved to show a mixed-type character for mild steel by suppressing both anodic and cathodic reactions on the steel surface. The adsorption models of three compounds were established at different temperatures according to their adsorption isotherms. The results of the quantum chemical calculation method indicated that the adsorption sites of 2H-pyrazole-triazole derivatives were strongly centralized on benzene ring, triazole ring, or other substituents. All the results showed that the three derivatives were excellent inhibitors in 1 M HCl solution for mild steel.     

Selectivity recovery of molybdenum(VI) from rhenium(VII) by amine-modified persimmon waste

Amine functional group was grafted to obtain modified persimmon waste gel(NH_2–CPT) with the focus of development of selective recovery of molybdenum from rhenium. The adsorption behavior of the NH_2–CPT gel for various metal ions at varying hydrochloric acid concentrations was studied. It is found that the NH_2–CPT exhibits high affinity for Mo(VI) and no affinity for Re(VII), Cu(II),Fe(III), Mn(VII), and Zn(II) under the operating conditions. The maximum adsorption capacity for Mo(VI) is 172 mgág-1, and the adsorption behavior obeys the Langmuir model. Owing to Mo(VI) as poly-anions, the adsorption mechanism of molybdenum anions could be explained as the anion exchange reactions at weak acid concentration, while neutral molecules could be explained as the complexation reactions at strong acid concentration,respectively. In addition, its excellent adsorption characteristics for Mo(VI) are confirmed by separation of Mo(VI)from Mo to Re containing industrial effluent.     

樟树叶提取液与碘化钾的缓蚀协同效应

采用电化学方法研究了樟树叶提取液(CCIE)和碘化钾复配后(FPCCLE),对Q235钢在硫酸溶液中的缓蚀协同效应,结果表明:樟树叶提取液与碘化钾复配后,腐蚀电流密度减小,腐蚀电位负移,脱附电位Edes正移,增大了缓蚀剂的有效作用范围,提高了缓蚀剂的吸附稳定性,表现出更好的缓蚀作用,且缓蚀效率随提取液浓度的增加而增大;...     

CO2饱和溶液中缓蚀剂的电化学行为及缓蚀性能

利用电化学交流阻抗（ＥＩＳ）、极化曲线和高压釜实验装置,分别在ＣＯ２饱和及高ＣＯ２分压下的模拟油田产出水中,对ＩＭＣ－８７１－Ｇ缓蚀剂的电化学行为及缓蚀性能进行了研究,结果表明：随着缓蚀剂的加入,阴阳极腐蚀电流密度明显减小,腐蚀电位逐渐正移,阳极过程受到较大程度的抑制,表明药剂为阳极吸附型缓蚀剂,且附合Ｌａｎｇｍｕｉｒ等温吸附规律。     

Critical phenomena at electrosorption of organic compounds on electrodes

Problems associated with the effect of surfactants on polarization characteristics of a liquid metal electrode-electrolyte interface, as well as the fluctuations of its adsorption coverage, are considered. For the effective adsorption potential, the analytical dependence of which on the state parameters is determined by a nonequilibrium surface pressure, an expression derived earlier in terms of a quasichemical approximation is proposed. It is shown that the excessive differential capacitance of the interface, associated with the specific adsorption of surfactants, turns to infinity on the spinodal. The relaxation and correlation of equilibrium fluctuations of the adsorption process completeness in the interface plane at different electrode potentials are studied. Expressions for the correlation length of fluctuation are obtained. Their fundamental importance as the natural scale for the size and the duration of a nanochemical process is discussed. It is shown that the relaxation time and the correlation radius of fluctuations turn to infinity at the adsorption phase stability limit.     

螺旋流和缓蚀剂协同作用抑制管道冲刷腐蚀

目的 探讨螺旋流和缓蚀剂协同作用下的减蚀机理,为开发基于螺旋流的新型冲刷腐蚀控制方法提供理论支撑。方法 利用循环式管流冲刷腐蚀试验装置,结合失重测试法、电化学测试法、形貌分析、高速摄像和XPS腐蚀产物分析开展非螺旋流和螺旋流条件下加入水溶性咪唑啉缓蚀剂的管道冲刷腐蚀对比试验研究。结果 失重法和电化学测量结果一致表明:在非螺旋流和螺旋流条件下缓蚀剂对20号钢冲刷腐蚀的纯冲刷速率、纯腐蚀速率、腐蚀促进冲刷速率和冲刷促进腐蚀速率均具有有效的抑制作用,但对纯冲刷的缓蚀率均小于对其他三者的缓蚀率。螺旋流和缓蚀剂协同作用对纯冲刷速率、纯腐蚀速率、腐蚀促进冲刷速率和冲刷促进腐蚀速率4个分量的协同缓蚀率均高于缓蚀剂单独作用对4个分量的缓蚀率。其中对冲刷促进腐蚀分量的缓蚀率最高,达到93.75%。高速摄像结果表明扭带产生的螺旋流使砂粒切向速度增大,产生砂粒悬浮效应,改善了砂粒的分布状态。从形貌观察来看,螺旋流和缓蚀剂协同作用下工作电极表面腐蚀产物层最为完整致密且蚀坑数量最少。XPS分析证明了螺旋流和非螺旋流条件下缓蚀剂在电极表面的吸附且螺旋流促进了氧气和缓蚀剂的传质。结论 螺旋流产生的砂粒悬浮效应和传质增强效应进一步促进缓蚀剂对纯冲刷速率、纯腐蚀速率、腐蚀促进冲刷速率和冲刷促进腐蚀速率4个分量的抑制,更充分地发挥了缓蚀剂的缓蚀效果。螺旋流与缓蚀剂的协同作用在降低管道冲刷腐蚀方面具有潜在的优势。     

大肠杆菌对钯(Ⅱ)的吸附机理研究

用FTIR、XPS、TEM等表征方法对溶液中大肠杆菌吸附钯(Ⅱ)的机理行了研究。结果表明,该吸附过程与大肠杆菌和钯(Ⅱ)间静电作用有关,在pH为2.0时吸附量最大,可达120.08 mg/g;对大肠杆菌进行化学修饰,FTIR结果表明细胞表面的氨基、羧基可能为吸附钯(Ⅱ)的主要基团,涉及到表面络合机制;TEM及XPS结果显示吸附6 h后菌体内有尺寸为5~15 nm的钯纳米颗粒生成,说明该吸附过程还存在还原反应。大肠杆菌对钯(Ⅱ)的吸附过程是静电作用、表面络合、氧化还原等机制共同作用的结果。     

Adsorption mechanism of non‐toxic organic inhibitors on steel in solutions at pH 8 determined by electrochemical quartz crystal microbalance measurements

The adsorption on steel of two compounds, ascorbic acid salts (SA) and 1‐hydroxyethylidene,1‐diphosphonic acid salts (SHEDP), used alone or simultaneously, was studied using an electrochemical quartz crystal microbalance (EQCM). These products are considered to be non‐toxic organic corrosion inhibitors. SA adsorption was greater at cathodic potentials than at the corrosion potential, while SHEDP adsorbed better at the corrosion potential. The effectiveness of these two inhibitors is discussed in relation to the polarization curves. Several hypotheses are discussed to explain the adsorption mechanism in the presence of the two compounds used either alone or together.     

Photocatalytic reaction kinetics model based on electrical double layer theory Ⅲ.Surface complexation model of methyl orange adsorption on TiO_2 surface

1　INTRODUCTIONTiO2 heterogeneousphotocatalysisisarelativelyinnovativetechnologyforthedegradationofgaseousoraqueousorganicpollutants .Therewereanumberofliteraturesrelatedtotheeffectofphotocatalyst ,re actordesign ,solutioncomposition ,theorganicsub strate ,lightintensityonthereactionrateandkinet ics[16 ] .Theinvestigationofintermediatesandprod uctshadbeenfocusedonbymeansofGC MS ,ESR ,FTIRandionchromatography[7,8] .However ,onlyfew papersrelatedtotheinteractionsbetweenorganicmatterand…     

离子液体对PbO2电极性能的影响

目的 提升PbO2电极寿命以及对酚类废水的电氧化催化活性和选择性。方法 分别添加离子液体1-丁基-3-甲基-咪唑六氟磷酸盐（[BMIM]PF6）和1-乙基-3-甲基-咪唑四氟硼酸盐（[Emim]BF4）至Pb(NO3)2溶液中，用阳极电积法制备了有SnO2+Sb2O3中间层的PbO2电极。通过扫描电镜（SEM）、X射线衍射仪（XRD）、加速寿命实验、线性扫描和循环伏安测试、电氧化降解实验等考察了不同离子液体的电离产物对电极性能的影响，并与采用F-修饰的常规PbO2电极的性能进行了对比。结果 离子液体修饰的PbO2电极晶粒结晶度高，晶面取向发生改变，晶粒大小均一度高，表面平整致密、棱角多，电极有效表面积和活性点增多，且[BMIM]PF6修饰的PbO2优于[Emim]BF4修饰的PbO2。[BMIM]PF6修饰的PbO2和F-修饰的PbO2的加速寿命和电极性能稳定期分别为168.8、162.6 h和101.2、69.8 h，析氧电位分别为1.71 V和1.59 V。循环伏安显示，[BMIM]PF6修饰PbO2氧化峰电位更小，氧化峰电流更大，相同条件下，[BMIM]PF6和F-修饰PbO2对p-NP废水的电氧化降解率和有机碳去除率分别为95.7%、87.1%和85.2%、61.5%，而电解槽槽压分别为3.26 V和3.47 V。结论 离子液体[BMIM]PF6、[Emim]BF4修饰PbO2电极的结晶度、晶粒均一性、致密性增强，电极活性点增多，且由于两种离子液体电离的离子大小不同，导致对电沉积晶粒的空间位阻不同，使得前者强于后者。晶粒形态和组织结构的差异，使得[BMIM]PF6修饰PbO2对酚类废水的电氧化催化活性、选择性和寿命显著增强。     

The effect of neutral red on the corrosion inhibition of cold rolled steel in 1.0 M hydrochloric acid

The corrosion inhibition of neutral red on the corrosion of cold rolled steel in 1.0 M hydrochloric acid (HCl) was studied using weight loss method and potentiodynamic polarization method. Results obtained revealed that neutral red is an effective inhibitor. It was found that the adsorption of neutral red could prevent steel from weight loss and the adsorption accorded with the Langmuir adsorption isotherm. Potentiodynamic polarization studies showed that neutral red mainly acted as a mixed-type inhibitor for steel in 1.0 M hydrochloric acid. Thermodynamic parameters such as adsorption heat, adsorption entropy and adsorption free energy were obtained from experimental data of the temperature studies of the inhibition process at four temperatures ranging from 30 to 45 °C. The most suitable range of inhibitor concentration was discussed. The kinetic data such as apparent activation energies and pre-exponential factors at different concentrations of the inhibitor were calculated, the effect of the apparent activation energies and pre-exponential factors on the corrosion rates of cold rolled steel was discussed. The inhibitive action was satisfactorily explained by using both thermodynamic and kinetic models. Synergism between chloride ion and neutral red was proposed. The results obtained from weight loss and potentiodynamic polarization were in good agreement.     

Impedance spectroscopic study of corrosion inhibition of copper by surfactants in the acidic solutions

The inhibitive action of the four surfactants, cetyltrimethylammonium bromide (CTAB), sodium dodecyl sulfate, sodium oleate and polyoxyethylene sorbitan monooleate (TWEEN-80), on the corrosion behavior of copper was investigated in aerated 0.5 mol dm⁻³ H₂SO₄ solutions, by means of electrochemical impedance spectroscopy. These surfactants acted as the mixed-type inhibitors and lowered the corrosion reactions by blocking the copper surface through electrostatic adsorption or chemisorption. The inhibitor effectiveness increased with the exposure time to aggressive solutions, reached a maximum and then decreased, which implies the orientation change of adsorbed surfactant molecules on the surface. CTAB inhibited most effectively the copper corrosion among the four surfactants. The copper surface was determined to be positively charged in sulfuric acid solutions at the corrosion potential, which is unfavourable for electrostatic adsorption of cationic surfactant, CTAB. The reason why CTAB gave the highest inhibition efficiency was attributed to the synergistic effect between bromide anions and positive quaternary ammonium ions. C₁₆H₃₃N(CH₃)₄⁺ ions may electrostatically adsorbed on the copper surface covered with primarily adsorbed bromide ions. On the basis of the variation of impedance behaviors of copper in the surfactant-containing solutions with the immersion time, the adsorption model of the surfactants on the copper surface was proposed.     

Na2SO4溶液中磷酸环己胺的缓蚀机理及其吸附与脱附行为

应用极化曲线和交流阻抗技术研究了磷酸环己胺在Ｎａ２ＯＳ４溶液中的缓蚀机理及其吸附与脱附行为。结果表明，磷酸环己胺是一种负催化效应作用机理的阳极型缓蚀剂。它在铁电极上的吸附等温式符合Ｔｅｍｋｉｎ模型。由于缓蚀剂的吸附与脱附作用，其阴极极化曲线存在着氧扩散极限电流区，强吸附区和Ｔｅｆｅｌ线性区，而阳极极化曲线存在着Ｔａｆｅｋ线性区，脱附区和无缓蚀区。     

天然多糖及衍生物在金属缓蚀剂中的研究进展

缓蚀剂是一种减缓金属在外界环境中发生腐蚀反应的有效物质.随着人类绿色环保意识的增强,来源广、可再生、易降解、含有大量活性吸附中心的天然大分子链多糖物质已成为目前环境友好型缓蚀剂的研究热点之一.概述了近几年国内外天然多糖及衍生物和复合材料在抑制金属腐蚀方面的研究,重点综述了淀粉、纤维素、壳聚糖和其他天然多糖类物质的分子结构特点及在不同腐蚀环境中对金属的缓蚀性能.在此基础上,梳理了各类天然多糖物质的化学改性合成方法及改性后各衍生物的缓蚀能力,简要介绍了部分基于多糖物质或其衍生物制备的复合材料在缓蚀领域的研究进展.同时,从吸附模型及吸附方式(物理吸附、化学吸附)等方面,归纳了多糖类物质保护金属的作用机制.最后,分析了各类多糖及衍生物在金属缓蚀方面所存在的几点不足,如单一未改性的天然物质缓蚀效果差,部分改性产品溶解性差,部分改性方法复杂,缓蚀机理研究较少等,并展望了各类多糖及衍生物在未来缓蚀剂领域的发展趋势.     

酸性溶液中不同电位下脆硫锑铅矿/DDTC界面的电化学机制

用循环伏安和交流阻抗法,研究了脆硫锑铅矿在含乙硫氮的pH 4.0缓冲溶液中的表面电化学行为,讨论了在不同电位下脆硫锑铅矿表面的反应、电化学吸附、钝化作用、电化学阻抗、微分电容的变化.结果表明:在酸性溶液中,脆硫锑铅矿具有盐的特性;电极过程呈现出受电化学反应及产物吸附控制的动力学特征.当电极电位为-78 mV～422 mV,矿物表面疏水性膜逐渐增长并产生钝化作用;当电极电位为522 mV时,电极过程完全由离子扩散决定的电化学反应所控制;当电位大于622 mV后,电极反应产生大量的PbSO4沉淀,并覆盖在电极表面,矿物表面的亲水性强.