Chemically modified guar gum and ethyl acrylate composite as a new corrosion inhibitor for reduction in hydrogen evolution and tubular steel corrosion protection in acidic environment

The paper deals with the synthesis of Guar gum and ethyl acrylate (GG-EEA) composite. The synthesized natural polysaccharide composite was used as a corrosion inhibitor to reduce hydrogen evolution and P110 steel corrosion protection in 15% HCl (Hydrochloric acid). The primary corrosion techniques like weight loss, electrochemical impedance spectroscopy (EIS), and potentiodynamic polarization (PDP) was used to analyze the corrosion inhibition process. The PDP proposed that GG-EEA composite is a mixed-type corrosion inhibitor and inhibits corrosion by blocking the active sites presenting over the metal surface. The corrosion inhibition performance of GG alone is 77.5%, and that of GG-EEA is 92.3% at 500 mg/L. The adsorption of GG-EEA onto P110 steel is spontaneous and mixed type, i.e., both physical and chemical. The conformation of GG-EEA molecule adsorption was done using a scanning electron microscope (SEM), Energy dispersive x-ray spectroscopy (EDX), Atomic force microscopy (AFM), and X-ray photoelectron spectroscopy studies. Density functional theory (DFT) analysis was done to explore the active sites over the inhibitor in metal-inhibitor interaction. Molecular dynamic simulation (MD) simulations study reveals that GG-EEA has more adsorption capacity than GG alone.     

Corrosion inhibition, hydrogen evolution and antibacterial properties of newly synthesized organic inhibitors on 316L stainless steel alloy in acid medium

Electrochemical corrosion behavior and hydrogen evolution reaction of 316L stainless steel has been investigated, in 0.5 M sulfuric acid solution containing four novel organic inhibitors as derivatives from one family, using potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) measurements and surface examination via scanning electron microscope (SEM) technique. The effect of corrosion inhibitors on the hydrogen evolution reaction was related to the chemical composition, concentration and structure of the inhibitor. The inhibition efficiency, for active centers of the four used compounds, was found to increase in the order: -Cl < -Br < -CH₃ < -OCH₃. The corrosion rate and hydrogen evolution using the compound with methoxy group as a novel compound was found to increase with either increasing temperature or decreasing its concentration as observed by polarization technique and confirmed by EIS measurements. The compound with methoxy group (newly synthesized) has very good inhibition efficiency (IE) in 0.5 M sulfuric acid (98.3% for 1.0 mM concentration). EIS results were confirmed by surface examination. Also, antibacterial activity of these organic inhibitors was studied. The results showed that the highest inhibition efficiency was observed for the compound that posses the highest antibacterial activity.     

Influence of 2-(4-chlorophenyl)-2-oxoethyl benzoate on the hydrogen evolution and corrosion inhibition of 18 Ni 250 grade weld aged maraging steel in 1.0 M sulfuric acid medium

Electrochemical corrosion behavior and hydrogen evolution reaction of weld aged maraging steel have been investigated, in 1.0 M sulfuric acid solution containing different concentrations of 2-(4-chlorophenyl)-2-oxoethyl benzoate (CPOB). The data obtained from polarization technique showed that the corrosion current density (i_corr) and the hydrogen evolution rate decrease, indicating a decrease in the corrosion rate of weld aged maraging steel as well as an increase in the inhibition efficiency (η%) with the increase in inhibitor concentration. Changes in impedance parameters were indicative of adsorption of CPOB on the metal surface, leading to the formation of protective film. Both activation (E_a) and thermodynamic parameters (ΔG_ads⁰, ΔH_ads⁰ and ΔS_ads⁰) were calculated and discussed. The adsorption of CPOB on the weld aged maraging steel surface obeyed the Langmuir adsorption isotherm model. Scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS) study confirmed the formation of an adsorbed protective film on the metal surface.     

Insight of corrosion mitigation performance of SABIC iron in 0.5 M HCl solution by tryptophan and histidine: Experimental and computational approaches

The inhibitory strength of two amino acids namely, tryptophan (Tryp) and histidine (Hist) on the corrosion of SABIC iron (SABIC Fe) in a 0.5 M HCl solution was examined utilizing mass loss (MS), electrochemical (PDP and EIS) and theoretical studies. Density functional theory (DFT) and Monte Carlo (MC) simulation were inspected for Tryp and Hist inhibitors. All the corrosion parameters and theoretical data obtained from these studies confirm the inhibiting impact of the two amino acids. The efficacy of inhibition augment with augmentation the concentration of two amino acids from 100 to 500 ppm and reducing at elevated temperature. The effectiveness of the inhibition depends on the presence of some active centers that accelerate the adsorption process and the molar mass of the inhibitors. The inhibition efficacy of Tryp is greater than that of Hist reaching 92.09% at a concentration of 500 ppm while in the presence of Hist it is 89.37% using PDP measurements. Inhibition was demonstrated by spontaneous adsorption of Hist and Tryp on the surface of SABIC Fe according to the Langmuir adsorption isotherm. PDP curves clarified that the Tryp and Hist compounds acted as mixed type inhibitors. A variety of thermodynamic and kinetics parameters were computed and explained. SEM images demonstrate that the protective layer constructed on the surface of S– Fe in the presence of both amino acids. The results obtained from DFT are in complete agreement with the experimental work. Tryp and Hist compounds are adsorbed horizontally onto the surface of Fe (110).     

Inhibition effect of natural polysaccharide composite on hydrogen evolution and P110 steel corrosion in 3.5 wt% NaCl solution saturated with CO2: Combination of experimental and surface analysis

For the analysis of corrosion and hydrogen production inhibition, we have synthesized Guar gum and methylmethacrylate (GG-MMA) composite. The synthesized composite was used as an eco-friendly corrosion inhibitor for P110 steel in 3.5% NaCl solution saturated with carbon dioxide at 50 °C. The primary corrosion techniques like weight loss, electrochemical impedance spectroscopy (EIS), and potentiodynamic polarization (PDP) was used to analyze the corrosion inhibition process. EIS study reveals the kinetically controlled corrosion inhibition process. The results of PDP proposed that GG-MMA composite is the cathodic type of inhibitor. The corrosion inhibition performance of GG-MMA alone is 90% at 400 mg/L, and that of formulation with KI (5 mM) + GG-MMA (300 mg/L) is 96.8%. The adsorption of GG-MMA over P110 steel is spontaneous and mixed type i.e., both physical and chemical. The conformation of GG-MMA molecule adsorption was done using a scanning electron microscope (SEM), Contact angle measurement, Atomic force microscopy (AFM), Scanning Electrochemical Microscopy (SECM) and X-ray photoelectron spectroscopy studies.     

Inhibition effect of newly synthesized benzoxanthonesderivative on hydrogen evolution and Q235 steelcorrosion in 15% HCl under hydrodynamic condition: Combination of experimental,surface and computational study

The investigation of this study deals with the synthesis using green synthetic approach, characterization and application of benzoxanthones derivative namely 9,9-Dimethyl-12-p-tolyl-8, 9,10, 12-tetrahydrobenzo[a]xanthen-1-one (TBX) for the inhibition of Q235 steel corrosion in 15% HCl under dynamic condition. The results of EIS confirmed towards the increment in R_ct values with rise in concentration. Additionally, results of PDP reveals that TBX is cathodic type inhibitor. The maximum inhibitive excellency of TBX was given at 200 mg/L with the value of 92.3%. The increasing temperature tends to increase in corrosion rate. Langmuir adsorption isotherm provides the excellent fitting. The surface morphology and adsorption of TBX molecules were confirmed using scanning electron microscopy (SEM) and X-photo electron microscopy (XPS). Density functional theory (DFT) and Molecular dynamic simulation (MD) confirmed that corrosion inhibition efficiency ranking obtained for studied molecules is TBXH⁺> TBX.     

Evaluation of vacuum heat-treated α-C films for surface protection of metal bipolar plates used in polymer electrolyte membrane fuel cells

Proton exchange membrane fuel cells (PEMFCs) assembled with metal bipolar plates (BPPs) is a promising power source for new energy vehicles. However, metal BPPs have serious corrosion issues and the surface electrical performance degrades in the harsh PEMFC environment. Amorphous carbon (α-C) films exhibit improved properties with both high corrosion resistance and electrical conductivity. Subsequent vacuum heat treatment of the as-coated α-C films can change their phase composition and film structure, modifying their performance. This study prepared α-C films with a titanium interlayer on a SS316L substrate by DC balance magnetron sputtering and then subjected them to vacuum heat treatment at different temperatures (400–700 °C). These treated α-C films are systemically analyzed in terms of surface and cross-sectional morphologies, sp bond hybridization, interfacial electrical conductivity, and corrosion resistance. The results indicate that the conversion of sp³ to sp² and the compact density of α-C films are greatly enhanced with an increase in temperature, greatly improving the corrosion resistance and surface conductivity of the films. These promising results lead to a potential direction for the post-coating treatment of α-C films on metal BPPs in PEMFCs.     

焦化厂实行梯级用水降低水耗的实践

通过对焦化厂所用水水质和不同用水系统工艺特点的分析,制订焦化厂梯级用水制度,降低水耗30％;对水处理设备进行改进,稳定水处理药剂浓度;根据阻垢及缓蚀实验结果,确定适用于高氯离子浓度循环水系统的阻垢缓蚀剂。     

地热流体的腐蚀与结垢控制现状

在地热发电或直接利用过程中,与地热流体（液体或蒸汽）接触的设备、管道或管件存在着腐蚀和结垢现象,往往成为地热开发利用的技术瓶颈。因此,开展地热流体的腐蚀与结垢控制技术研究至关重要。本文主要分析了近年来国内外在地热流体的腐蚀和结垢控制方面的研究进展,包括选材、涂层、流体预处理、化学添加剂等控制方法,并提出了进一步的研究方向,包括全面的地热流体腐蚀结垢趋势预测及地球化学模拟,结垢机理研究,涂层和基底的结合力和耐久性研究,阴极保护以及复合控制方法开发等。     

Recycling of some domestic wastes to produce green corrosion inhibitors and biocides for sulfate reducing bacteria

Egypt suffers from a huge amount of domestic wastes which causes a lot of economic and environmental problems. This work investigated the possibility of recycling of some of these wastes into green corrosion inhibitors and biocides. The studied aqueous extracts of outer brown peels of onion (A), outer peels of garlic (B), orange (C), and mandarin (D) peels reduced markedly the corrosion rate of carbon steel alloy in 1.0 M HCl and behaved as mixed inhibitors. The inhibition efficiency decreased in the following order: C > B > A > D and generally increased with the increase of the extract concentration. The inhibition mechanism and adsorption isotherms were discussed to describe the adsorption characteristics of the extracts on the carbon steel surface. The extracts of orange and mandarin peels expressed biocidal effect on sulfate reducing bacteria (SRB). However, those of onion and garlic peels did not express any biocidal activity against SRB.     

Catalytic inhibition of laminar flames by transition metal compounds

Some of the most effective flame inhibitors ever found are metallic compounds. Their effectiveness, however, drops off rapidly with an increase of agent concentration, and varies widely with flame type. Iron pentacarbonyl, for example, can be up to two orders of magnitude more efficient than CF₃Br for reducing the burning velocity of premixed laminar flames when added at low volume fraction; nevertheless, it is nearly ineffective for extinction of co-flow diffusion flames. This article outlines previous research into flame inhibition by metal-containing compounds, and for more recent work, focuses on experimental and modeling studies of inhibited premixed, counterflow diffusion, and co-flow diffusion flames by the present authors. The strong flame inhibition by metal compounds when added at low volume fraction is found to occur through the gas-phase catalytic cycles leading to a highly effective radical recombination in the reaction zone. While the reactions of these cycles proceed in some cases at close to collisional rates, the agent effectiveness requires that the inhibiting species and the radicals in the flame overlap, and this can sometimes be limited by gas-phase transport rates. The metal species often lose their effectiveness above a certain volume fraction due to condensation processes. The influence of particle formation on inhibitor effectiveness depends upon the metal species concentration, particle size, residence time for particle formation, local flame temperature, and the drag and thermophoretic forces in the flame.     

Hydrogen generation during the corrosion of carbon steel in crotonic acid and using some organic surfactants to control hydrogen evolution

The purpose of this paper is to describe and evaluate the corrosion of carbon steel in crotonic acid for hydrogen production and using polysorbate 20 (NS), dioctyl sodium sulfosuccinate (AS) and benzalkonium chloride (CS) to control hydrogen evolution. Measurements were conducted in tested solutions using hydrogen evolution and electrochemical impedance spectroscopy (EIS) measurements and complemented by scan electron microscope (SEM) and energy dispersive X-ray (EDX) investigations. It is shown that the hydrogen generation rate obtained during the corrosion of carbon steel in crotonic acid increased with increase in acid concentration, temperature and immersion time. The addition of organic surfactants inhibits the hydrogen generation rate. The inhibition occurs through adsorption of organic surfactants on the metal surface. Adsorption processes followed the Langmuir isotherm. The order of effectiveness of the surfactants was AS > NS > CS. The values of activation energy (E_a) and heat of adsorption (Q_ads) were calculated and discussed.     

含硫循环水增效缓蚀阻垢处理工艺及应用

为减少新鲜水用量和排污量．中国石化九江分公司在循环水硫化物浓度偏高的情况下应用了增效缓蚀阻垢处理工艺。应用结果表明,循环水中硫化物浓度在0．1～1．0mg／L的条件下,采用增效缓蚀阻垢处理工艺可使试验试管腐蚀速率由0．134mm／a降至0．062mm／a,试管黏附速率由10．72mg／（cm^2·月）降至0．140mg／（cm^2·月）,缓解了因物料泄漏对设备造成的严重腐蚀。     

Corrosion-protection of moulded graphite conductive plastic bipolar plates in PEM electrolysis by plasma processing

Proton exchange membrane electrolysis is one of the key technologies for the implementation of renewable energy. The main advantage is the conversion of electrical energy into storable chemical energy. The objective of this work is to enhance our understanding of protective coatings for carbon-polymer composite compound materials used as bipolar plates in acidic electrolysis cells. A two-step plasma process was developed to deposit a corrosion protection. As a first step, the composite compound surface was roughened by applying RF high voltage and using it as a powered electrode. As a second step, titanium coatings were deposited by pulsed DC magnetron sputtering. The plasma process was monitored by in-situ temperature measurements. The corrosion resistance of the coated compound surface was evaluated by cyclic voltammetry and chronoamperometry at 2 V vs. SHE as well as light microscopy. Furthermore, we analysed the activation effect by SEM; the titanium coatings were analysed by the van-der-Pauw method and SEM.     

氮基阻滞剂抑制二恶英生成研究综述

介绍了近年来国内外氮基阻滞剂抑制二恶英生成的研究进展,阐述了温度、浓度、反应物种类等因素对氮基阻滞剂抑制效果的影响.通过对比分析硫酸铵、尿素和氨气等氮基阻滞剂抑制二恶英生成效果的差异,总结了可能的氮基抑制机理,包括阻滞氯化作用、减弱Deacon反应、催化剂中毒等.最后简要地介绍了污泥干化气作为一种新型阻滞剂的可能性,并指出了此方向今后研究的重点和难点.氮基阻滞剂作为一种十分有效的二恶英生成阻滞剂,仍需加强机理的探索和新型阻滞剂的开发.     

Analysis of corrosion inhibition of Kleinhovia hospita plant extract aided by quantification of hydrogen evolution using a GLCM/SVM method

During a corrosion inhibition test, a combination of common electrochemical corrosion test methods with an in-situ quantification of H₂ evolution could provide a comprehensive analysis of the effectiveness of an organic inhibitor. This work analyzes the corrosion inhibition efficiency of Kleinhovia hospita plant extract on carbon steel specimens polarized in 1 M HCl, based on acquired H₂ bubbles images, by using gray level co-occurrence matrix (GLCM) and support vector machine (SVM) classification. A conformity was established between the classified-algorithm models and the corrosion test results obtained by potentiodynamic polarization test and electrochemical impedance spectroscopy. Hydrogen rate and corrosion rate show the same lowest trends at the addition of 3000 mg/L of KH extract. The inhibitor addition led to 99% of maximum inhibition efficiency. Based on the polarization data, KH extract is a mixed type inhibitor. Supported by Langmuir calculation for adsorption isotherm, a physisorption is stated as the main inhibition mechanism. The feature extraction using GLCM was able to distinguish changes in H₂ bubbles characteristics where the addition of inhibitor affected the corrosion rate. The GLCM/SVM method applied as a linear kernel function and showed 88% accuracy with d = 5 for image data testing. Remarkable changes in H₂ gas bubbles characteristic were observed in the specimen immersed in the solution with 3000 mg/L inhibitor addition, signified by 99% inhibition efficiency.     

带脱硫系统的火电厂烟囱低温腐蚀模拟实验研究

采用人工加速腐蚀实验方法,研究了电站尾部烟气对烟囱混凝土的影响。对在H2SO4、HCl和HF酸液下的低温腐蚀进行了比较研究。结果表明:3种酸液对混凝土腐蚀的发展规律符合幂函数的变化关系;在H2SO4和HCl腐蚀下,抗压强度随腐蚀时间的延长而降低,但在HF酸中,抗压强度增加;抗压强度的变化值随着中性化深度增加而增加。混凝土中CaO含量下降是引起强度降低的主要原因;强度大幅度降低(HF酸除外)的根本原因,是由于混凝土中Ca(Al2Si2O8)·4H2O、Na6AlSi2O7和Ca2SiO4·4H2O等组分大量减少。     

烟机入口管线露点腐蚀原因分析及解决措施

分析了中国石油庆阳石化公司催化裂化装置三机组烟机入口管线露点腐蚀问题的成因,提出了整改措施和预防办法,即减少原料中的含硫物质;及时清除金属表面的附着物和沉积物;保持金属壁面的温度在硫酸露点以上;对排尘阀结构进行改造,增设第二道阀门,使腐蚀点外移。     

An investigation into factors affecting the stability of carbons and carbon supported platinum and platinum/cobalt alloy catalysts during 1.2 V potentiostatic hold regimes at a range of temperatures

To meet automotive targets for fuel cell operation and allow higher temperature operation an understanding of the factors affecting carbon and platinum stability is critical. The stability of both carbons and carbon supported platinum and platinum/cobalt alloy catalysts was studied during 1.2 V versus RHE potentiostatic hold tests using carbon and catalyst coated electrodes in a three-chamber wet electrolyte cell at a range of temperatures. At 80 °C the wt% of carbon corroded increases with increasing BET area. Surface oxidation was followed electrochemically using the quinone/hydroquinone redox couple. Increasing temperature, time at 1.2 V and wt% platinum on the carbon increases surface oxidation. Although increasing temperature was shown to increase the extent of carbon corrosion, catalysing the carbon did not significantly change how much carbon was corroded. Platinum stability was investigated by electrochemical metal area loss (ECA). Platinum catalysts on commercial carbons lost more ECA with increasing temperature. A platinum/cobalt alloy on a low surface area carbon was demonstrated to be more stable to both carbon corrosion and metal area loss at temperatures up to 80 °C than platinum catalysts on commercial carbons, making this material an excellent candidate for higher temperature automotive operation.     

Hydrogen-induced cracking and corrosion behavior of friction stir welded plates of API 5L X70 pipeline steel

The use of friction stir welding (FSW) has proven to be an excellent alternative to join engineering components. Although FSW has had a significant development in recent years, challenges for new applications have been raised, such as offshore steel parts suffering hydrogen embrittlement in the gas and oil industry. Therefore, in this work, the microstructure, corrosion, and hydrogen-induced cracking were investigated in a two-pass FSW welded joint of API 5L X70 pipeline steel. The electrochemical results indicate an inhibitory effect on corrosion reaction because of a carbonate product generation in the steel surface. The polygonal ferritic and degenerated pearlite bands microstructure in the base metal fixed carbonate deposits in the steel surface. In the welded regions, the bainitic microstructure and the carbide particle distribution are less efficient in setting the weld surface carbonate deposit. HIC tests showed cracks initiation and propagation to be more prone in hard phases.