Chemical and electrochemical studies of the inhibition performance of hydro-alcoholic extract of used coffee grounds (HECG) for the corrosion of C38 steel in 1M hydrochloric acid

The corrosion protection of C38 steel in 1M HCl solution with hydro-alcoholic used coffee grounds extract (HECG) was studied using measurements of hydrogen gas evolution, potentiodynamic polarization and electrochemical impedance spectroscopy. This work revealed that the HECG studied acts as a mixed type inhibitor. It has also been shown that the corrosion inhibition efficiency (IE) increases with increasing extract concentration, an IE value of 97.4% was reached with 2 g/L HECG. The inhibitory action of the inhibitor was mainly due to the adsorption of HECG molecules on the C38 steel surface. The studies have shown that HECG adsorbs on the C38 steel surface according to Langmuir's isotherm, with a standard free energy (ΔG⁰_ads) of −18,477 KJ mol⁻¹, which means that HECG delays the corrosion process by physical adsorption. The scanning electron microscope (SEM) study confirmed that corrosion inhibition of C38 steel occurs by adsorption of inhibiting molecules on the metal surface. These results show that the HECG can be used as an excellent corrosion inhibitor for C38 steel in a hydrochloric acid medium.     

Mild steel corrosion inhibition by Parsley (Petroselium Sativum) extract in acidic media

The inhibition effect of Parsley (Petroselium Sativum) leaves extract (PSL) on mild steel in one molar HCl solution was investigated by weight loss, potentiodynamic polarization, impedance spectroscopy and scanning electron microscopy. Steel corrosion rate decreased significantly in the presence of PSL. The corrosion inhibition efficiency increased with the increase of PSL concentration up to 92.39% obtained at 25 °C for a 5 gL⁻¹ concentration. Polarization showed that PSL acts as a mixed type inhibitor. The adsorption of the extract on mild steel surface was spontaneous, physisorption type and according to the Langmuir adsorption isotherm. Results obtained by different tests proved that the extract is an effective green inhibitor for mild steel corrosion in acid solution.     

油气田酸化用缓蚀剂双咪唑啉季铵盐的合成及评价

采用癸二酸、三乙烯四胺、氯化苄为原料合成一种双咪唑啉季铵盐缓蚀剂,用红外光谱表征。模拟油气田压裂酸化液,用失重法研究缓蚀剂浓度、介质温度、酸化液含量对缓蚀性能的影响。结果表明,缓蚀剂最佳使用量为300mg／L;随着温度升高和酸化液含量增加,缓蚀效率逐渐降低,在土酸介质中的缓蚀性能优于盐酸介质;极化曲线表明,该缓蚀剂是吸附型、以阳极型为主的缓蚀剂;扫描电镜观察表明,加入缓蚀剂的试样表面腐蚀形貌比未加入缓蚀剂的试样表面腐蚀形貌光滑。     

喹啉与硫脲在含饱和CO_2气井采出水中的协同效应

加注缓蚀剂抑制CO_2腐蚀是天然气开发过程中的常见工艺,利用缓蚀协同效应可以有效降低缓蚀剂的用量,减少对环境的污染,提高经济效益。为此,采用静态失重法、电化学极化曲线、阻抗谱(EIS)、扫描电子显微镜(SEM)及电子能谱等实验分析方法,研究了在含饱和CO_2模拟气井采出水腐蚀体系中,喹啉季铵盐(QN)与硫脲(TU)对N80碳钢的缓蚀协同效应。结果表明:①喹啉季铵盐和硫脲均能有效抑制N80碳钢的腐蚀;②喹啉季铵盐是一种以抑制阴极型为主的缓蚀剂;③硫脲对N80碳钢的阴极和阳极均具有较强的抑制作用,是一种混合型缓蚀剂;④当喹啉季铵盐与硫脲复配使用时,在较低的使用浓度下,喹啉季铵盐缓蚀剂与硫脲具有较好的缓蚀协同效应,当3 mg/L喹啉季铵盐缓蚀剂与7 mg/L硫脲复配使用时,缓蚀效果最佳,缓蚀率可达到93.59%;⑤喹啉季铵盐与硫脲相互作用在N80碳钢表面能形成稳定的吸附膜,较大程度地抑制N80碳钢的腐蚀过程。进而还对喹啉季铵盐与硫脲之间的协同作用机理进行了探讨。     

Thermodynamic,adsorption and electrochemical studies for corrosion inhibition of carbon steel by henna extract in acid medium

Corrosion inhibition of carbon steel in the presence of different concentrations of aqueous extract from henna leaves in 1 M HCl solution has been studied using the weight loss and potentiodynamic polarization techniques. The effect of temperature on the corrosion behavior of carbon steel was studied in the temperature range 293–333 K. The inhibition efficiency increases with increasing inhibitor concentration but decreases with increasing temperature. The activation and free energies for the inhibition reactions support the mechanism of physical adsorption. The adsorption of henna extract on C-steel surface is endothermic, spontaneous and consistent with the Langmuir adsorption isotherm. The potentiodynamic polarization measurements indicate that henna extract acts as a mixed inhibitor. Surface and protective film analysis have been carried out using; energy dispersive X-ray (EDX), scanning electron microscopy (SEM), Fourier transforms infrared (FT-IR) spectroscopy and X-ray diffraction (XRD) analysis.     

Adsorption and inhibition behavior of a novel Schiff base on carbon steel corrosion in acid media

In this study, the inhibition effect of 2,2′-(heptane-1,7-diylbis(azanylylidene)bis-(methanylylidene))diphenol (HAMD) on carbon steel corrosion in 0.5 mol L⁻¹ H₂SO₄ solution was studied. Weight loss and electrochemical techniques such as open circuit potential (OCP), potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) were used to inspect the efficiency of HAMD as corrosion inhibitor. Scanning electron microscopy (SEM) and energy dispersion X-ray (EDAX) were used to characterize the steel surface. Polarization measurements indicated that, the studied inhibitor acts as mixed-type inhibitor. The adsorption of HAMD molecules on the carbon steel surface obeys Langmuir adsorption isotherm.     

Corrosion inhibition efficiency of water soluble ethoxylated trimethylol propane by gravimetric analysis

Polyoxyethylenated trimethylol propane monolaurate surfactants with varied ethylene oxide content were tested as corrosion inhibitors via the weight loss method. Weight loss measurements for carbon steel dissolution were performed in 1 N HCl containing different inhibitor concentrations at 30, 40 and 50 °C. These measurements were utilized for calculating corrosion rate, surface coverage area and percentage inhibition. The obtained data show that the adsorption of these inhibitors obeys Langmuir adsorption isotherm. Thermodynamic parameters (ΔG¹, ΔH¹ and ΔS¹) of the corrosion process are evaluated and correlated to inhibitors structures.     

Surface protection of mild steel in acidic chloride solution by 5-Nitro-8-Hydroxy Quinoline

The effect of commercially available quinoline nucleus based pharmaceutically active compound 5-Nitro-8-Hydroxy Quinoline (NHQ) against the corrosion of mild steel (MS) in 1 M acidic chloride (HCl) solution was investigated by chemical (weight loss – WL) and electrochemical (Tafel polarization, Linear polarization and Electrochemical impedance spectroscopy) techniques. From all the four methods, it is inferred that the percentage of inhibition efficiency increases with increasing the inhibitor concentration from 50 to 300 ppm. The adsorption behavior of inhibitor obeyed through Langmuir isotherm model. Thermodynamic parameters were also calculated and predict that the process of inhibition is a spontaneous reaction. EIS technique exhibits one capacitive loop indicating that, the corrosion reaction is controlled by charge transfer process. Tafel polarization studies revealed that the investigated inhibitor is mixed type and the mode of adsorption is physical in nature. The surface morphologies were examined by FT-IR, SEM and EDX techniques. Theoretical quantum chemical calculations were performed to confirm the ability of NHQ to adsorb onto mild steel surface.     

Environmental-friendly shrimp waste protein corrosion inhibitor for carbon steel in 1 M HCl solution

Recovery shrimp waste protein (RSWP) was extracted, characterized and tested their inhibition effects as a corrosion inhibitor for carbon steel in 1?M HCl solution using different electrochemical techniques. The results have been shown that the corrosion rate decreases with increasing inhibitor concentration. To verify the morphology of RSWP film formed on the carbon steel surface, scanning electron microscopy (SEM) was used. The inhibition mechanism of the extracted RSWP is discussed in terms of adsorption on the carbon steel surface. The results of the energy adsorption were showed chemisorption effect for RSWP on the carbon steel surface.     

聚天冬氨酸在KNO3介质中的缓蚀性研究

采用极化曲线法研究了聚天冬氨酸缓蚀剂在KNO，的量浓度为0．1mol/L的溶液中对碳钢的缓蚀作用。试验结果表明：聚天冬氨酸对碳钢的阴极和阳极极化都有抑制作用，但以抑制阳极为主，是一种混合型缓蚀剂。试验中随着聚天冬氨酸质量浓度的增大，缓蚀效率提高，最佳质量浓度是400mg／L。根据试验结果，初步认为聚天冬氨酸属于吸附膜缓蚀剂。     

Rosemary oil as a corrosion inhibitor for carbon steel in 0.5 M sulfuric acid solution

The possibility of using rosemary oil as a corrosion inhibitor of carbon steel in 0.5 M sulfuric acid solution was investigated by determination of weight loss, potentiodynamic polarization, and electrochemical impedance spectroscopy. It was shown that the inhibition effectiveness increases with an increase in the concentration of oil and a decrease in the temperature. The inhibiting effect of the investigated oil is due to its adsorption on the surface of the steel and complexation. Adsorption is described by a Langmuir isotherm. The effect of the temperature on the corrosion rate was studied in the presence and absence of the oil and the thermodynamic parameters of the corrosion process were calculated.     

1,3-双(2-苯并咪唑基)-2-氧杂丙烷对N80钢的缓蚀性能

以1,3-双(2-苯并咪唑基)-2-氧杂丙烷为N80油管钢缓蚀剂,采用热重分析（TGA）方法考察其热稳定性,通过电化学工作站测定Tafel极化曲线,评价1,3-双(2-苯并咪唑基)-2-氧杂丙烷在饱和CO2环境中的投加量与缓蚀率之间的关系,并探讨其缓蚀机理。结果表明：1,3-双(2-苯并咪唑基)-2-氧杂丙烷的热稳定性良好;将其作为油管钢缓蚀剂,缓蚀率高,当缓蚀剂浓度为1 mmol/L时,缓蚀率可达87.84 %。通过Langmuir吸附等温线可以看出,该缓蚀剂通过物理化学作用在金属表面吸附成膜,从而对金属起缓蚀作用。     

Inhibition of corrosion of carbon steel 1018 in acid medium with ethoxylated aliphatic alcohols

The effectiveness of inhibition of carbon steel 1018 in 1 M solution of HCl by three ethoxylated aliphatic alcohols with a different number of ethylene oxide units was investigated by measuring the weight loss of the steel and galvanostatic polarization. An increase in the effectiveness of inhibition with an increase in the concentration of the inhibitor, number of ethylene oxide units in its molecule, and decrease in the temperature was found. Inhibition of corrosion is due to adsorption of ethylene oxide groups in the inhibitors on the metal surface. Adsorption is described by a Langmuir isotherm. The effect of the temperature on the corrosion rate in the presence and absence of inhibitors was investigated. Some thermodynamic parameters of corrosion were calculated.     

Inhibition of carbon steel corrosion in hydrochloric acid solutions using polyoxyethylene sorbitan fatty acid esters (tween compounds)

Inhibition of carbon steel corrosion in 1 M hydrochloric acid solution in the presence of some polyoxyethylene sorbitan fatty acid esters (Tween compounds) is studied by weight loss and galvanostatic polarization measurements. The inhibition efficiency increases with increasing surfactant concentration and decreasing temperature. The inhibiting effect of the investigated compounds is explained by their adsorption on the metal surface. The adsorption process is described by a Langmuir isotherm. The effect of rising temperature on the steel corrosion rate in the absence and in the presence of the inhibitors is investigated. Some thermodynamic corrosion parameters are calculated.     

两种金属化合物对喹啉季铵盐缓蚀性能的影响

为了提高喹啉季铵盐对N80钢的缓蚀性能,采用静态失重法和动电位极化曲线法,研究了在90℃、15%HCl溶液中添加Al_2O_3及Al_2O_3+Cu Cl2对喹啉季铵盐缓蚀性能的影响。试验结果显示,160℃温度下合成的喹啉季铵盐缓蚀效果较差,不能满足SY/T 5405—1996中的一级指标要求;Al_2O_3的加入能有效提高喹啉季铵盐对N80钢的缓蚀效果,并且能大大降低喹啉季铵盐的用量;Al_2O_3+CuCl_2和喹啉季铵盐复配后,能更大程度上提高喹啉季铵盐的缓蚀效果,缓蚀性能明显好于Al_2O_3与喹啉季铵盐形成的复配缓蚀剂。结果表明,喹啉季铵盐能与金属离子形成较为稳定的螯合物,螯合物通过化学作用吸附在挂片表面形成一层致密的铜膜,阻止了腐蚀离子向金属表面移动,从而表现出较好的缓蚀效果。     

Inhibition of mild steel corrosion and calcium sulfate formation in highly saline synthetic water by a newly synthesized anionic carboxylated surfactant

A newly anionic surfactant; namely (2Z,2′Z)-4,4′-(ethane-1,2-diylbis((2-((4-dodecylphenyl)sulfonamido)ethyl)azanedinyl)bis(4-oxobut-2enoate), desined as Tetra-anionic surfactant was synthesized. Its chemical structure was confirmed by FTIR and ¹HNMR spectroscopic techniques. The corrosion mitigation behavior of the prepared surfactant for mild steel (MS) in high saline synthetic water was monitoring by chemical technique (weight loss), electrochemical techniques (Tafel and EIS). The obtained results showed that the corrosion resistance has been improved after the addition of the surfactant molecules. The inhibition efficiency grown up with the inhibitor concentration reaching the maximum at concentration 120?ppm, where the IE% values were 84, 82, and 79.5% in cases of weight loss, Tafel and EIS techniques, respectively. The mixed-type inhibitor with permanent anodic effect can be inferred from polarization data of mild steel in the presence of different concentration of Tetra- compound. The corrosion protection performance of the used inhibitor was related to its adsorption ability on the MS surface. The adsorption of Tetra-molecules increased the charge transfer resistance of MS. The adsorption process of the tested corrosion inhibitor obeyed Langmuir adsorption isotherm. The corrosion and scale produced layer formed on the mild steel surface in absence and presence of the insight anionic surfactant was depicted by SEM. The chemical analysis of this layer was examined by EDX, and show the corrosion and Ca- scale inhibition performance of Tetra- molecules. Quantum chemical calculations were compatible with the experimental results.     

Evaluation of N-(3-(dimethyl hexadecyl ammonio)propyl) palmitamide bromide as cationic surfactant corrosion inhibitor for API N80 steel in acidic environment

A new cationic surfactant named (N-(3-(dimethyl hexadecyl ammonio)propyl) palmitamide bromide has been evaluated as corrosion inhibitor for API N80 Steel Pipelines in 1M HCl solution. Four different techniques have been utilized for studying the corrosion behavior of the synthesized cationic amphipathic corrosion inhibitor. The prepared corrosion inhibitor was evaluated at five different temperatures 25, 30, 40, 50 and 60?°C, using weight loss technique. The three other techniques which are potentiodynamic polarization, Electrochemical impedance (EIS) and Electrochemical frequency modulation (EFM) were used for evaluation at room temperature (25?°C?±?1). The results outlined that the synthesized DMHPP amphipathic corrosion inhibitor was good inhibitor and their inhibition efficiencies were directly proportional with both the inhibitor concentration and temperature. Polarization curve revealed that the studied inhibitor act as a mixed-type of inhibitor. The adsorption of the used inhibitor led to a reduction in the double layer capacitance and an increase in the charge transfer resistance. The adsorption behavior of the amphipathic inhibitor obey Langmuir adsorption model. The change in free energy of adsorption of the synthesized inhibitor range from ?40.5 to ?45.5?kJ?mol^?1 as an indication for chemisorption process between inhibitor and steel. A clear correlation was found between corrosion inhibition efficiency and theoretical parameters obtained using density functional theory (DFT).