Synergistic effect of polyethylene glycol 600 and polysorbate 20 on corrosion inhibition of zinc anode in alkaline batteries

Polyethylene glycol 600 (PEG 600) and polysorbate 20 (Tween 20) were used as a composite corrosion inhibitor of zinc in alkaline solution for the first time. The effects of the composite and individual inhibitors on corrosion inhibition of zinc were evaluated by weight-loss analysis and electrochemical methods including potentiodynamic, potentiostatic, and electrochemical impedance spectroscopic measurements. It was found that there was a synergistic effect between PEG 600 and Tween 20 on corrosion inhibition of zinc. The corrosion inhibition efficiency of the composite inhibitor, 500 ppm PEG 600 + 500 ppm Tween 20, was 89%, much higher than that of the individual inhibitor, 1000 ppm Tween 20 (71%) or 1000 ppm PEG 600 (55%). The battery (Zn/MnO₂) discharge performance tests showed that the composite inhibitor reduced the self-discharge of zinc anode more effectively than the individual inhibitor. The synergistic mechanism between PEG 600 and Tween 20 was discussed.     

H<Subscript>2</Subscript>S corrosion inhibition of an ultra high strength pipeline by carboxyethyl-imidazoline

The H₂S corrosion inhibition of ultra high strength steel with carboxyethyl-imidazoline has been evaluated with electrochemical techniques. Tested material included a water quenched Fe–C–Mn steel micro alloyed with Si, Nb, Cr, and Ti, equivalent to an API X-120 pipeline steel, whereas electrochemical techniques included polarization curves, linear polarization resistance, electrochemical impedance spectroscopy, and electrochemical noise measurements. Tested solutions included H₂S-containing 3% NaCl with and without 10 vol% of diesel and different inhibitor concentrations (0, 5, 10, 25, 50, and 100 ppm) at 50 °C. Different techniques have shown that the optimum carboxyethyl-imidazoline efficiency was obtained with 50 ppm, but the efficiency decreases as time elapsed. Corrosion rates obtained with diesel were lower than those obtained without diesel.     

Corrosion inhibition of mild steel in sulfamic acid solution by S-containing amino acids

R_p, potentiodynamic polarization curves and EIS techniques were applied to study the effect of five S-containing amino acids on the corrosion of mild steel in 5% sulfamic acid solution at 40 °C. The compounds are effective inhibitors and the inhibition efficiency follow the order: N-acetylcysteine (ACC) > cysteine (RSH) > S-benzylcysteine (BzC) > cystine (RSSR) ≅ methionine (CH₃SR). The inhibitors affect the anodic dissolution of steel by blocking the anodic sites of the surface. EIS measurements indicated that charge transfer is the rate determining step in the absence and presence of the inhibitors and the steel/solution interface can be represented by the equivalent circuit R_s(R_ctQ_dl). Adsorption of RSH, CH₃SR and RSSR follows the Langmuir model while the Temkin isotherm describes the adsorption of ACC and BzC. From the application of the Flory–Huggins isotherm, the number of water molecules displaced by the adsorbing inhibitor molecules was estimated. The potential of zero charge pzc of mild steel without and with the inhibitors is calculated and the mechanism of corrosion inhibition is discussed in the light of the molecular structure.     

三氯异氰尿酸对有机磷缓蚀阻垢剂性能的影响

试验研究了三氯异氰尿酸(TCCA)对羟基亚乙基二膦酸(HEDP)、2-膦酰基丁烷-1,2,4-三羧酸(PBTCA)、羟基膦乙酸(HPAA)和多氨基多醚基亚甲基膦酸(PAPEMP)四种有机磷缓蚀阻垢剂的分解作用和对它们缓蚀、阻垢性能的影响.结果表明,三氯异氰尿酸对有机磷类缓蚀阻垢剂有分解作用,其分解程度为PAPEMP＞HPAA＞HEDP＞PBTCA;三氯异氰尿酸可使水的pH降低,造成碳钢迅速腐蚀;随着水中三氯异氰尿酸浓度的增加,HEDP、PBTCA和HPAA的阻CaCO3垢率先增加而后降低,PAPEMP的阻CaCO3垢率则持续降低.     

Adsorption and inhibitive corrosion properties of thiourea derivatives on cold rolled steel in 1 M HClO<Subscript>4</Subscript> solutions

Thiourea derivatives namely, phenylthiourea (PTU), N, N′-diphenylthiourea (DPTU) and N-naphtyl N′-phenylthiourea (NPTU) synthesised in our laboratory, were tested as inhibitors for the corrosion of cold rolled steel in 1 M HClO₄ using polarisation and electrochemical impedance measurements. At 30 °C, PTU and DPTU stimulated corrosion at low concentrations while addition of NPTU caused inhibition at all concentrations. The best protection (93%) was obtained by adding NPTU at 2.5 × 10⁻⁴ M. Polarisation curves showed that NPTU acted as a mixed inhibitor. The degree of surface coverage of the adsorbed inhibitors was determined by the ac impedance technique. The adsorption of NPTU on the cold rolled steel surface obeyed the Langmuir adsorption isotherm. Corrosion behaviour in the presence of NPTU at various concentrations was studied in the temperature range 20–50 °C. Both the corrosion rate of cold rolled steel and protection efficiency increased with increasing temperature. Activation energies with and without NPTU were obtained from the temperature dependence of corrosion current. The thermodynamic functions of the adsorption processes were calculated from the polarisation data and were used to analyse the inhibitor adsorption mechanism.     

有机膦酸对碳钢缓蚀性能及机理研究

采用失重法评定了氨基三亚甲基膦酸（ATMP）、羟基乙叉二膦酸（HEDP）、乙二胺四亚甲基膦酸（EDTMP）、二乙烯三胺五甲叉膦酸（DTPMP）、羟基膦酰基乙酸（HPAA）及2-磷酸丁烷-1,2,4-三羧酸（PBTC）在酸性条件下对碳钢的缓蚀性能,并结合电化学极化曲线研究了有机膦酸的缓蚀机理。结果表明：DTPMP、HEDP、ATMP、PBTC及HPAA为阳极型缓蚀剂,其缓蚀效率由大到小为：DTPMP〉EDTMP〉HEDP〉ATMP〉PBTC〉HPAA。     

Understanding the inhibitory effect of sodium oleate on the corrosion of Al and Al–Cu alloys in 1.0 M H<Subscript>3</Subscript>PO<Subscript>4</Subscript> solution—Polarization studies

Polarization measurements were employed, as a first step towards studying the corrosion behaviour of Al and two Al–Cu alloys, namely Al–4.5%Cu, and Al–7.5%Cu alloys in deaerated stirred 1.0 M H₃PO₄ solution at 25 °C. Inhibition of Al and Al–Cu alloys corrosion in 1.0 M H₃PO₄ solution, using sodium oleate (SO) as an anionic surfactant inhibitor, was also studied. Polarization curves showed that SO acted as a mixed-type inhibitor to Al corrosion, while it acted mainly as a cathodic inhibitor to the acid corrosion of Al–4.5%Cu, and Al–7.5%Cu alloys. Inhibition is accomplished by inhibitor adsorption on the electrode surface without detectable changes in the chemistry of corrosion. The relationship between surfactant concentration, surfactant critical micellar concentration (CMC), and corrosion inhibition is also discussed based on the Langmuir isotherm assumption, commonly applied in corrosion inhibition evaluations. The protection efficiency increases with increase in surfactant concentration and %Cu in Al samples. Maximum protection efficiency of the surfactant is observed at concentrations around its CMC. The mechanism of adsorption is discussed based on the surface charge of the electrode surface.     

Piperazine derivatives as inhibitors of the corrosion of mild steel in 3.9 M HCl

The inhibitory action of two piperazine derivatives, 1-benzyl piperazine (P1) and bis(1-benzylpiperazine) thiuram disulfide (P2) on the corrosion of mild steel in 3.9 M HCl at different concentrations has been investigated in the temperature domain 298–333 K. Both weight loss measurements and potentiodynamic polarization methods showed that P2 was the best inhibitor and that its inhibition efficiency increased with concentration to a value >92% at 10⁻³ M. Potentiodynamic polarization studies clearly revealed that P2 acts as cathodic-type inhibitor. The activation energy for the corrosion rates was evaluated in the temperature range 298–333 K. Adsorption of P2 on the mild steel surface in 3.9 M HCl followed a Langmuir isotherm model. A physical adsorption phenomenon is proposed.     

Role of some thiadiazole derivatives as inhibitors for the corrosion of C-steel in 1 M H<Subscript>2</Subscript>SO<Subscript>4</Subscript>

Inhibition of C-steel corrosion by some thiadiazole derivatives (I–VI) in 1 M H₂SO₄ was investigated by weight loss, potentiodynamic polarization, linear polarization resistance (LPR) and electrochemical impedance spectroscopy (EIS) techniques. The presence of these compounds in the solution decreases the double layer capacitance, increases the charge transfer resistance and increase of linear polarization. Polarization studies were carried out at room temperature, and showed that all the compounds studied are mixed type inhibitors with a slight predominance of cathodic character. The effect of temperature on corrosion inhibition has been studied and the thermodynamic activation and adsorption parameters were calculated and discussed. Electrochemical impedance was used to investigate the mechanism of corrosion inhibition. The adsorption of the compounds on C-steel was found to obey Langmuir’s adsorption isotherm. The synergistic effect brought about by combination of the inhibitors and KSCN, KI and KBr was examined and explained. The mechanism of inhibition process was discussed in the light of the chemical structure and quantum-chemical calculations of the investigated inhibitors.     

聚环氧琥珀酸的阻垢缓蚀性能研究

聚环氧琥珀酸（PESA）是一种新型的无磷有机阻垢缓蚀剂。通过鼓泡法和旋转挂片失重法对其阻垢性能和缓蚀性能进行了评价。结果表明,PESA比常用药剂HEDP、HPMA的阻垢性能好,但比PBTCA性能稍差;PESA也有一定的缓蚀性能,可以和其他的药剂复配生成低磷或无磷的缓蚀剂。     

Novel calixarene derivatives as inhibitors of mild C-38 steel corrosion in 1 M HCl

Calixarenes CA1–CA4 containing one to four 4-imidazolylethylamidocarbonyl groups were synthesized and tested as inhibitors for the corrosion of mild steel in 1 M HCl at 308 K. The study was made using Tafel polarisation and weight-loss methods. In contrast to CA1, calixarenes CA2–CA4 were good inhibitors, reaching inhibition efficiencies (E%) of 94 to 100% at 10⁻⁴ M. The values of the inhibition efficiency calculated by the two techniques were in acceptable agreement. E% increased with the number of 4-imidazolylethylamidocarbonyl groups attached to the calixarene. Polarisation curves showed that CA2–CA4 act as mixed-type inhibitors. Their adsorption on the steel surface followed a Langmuir isotherm. Thermodynamic parameters of adsorption were also deduced.     

Corrosion inhibition of carbon steel in acid chloride solution using ethoxylated fatty alkyl amine surfactants

Four novel non-ionic ethoxylated fatty alkyl amine surfactants (I–IV) were synthesised and investigated as corrosion inhibitors of carbon steel in 1 M hydrochloric acid solution using gravimetric, open circuit potential and potentiostatic polarisation techniques. The percentage inhibition efficiency (η%) for each inhibitor increased with increasing concentration until the critical micelle concentration (cmc) was reached. The maximum inhibition efficiency approached 95.1% in the presence of 400 ppm of the inhibitor (IV). It was found that the adsorption of the surfactants on carbon steel followed the Langmuir adsorption isotherm. Potentiostatic polarisation data indicated that these surfactants act as mixed type inhibitors. The values of activation energy (E _a*) of carbon steel dissolution in 1 M HCl were calculated in the absence and presence of 400 ppm of each inhibitor. Finally, scanning electron microscopy (SEM) was used to examine the surface morphology of polished carbon steel surfaces and those immersed in 1 M HCl in the absence and presence of 400 ppm of inhibitor (IV).     

Impacts of different antiscalant dosing rates and their thermal performance in Multi Stage Flash (MSF) distiller in Kuwait

This paper describes and compares the thermal schemes, thermal efficiency and thermal performance ratios of three different antiscalants (scale inhibitors) of 7.2 MIGPD Multi Stage Flash (MSF) distillers which have operated satisfactorily for an extremely long period. The evaluation tests conducted on the Multi Stage Flash (MSF) distillers revealed that all the examined antiscalants were successful in inhibiting alkaline scale formation and improving plant performance at top brine temperature ranging between 105 °C and 110 °C with respective dosing rates of 1.5 and 3.0 ppm.     

Effects of minor additions of ruthenium on the passivation of duplex stainless-steel corrosion in concentrated hydrochloric acid solutions

The effects of minor additions of ruthenium (0.14%, 0.22%, and 0.28%) on the passivation of duplex stainless-steel (DSS, Fe–22%Cr–9%Ni–3%Mo) corrosion in 2 M HCl solutions have been studied using open-circuit potential (OCP), potentiodynamic cyclic polarization, potentiostatic current–time, electrochemical impedance spectroscopy (EIS), and weight loss measurements. OCP measurements showed an increased shift in the corrosion potential to more positive values with increasing Ru content. Polarization and EIS experiments indicated that the presence of Ru and the increase of its content decrease the corrosion rate, critical and passive current density, and polarization resistance. Moreover, it shifts the corrosion and pitting potentials to more positive values. Current–time measurements at −100, −50, and 50 mV versus Ag/AgCl also confirmed that the severity of pitting corrosion decreases with an increasing Ru content. Weight-loss time data showed good agreement with the electrochemical measurements.     

Efficient Immobilization of Lecitase in Gelatin Hydrogel and Degumming of Rice Bran Oil Using a Spinning Basket Reactor

Immobilization of Lecitase (Phospholipase A1) in gelatin hydrogel and its stability is studied with a view to utilizing the immobilized enzyme for degumming rice bran oil. Excellent retention of enzyme activity (>80%) is observed in hydrogel containing 43.5% gelatin crosslinked with glutaraldehyde. Compared to the free enzyme which has a broad pH-activity profile (6.5–8.0), the activity of the immobilized enzyme is strongly dependent on pH and has a pH-optimum of pH 7.5. The optimum temperature of enzyme activity increases from 37 to 50 °C. Compared to the free enzyme which loses all its activity in 72 h at 50 °C, the immobilized enzyme retains its activity in full. The immobilized enzyme has been used efficiently in a spinning basket bioreactor for the degumming of rice bran oil with 6 recycles without loss of enzyme activity. The phosphorus content of the oil decreases from 400 ppm to 50–70 ppm in each cycle. After charcoal treatment and dewaxing, a second enzymatic treatment brings down the phosphorus content to <5 ppm.     

复配阻垢剂体系的协同效应研究

研究羟基二乙基二膦酸(HEDP)、次膦酸基聚丙烯酸(PCA)、聚丙烯酸(PAA)、含膦磺酸基聚磷酸类共聚物阻垢剂(PAMPS)(自制)分别对CaCO3、CaSO4单独的阻垢性能,以及二元复配体系的协同效应。实验表明,在阻CaCO3垢方面,对于单一阻垢剂,PCA是一种可选产品。对于二元复配体系,PAMPS与HEDP以2∶3和1∶4复配、PAMPS与PAA以3∶2,2∶3和1∶4复配均存在协同效应,PAMPS与PCA复配不存在协同效应;在阻CaSO4垢方面,对于单一阻垢剂,PAMPS和PCA是可选产品。对于二元复配体系,PAMPS与HEDP,PAMPS与PCA均以4∶1和3∶2复配都存在协同效应,PAMPS与PAA复配不存在协同效应。     

Corrosion inhibition of triethanolammonium bromide mono- and dibenzoate as cationic inhibitors in an acidic medium

A weight loss technique was used to determine the corrosion inhibition efficiency of synthesized alkyl mono-and dibenzoate triethanolammonium bromide derivatives (TEAMB, TEADB) in an acidic medium (2 N HCl) at different doses (50, 100, and 200 ppm). The results showed that monoderivatives had a higher corrosion inhibition efficiency than diderivatives. The results were correlated with several factors, including the alkyl chain length of the hydrophobic chains, interfacial tension (IT), critical micelle concentration (CMC), and adsorption free energy of these inhibitors. Increasing the geometric length of the alkyl chains in the synthesized inhibitors had an increasing effect on their corrosion inhibition efficiency, whereas decreasing the CMC and IT had an increasing effect on their tendency toward corrosion inhibition. The number of hydrophobic chains attached to the inhibitor molecules had a vital influence on their efficiency as corrosion inhibitors.     

Extractable Bray-1 phosphorus and crop yields as influenced by addition of phosphatic fertilizers of various solubilities integrated with manure in an acid soil

Soil extractable Bray-1 P (B1P) and response to phosphate (P) of Setaria anceps cv. Kazungula (Setaria grass) were monitored in a field trial bimonthly for 14 months in an acid soil fertilized with triple super phosphate (TSP), Gafsa phosphate rock (GPR) or Christmas Island phosphate rock (CIPR) integrated with or without manure. Extractable B1P from the same soil incubated with the same fertilizers in wet and dry 3-day cycles for 91 days was determined. Field experimental design was randomized complete block (RCB) with three replications. Results indicated that B1P magnitude for field and incubation trial were; TSP > GPR > CIPR, consistent with their solubility. An integration of manure and fertilizers resulted in much higher extractable B1P than sole fertilizers or manure. Over time, P availability decreased at a fast rate for the first 6 months and later was relatively constant. The dry matter yields (DMYs) exhibited quadratic relationships with P rates. Maximum DMYs (6–11 t ha⁻¹) were attained between 100 and 200 kg P ha⁻¹, above which they declined. Average DMYs were not significantly different for TSP, GPR and CIPR (6.1–6.6 t ha⁻¹). Maximum individual DMY were attained at 2–6 months and then declined to a minimum (2–4 t ha⁻¹) after 1 year. Cumulative yields (20–55 t ha⁻¹) also were not significantly different for the three fertilizers. Manure-CIPR integration increased DMY whilst in GPR and TSP/manure combinations DMYs were depressed. The PRs could supplement the expensive TSP without loss of yields but the non-reactive PR should be integrated with manure.     

Dodigen 213-N as corrosion inhibitor for ASTM 1010 mild steel in 10% HCL

This article describes a study of the behavior of a mixture of amines and amides, commercially known as Dodigen 213-N (D-213 N), as a corrosion inhibitor for ASTM 1010 mild steel in 10% w/w HCl solution. The concentration range used was 1 × 10⁻⁵ M to 8 × 10⁻⁴ M. The weight loss and electrochemical techniques used were corrosion potential measurement, anodic and cathodic polarization curves, and electrochemical impedance spectroscopy (EIS). The solution temperature was 50 ± 1 °C and it was naturally aerated. The corrosion potential values shifted to slightly more positive values, thus indicating mixed inhibitor behavior. The anodic and cathodic polarization curves showed that D-213 N is an effective corrosion inhibitor, since both the anodic and the cathodic reactions were polarized in comparison with those obtained without inhibitor. For all concentrations the cathodic polarization curves were more polarized than the anodic ones. The inhibition efficiency was in the range 75–98%, calculated from values of weight loss and corrosion current density, i _corr, obtained by extrapolation of Tafel cathodic linear region.     

植酸的缓蚀阻垢性能的研究

植酸是从粮食作物中提取的有机磷酸化合物,它是天然的无毒化工产品。通过鼓泡法和旋转腐蚀挂片失重法对其阻垢性能和缓蚀性能进行了评价。结果表明植酸具有一定的缓蚀性能和阻垢性能,其阻垢性能虽比常用的药剂PBTCA、HEDP、HPMA稍差,但可通过同其他的药剂复配生成低磷或无磷的阻垢剂,是较有发展前景的绿色缓蚀阻垢产品。