A sustainable method of mitigating acid corrosion of mild steel using jackfruit pectin (JP) as green inhibitor: Theoretical and electrochemical studies

This study is attempted to develop a green corrosion inhibitor from a waste material of Jack fruit (Artocarpus heterophyllus). This method is therefore quite valuable to health, environment, and economic point of view. Pectin is isolated from the jackfruit peel waste using 0.05 ?N oxalic acid and used as an inhibitor for mild steel corrosion in acidic environment as it is highly water soluble. 250–1000 ?ppm of pectin was used in this study at a temperature range of 303–323 ?K. The protection efficiency of jack fruit pectin (JP) in 0.5 ?M HCl was evaluated by conventional weight loss and electrochemical techniques. The potentiodynamic polarization results revealed that JP could effectively reduce the corrosion of mild steel in acidic medium at 1000 ?ppm concentration with an inhibition efficiency of 89.75% and corrosion rate of 2.392 mpy. The mixed type behavior of the inhibitor is identified from Tafel polarization studies. Electrochemical impedance spectroscopy (EIS) measurements suggest that the corrosion inhibition process is kinetically controlled. adsorption and kinetic behavior of the inhibitor also have been studied. Surface manifestations were followed using FESEM and AFM techniques. DFT calculations and Monte Carlo simulations were also carried out to corroborate the experimental results with theoretical outputs and succeeded to a great extent.     

The electrochemical corrosion of bulk nanocrystalline ingot iron in acidic sulfate solution

The corrosion properties of bulk nanocrystalline ingot iron (BNII) fabricated from conventional polycrystalline ingot iron (CPII) by severe rolling were investigated by means of immersion test, potentiodynamic polarization (PDP), electrochemical impedance spectroscopy (EIS) tests, and scanning electron microscopy (SEM) observation. These experimental results indicate that BNII possesses excellent corrosion resistance in comparison with CPII in acidic sulfate solution at room temperature. It may mainly result from different surface microstructures between CPII and BNII. However, the corrosion resistance of nanocrystalline materials is usually degraded because of their metastable microstructure nature, and the residual stress in nanocrystalline materials also can result in degradation of corrosion resistance according to the traditional point of view.     

Accelerated aging studies of silicon-rubber based polymeric insulators used for HV transmission lines

Accelerated aging experimental investigations are performed on polymeric insulators which are used for extra high voltage (EHV) and ultra high voltage (UHV) transmission. A newly developed rotating wheel and dip test facility as per std. IEC 62217 is used for the study. The experimental study is conducted with AC stress for 15000 cycles. The specimen insulators used are of 725 mm creepage and treated under different environmental stresses close to the real service life. The present study focuses on the effect of acidic environment during acid rain encountered by the polymeric insulators. The contaminants used for the study are as per standard and practically observed acid rain information. A comparative study is carried out for normal and acidic environmental conditions, some interesting results are observed. Leakage current monitoring and visual observation were conducted at regular intervals. Results show acid treatment is found to be comparatively more severe than the normal treatment. Further Physico-chemical investigation are carried out using Fourier Transform Infrared (FTIR) Spectroscopy and Scanning Electron Microscopy (SEM), Energy dispersive X-ray Analysis (EDAX) and Thermo-Gravimetric Analysis (TGA) which confirm the severity of material degradation of polymeric insulators and corrosion over metal end fittings under acidic environmental condition.     

Abatement of hydrocarbons by acid ZSM-5 and BETA zeolites under cold-start conditions

Simulated cold-start tests have been carried out to evaluate the performance of H-ZSM-5 and H-BETA zeolites as hydrocarbon traps under simulated gasoline car exhaust gases, paying special attention to the effect of water on their behaviour. It is concluded that the hydrothermal treatment of the zeolites in the acidic form contributes to the better performance of these materials as hydrocarbon traps since the stabilization of the zeolites takes place. Moreover, the decrease of the surface acidity of the zeolites results in an increase of the Si/Al ratio, which contributes to the decrease of the water affinity for adsorption sites. Thus, the competition with hydrocarbon molecules in the exhaust for the adsorption sites is reduced which increases their trap efficiency. The stabilized H-ZSM-5 is the zeolite that showed the best performance with a propene offset temperature of 240 °C, which should be high enough for the three-way catalyst to carry out its role as catalytic converter.     

Laser treatment of A286 superalloy: corrosion resistance of the treated surface

Laser controlled melting of metal surface provides a local treatment with improved surface properties such as corrosion resistance. In the present study, laser surface treatment of iron base superalloy (A286) is carried out. The corrosion resistance of the laser‐treated surface is examined through potentiodynamic tests using 0.5 N NaCl solution. The microstructural and morphological changes in the laser‐treated layer are investigated incorporating scanning electron microscopy (SEM), X‐ray diffraction (XRD) and energy dispersive spectroscopy. The residual stress formed at the laser‐treated surface is measured using the XRD technique. It is found that laser treatment enhances corrosion resistance of A286 superalloy surface, which is attributed to the formation of fine grains and dense layer at the treated surface. Although locally scattered few corrosion induced microcracks are observed at the treated surface, they are not extended to form large cracks or crack network at the surface. Copyright © 2012 John Wiley & Sons, Ltd.     

A closer look at the internal corrosion test for automotive heat exchangers: the OY water test

Nowadays, automotive heat exchangers are mainly made from aluminum. Over the last few decades, the development of aluminum brazing sheet has been mainly focused on the improvement of the external corrosion resistance. Recently, the interest of the heat exchanger manufacturers has also moved toward the assessment of the internal corrosion resistance. Accelerated tests are used to simulate in‐service conditions. These tests are crucial as they provide information to predict the material and product performance. Various internal corrosion tests have been developed, the so‐called ‘OY water tests’. Among all companies, the testing parameters can be varied in terms of ion concentrations or pH. Although the OY water tests are constantly being improved, there is so far no common internal corrosion standard as existing for external corrosion assessment. The present work aims at providing better understanding corrosion mechanisms encountered in the OY water media. The role of various elements present in the solution, cupric, chloride, sulfate ions, has been determined. These parameters were assessed via immersion testing. In order to get better understanding of the corrosion mechanism, electrochemical analysis combined with SEM characterization was carried out. The electrochemical analysis enables the understanding of the thermodynamics and kinetics of the corrosion process while immersion tests are performed to quantify the level of corrosion and follow the surface evolution over time. Copyright © 2010 John Wiley & Sons, Ltd.     

Development of polyaniline – TiO2 nano composite films and its application in corrosion inhibition of oil pipelines

Oil and gas industries are the driving force of Oman’s economy and have a relatively diversified wealth among Gulf Cooperation Council Countries. Oil pipelines play an important role in transporting oil and gas from the wellheads to the processing facilities. Corrosion normally results in the deterioration of the pipe material with exposure to the surrounding environment and complete control of corrosion is difficult. Corrosion in oil transmission pipeline would be effectively addressed by introducing conventional corrosion control practices. Most of the conventional techniques are either less effective or too expensive in controlling the deterioration rate of the pipe materials. However, preventative measures may be taken to protect the metal surface from corrosion is a possible way to reduce corrosion. This research work aimed to develop a novel technique utilizing Polyaniline (PANI) and Titanium dioxide (TiO₂) nanocomposites to assess its corrosion inhibition effect on mild steel. TiO₂ was synthesized by sol-gel process. Polyaniline-Titanium dioxide (PANI/TiO₂) nanocomposites were coated on mild steel specimen by dip coating technique. The coated specimen was subjected to stability studies at different environmental conditions and exposure time. The stable thin film coated specimen was employed in the corrosion inhibition studies at various processing environments. The characteristics of TiO₂ nanoparticles and PANI-TiO₂ thin films were analyzed using Fourier Transform Infra-Red Spectroscopy (FTIR), Energy Dispersive X-Ray analysis (EDX) and X-Ray Diffraction (XRD) and Dynamic Light scattering (DLS). Scanning Electron Microscopy (SEM) was used to visualize the surface morphology and micro structural characteristics of the preformed thin layer. Potentio dynamic test, Atmosphere test and Wet/Dry tests were carried out to investigate the corrosion behaviour of coated and uncoated specimen. The study demonstrates that the Polyaniline – TiO₂ composite thin films fabricated using dip coating technique with minimum film thickness could be a feasible solution in controlling the corrosion in oil pipelines with good film stability, high durability, with a cost effective and environmentally friendly approach.     

Corrosion resistance in chloride solution of the AlSi10Mg alloy obtained by means of LPBF

The paper deals with the corrosion resistance in chloride solutions of an AlSi10Mg alloy obtained by laser powder bed fusion (LPBF) process. The potentiodynamic tests were carried out in solutions having different chloride contents. The results emphasize the role of chloride concentration on localized corrosion. The increase of concentration reduces pitting potential. In addition, the influence of the post-processing heat treatment temperature was recognized. Penetrating attacks occurred either on after low temperatures stress relieving or specimens without any treatment, promoted by selective dissolution of the α-Al phase stimulated by galvanic coupling with noble silicon precipitates at the border of the melt pool. Such penetrating morphology was not observed after heat treatments at high temperature.     

Fire behavior of flame retarded unsaturated polyester resin with high nitrogen content additives

The novel flame retarded unsaturated polyester resins have been developed and prepared by introduction of high nitrogen content additives into the polymer matrix in order to verify their effectiveness in the formation of swollen carbonaceous char inhibiting the burning process of the polymer. The intumescent flame retardants (IFRs) based on mixture or metal complex were developed and characterized by particle size distribution, Fourier-transform infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR), powder X-ray diffraction (XRD), elemental analysis (CHN) and thermogravimetric analysis (TGA). The evaluation of the efficiency of IFRs addition on the flammability and smoke emission of the unsaturated polyester resins (UP) was carried out using the fire hazard (UL-94), limiting oxygen index (LOI) and cone calorimeter (CC) tests, as well as smoke density chamber tests. The volatile compounds evolved during the burning of materials were determined using a steady state tube furnace and a gas chromatograph with mass spectrometer. Furthermore, the prepared materials were subjected to differential scanning calorimetry (DSC), thermogravimetric analysis and water resistance tests. The mechanical properties of the materials were investigated using Shore D hardness and dynamic mechanical thermal analysis (DMA). The structural evaluation of the manufactured materials and samples after the cone calorimetry tests was carried out using scanning electron microscopy (SEM). It was found that the incorporation of new intumescent flame retardants led to the formation of carbonaceous char layers’ inhibiting the decomposition process and limiting the smoke emission. The most promising results were obtained for the resin containing complex designated as ZN3AT, for which the highest reduction in maximum values of heat release rate (419 kW/m²) compared to unmodified polymer (792 kW/m²) were recorded. Apart from that, the prepared intumescent flame retardants affect the cross-linking process as well as the thermal and mechanical properties of the UP.     

Solid-phase microextraction with on-fiber derivatization for the analysis of anti-inflammatory drugs in water samples

A sensitive and solvent-free procedure for the determination of non-steroidal acidic anti-inflammatory drugs in water samples was optimized using solid-phase microextraction (SPME) followed by on-fiber silylation of the acidic compounds and gas chromatography-mass spectrometry (GC-MS) determination. Microextraction was carried out directly over the filtered water samples using a polyacrylate fiber. Derivatization was performed placing the SPME fiber, loaded with the extracted analytes, in the headspace of a vial containing 50 microl of N-methyl-N-(tert-butyldimethylsilyl)-trifluoroacetamide (MTBSTFA). Derivatives were desorbed for 3 min in the GC injector. Influence of several parameters in the efficiency of microextraction (volume of sample, time, pH, type of fiber coating, etc.) and derivatization steps (time, temperature and volume of MTBSTFA) was systematically investigated. In the optimal conditions an excellent linearity over three orders of magnitude and quantification limits at the ng/l level (from 12 to 40 ng/l) were achieved. The proposed method was applied to the determination of acidic compounds in sewage water and results compared to those obtained using solid-phase extraction (SPE) followed by the derivatization of the compounds in the organic extract of the solid-phase extraction cartridge.     

一种氨烷基膦酸型水处理剂的合成及缓蚀阻垢性能的研究

介绍了一种氨烷基膦酸型水处理剂二甲基氨基甲叉二膦酸(DMAMDP)的合成方法,并进行了缓蚀阻垢性能的研究。结果表明,DMAMDP在阻碳酸钙、硫酸钙、磷酸钙和稳定锌等方面,以及缓蚀性能均优于常用有机膦酸水处理剂HEDP和ATMP。     

EIS and adjunct electrical modeling for material selection by evaluating two mild steels for use in super-alkaline mineral processing

The production of metal concentrates during mineral processing of ferrous and non-ferrous metals involves a variety of highly corrosive chemicals which deteriorate common mild steel as the material of choice in the construction of such lines, through rapid propagation of localized pitting in susceptible parts, often in sensitive areas. This requires unscheduled maintenance and plant shut down. In order to test the corrosion resistance of different available materials as replacement materials, polarization and electrochemical impedance spectroscopy (EIS) tests were carried out. The EIS numerical outputs were then transformed into an equivalent electric circuit using Z-View software, and the predictive behavior was contrasted with actual performance after long-term immersion, depicted through SEM, EDS, XRD and weight change observations. Also, results of pits and cracks, obtained with climax software-enhanced polarization resistance, and reduced capacitance added to much diminished current densities, verified the acceptable performance of CK₄₅ compared with high priced stainless steel substitutes with comparable operational life. Therefore, CK₄₅ can be a suitable alternative in steel constructions which are exposed to super-alkaline and corrosive environments.     

Multiresidue Analysis of Organic Pollutants in Water by SPE with a C8 and SDVB Combined Cartridge

Abstract

A multi-component target method for screening purposes to determine organic pollutants of different polarities in water is reported. The following classes of chemicals were tested: base-neutral and acidic herbicides, phenolic compounds, polycyclic aromatic hydrocarbons and phthalic acid esters.

Data was initially obtained from the extraction of one liter of water sample, using separate octyl bonded porous silica (C8) and highly crosslinked polystyrene based polymer columns (SDVB) cartridges. A second set of data was obtained using for the extraction a combined cartridge containing both phases. The analysis was carried out directly by GC-MS in SIM mode, without any derivatisation, with the exception of acidic herbicides, derivatised with pentafluorobenzylbromide. The obtained results showed recoveries between 75% and 98% at two different spiking levels, with relative standard deviations below 15%.     

Stress relaxation in compression: A detailed discussion of the experimental method for ring test pieces

Following a careful study of the main sources of error in the Lucas test method for compression stress relaxation, improvements to the test procedure are suggested. In particular, a new method of loading the jigs is proposed which is easier and more reliable than those used previously. Slight modifications to standard jigs have overcome the problem of electrolytic corrosion by water and have enabled tests to be carried out in water for periods of up to two years.     

Evaluation of corrosion behaviour of selected metallic samples by electrochemical noise measurements

Electrochemical noise (EN) denotes spontaneous fluctuations in potential and current originating from the corrosion processes. In this work, EN was measured for three model metallic materials of known corrosion properties: Al, Fe and Fe30Al. Corrosion behaviour was assessed in neutral, acidic or alkaline solutions containing 4 wt% NaCl. Correlation between the electrochemical noise and corrosion intensity was established on the basis of appropriate treatment of the recorded numerical data and ex situ examination of the specimen surface. The parameter, referred to as EN resistance, allowed relatively simple and rapid evaluation of the corrosion behaviour of the investigated metallic materials.     

Simultaneous determination of Pt and Rh by catalytic adsorptive stripping voltammetry, using hexamethylene tetramine (HMTA) as complexing agent

Characteristics of the adsorption/electro-reduction of Pt/Rh hexamethylene tetramine (HMTA) complex on static mercury drop electrode surface were studied. Cyclic voltammetry was carried out to get the insight about the mechanistic behaviour of the catalytic current obtained in the voltammetric scan of Pt/Rh HMTA complex in acidic solution. Adsorptive stripping voltammetry using HMTA as the complexing agent was found to be highly sensitive method for the determination of Pt/Rh. Voltammetric measurements were carried out using hanging mercury drop electrode (HMDE) as the working electrode, a glassy carbon rod as the counter and an Ag/AgCl/KCl_saturated as the reference electrode. Various electrochemical parameters like deposition potential, deposition time, concentration of the ligand, supporting electrolyte etc. were optimized. The detection limit of Pt and Rh was found to be 4.38 pML⁻¹ and 2.80 pML⁻¹, respectively for the deposition time of 30 s. Simultaneous determination of Pt(II) and Rh(III) in water samples was possible. The method was found to be free from the commonly occurring interfering ions such as Cu(II), Cd(II), Zn(II), Pb(II), Cr(III), Cr(VI), Fe(III), Fe(II), Ni(II) and Co(II). Spike recovery tests for both Pt and Rh in tap water and sea water samples were also carried out. The method has been verified by analyzing certified reference material (WMG-1).     

燃煤电厂3种固体废物对水环境影响的研究

以某电厂灰渣作为研究对象,分别对锅炉渣、粉煤灰和烟道灰3种材料对水环境的影响进行了试验,全面分析了灰渣的物理性质和化学成分。分别做了灰渣的浸出毒性试验、浸出剂的pH值对粉煤灰重金属浸出毒性试验,灰渣的腐蚀性、灰渣的淋溶、灰渣的沉降试验,从而得出燃煤电厂固体废物对水环境潜在的毒性影响。     

Utilization of Ferromagnetic Fluids in Mineral Processing and Water Treatment

The paper is devoted to the utilization of ferrofluid as a separating medium and modifying agent affecting the magnetic properties of solid and liquid materials. The separation tests in a MHS separator have been carried out under laboratory condition. The selectivity of ferrofluid's adsorption to the surface of some materials can be used for enhancing the magnetic susceptibility and influencing the efficiency of separation process. The enhancement of magnetic susceptibility of oil products up to a level sufficient for their magnetic extraction from water is possible by admixing of a definite amount of kerosene-based ferrofluid, which is non-miscible with water. The results point to the fact that the MHS method is suitable for the separation of non-magnetic materials according to their density and the modification of magnetic properties of materials by ferrofluid enhancing their magnetic separability.     

Removal of tetramethyl ammonium hydroxide from synthetic liquid wastes of electronic industry through micellar enhanced ultrafiltration

In this paper, the separation of tetramethyl ammonium hydroxide (TMAH) from synthetic liquid wastes of electronic industry is carried out by using a micellar enhanced ultrafiltration (MEUF) process. This treatment represents the first step of an integrated process, aimed at the recovery of TMAH and surfactant and water reuse. The laboratory tests are carried out with an ultrafiltration module using initial solutions having a concentration of pollutant equal to 2?g/L and by adding sodium dodecyl sulfate as a surfactant, at a concentration in the range 4–10?mM/L, that is, under and above its critical micellar concentration (CMC). The experiments have been carried out at a fixed temperature of 25°C. The obtained results showed that very good percentage removals of TMAH are achieved (99%), especially when the surfactant was above the CMC.     

Parameters controlling the evaluation of polymeric coatings for carbon steel alloy

The efficiency of polymeric coatings as corrosion protective materials for carbon steel alloy in sea water was evaluated by different methods: electrochemical techniques (open circuit and potentiodynamic measurements), analytical and spectroscopic techniques (inductive coupled plasma, scanning electron microscopy and X‐ray diffraction). The study was made using ethylene propylene diene monomer (EPDM)/poly&!lpar;ethylene&!rpar; (PE) blend of different ratios. The effect of blend ratio on corrosion protection efficiency was investigated. The best results for corrosion control were achieved using samples with 2 mm thickness. The data obtained reveal that applying adhesive on the substrate increases the protective properties of the coatings. Copyright © 2006 John Wiley & Sons, Ltd.