Corrosive Compound Research Articles

Investigating the effect of C3N membrane geometry on the separation and selectivity of gases

Sour gas includes acidic gases such as hydrogen sulfide and carbon dioxide, which lead to a specific smell, toxicity effect, and a reduction in the overall energy of the gas. In addition, the proximity of these acid gases with water causes the production of a very corrosive acid compound, which increases the price of its transportation. Today, membrane technology is widely used in the separation process due to less energy consumption, low weight and volume, ease of access, as well as the high flexibility of the process. In this research, molecular dynamics simulation of CO2/CH4 separation by modified graphene membrane (C3N) was investigated. First, problem different cavities with different geometrical shapes investigated. By increasing the hole size, regardless of the type of the hole, the efficiency of gas passage increases and reaches a constant value for the size of the holes greater than 3.5 Å. Therefore, increasing the hole size by more than 3.5 Å does not affect the efficiency of the gas passage. Meanwhile, for the size of the holes greater than 2.75 Å, the selectivity between gases reaches zero. Therefore, this hole size is an optimal value. Furthermore, a 4.9 Å hole led to high selectivity (infinity) for carbon dioxide flux of 365.65 (mol/m2.s) that means no methane molecules passed through it.

Isotherm, Thermodynamic and Kinetic Studies of Elemental Sulfur Removal from Mineral Insulating Oils Using Highly Selective Adsorbent.

Elemental sulfur (S8) is a corrosive sulfur compound which was found to be extremely reactive to silver, causing intensive silver sulfide (Ag2S) deposition on on-load tap changer (OLTC) contacts in power transformers. A highly selective adsorbent (HSA), called Tesla'Ssorb, for the removal of S8 from mineral insulating oils was prepared from raw material (RM) using the novel procedure. In this study, the adsorption properties of HSA for the removal of S8 from the oil were determined. RM and HSA were characterized using various techniques, such as field-emission scanning electron microscopy (FESEM), energy-dispersive X-ray (EDX), and X-ray diffraction (XRD). The performance of HSA was determined by adsorption equilibrium, thermodynamic, and kinetic study through batch experiments, at various temperatures and initial concentrations of S8. The obtained results were analyzed by Langmuir and Freundlich adsorption isotherms and it was found that equilibrium data were fitted better with the Langmuir isotherm model. The maximum adsorption capacity was 4.84 mg of S8/g of HSA at 353 K. Thermodynamic parameters, such as enthalpy (ΔH°), Gibbs free energy (ΔG°), and entropy (ΔS°), were calculated and it was found that the sorption process was spontaneous (ΔG° < 0) and endothermic in nature (ΔH° > 0). It was found that the adsorption of S8 follows pseudo-second-order kinetic model, and the activation energy indicated the activated chemisorption process.

Preparation and Characterization of New Azo Dye and its use as a corrosion inhibitor in (1 M) HCl

The azo dye N-{4-hydroxy-3-[(E)-(4-hydroxyphenyl) diazenyl]phenyl} acetamide The dye features infrared spectroscopy, HNMR spectrometry, and mass spectrometry. Inhibitor A2 has been evaluated to be an effective corrosive compound at different concentrations and temperatures. Effective measurements of dynamic polarization were used. We note from the results that increasing the inhibitory concentration (A2) leads to an increase in inhibition while increasing the temperature leads to a decrease in it, as the highest inhibition efficiency (91%) was obtained at a concentration of 5*10-3 at a temperature of 298 K

Anaerobic sulphide removal by haloalkaline sulphide oxidising bacteria

Sulphide is a toxic and corrosive compound and requires removal from waste streams. Recent discoveries show that sulphide oxidising bacteria (SOB) from modern desulphurisation plants are able to spatially separate sulphide removal and oxygen reduction when exposed to intermittent anaerobic and aerobic environments. Here, SOB act as electron shuttles between electron donor and acceptor. The underlying mechanisms for electron shuttling are of yet unknown. To investigate the anaerobic sulphide removal of SOB, batch experiments and mathematical models were applied. The sulphide removal capacity decreased at increasing biomass concentrations. At 0.6 mgN/L SOB could remove up to 8 mgS/mgN in 30 min. It was found that biological activity determines sulphide removal, alongside chemical processes. Anaerobic oxidation of electron carriers was determined to only explain 0.1% of charge storage, where irreversible cleavage of long chain polysulphides could explain full sulphide storage. Different sulphide removal and intracellular storage processes are postulated.

Synergetic effect of temperature and humidity on the leakage of KOH electrolyte and related reliability of zinc-air batteries

The Zinc-air primary batteries (ZAB’s) are prone to electrolyte leakage upon exposure to high temperature and humidity conditions. Potassium hydroxide is a hygroscopic and corrosive compound and it can cause various electrochemical corrosion failures for the attached electronics inside a device. In this study, the effect of temperature and humid conditions on the leakage of Potassium hydroxide electrolyte from three different Zinc Air Battery variants were investigated. The batteries were exposed to hot and humid conditions, and a qualitative Gel test with pH indicator was used to visually observe the leakage from the individual set of battery variants. The residues of the released electrolyte was identified by FTIR and quantified using a titration method. SEM-EDS analysis was also performed to examine the surface of the batteries and sealants for eventual damage. The related effect of electrolyte leakage on the reliability of the batteries was performed by a voltage discharge test. The hygroscopicity properties of pure Potassium hydroxide were studied using a water sorption/desorption equipment and was correlated with electro impedance spectroscopy analysis using an interdigitated test board. The results from the study indicate that the increase in temperature caused an increased amount of electrolyte leakage under saturated humid conditions. Leakage of Potassium hydroxide electrolyte caused damage to the sealant gasket, clogged the oxygen ventilation holes of the batteries, and exhibits high hygroscopic properties when exposed to high temperature and humid conditions.

An indirect electrochemical method for aqueous sulfide determination in freshwaters using a palladium chelate as a selective sensor

Sulfide anion is a highly toxic and corrosive compound and its presence above the threshold concentrations (i.e. μmol L−1) in freshwaters may indicate environmental pollution. Besides, the increase in sulfide concentration results in modifications of the organoleptic proprieties of water and air. Many analytical methodologies have been designed for aqueous sulfide quantification, however, due to the high reactivity and instability of sulfide, the pursue of a simple, sensitive, selective, and portable analytical method is still a current demand. In this study, an indirect electrochemical method for the determination of sulfide based on its interaction with a palladium complex – bis(2-aminobenzoate) palladium(II) – acting as a selective chemosensor is described. The reaction leads to the demasking of the electroactive ligand 2-aminobenzoic acid (i.e. anthranilic acid) and square wave voltammetry is employed to monitor its concentration using a glassy carbon electrode (GCE). Experimental conditions were optimized and the reaction was performed in Britton-Robinson (BR) buffer at pH 5 for 4 min, providing the higher magnitude of the analytical signal. A linear relation (r2 > 0.99) from 3 to 30 μmol L−1 of sulfide was obtained with a limit of detection of 0.10 μmol L−1. Recovery experiments using freshwater samples spiked with sulfide revealed overall satisfactory results for the limit concentration levels permitted by regulatory agencies. Therefore, the proposed methodology shows advantages in terms of portability, selectivity, sensitivity, low-cost, and easiness-to-use enabling monitoring of sulfide in a variety of waters.

Rešavanje problema eksploatacije transformatora sa korozivnim sumporom desulfurizacijom ulja primenom jake neorganske baze i organskog rastvarača

Most power transformer failures are associated with the presence of corrosive sulfur compounds in mineral insulating oil, of which dibenzyl disulfide (DBDS) is the best known and most widespread corrosive sulfur compound. The oil of failed transformers usually contained DBDS, a compound with a pronounced affinity for the formation of copper (I) sulfide (Cu2S). Copper (I) sulfide is a compound that does not dissolve in oil, conducts electricity, and can be deposited on the paper insulation or copper conductor of the transformer. Created conductive paths between the windings can initiate turn-to-turn breakdown and failure of the transformer. Several technological procedures have been developed as a solution to oil corrosivity. The application of desulfurization technology developed by the Electrical Engineering Institute "Nikola Tesla" enables the efficient removal of DBDS and aging products from mineral insulation oils.

Electrochemical Modeling and Performance Assessment of H2S/Air Solid Oxide Fuel Cell

Hydrogen sulfide (H2S) is an abundantly present, corrosive, and noxious compound. Though the Claus process is effective in processing H2S, it extracts minimal energy from H2S. Solid oxide fuel cell (SOFC) can harvest the chemical energy of H2S to generate electric power. For practical implementations, the performance of H2S/air SOFCs and the potential losses in the system are determined. The present study aims to develop the complete electrochemical model of H2S/air SOFC system and to analyze its performance. The theoretical cell potential of H2S/air SOFC is determined, and the deviations from the theoretical cell potential due to polarization are studied. According to the results, H2S/air SOFC generates electric power with energetic, exergetic, and voltaic efficiencies of 59.0%, 43.0%, and 89.7%, respectively, at atmospheric pressure and a temperature of 1100 K. Further efficiencies can be achieved if the output heat is utilized for useful applications. Moreover, the SO2 formed by the electrochemical reactions in SOFC can be recovered as elemental sulfur or sulfuric acid as an additional useful commodity. In brief, this study demonstrates the performance of H2S/air SOFC to serve as a basis for the implementation of H2S/air SOFC toward eliminating the environmental impact of H2S and converting it into electric power.

Removal of Dibenzyl Disulfide (DBDS) by Polyethylene Glycol Sodium and Its Effects on Mineral Insulating Oil

Dibenzyl disulfide (DBDS) is the major corrosive sulfur compound in mineral insulating oils, which will corrode the copper wires of windings in the oil-immersed power transformers and reactors and eventually cause operation failures. This paper studies the method to eliminate DBDS in insulation oils using the Polyethylene Glycol Sodium (Na-PEG) reagent. The preparation method of the Na-PEG reagent from NaOH and polyethylene glycol 400 is studied in the laboratory. The effect of the Na-PEG reagent dosage and reaction temperature on eliminating DBDS in insulating oils is studied, and a treatment process is recommended. An automatic processing device to remove DBDS from the transformer oil is developed, and the short-term electrical properties and long-term thermal stability of the insulating oil after the Na-PEG reagent treatment are tested. The results show that the Na-PEG reagent can efficiently eliminate DBDS in the insulating oil (the DBDS concentration decreases from 448 mg/kg to less than 5 mg/kg (undetectable) within 1 hour) and will not significantly negatively affect the oil properties such as the breakdown strength at the power frequency, dissipation factor or acidity. A preliminary exploration of the reaction mechanism is explored.

Evaluation of density influence on resistance to carbonation process in oil well cement slurries

The carbon dioxide (CO2), in the presence of water, forms a corrosive medium that reacts with the Portland cement hydrated products in a process denominated carbonation. Carbonation is a topic of great interest for the oil and gas industry due to deleterious and negative effects caused by formations that contain CO2 in their pores to the cements used in cementing operations, as primary and remedial cementing. The corrosive compound present in subsurface can be originated from geological processes, injection techniques for enhanced oil recovery and geological storage. This work evaluated characteristics of CO2 attack in class G Portland cement slurries formulated with different densities: 1890 kg/m3 (15.8 ppg), 1970 kg/m3 (16.5 ppg) and 2030 kg/m3 (17.0 ppg). The slurries were prepared, cured, and subsequently exposed to CO2 during periods of 30, 60 and 90 days in an autoclave with controlled temperature and pressure conditions. After the times inside the autoclave, the samples were analyzed with a pH indicator solution, sedimentation test and scanning electronic microscopy (SEM). The results showed an inversely proportional pattern: the higher the density, the lower the carbonation. The higher content of reactive solids contributed to make the matrix more closed and with a greater availability of hydrated cement products, acting as a barrier to the carbonation advancement.

Treatment of tannery wastewater using aluminium formate: influence of the formate over sulphate based coagulant

&lt;p&gt;Tannery industries provoke the conspicuous quantity of deleterious effluent which has to be treated prior to discharge into the environment. Pre-treatment of tannery wastewater with aluminium sulphate is well known over decades, but due to the corrosive nature of sulphate this pre-treated water causes several issues in the biological treatment system. To overcome this issue a study was performed to understand the coagulant activity of aluminium formate and aluminium sulphate. The effect of coagulant activity as a function of pH and coagulant dose of Aluminium formate was studied and found that it surpassed aluminium sulphate in terms of Cr(VI), sulphate and COD removal by 10%, 6% and 10% respectively, while turbidity removal for both coagulants was found approximately equal. Possible mechanistic approach to the coagulation property of aluminium formate and aluminium sulphate could be inter particle bridging and sweep coagulation respectively. Formate [HCOO-] can be utilized as a counter anion in the place of commonly used sulphate anions as it is biodegradable, non-toxic and corrosive free compound. Therefore, Aluminium formate can be a promising coagulant for the pre-treatment of tannery wastewater.&lt;/p&gt;

Laser Irradiation of Organic Tattoo Pigments Releases Carcinogens with 3,3′-Dichlorobenzidine Inducing DNA Strand Breaks in Human Skin Cells

Laser Irradiation of Organic Tattoo Pigments Releases Carcinogens with 3,3′-Dichlorobenzidine Inducing DNA Strand Breaks in Human Skin Cells

Ethanol–water organosolv delignification of liquid hot water (LHW) pretreated sugarcane bagasse enhanced by high–pressure carbon dioxide (HP–CO2)

Organosolv delignification assisted by high–pressure carbon dioxide (HP–CO2), a low cost, non–corrosive and recoverable compound was evaluated as a potential green pretreatment technology for lignin extraction from liquid hot water (LHW) pretreated sugarcane bagasse to produce fermentable sugars in a lignocellulosic biorefinery concept. In this study, LHW pretreated bagasse (180°C for 20min with a liquid–to–solid ratio (LSR) of 9 (v/w)) was delignified with an ethanol–water mixture (1:1, v/v) and HP–CO2 as a co–solvent at milder temperatures (111.7–168.3°C) and times (23.8–66.2min) at a LSR of 5 (v/w). To evaluate the effects of varying operational conditions on the lignin content and delignification extent, while preserving the glucan fraction, a 22 central composite design was used as a factorial planning. Solid fractions with low lignin contents (7.35% and 10.78%) and high delignification extents (82.5% and 72.2%) with good glucan preservations (84.6% and 85.3%) were obtained at 140°C for 45min and 111.7°C for 45min, respectively. These solid fractions were subjected to enzymatic hydrolysis, yielding enzymatic conversions of 60.8% and 63.7%, respectively.

A new luminescent silver-based probe for on/off sulfide determination

The sulfide anion is a corrosive, toxic and harmful compound found in a wide range of anoxic environments. Metal-based complexes have been used as luminescent probes for sulfide determination. However, their synthesis usually involves laborious procedures and the use of toxic reagents. In this paper, we describe the synthesis, characterization and application of a new, sensitive and selective silver complex probe for sulfide detection. The process of sulfide determination is based on rapid reaction in aqueous/methanolic media between the silver (I) complex and sulfide leading to an increase in fluorescence intensity. Analytical performance has been studied in the concentration range of 190 to 950nmolL−1 of sulfide with suitable linearity, and the limit of detection was calculated to be (3σ/S) to 20nmolL−1. The probe's selectivity to S2− was evaluated over other competing anions showing excellent results and its reversibility was demonstrated upon addition of AgCF3SO3.

Reliability of copper wire bonds on a novel over-pad metallization

Wire bonding technology is used in most semiconductor products. Recently, high gold prices have forced semiconductor manufacturers to replace Au wires with Cu wires. Because Cu wire bonds are vulnerable to high temperature and humidity, they remain unpopular in automotive and industrial applications with narrow-bond-pad pitches and small deformed ball diameters. To avoid forming the corrosive Cu-rich intermetallic compound Cu9Al4, the use of a Ni/Pd(/Au) over-pad metallization (OPM) structure produced by electroless plating on the Al metallization has been proposed. However, certain technical issues must be overcome, such as variations in the purity and thickness of the plating. To tackle these issues, a novel OPM structure produced by physical vapor deposition is proposed and evaluated in this study.

The corrosion product of Cs–Te corrosive compound with 11Cr-Ferritic/Martensitic Steel and 9Cr-Oxide Dispersion Strengthened steel

Cs–Te corrosion tests were performed to FBR fuel cladding candidate materials listed below: 11Cr-Ferritic/Martensitic Steel (F/M steel) and 9Cr Oxide Dispersion Strengthened steel (ODS steel). The corrosion products of Cs–Te corrosive compound Cs2Te3 with F/M steel or ODS steel were picked up from the specimens after the corrosion test by focus ion beam method (FIB) and the corrosion products were specified based on element analysis and crystal analysis by transmit electron microscopy (TEM) with electron dispersion X-ray spectrum (EDS). The result of analysis allowed us to presume Cs–Te corrosion reactions in the Fe–Cr based fuel cladding material. The presumable reactions are 4Te+323Cr23C6→Cr3Te4+1823C and 4Te+3Cr→Cr3Te4.

Experimental and mathematical study on ammonia emission from Kahrizak landfill and composting plants, Tehran, Iran

Ammonia (NH3) as a toxic, reactive and corrosive compound with a sharp odor, found in landfills and composting plants. In this paper, ammonia emission from Kahrizak landfill and composting plants in the south of Tehran was studied. A mathematical model for ammonia emissions based on Gaussian fluctuating plume theory was developed using the two-dimensional theory of dispersion. This model was based on Pasquill–Gifford and Gaussian theory. Dispersion parameters and emission equation were analyzed using meteorological data in Pasquill–Gifford equations. WRPLOT software was applied to determine the wind direction, and the Land gem software was used to calculate the ammonia emission rate from the landfill. Monin–Obukhov length and net radiation were used for stability class specification. Radiation angle and topographic parameter effects were considered in these computations. The results showed the ammonia emission rate from the Kahrizak complex is about 163 g/s that had good agreement with other studies. Also the emitted ammonia could be detected up to 2 km away from the complex, which was verified by the field measurement of ammonia monitored at 9 stations in the complex.

H2S photocatalytic oxidation over WO3/TiO2 Hombikat UV100

Hydrogen sulfide (H2S) is a toxic, corrosive and malodorous compound with damaging effects even when present at a low concentration in air. Consequently, the development of efficient and environmentally friendly remediation technologies as an alternative to conventional techniques is justified for environmental reasons and public concern over human health and well-being. In the context of indoor air quality control, the use of photocatalysis over semi-conductor oxides could be a valuable alternative purification technology due to its wide-ranging effect and its easy way of implementation. The superiority of the TiO2 Hombikat UV100 photocatalyst in comparison with the Aeroxide© TiO2 P25 standard was already apparent in the UV-A photocatalytic oxidation of H2S. We report here on the first use of WO3/TiO2 UV100 photocatalysts for this reaction. Associating WO3 to TiO2 UV100 was not beneficial in terms of semiconductor coupling and of charge transfer between both phases. Even if such coupled wide band-gap oxide semi-conductor photocatalysts suffered from on-flow deactivation due to the formation of poisoning sulfates as ultimate reaction products continuously stored at the surface, by contrast, their ability to strongly lower and delay the release of SO2 to the gas phase was very positive for maintaining a weak selectivity into the unwanted SO2 by-product.

IEC 62697-2012: State of the art methods for quantification of DBDS and other corrosive sulfur compounds in unused and used insulating liquids

This article describes state of the art methods developed by IEC TC-10 WG-37 for quantitative determination of a highly corrosive sulfur compound dibenzodisulfide (DBDS) and other corrosive sulfur compounds in unused and used insulating liquids. The methods permit an objective approach for assessing corrosiveness of insulating liquids rather than subjective assessment based on color perception that is prevalent in the current standard test methods for corrosive or potentially corrosive sulfur in insulating liquids. In addition, quantification of total corrosive sulfur TCS) in insulating liquids permits an objective ranking of sulfur compounds according to their corrosivity towards copper.

Chemicals inducing acute irritant contact dermatitis mobilize intracellular calcium in human keratinocytes

Intracellular Ca2+ increase is a common feature of multiple cellular pathways associated with receptor and channel activation, mediator secretion and gene regulation. We investigated the possibility of using this Ca2+ signal as a biomarker for a reaction to chemical irritants of normal human keratinocytes (NHK) in submerged primary cell culture. We tested 14 referenced chemical compounds classified as strong (seven), weak (four) or non- (three) irritants in acute irritant contact dermatitis. We found that the strong irritant compounds tested at 20–40mM induced an intracellular Ca2+ increase measurable by spectrofluorimetry in an automated test. Weak and non-irritant compounds however did not increase intracellular Ca2+ concentration. We further investigated the mechanisms by which the amine heptylamine, classified as a R34 corrosive compound, increases intracellular Ca2+. Heptylamine (20mM) induced an ATP release that persisted in the absence of intra- and extra-cellular Ca2+. In addition, we found that this ATP activates NHK purinergic receptors that subsequently cause the increase in intracellular Ca2+ from sarcoplasmic reticular stores. We conclude that measuring the intracellular Ca2+ concentration in NHK is a suitable and easy way of determining any potential reaction to soluble chemical compounds.