Presence Of Chloride Research Articles

Electrical resistivity and corrosion potential of reinforced concrete: influencing factors and prediction models

This paper presents two models: one for predicting the electrical resistivity of concrete and the other for the corrosion potential of reinforcing steel. The prediction models were developed based on experimental results, considering various influencing factors. The experiment approach included the concrete mix proportion, chloride content, concrete cover thickness and time of exposure as the parameters. The results revealed that fly ash concrete showed significantly high electrical resistivity even in the presence of chloride ions. The effects of fly ash became more significant when the water to binder ratio was lower. Chloride ions also decreased the corrosion potential of steel in both the OPC and fly ash concrete. The corrosion potential was found less negative for fly ash concrete due to higher electrical resistivity. The prediction results show good agreement with the experimental results of this study and some other researchers.

A Bilayer Structure Composed of Mg|Co-MnO2 Deposited on a Co(OH)2 Film to Realize Selective Oxygen Evolution from Chloride-Containing Water.

A fluorine-doped tin oxide-coated glass electrode modified with a bilayer film of underlying α-Co(OH)2 and overlying Mg-intercalated and Co-doped δ-type (layered) MnO2 (Mg|Co-MnO2) preferentially yielded oxygen with a Faradaic efficiency as high as 79% in the presence of chloride ions at high concentration (0.5 M). This noble metal-free electrode was fabricated by cathodic electrolysis of aqueous Co(NO3)2 followed by anodic electrolysis of a mixture of Mn2+, Co2+, and cetyltrimethylammonium (CTA+) ions in water. The CTA+ ions accommodated in the interlayer spaces of Co-doped δ-MnO2 were replaced with Mg2+ by ion exchange. The upper Mg|Co-MnO2 could effectively block the permeation of Cl- ions and allow only H2O and O2, while the under α-Co(OH)2 acted as an oxidation catalyst for the H2O penetrated through the upper coating. Thus, the oxygen evolution reaction (OER) was preferred to the chlorine evolution reaction (CER). In artificial seawater (pH 8.3), the blocking effect against Cl- decreased because of ion exchange of the intercalated Mg2+ ions with Na+ in solution, but the OER efficiency still remained at 57%, much higher than that (28%) without the upper Mg|Co-MnO2. This demonstrates that the interlayer spaces between MnO2 layers acted as pathways for H2O molecules to reach the active sites of the underlying Co(OH)2. Density functional theory (DFT) calculations revealed that the most stable structure of hydrated Mg2+ ion, in which a part of coordinated H2O molecules is hydrolyzed, has less affinity toward Cl- ion than that of hydrated Na+ ion.

Studies on synthesis and antioxidant property of anthraquinone analogues

Abstract This study concerns the synthesis of Anthraquinone analogue 2-chloro-5-(methylsulfonamide) anthraquinone and its effect on antioxidant property. Nitration of phthalic anhydride at 80 °C followed to yield a mixture of 2-nitrophthalic acid and 3-nitrophthalic acid. After following a sequence of reactions the product 2-Chloro 5-amino anthraquinone was formed. Then this compound was treated with methanesulfonyl chloride in presence of K2CO3 in the solvent acetone to produce 2-chloro-5-(methylsulfonamide) anthraquinone. The structure of the compound so obtained was exposed to structural characterization by following Infra Red (IR) and 1H Nuclear Magnetic Resonance spectroscopic (1H NMR) analyses. The antioxidant property of the compound was assessed by In vitro methods consisting of 2,2′-diphenyl-1-picrylhydrazyl (DPPH), 2,2′-azinobis (3-ethylbenzthiazoline-6-sulphonic acid) (ABTS) procedures. It was suggested that the compound has the potent antioxidant property.

Metoprolol beta-blocker decontamination from water by the adsorptive action of metal-organic frameworks-nano titanium oxide coated tin dioxide nanoparticles

Due to prevalent use, resistance to hydrolysis and confined human metabolism, metoprolol (METP) b-blockers are excessively detected in water effluents and therefore must be removed. Adsorption of METP onto metal-organic frameworks-nano titanium oxide coated tin dioxide (nTiO2@SnO2@Mn(5AB-HQ)) nanocomposite was monitored to examine the potential decontamination from wastewater contaminated. The nTiO2@SnO2@Mn(5AB-HQ) nanocomposite was synthesized by the reaction of 5-azobenzoate-8-hydroxyquinoline (5AB-HQ) with manganese chloride in presence of mixed metal oxides (nTiO2@SnO2) under microwave heating irradiation for 3 min and effectively implemented for adsorption of METP. Excellent surface area was evident (267.75 m2g−1) and the maximum METP recoveries were 65.42, 82.55 and 95.89% using 50, 100 and 150 mg L−1, respectively. The possible interaction mechanisms are suggested to take place by both physical adsorption in the forms of electrostatic and π-π interaction as well as chemical adsorption as coordination bond formation based on the effect of solution pH and zeta potential of METP. Five kinetics models were monitored to assure adsorption fitting of METP via pseudo-second and pore film diffusion models. Seven isotherm models confirmed adsorption suitability of Langmuir and Redlich-Peterson models. Finally, the assembled nTiO2@SnO2@Mn(5AB-HQ) was confirmed as a substantially functionalized and recyclable nanocomposite to afford powerful nanomaterial for water decontamination of metoprolol b-blocker.

Sonoelectrochemical Degradation of Propyl Paraben: An Examination of the Synergy in Different Water Matrices.

The synergistic action of anodic oxidation using boron-doped diamond and low-frequency ultrasound in different water matrices and operating conditions for the decomposition of the emerging contaminant propyl paraben was investigated. The degree of synergy was found to decrease with an increase in current in the range 1.25–6.25 mA/cm2 or the ultrasound power until 36 W/L, where a further decrease was observed. Despite the fact that the increased propyl paraben concentration decreased the observed kinetic constant for both the separated and the hybrid process, the degree of synergy was increased from 37.3 to 43.4% for 0.5 and 2 mg/L propyl paraben, respectively. Bicarbonates (100–250 mg/L) or humic acid (10–20 mg/L) enhanced the synergy significantly by up to 55.8%, due to the higher demand for reactive oxygen species. The presence of chloride ions decreased the observed synergistic action in comparison with ultrapure water, possibly due to the electro-generation of active chlorine that diffuses to the bulk solution. The same behavior was observed with the secondary effluent that contained almost 68 mg/L of chlorides. The efficiency was favored in a neutral medium, while the hybrid process was delayed in alkaline conditions.

Al2O3–TiO2 composite coatings with enhanced anticorrosion properties for 316L stainless steel

Abstract316L stainless steel is used as an important structural material in various industries. However, its service life is limited in the presence of chloride ions due to severe chemical corrosion. Herein, a facile radiofrequency magnetron sputtering process is reported for the synthesis of various Al2O3–TiO2 composite coatings as an anticorrosion layer for 316L stainless steel substrates. The enhanced chemical stability of Al2O3–TiO2 composite coatings was investigated by X‐ray photoelectron spectroscopy, electron paramagnetic resonance, and X‐ray diffraction measurements. Moreover, the high specific surface area of Al2O3–TiO2 composite coatings displayed better hydrophobic property which can be confirmed by scanning electron microscopy and contact angle measurements. Finally, the direct characterization of anticorrosion properties was carried out using electrochemical tests. All of the above results exhibited the enhanced anticorrosion properties of Al2O3 coating after the incorporation of TiO2. Significantly, the Al2O3–TiO2 composite coatings with 15.56% Ti content provided the best corrosion resistance for 316L stainless steel.

Fractal Dimension Analysis of Aluminum Corrosion Roughness by Electrochemical and Optical Methods

Fractal dimension is a versatile method to study and evaluate corrosion from the point of view of metallic conditions, namely: surface roughness, electrochemical measurements and microscopy images. Aluminum corrodes at different rates, under different pH electrolytes with or without the presence of chloride ions. In this work, corrosion and the surface roughness for aluminum corrosion at different pH electrolytes: acid, with and without chlorides, neutral and basic solutions, were obtained. It was measured and obtained using electrochemical and optic techniques. The results of Electrochemical Impedance Spectroscopy (EIS) and Noise Measurements (ENM), Digital Holographic Microscopy (DHM), Scanning Electron Microscope (SEM) micrographs and their respective Fractal Dimension analysis were obtained.. For the different experimental techniques and conditions, fractal dimension was obtained and presented, reflecting the surface condition of aluminum corrosion as a function of pH solution.

Fractal Dimension Analysis of Aluminum Corrosion Roughness by Electrochemical and Optical Methods

Fractal dimension is a versatile method to study and evaluate corrosion from the point of view of metallic conditions, namely: surface roughness, electrochemical measurements and microscopy images. Aluminum corrodes at different rates, under different pH electrolytes with or without the presence of chloride ions. In this work, corrosion and the surface roughness for aluminum corrosion at different pH electrolytes: acid, with and without chlorides, neutral and basic solutions, were obtained. It was measured and obtained using electrochemical and optic techniques. The results of Electrochemical Impedance Spectroscopy (EIS) and Noise Measurements (ENM), Digital Holographic Microscopy (DHM), Scanning Electron Microscope (SEM) micrographs and their respective Fractal Dimension analysis were obtained.. For the different experimental techniques and conditions, fractal dimension was obtained and presented, reflecting the surface condition of aluminum corrosion as a function of pH solution.

Electro-oxidative decolorization and treatment of model wastewater containing Acid Blue 80 on boron doped diamond and platinum anodes

This paper aims to study the decolorization and degradation of textile dye Acid Blue 80 using indirect electrochemical oxidation on active platinum (Pt) and non-active boron doped diamond (BDD) anodes in the presence and formation of chloride ions. Ultraviolet-visible (UV–VIS) spectroscopy helped to monitor the rate of decolorization in relation to the amount of electrolyte, input voltage as well as current density. The effect of pH on the rate of decolorization was also assessed. Following the decolorization of model wastewater, we monitored the subsequent degradation of Acid Blue 80 by repeatedly measuring the values of total organic carbon (TOC), total nitrogen (TN), chemical oxygen demand (COD) and adsorbable organically bound halogens (AOX). Using liquid chromatography-mass spectrometry (LC-MS), we analyzed the reaction mixture and examined the mechanism of Acid Blue 80 decomposition both with the presence and with the exclusion of chloride ions. In the presence of chloride ions, oxidation was also accompanied by substrate chlorination, along with the formation AOX. Their concentration culminated between 6 and 12 h of electro-oxidation, which was then followed by a decrease in AOX values across the entire pH range of 3.0–11.0. After 24 h, Acid Blue 80 was mineralized by 90% at pH = 3.0 on the BDD anode, coupled with a 99% decrease in COD. Under the same conditions, the Pt anode showed a 94% decrease in COD and 64% in TOC.

Interfacial interaction between diverse microplastics and tetracycline by adsorption in an aqueous solution

The accumulation of microplastics in offshore aquaculture waters has gradually become a threat to the survival of marine life, and the combined pollution of microplastics and other pollutants is attracting widespread attention. In this paper, tetracycline (TC) was selected as a typical antibiotic, and its adsorption behavior on the surface of diverse type and different sizes of microplastics was studied to explore their combined pollution in an aqueous solution. The results of isotherm fitting showed that the maximum adsorption capacity and coefficient of polyethylene (PE) were the largest, and the adsorption capacity of PE was the strongest among the three microplastics: polyethylene (PE), polystyrene (PS) and polyvinyl chloride (PVC). With increasing PE particle size, the maximum adsorption capacity and adsorption coefficient of TC showed a significant decreasing trend, with a slight fluctuation in the middle. The presence of Pb2+, Cr3+, Cd2+, and Zn2+ markedly enhanced the adsorption of TC to PE, and Cu2+ could reduce the adsorption of TC to PE. The presence of chloride ions did not affect the adsorption process, which indicated that the adsorption mechanism between TC and microplastics is mainly an ion exchange mechanism. These results showed that the surface properties of microplastics and the chemical properties of the aqueous solution played an important role in the adsorption of TC. This study provides important scientific guidance and a theoretical basis for the study of the interfacial behavior, migration and transformation of marine microplastics.

Probing the degradation of carbon black electrodes in the presence of chloride by electrochemical impedance spectroscopy

The influence of the presence of chloride ions (Cl−) on the electrochemical stability of a porous carbon black electrode was examined. Using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS), we have observed that the durability of this porous carbon layer, similar to those used in fuel cells and supercapacitors, is altered in the presence of chloride. The presence of as little as 1 mM chloride leads to a substantial reduction in electrode capacitance and an increase in the total resistance of the porous layer, which will impact performance in electrochemical energy applications. The effect is more pronounced at higher chloride concentrations.

Fresh, mechanical, and corrosion performance of self-compacting concrete in the presence of chloride ions

In this study, influence of admixed chloride on performance of self-compacting concrete (SCC) was evaluated through fresh, mechanical, microstructure, thermal and durability properties. Presence of chloride ions decreased slump flow spread, passing ratio and segregation index, whereas it increased T50cm and V-funnel flow times. Variations in Ca/Si ratio of bulk of the hydrated cement matrix obtained from EDX and calcium hydroxide content obtained from TGA were consistent with compressive strength development with curing age. There is a linear variation between free and total chloride. Probability of corrosion occurrence was lower in all SCC mixes. Corrosion current density decreased significantly with age in OPC than PPC.

Synthesis and Antimicrobial Studies of New [Tetrakis (1, 2, 4-Triazole / 1, 3, 4-Oxadiazole / 1, 3, 4-Thiadiazole] [Bis-(Benzene-1, 3, 5-Triyl)] Dioxymethylene Compounds

Synthesis of new heterocyclic compounds containing four five-membered rings together was the main goal of this work. The new derivatives of [tetrakis (1,2,4-triazole /1,3,4-thiadiazole /1,3,4-oxadiazole][bis-(benzene-1,3,5-triyl)] dioxymethylene A7-A18 were synthesized by the reaction of [bis-(dimethyl 5-yl-isophthalate)] dioxymethylene compound A1 which was previously prepared from the reaction of 1,2-dibromomethan and dimethyl 5-hydroxyisophthalate, then treated with hydrazine hydrate to yield the corresponding acid hydrazide A2. In the next step, compound A2 was refluxed with 4-substituted isothiocyanate to give substituted thiosemicarbazides A3-A6. The treatment of the latter compounds in basic medium of 2M of NaOH afforded 1,2,4-Triazole derivatives A7-A10. Whereas the reaction of the same compounds with concentrated sulfuric acid gave 1,3,4-thiadiazoles A11-A14. Furthermore, the new derivatives of 1,3,4-oxadiazole A15-A18 were obtained by the reaction of thiosemicarbazides and tosyl chloride in presence of pyridine. (C. H. N.) elemental analysis, FT-IR, and 1HNMR techniques were used to characterize the chemical structure of some of the new synthesized compounds which also exhibited an important biological activity.

Synthesis, Characterization and in vitro Antimicrobial Screening of Some Novel Series of 2-Azetidinone Derivatives Integrated with Quinoline, Pyrazole and Benzofuran Moieties

A series of 5-(benzofuran-2-yl)-N-(3-chloro-4-(2-(p-tolyloxy) substituted quinolin-3-yl)-2-oxoazetidin-1-yl)-1-phenyl-1H-pyrazole-3-carboxamide derivatives (4a-f) were synthesized with excellent yields by cyclocondensation reaction of 5-(benzofuran-2-yl)-N′-(2-(p-tolyloxy) substituted quinolin-3-yl)methylene)-1-phenyl-1H-pyrazole-3-carbohydrazide (3a-f) with chloroacetyl chloride in presence of triethylamine in DMF. One pot condensation of 5-(benzofuran-2-yl)-1-phenyl-1H-pyrazole-3-carbohydrazide (1) with 2-(p-tolyloxy) substituted quinoline-3-carbaldehyde (2a-f) in ethanol solvent in presence of catalytic amount of acetic acid gave intermediate compounds (3a-f). The structures of newly synthesized compounds have been substantiated through elemental analysis and spectral studies viz. 1H NMR, 13C NMR, IR and mass spectra. All the synthesized compounds were screened for their in vitro antibacterial activity against pathogenic bacteria such as S. aureus and E. coli at different concentrations.

Corrosion of discontinuous reinforcement in concrete subject to railway stray alternating current

Alternating current (AC) traction power systems account for 64% of the UK electrified railway network. However, the investigation of stray AC induced corrosion in reinforced segmental lining tunnels is still very limited. Electrochemical modelling and numerical simulation, validated by the experimental data, indicate that the severity of stray AC induced steel reinforcement corrosion mainly depends on the AC current density, frequency and the chloride content in concrete. Concrete containing discontinuous steel fibres has an inherent corrosion resistance to stray AC attacks due to the electrical double layer developed on the steel surface; the presence of chloride ions in the concrete pore solution however reduces the corrosion resistance. Special attention is therefore needed for steel fibre reinforced concrete (SFRC) subjected to AC current in the presence of high concentration chloride.

Operando Studies of the Electrochemical Dissolution of Silver Nanoparticles in Nitrate Solutions Observed With Hyperspectral Dark-Field Microscopy.

Since nanoparticles are frequently used in commercial applications, there is a huge demand to obtain deeper insights into processes at the nanoscale. Especially, catalysis, chemical and electrochemical reaction dynamics are still poorly understood. Thus, simultaneous and coupled opto-and spectro-electrochemical dark-field microscopy is used to study in situ and operando the electrochemically driven dissolution mechanism of single silver nanoparticles in the presence of nitrate ions as non-complexing counter-ions, herein. Hyperspectral imaging is used to probe the intrinsic localized surface plasmon resonance of individual silver nanospheres before, during and after their electrochemical oxidation on a transparent indium tin oxide (ITO) electrode. Furthermore, optical video imaging was performed for additional information. Based on the complete loss of spectral information and intensity, a dissolution of the particles during the reaction was concluded. This way it is revealed that the dissolution of individual particles proceeds over several seconds, indicating a hindrance by the nitrate ions. Only electrochemical analysis does not provide this insight as the measured current does not allow distinguishing between successive fast dissolution of one particle after another or slow dissolution of several particles in a concerted manner. For comparison, experiments were performed in the presence of chloride ions. It was observed that the silver chloride formation is an instantaneous process. Thus, it is possible to study and define the reaction dynamics on the single nanoparticle level in various electrochemical systems and electrolyte solutions. Accordingly, operando opto- and spectro-electrochemical studies allow us to conclude, that the oxidation of silver to solvated silver cations is a kinetically slow process, while the oxidation to silver chloride is fast. We propose this approach as a new method to study electrocatalyst materials, their transformation and degradation under operando conditions.

Study Comparative of Corrosion Rate Scrap Aluminium in Chloride Acid (HCl) and Natrium Chloride (NaCl) Solutions

Scrap aluminium is waste aluminium, the result of recycling that can be used as an alternative raw material with consideration of cheap and affordable prices. The use of aluminium scrap has been widely used both on a large scale such as the automotive industry, ships, aircraft, construction, etc., as well as on a small scale such as household appliances. Chloride acid is used in the process of purifying salt, cleaning porcelain, and as a stain remover on kitchen utensils, and sodium chloride, known as salt, is very corrosive due to the presence of chloride ions. The corrosive nature of chloride ions can be influenced by the concentration and duration of immersion, so it is necessary to research changes in the corrosion rate caused by the concentration and time of immersion. This study uses a method of immersion with weight loss where the specimen is immersed in HCl and NaCl with a concentration of 0. 1%; 0. 3%; and 0. 5% with an immersion time of 5 days, 10 days and 15 days. The results showed that the highest corrosion rate of HCl occurred at 15 days immersion with a concentration of 0. 1% at 1542. 314 Mpy, and the smallest corrosion rate at 5 days with a concentration of 0. 5% at 181. 09 Mpy. For the largest NaCl corrosion rate occurred at 15 days immersion with a concentration of 0. 1% from 101. 171 Mpy, and the smallest corrosion rate at 5 days immersion with a concentration of 0. 5% 41. 793 Mpy.

Geoenvironmental Investigation of Some Physical and Chemical Constituents of Ground Waters in of Sapele and Environs, Western Niger Delta, Nigeria

Hydrogeochemical studies have been carried out in parts of Sapele and Warri Local Government Areas of Delta State in order to determine the different hydrogeochemical facies and understand the groundwater flow regime and its effect on the chemical composition of the groundwater so as to evaluate the anthropogenic effects on groundwater quality in the study area. Twenty-five (25) water samples were taken from Sapele (18) and Warri (7) in one liter plastic cans with temperature, pH, electrical conductivity and Total Dissolved Solids (TDS) determined in-situ. The samples were then taken to the laboratory where the analyses were done using the Varian 220 flame atomic absorption spectrophotometer. Salinity and chloride in water was carried out in accordance with the American Petroleum Institute (API-RP) 45. Phosphate, Nitrate, Sulphate, Calcium, Potassium, Sodium, Magnesium and Ammonium were all determined in accordance with the American Public Health Association (APHA) 425C,427C and 417C.The analyses carried out indicated the presence of chloride ion as the dominant parameter. Chloride shows a negative correlation with all other parameters thus indicating that its source is from surface saline waters close to those areas with high chloride concentrations. The presence of ammonia in such high concentrations and its strong positive correlation with phosphate supports that its source is as a result of pollution from sewage. The positive correlation of phosphate, sulphate, nitrate and TDS also indicate pollution from sewage. GPS readings and computation of several hydrogeological parameters showed a SW direction of groundwater flow for Sapele and a SE flow direction for Warri. The presence of ammonium at levels higher than geogenic (geologically related processes) levels is a strong indicator of fecal pollution. The groundwater in the area is mostly acidic with high chloride concentrations.Contamination from anthropogenic sources is mainly as a result of waste waters from brines released as by-products of oil exploration activities and leaky septic tanks. The presence of chloride is from the proximity of areas that lie southward towards the Atlantic Ocean and the fact that water doesn't mix excessively at greater depths but the chloride levels are still within accepted standards for domestic use. Domestic wastes from septic tanks and improper waste disposal are the main sources of ammonium in the groundwater of the study area, and this reduces the groundwater quality in the area markedly.

Utilizing waste corn-cob in biosynthesis of noble metallic nanoparticles for antibacterial effect and catalytic degradation of contaminants.

In the present study, cost-effective, and environmentally friendly fabrication of silver and gold nanoparticles was performed by using aqueous extract of waste corn-cob. The formation of the metallic nanoparticles (MNPs) was optimized by UV-Vis method. The phytoconstituents were responsible for reduction of silver and gold ions to silver nanoparticles (CC-AgNPs) and gold nanoparticles (CC-AuNPs) which were demonstrated by Fourier-transform infrared (FTIR) spectroscopy while formation of AgCl was attributed to the presence of chloride ions in the aqueous extract. The crystalline nature of the AgNPs, AgCl, and AuNPs was confirmed using the X-ray diffraction (XRD) and selected area electron diffraction (SAED) patterns. Morphological studies showed that the synthesized CC-AgNPs existed in spherical shape with the size ranging from 2 to 28nm possessing an average value of 11nm while CC-AuNPs were present in the multiple shapes with size ranging from 5 to 50nm possessing an average value of 35nm. For studies on bioactive application, the CC-AgNPs exhibited a high antibacterial activity against three bacterial strains including Salmonella typhimurium, Bacillus cereus, and Staphylococcus aureus. In addition, the catalytic efficiency of MNPs was investigated for reduction of o-, m-, p-nitrophenols, and degradation of organic dyes including Eosin Y and Rhodamine 6G. The rate constants calculated from the kinetical data revealed that the biosynthesized nanoparticles are excellent catalysts in potential applications for treatment of wastewater. Graphical abstract .

Photoelectrolysis of clopyralid wastes with a novel laser-prepared MMO-RuO2TiO2 anode.

This paper studies the applicability of a novel laser-prepared mixed metal oxide (MMO-RuO2TiO2) anode in the photoelectrochemical degradation of clopyralid, a toxic and biorefractory herbicide. Results are compared to those obtained using the well-known boron-doped diamond (BDD) anode and demonstrate that, although the electrolysis with diamond is more effective than that obtained with the new electrode, the irradiation of UVC light makes the novel MMO material more effective in chloride media. It was explained in terms of the homolysis of hypochlorous acid/hypochlorite to form chloride and hydroxyl radicals. Photoelectrochemical degradation with MMO produced a marked synergistic effect in TOC removal, especially in the presence of chloride ions. On the contrary, for the BDD anode, at the tested conditions, antagonisms were found in both sulfate and chloride media. These important synergisms allows finding conditions in which the novel anode can be competitive with the BDD.