Different Concentrations Of Chloride Research Articles

Zero valent copper-mediated ferrate (Ⅵ) for the degradation of bisphenol AF

This study presented a novel zero valent copper-mediated ferrate (VI) oxidation system for the degradation of bisphenol AF (BPAF). The effect of various factors (such as the dosage of ZVC, the concentration of ferrate(VI), the reaction temperature, the initial pH of reaction solution, inorganic anions and HA) on the BPAF degradation process was investigated. It was discovered that ZVC had a good catalytic effect on ferrate(VI), with a removal efficiency of 92.4% achieved in 3 min under a standard condition([ZVC]0 =50 mg/L, [Fe(Ⅵ)]0 = 30 μM, [BPAF]0 = 3 μM, [pH]0 = 7, T = 25 ℃). Nitrate ions (NO3-) have no obvious effect on the degradation of BPAF. Sulfate ions (SO42-) promoted BPAF degradation at low concentrations but inhibited it at high concentrations, whereas different concentrations of chloride (Cl-) or bicarbonate ions (HCO3-) inhibited it. Furthermore, methyl phenyl sulfoxide (PMSO) was used as a probe to detect the presence of active species in this system. The results showed that the intermediate iron substances (Fe(IV)/Fe(V)) with strong oxidation ability and Fe(VI) completed the degradation of BPAF collectively. The use of zero-valent copper and ferrate (VI) provided a viable method for removing refractory organics from wastewater.

Evaluation of chlorides in fly ash for use in concrete

This paper investigates the use of fly ash with various levels of chlorides as a supplementary cementitious material for use in portland cement concrete. The varying levels of chlorides in the fly ashes originated from the air-quality control systems used during collection, rather than chlorides admixed into the fly ashes. Reducing mercury emissions of the thermoelectric power plant resulted in higher concentrations of chlorides in the fly ash. Three different concentrations of chloride (approximately 0.20%, 0.10%, and 0.01%) in fly ash were measured and incorporated into concrete at 25% and 50% replacement. Specimens cured for 7 days in a 73 °F (23 °C) 100% RH fog room followed by 21 days submerged in limewater in a 100 °F (38 °C) environmental chamber resulted in concrete that has similar maturity to concrete cured at ambient conditions for 1 year. Surface resistivity, chloride-ion penetration resistance, and impressed current testing were used to evaluate performance and durability. Acid and water-soluble chloride content were determined to elucidate the binding capacity of the concrete amended fly ashes with different chloride contents. The research clearly indicates that incorporating fly ash with varying levels of chlorides do not reduce the durability; it outweighed the performance as compared to concrete without fly ash. Additionally, increasing the fly ash replacement from 25% to 50% resulted in concretes exhibiting increased durability properties.

Physicochemical properties and antibacterial application of silver nanoparticles stabilized by whey protein isolate

Nano metal materials have been widely explored to be applied in medical, environmental, and material science. Among these nanoparticles, especially silver nanoparticles (AgNPs), have drawn increasing attention for antimicrobial applications. Most researchers are keen on the development of the biologically friendly capping reagents for the synthesis of AgNPs, instead of unfriendly organic polymers. In this study, the liquid chemical reduction method was used to synthesize AgNPs with edible whey protein isolate (WPI) as a capping reagent. These WPI-AgNPs had a broad size distribution (average diameter of 138.6 nm), and their dimensions could be readily controlled in the range of 22.5–149.6 nm by introducing different concentrations of chloride. Subsequently, it was confirmed that WPI-AgNPs were formed through two mechanisms, which were respectively reduced in situ (without the addition of NaCl) and ex situ (in presence of NaCl) to yield silver nanoparticles. The WPI-AgNPs synthesized in presence of 10 mM of NaCl as mediation reagent were stable at room temperature or 4 °C up to 3 months. Furthermore, the synthesized WPI-AgNPs had a good antibacterial activity toward pathogens including Gram-negative E. coli and Gram-positive S. aureus. The results shed light on method and capping reagent to stabilize silver nanoparticles, which highlighted the potential of WPI and chloride in metal nanoparticle synthesis.

Intelligentization of traditional sacrificial anode Zn by Mg-alloying for reinforcing steel

Traditional sacrificial anode Zn was intelligentized by Mg-alloying to automatically detect chloride contamination and smartly protect reinforcing steel. The intelligence of the Zn-Mg alloys was investigated in a simulated concrete pore solution (SCPS) contaminated by different concentrations of chloride. The results showed that the Zn-11Mg, Zn-32Mg, Zn-43Mg and Zn-66Mg were more sensitive to chloride contamination and could provide more sufficient current to protect the steel according to the corrosivity of the contaminated solution than the Zn, Zn-6Mg, Zn-19Mg and Mg. The corrosion resistance and the anodic behavior of these alloys coupled with the steel were systematically analyzed.

The Effect of Deposited Dust on SCC and Crevice Corrosion of AISI 304L Stainless Steel in Saline Environment

Crevice corrosion has become an important issue of the safety of AISI 304L austenitic stainless steel canister when exposed to the chloride environments located in coastal areas. Moreover, dust deposited on the canister surface may enhance the corrosion effect of 304L stainless steel. In this work, white emery was adopted to simulate the dust accumulated on the as-machined specimen surface. To investigate the effect of deposited white emery, chloride concentration, and relative humidity on the crevice corrosion behavior, an experiment was conducted on 304L stainless steel specimens at 45 °C with 45%, 55%, and 70% relative humidity (RH) for 7000 h. The surface features and crack morphology of the tested 304L stainless steel specimens were examined by SEM equipped with energy-dispersive spectrometry (EDS) and electron back scatter diffraction (EBSD). From the experimental results, a threshold RH for the stress corrosion cracking (SCC) initiation of AISI 304L austenitic stainless steel with different concentrations of chloride was proposed.

THE EFFECTS OF SOME ENVIRONMENTAL FACTORS ON THE ENTEROBACTER GROUP

In nature, E. coli takes place in different forms, separate from commensal to human or animal hosts pathogenies. Though E. coli genetics, physiology, and biochemistry have been extremely elaborated, there is not recognize in passing how they behave in natural habitats. Such an environment has been separated in a primary that is animal-human host-related, while the secondary is non-host-related habitat.. Thus, this study comes to investigate how its survival in different concentrations of different environmental variables and assess the potential effects of some environmental factors (salinity, sulfates, and chloride) on the enterobacter group. API20E kit and VITEK®2 GN were used to identification of studied bacteria. We identified five strains of enterobacter bacteria and one mix-bacteria to test the hypothesis of the current study and using normal saline for preparing serial dilutions. The results showed that the increase of salinity could affect studied bacteria significantly (p-value <0.01), also the increasing of sulfate (as NaSO4) was leading to significantly inhibited of bacterial growth at > 600 mg/L sulfates (p-value <0.01), while the concentration in-between 400-500 mg/L was worked positively with all of the studied bacteria, moreover there were negative effects of different concentrations of chloride (P-value < 0.01), except Var.2 was increased with adding 2gm/L of chloride.

Theoretical and experimental studies of passivity breakdown of Aermet 100 ultra‐high stainless steel in chloride ion medium

AbstractPassivity breakdown and pitting behavior in the presence of aggressive Cl− on ultra‐high strength steel Aermet 100, commonly used for landing gear, has been studied, the data are explained in view of the point defect model (PDM). Cyclic potentiodynamic polarization (CPP), electrochemical impedance spectroscopy (EIS), and X‐ray photoelectron spectroscopy (XPS) were examined to observe corrosion progress and corrosion products in the salt spray tests at 4, 8, 12, 16, and 20 days intervals. The breakdown behavior was studied using CPP, whereas scanning electron microscopy (SEM) and digital confocal microscopy were used to explore the micromorphology and depth distribution of pits. The cumulative distribution basically satisfies a normal probabilistic distribution at the different concentrations of chloride and pH, which is consistent with PDM assuming a near‐normal distribution of potential breakdown sites regarding to the cation vacancy diffusivity.

Physiological effects of different concentrations of chloride deicing salt and freeze–thaw stress on Secale cereale L. seedlings

Chloride deicing salt stress usually coincides with the event of freeze–thaw, and the short-term adaptation of Dongmu-70 Secale cereale L. seedlings to these stresses was investigated in this paper. The chloride deicing salt and the freeze–thaw (FT) simulation experiments were carried out in the lab and alternation refrigerator. The changes of soluble sugar, soluble protein, relative conductivity (RC), malondialdehyde (MDA), and catalase (CAT) activity in seedlings were studied under freeze–thaw stress (10, 5, 0, − 5, 0, 5, and 10 °C) and 0, 200, 400, and 600 mmol L−1 of chloride deicing salt stress (CK, D1, D2, and D3). The results indicated that the content of physiological index in different treatment groups rose first and then decreased within a freeze–thaw cycle. During the recovery phase (T8: 24 h after freeze–thaw stress and T9: 6 days after freeze–thaw stress), there was significant difference either in MDA and CAT activity between D2 × FT and D2 or in RC, MDA, soluble sugar, and CAT activity between D3 × FT and D3. The seedlings showed different adaptability under different intensities of combined stress, and the sequence of the changes in physiological index can be patterned as D × FT > FT > D > CK. Freeze–thaw and chloride deicing salt complex stress exhibited a synergistic effect on the plant, which indicates that the snow-melting operation would be more harmful in spring and autumn to plants than in winter.

Iron stability on the inner wall of prepared polyethylene drinking pipe: Effects of multi-water quality factors

Iron is currently one of the main contaminants of drinking water. The inner walls of drinking pipes can cause iron to release in water chemistry, which alters the water quality, including its chloride, sulfate, bicarbonate, pH, and humic acid (HA) levels. Hence, the goal of this research was to improve our understanding of the multi-water quality factors affecting iron release in polyethylene pipes. An array of bench-scale experiments were conducted exposing model water with different concentrations of chloride, sulfate, bicarbonate, HA, and different pH levels to prepared polyethylene pipes following the response surface methodology. The single role of HA during iron release is also evaluated by changing its concentration. A comprehensive study revealed that regression models could be used to describe the relationship between the five water quality parameters and iron release. The coefficients of determination were 0.890 and 0.870 for the fitting equations of total and soluble iron concentrations in water, respectively. In the presence of HA, the concentration of iron in water increased more rapidly than that for the other four factors (chloride, sulfate, bicarbonate, and pH). In addition, the Visual MINTEQ results suggest that a lower HA concentration tended to increase the degree of saturation of iron solids. In turn, this limits iron release and considerably increases the iron concentration in water.

Passivity breakdown on 436 ferritic stainless steel in solutions containing chloride

Passivity breakdown on 436 ferritic stainless steel (FSS) has been investigated in solutions containing different concentrations of chloride at 25 °C and interpreted in terms of the point defect model (PDM). The measured near-normal distributions of passivity breakdown potentials for 436 FSS under experimental conditions are in good agreement with the calculated results according to the PDM. The linear dependence of breakdown potential on the square root of potential scanning rate, which was described by the PDM, provides the estimation of the critical concentration of condensed vacancies at the metal/film interface, which leads to the passivity breakdown. This value is in good agreement with that calculated from the microstructure properties of the alloy substrate and the barrier layer of the passive film. This study demonstrates the validity of the PDM in describing the passivity breakdown on 436 FSS in NaCl solutions.

Passivity breakdown on 300 M and S280 ultra-high strength steels in borate buffer solutions containing chloride ion

Passivity breakdown and the pitting behavior of ultra-high strength 300M and S280 steels, which are commonly employed for aircraft landing gear, in the presence of chloride has been explored and compared, and the data were interpreted using the point defect model (PDM). The breakdown behavior was studied using cyclic potentiodynamic polarization while SEM and digital confocal microscopy were employed to explore the micro morphology and depth distribution of pits. The cumulative distributions in the breakdown voltage are near-normal, which are consistent with the PDM, assuming the distributions of potential breakdown sites in terms of the cation vacancy diffusivity for different concentrations of chloride are normal. Compared to 300M, S280 steel exhibits shallower pitting and is more resistant to breakdown. From the potential scan rate dependence of the breakdown potential, the critical areal cation vacancy concentration, ξ, resulting in passivity breakdown, is 8.6×1013 No.cm−2 for 300M and 2.4×1013 No.cm−2 for S280. These values are structurally in close agreement with the calculated results, considering the vacancy condensation is either on the cation sublattice of the barrier layer or on the steels lattice.

Passive Behaviour of New Alloy Corrosion Resistant Steel Cr10Mo1 in Simulating Concrete Pore Solutions with Different Chloride Contents

This work aims at studying the passive behaviour of new alloy corrosion resistant steel Cr10Mo1 and plain carbon steel (as a reference), in simulating concrete pore solutions contaminated with different concentrations of chloride (0 M, 0.2 M, 0.6 M and 1.0 M, as NaCl). The electrochemical behaviour was evaluated by linear polarization resistance, d.c. potentiodynamic polarization and electrochemical impedance spectroscopy. The surface films composition was investigated by X-ray photoelectron spectroscopy (XPS). The results show that the passivity of the corrosion-resistant steel has no significant decline with chloride contents increasing, while carbon steel hardly passivates with chloride above 0.6 M. The primary constituents of the passive films formed on the corrosion-resistant steel and carbon steel are very different; the former contains both Cr and Fe oxides while the letter consists of only Fe species. Cr oxides, as the key components for the passive film on the corrosion-resistant steel, can still remain stable and protective under high concentration of chloride, which supports the excellent passive performances of the corrosion-resistant steel in severe conditions.

Corrosion behaviour of steel in CAC-mixed concrete containing different concentrations of chloride

High aluminate in cement arising from Al2O3 in oxides is presumed to form the higher level of CA-type of hydration, which can subsequently bind chlorides then to reduce the corrosion risk. To maximise the chloride binding in the cement matrix, in this study, a mixture of calcium aluminate cement (CAC) with ordinary Portland cement (OPC) was used as binder. The ratio of CAC to total binder was 5%, 10% and 15%. The resistance of CAC mixture to chloride-induced corrosion was assessed by a monitoring of the corrosion rate, and its binding of chlorides and buffering against a pH fall of the cement matrix were simultaneously measured. As a result, the CAC mixture was very resistive to corrosion; there was no corrosion observed in CAC mixture at exceeding 3.0% of chlorides by weight of binder, whilst OPC produced about 0.5–1.0% of the critical chloride threshold for the onset of corrosion. The inhibitive measure of CAC mixture may arise from increased binding capacity of chlorides and buffering to acidification. In particular, the buffering zone for CAC mixture occurred at 10.5–11.5 and 11.8–12.6 in the pH, at which bound chlorides in the matrix would be kept immobile, unreactive in the corrosion process.

Prediction of The Chromium (III) Separation From Acidic Salt Solutions On Nanofiltration Membranes Using Donnan And Steric Partitioning Pore (DSP) Model

Abstract This paper presents experimental and modelling analysis of the application of nanofiltration for separation of chromium (III) from acidic salt solution. In the studies commercial nanofiltration HL membrane has been used. The experimental results have been interpreted by, based on the extended Nernst-Planck equation, Donnan and Steric Partitioning Pore (DSP) model. The obtained results showed satisfactory agreement between experimental and modelling data for the pressure range 10-24 bar and different concentrations of chloride and sulfate ions. It means that the DSP model may be helpful for the monitoring of nanofiltration applied to treatment of chromium wastewater.

Effect of chloride and conjoint chloride–sulfate ions on corrosion of reinforcing steel in electrolytic concrete powder solution (ECPS)

In the present work an experimental investigation has been carried out to assess the corrosion behaviour of bare steel in electrolytic concrete powder solution (ECPS) prepared from various concrete mixes. The corrosion behaviour of steel has been evaluated through anodic polarization study by conducting potentiodynamic linear sweep test on bare steel specimens immersed in electrolytic concrete powder solutions contaminated with different concentrations of chloride and sulfate ions. The electrolytic concrete powder solution extracts were prepared from concrete mixes made with OPC (ordinary Portland cement) and PPC (Portland pozzolana cement). Sodium chloride and sodium sulfate were used as the source of chloride ions and sulfate ions respectively. From experimentally obtained polarization curves, different zones of corrosion of steel reinforcement were identified. XRD analysis was also conducted on concrete powder samples to analyze the products formed due to presence of chloride and composite chloride–sulfate ions. The compressive strength results indicated that, specimens made with PPC exhibited higher compressive strength as compared to those made with OPC in both chloride and composite chloride–sulfate contaminated concrete. In addition, strength was more in chloride contaminated concrete as compared to that in mixed chloride–sulfate contaminated concrete for both OPC and PPC. The polarization study results indicated that, passivity range of steel reinforcement decreased with increase in free chloride ion concentration in both chloride and composite chloride–sulfate contaminated ECPS. The range of passive zone was less in PPC as compared to that in OPC in both chloride and composite chloride–sulfate contaminated concrete, which is attributed to lower chemical chloride binding in PPC than that in OPC and this was confirmed through appearance of lower intensity peaks of Friedel’s salt (calcium chloroaluminate) in XRD profiles of PPC than that of OPC. Further sulfate ions mitigated the effect of chloride ions in reducing the passivity range of steel, in the conjoint presence of both ions. PPC showed slightly higher chloride tolerance against chance of pitting corrosion as compared to OPC. It was observed that, presence of higher concentration of sulfate ions may mitigate the chance of pitting corrosion as chloride tolerance against the risk of pitting corrosion increased with increase in sulfate ion concentration in the conjoint presence of both ions.

Identification of chlorinated oligomers formed during anodic oxidation of phenol in the presence of chloride

Chlorinated oligomer intermediates formed during the anodic electrochemical oxidation of phenol with a boron-doped diamond electrode were studied at two different concentrations of chloride (5mM and 50mM). Under the same ionic strength, with sodium sulfate being the make-up ion, a 10-fold increase in Cl− led to removal rates 10.8, 1.5, and 1.4 times higher for phenol, TOC, and COD, respectively. Mono-, di- and trichlorophenols resulting from electrophilic substitution were the identified by-products. Nevertheless, discrepancies between theoretical and measured TOC values along with gaps in the mass balance of chlorine-containing species indicated the formation of unaccounted-for chlorinated by-products. Accurate mass measurements by liquid chromatography quadrupole time-of-flight mass spectrometry and MS-MS fragmentation spectra showed that additional compounds formed were dimers and trimers of phenol with structures similar to triclosan and polychlorinated dibenzo-p-dioxins.

Bioleaching of copper secondary sulfide ore in the presence of chloride by means of inoculation with chloride-tolerant microbial culture

Mining faces today an enormous challenge in terms of the limited availability of water resources. This is especially significant for bioleaching operations where not only the accessibility but also the water quality can be critical for the successful treatment and processing of minerals. Bioleaching circuits may even require the implementation of bleed or purge systems in order to manage impurities, like chloride for example, at adequate levels for microbial activity, therefore increasing water consumption. This study evaluates the alternative of bioleaching copper secondary sulfide ores in high chloride systems (resulting in increased process water recirculation in chloride-rich ore systems or as result of seawater utilization) by means of an adapted chloride and copper-tolerant mixed culture. A chalcocite-rich ore was bioleached in columns under different concentrations of chloride. The chloride-tolerant culture consisted of a mixed of Acidithiobacillus thiooxidans-like strain and Leptospirillum ferriphilum strain Sp-Cl (DSM 22399). High redox potentials and complete ferrous iron oxidation was achieved in all columns up to 6g/L Cl− reaching good copper extractions (from 79.5 to 83.3%) comparable to low-chloride bioleaching systems. The microbial population on the ore phase was predominantly represented by A. thiooxidans-like strain in contrast to the column effluents where Leptospirillum strain Sp-Cl was the dominant microorganism.These results represent a significant example that biologically assisted leaching of secondary sulfide copper ores in the presence of moderate chloride is achievable and supports the possibility to incorporate the use of seawater, as a proportion of the global water make-up, as well as the increase of process water recirculation in industrial operations.

Electrochemical Protection of Steel in Concrete to Enhance the Service Life of Concrete Structures

Abstract Corrosion of steel in concrete is a major threat to the construction industry. Ingress of chloride is the main cause of reinforcement corrosion. To prevent corrosion many protection methods are adopted viz, coating to concrete, coating to rebar, adding inhibitors, using supplementary cementations materials and electrochemical protection of steel, etc., Electrochemical protection of steel is one of the method adopted to protect and minimize the rebar corrosion both for existing and new concrete structures. In the present investigation an inhibitor injection was formulated to mitigate reinforcement corrosion in chloride contaminated concrete. In the first stage, the efficiency of the inhibitor injection was tested in different cement environments. In the second stage, the inhibitor formulation was injected into Ordinary Portland Cement (OPC) and Portland Slag Cement (PSC) with different concentrations of chloride. The efficiency of the electro injection process was evaluated by electrochemical techniques. Electrochemical measurements show that the EI process has a high inhibition efficiency than migration process. Electro injection process showed a remarkable decrease in the corrosion rate of embedded in concrete steel even in the presence of aggressive chloride ions when compared to systems without electro injection. In the third, the long term performance of the effectiveness of the electro injection process was studied in concrete slab for an exposure period of 3 months. EI process not only enhanced the inhibition property but also removes the free chloride ions from the chloride contaminated concrete. FT-IR results confirmed that the inhibitor formulation has formed a passive layer on the surface of the steel rebar even in the presence of chloride through the electro injection process.

Electrochemical study of copper chloride complexes in the RTIL 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide

The electrochemistry of copper(I) and copper(II) chloride complexes in the RTIL 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide, BMPTf2N, has been studied with constant current electrolysis and cyclic staircase voltammetry at temperatures between 21.0 and 96.0°C and in different concentrations of chloride. The chloride concentration was controlled by addition of 1-butyl-1-methylpyrrolidinium chloride, BMPCl. An important finding is the evidence of a three-coordinated complex, Cu(I)Cl32− which has not been found in organic chloroaluminates without a significant increase in temperature. Two Cu(I) species were found at molar ratios of [Cl−]/[Cu]<4. The kinetic parameters for the quasi-reversible Cu(I)–Cu(II) electron transfer were obtained with non-linear fitting. Successful fits required that the charge transfer coefficients for the reduction of Cu(II) (α) and oxidation of Cu(I) (β) did not sum up to unity, i.e. α+β≠1. This result was interpreted using Tsallis non-extensive thermostatistics.

EIS analysis on chloride-induced corrosion behavior of reinforcement steel in simulated carbonated concrete pore solutions

The corrosion behavior of reinforcement steel in simulated carbonated concrete pore (SCCP) solution containing different concentrations of chloride was studied by electrochemical impedance spectroscopy (EIS) and linear polarization resistance (LPR) measurements simultaneously, and the topographies of the steel specimens and the elemental distribution at corrosion area were examined by scanning electron microscope (SEM)/electron microprobe analysis (EMPA). The results showed the capacitive loop and polarization resistance decreased with chloride increasing. Furthermore, when the chloride concentration reached a critical value, the Bode plots obviously exhibited two phase angle peaks indicating two time constants. However, when the chloride content exceeded a critical value, the phase angle peaks decreased to one phenomenal peak. An equivalent circuit with two RC loops was used to characterize the corrosion behavior of reinforcement steel in SCCP solution according to the measurements of EIS. Based on the dependence of the equivalent circuit elements on chloride content and immersion time, the formation, growth and breakdown of passive film of the steel were discussed. It was found that the EIS evaluation of corrosion behavior for reinforcement steel in SCCP solution was good agreement with the LPR and SEM measurements. The EMPA mapping revealed MnS inclusions at steel surface play a leading role in the initiation of pitting corrosion.