Addition Of Chloride Ions Research Articles

Superior protective performance of Ni Cr coating on stainless steel 316L in pure, oxygenated and chlorinated supercritical water

The protective effect of Ni Cr coating in supercritical water (SCW) was studied in this work. Ni Cr coated 316 L stainless steel showed an excellent microstructure and performance stability in SCW. The corrosion weight gains of as-received 316L were 2–3.6 times of that of Ni Cr coated sample in SCW with 5000 ppm oxygen content. The coating greatly reduced the corrosion weight gain of 316L in a SCW environment after 144 h exposure. The surface of Ni Cr coating was composed of the outermost hydration layer (Ni(OH) 2 ), oxide layer (NiO, NiCr 2 O 4 and Cr 2 O 3 ) and metallic layer (Ni 0 ) mixed in oxides. NiO on the surface of the Ni Cr coating decomposed with the addition of oxygen or chloride ions in SCW. • The corrosion weight gains of as-received 316L were 2–3.6 times of that of the two coated samples. • The coating greatly reduced the corrosion weight gain of 316L in SCW environment after 144 h exposure. • Small amount of Fe diffused to the coating surface along surface defects on the Ni-Cr coating. • Ni-Cr coating contains the outermost hydration layer, oxide layer and metal elementary layer.

One-Step Synthesis of Green Fluorescent Carbon Dots for Chloride Detecting and for Bioimaging.

The chloride ion is an essential ion in organisms, which plays an important role in maintaining normal cell functions. It is involved in many cell activities, such as cell proliferation, cell excitability regulation, immune response, and volume regulation. Accurate detection of the chloride ion can balance its concentration in vivo, which is of great significance. In this study, we developed a green fluorescent carbon quantum dot to detect chloride concentration through the “off–on” mechanism. First, the fluorescence of carbon dots is quenched by the complex of sulfhydryl and silver ions on the surface of carbon dots. Then, the addition of chloride ions pulls away the silver ions and restores the fluorescence. The fluorescence recovery is linearly related to the concentration of chloride ions, and the limit of detection is 2.817 μM, which is much lower than those of other reported chloride probes. Besides, cell and zebrafish experiments confirmed the biosafety and biocompatibility of the carbon dots, which provided a possibility for further applications in bioimaging in vivo.

Removal of drug losartan in environmental aquatic matrices by heat-activated persulfate: Kinetics, transformation products and synergistic effects

In this study, the oxidative degradation of losartan (LOS), a widely administered medicine for high blood pressure by heat-activated persulfate was investigated. Increased temperature and persulfate concentration, as well as acidic conditions enhance the degradation efficiency of LOS, whose rate follows pseudo-first order kinetics. From the respective apparent rate constants in the range 40–60 °C, an apparent activation energy of 112.70 kJ/mol was computed. Radical scavenging tests demonstrated that both HO• and SO4•− contribute towards LOS degradation. LOS degradation was suppressed in real water matrices including bottled water (BW) and secondary wastewater effluent (WW), while other experiments indicated that the presence of bicarbonates and humic acid negatively affected its oxidation. Instead, the addition of chloride ions at 250 mg/L resulted in a positive effect on LOS removal. The combination of heat-activated PS with low-frequency ultrasound exhibited a synergistic effect, with the ratio S being 2.29 in BW and 1.52 in WW. Five transformation products of LOS were identified through HRMS suspect and non-target screening approaches, among which two are reported for the first time. Using the in-house risk assessment program, ToxTrAMs was revealed that most of the identified TPs present higher toxicity than LOS against Daphnia magna.

Remediation and detoxification of water samples contaminated with 2, 4, 6-trichlorophenol by gamma radiation and ozonation

This paper investigates the treatment of water samples contaminated with 2, 4, 6-trichlorophenol (TCP) by gamma radiation. The effects of absorbed dose, initial pH, and chloride ions on the removal of TCP were investigated. In addition, the individual and combined effects of gamma irradiation and ozonation on the toxicity of TCP solutions were assessed. The results showed that the complete decomposition of TCP could be attained at 3.5 kGy in good agreement with previous studies. The pH of the solutions was found to affect the efficiency of the treatment, and the optimal removal of TCP was observed at pH 4.0. The addition of chloride ion to TCP solution before irradiation enhanced the removal% up to 46% depending on the absorbed dose and chloride ion source. Toxicity measurements indicated that the absorbed dose required for the detoxification was ca. 20 × higher than that required for TCP decomposition. The combination of gamma irradiation with ozonation enhanced the detoxification of TCP, and a synergistic effect was observed. This synergistic effect increases with the ozonation time and absorbed dose and led to a significant reduction in the absorbed dose required for a complete detoxification from 70 to 35 kGy.

Efficient electrocatalysis for denitrification by using TiO2 nanotube arrays cathode and adding chloride ions

Electrocatalysis is emerging as a promising alternative to bacterial denitrification for removing nitrate and ammonia from sewage. The technology is highly efficient and robust in actual wastewater treatment scenarios; however, there may be the generation of harmful intermediates (such as nitrite) on the traditional cathode material. In this study, we demonstrated that TiO2 nanotube arrays can be used as an effective cathode to reduce nitrate to ammonia without generation of nitrite. Alongside this, the addition of chloride ions in the solution can further oxidize ammonia to N2. We looked into the key factors influencing the electrocatalytic denitrification, including the current density (2–10 mA/cm2), initial pH values (3–11), and types of anions (HCO3−, Cl−, SO42−). The results showed that 90.8% of nitrate and 59.4% of total nitrogen could be removed in 1.5 h under optimal conditions, with degradation kinetic constants of 1.61 h−1 and 0.79 h−1, respectively. Furthermore, we investigated the formation of intermediate products and explored the electrocatalytic denitrification mechanism: (a) the surface oxygen vacancies and high specific surface area of TiO2 nanotube arrays electrode promote the reduction of nitrate to ammonia and N2; (b) the active chlorine generated at the anode surface can effectively oxidize ammonium to N2.

Environmental Conditions Affecting GABA Production in Lactococcus lactis NCDO 2118.

GABA (γ-aminobutyric acid) production has been widely described as an adaptive response to abiotic stress, allowing bacteria to survive in harsh environments. This work aimed to clarify and understand the relationship between GABA production and bacterial growth conditions, with particular reference to osmolarity. For this purpose, Lactococcus lactis NCDO 2118, a GABA-producing strain, was grown in glucose-supplemented chemically defined medium containing 34 mM L-glutamic acid, and different concentrations of salts (chloride, sulfate or phosphate ions) or polyols (sorbitol, glycerol). Unexpectedly, our data demonstrated that GABA production was not directly related to osmolarity. Chloride ions were the most significant factor influencing GABA yield in response to acidic stress while sulfate ions did not enhance GABA production. We demonstrated that the addition of chloride ions increased the glutamic acid decarboxylase (GAD) synthesis and the expression of the gadBC genes. Finally, under fed-batch conditions in a complex medium supplemented with 0.3 M NaCl and after a pH shift to 4.6, L. lactis NCDO 2118 was able to produce up to 413 mM GABA from 441 mM L-glutamic acid after only 56 h of culture, revealing the potential of L. lactis strains for intensive production of this bioactive molecule.

Improved sensitivity with chloride ions in nanoparticle enhanced laser-induced breakdown spectroscopy

The addition of chloride ions to silver colloid was proposed as an effective approach to enhance laser-induced breakdown spectroscopy (LIBS) signals.

Degradation of aniline by ferrous ions activated persulfate: Impacts, mechanisms, and by-products

Wastewater contains a large number of anions and organics which can scavenge reactive radicals and limit the application of sulfate radical-based advanced oxidation processes (SR-AOPs) in practical engineering. Here, we studied the removal rate and mechanism of aniline by SR-AOPs in different influencing factors, such as sodium persulfate dosage, ferrous ions dosage, solution pH, Cl-, HCO3-, NO3-, and other organic matter. By recognizing and analyzing free radicals, we concluded that SO4•- plays a major role in aniline degradation. The aniline removal rate increased with the initial concentrations of persulfate and ferrous ions, but aniline degradation was inhibited by excessive dosage. The aniline removal rate by ferrous-ions-catalyzed persulfate was higher under acidic conditions and could be improved under alkaline conditions if no ferrous ions were added. The addition of bicarbonate ions inhibited aniline removal, and the addition of nitrate ions barely caused the effect. While the addition of chloride ions promoted aniline degradation, which was confirmed that HClO generated from the reacting of Cl- and persulfate played a key role. However, TOC indicated that aniline was not completely mineralized in the process. Further analysis of the products from GC-MS demonstrated that chloride-ion additions produced some harmful halogenated by-products. Our results can act as a basis for developing processes for the aniline degradation in wastewater.

Heterogeneous crystallization of zinc hydroxystannate on galvanized steel for enhancing the bond strength at the rebar/concrete interface

Zinc hydroxystannate (ZnSn(OH)6) coatings were deposited on galvanized carbon steel samples by an electroless heterogeneous crystallization process. Structural and morphological features of the coatings as a function of the immersion time were determined by X-ray diffraction, Raman Spectroscopy and Scanning Electron Microscopy revealing the presence of truncated octahedrons of crystalline ZnSn(OH)6. Electrochemical characterization in a simulated concrete pore solution without and with addition of chloride ions proved that the cathodic protection is preserved and that ZnSn(OH)6 improved the corrosion resistance of the rebars. Pull-out tests demonstrated an enhanced bond strength at the rebar/concrete interface and, thus, an improved adhesion after the heterogeneous crystallization process.

Enhanced mechanism of 2,4-dichlorophenoxyacetic acid degradation by electrochemical activation of persulfate on Blue-TiO2 nanotubes anode

Electrochemical activation of persulfate (PS) using Blue-TiO2 nanotubes (Blue-TNT) anode was first attempted for 2,4-dichlorophenoxyacetic acid (2,4-D) decomposition with a low energy consumption of 0.14 kWh m−3, obtaining the rate constant 2.57 and 6.32 times higher than that using boron-doped diamond (BDD) anode and dimensionally stable anode (DSA), respectively. The contribution of responsible radical to 2,4-D degradation on Blue-TNT was 95% from OH while only 2% from SO4−, differing from that on BDD anode which was ascribed to both OH and non-radical oxidation. The superiority of Blue-TNT anode in PS system was certified by the apparent rate constant which was 6.4, 4.6 and 1.9 times higher than that in the NaNO3, NaClO4 and Na2SO4 electrolyte. Increasing current density and PS concentration and decreasing initial pH accelerated the removal of 2,4-D. The addition of chloride ions (Cl−) enhanced 2,4-D decay, while the presence of bicarbonate (HCO3−) and humic acid (HA) had an inhibition effect on 2,4-D degradation. Overall, electrochemical activation of PS using Blue-TNT was an effective method for contaminants degradation.

KINETICS AND MECHANISM OF TETRAHYDROFURAN OXIDATION BY CHLORAMINET IN ACIDIC MEDIA

The kinetics of tetrahydrofuran oxidation by sodium N-chloro-p-toluene sulfonamide in the hydrochloric acid medium was studied in this work at 308 K. The reaction rate shows a first-order dependence on [CAT] and fractional-order dependence each on [THF] and [H+]. The derivative rate law, which suitable for experimental results, is Equation 24. The first-order rate constant has been evaluated from the relationship of the plot of Log [CAT] versus Time. The variation of the ionic strength by the addition of sodium perchlorate (NaClO4) and chloride ion on the medium showed no significant effect on the reaction. The reaction rate raised with decreasing dielectric constant (D), while the addition of p-toluene sulfonamide retards the rate of reaction. The oxidation reaction of tetrahydrofuran have been studied at a different temperature, The equilibrium constants for the formation of hypochlorous acid, protonated hydrochlorous acid and protonated hydrochlorous acid–THF complex and its decomposition constant have been estimated. Also, the rate constant for the slow (rate-determining step) and the activation parameter have been calculated. A suitable mechanism for the oxidation reaction of tetrahydrofuran was proposed based on the experimental finding. The mechanism includes the reaction of active species (H2OCl) of the oxidizing agent with the tetrahydrofuran in a fast step to give the complex(X). This complex will then transformed into complex (X̅ ) in slow step then to γ-butyrolactone in another fast step.

Imaging electrochemically synthesized Cu2O cubes and their morphological evolution under conditions relevant to CO2 electroreduction

Copper is a widely studied catalyst material for the electrochemical conversion of carbon dioxide to valuable hydrocarbons. In particular, copper-based nanostructures expressing predominantly {100} facets have shown high selectivity toward ethylene formation, a desired reaction product. However, the stability of such tailored nanostructures under reaction conditions remains poorly understood. Here, using liquid cell transmission electron microscopy, we show the formation of cubic copper oxide particles from copper sulfate solutions during direct electrochemical synthesis and their subsequent morphological evolution in a carbon dioxide-saturated 0.1 M potassium bicarbonate solution under a reductive potential. Shape-selected synthesis of copper oxide cubes was achieved through: (1) the addition of chloride ions and (2) alternating the potentials within a narrow window where the deposited non-cubic particles dissolve, but cubic ones do not. Our results indicate that copper oxide cubes change their morphology rapidly under carbon dioxide electroreduction-relevant conditions, leading to an extensive re-structuring of the working electrode surface.

How do fluoride ions bind to tetrathiacalix[2]arene[2]triazines?

Two novel tetrathiacalix[2]arene[2]triazines 1a,b have been synthesized and investigated as halide ionophores. UV–vis titrations showed that these macrocycles have a high affinity for fluoride over other halide ions; 1H NMR spectroscopy revealed that only upon fluoride (and not chloride or bromide) ion addition does the spectrum undergo a dramatic loss of symmetry. Finally, a comprehensive DFT (B3LYP/6–311 + G(d,p)) investigation suggested that fluoride ions likely form σ-complexes upon binding to 1a and 1b.

Leaching Chalcopyrite with an Imidazolium-Based Ionic Liquid and Bromide

The unique properties of ionic liquids (ILs) drive the growing number of novel applications in different industries. The main features of ILs are high thermal stability, recyclability, low flash point, and low vapor pressure. This study investigated pure chalcopyrite dissolution in the presence of the ionic liquid 1-butyl-3-methylimidazolium hydrogen sulfate, [BMIm]HSO4, and a bromide-like complexing agent. The proposed system was compared with acid leaching in sulfate media with the addition of chloride and bromide ions. The results demonstrated that the use of ionic liquid and bromide ions improved the chalcopyrite leaching performance. The best operational conditions were at a temperature of 90 °C, with an ionic liquid concentration of 20% and 100 g/L of bromide.

Influence of chloride ion on zinc electrodeposition from choline chloride based deep eutectic solvent

When deep eutectic solvent (DES) is used to recycle Zn from zinc-containing dusts, chlorine present in these dusts will enter into the resulting solution and inevitably affects subsequent electrodeposition of zinc. This paper investigated the effect of added chloride ions on the electrodeposition behavior of zinc from choline chloride-urea-ethylene glycol (ChCl-urea-EG) DES-containing zinc oxide. Compared with the blank ChCl-urea-EG DES, the addition of chloride ion is found to increase the current efficiency, reduce the energy consumption, and improve the compactness of Zn deposits. In addition, cyclic voltammetry results and kinetic parameters lead to the conclusion that the added chloride ions have an inhibiting effect on Zn(II) ion migration, but have a promoting effect on reduction reaction of Zn(II) ion. The results of X-ray diffraction analysis reveal that the addition of chloride ions affects the crystallographic orientation by enhancing the growth of (101), (102), and (103) planes.

Photodegradation of Oxytetracycline in the Presence of Dissolved Organic Matter and Chloride Ions: Importance of Reactive Chlorine Species

This paper investigated the photodegradation of oxytetracycline (OTC) in the presence of dissolved organic matter (DOM) and chloride ions, which is relevant to the estuary environment. The separate effects of chloride ions and DOM on the photodegradation of OTC were first studied, and then, the combined effects were studied. The photodegradation of OTC showed a tendency to decrease with increasing DOM levels: a low concentration of DOM ( 5 mg/L) inhibited it. The addition of chloride ions (10–500 mmol/L) to DOM solutions (20 mg/L) significantly increased the degradation rate of OTC. The observed promotion effects may be a consequence of the participation of reactive chlorine species. Quenching experiments verified that the main active species in the presence of chloride ions and DOM are radicals including Cl•/Cl2•− and HO•. These results indicate a promotion of OTC degradation in saline water compared with fresh water, and this finding is important to better understand the environmental fate of OTC in estuarine and coastal waters.

Activity and stability of biochar in hydrogen peroxide based oxidation system for degradation of naphthenic acid

This study investigated the stability and catalytic activity of wheat straw biochar (WS), hardwood biochar (HW) and commercial activated carbon (AC) in hydrogen peroxide (H2O2) based oxidation system for degradation of model naphthenic acids compound, 1-methyl-1- cyclohexane carboxylic acid (MCCA). WS showed excellent catalytic activity for decomposition of H2O2 and MCCA degradation as demonstrated by high H2O2 decomposition rate (2.0*10−4 M−1s−1), amount of hydroxyl (OH) radicals generated (182 mg/L) and degradation efficiency of MCCA (100% at Co – 100 mg/L). 2-Methyl pentatonic acid was identified as reaction intermediate and 99% mineralization of MCCA was obtained within 4 h. The real wastewater conditions were simulated by addition of chloride (Cl−) and bicarbonate ions (HCO3−) and found that lower concentrations of Cl− and HCO3− have minimal influence on MCCA removal. Overall, biochar catalyzed H2O2 based oxidation process has great potential and can be applied for degradation of NAs in oil-sand processed water.

Chloropalladated tetranuclear and copper(I) complexes of propargylamines [RC≡CCH2NC4H8NCH2C≡CR

The reactions of propargylamines 1,4-bis(3-phenylprop-2-yn-1-yl)piperazine (1) and 1,4-bis(3-(trimethylsilyl)prop-2-yn-1-yl)piperazine (2) with PdCl2 and CuI is described. 1,4-Bis(3-phenylprop-2-yn-1-yl)piperazine reacts with one equivalent of PdCl2 to afford κ2-N,N-coordinated complexes [PdCl2{Me3SiCCCH2NC4H8NCH2C≡CSiMe3-κ2-N,N] (3) and [PdCl2{Me3SiCCCH2NC4H8NCH2C≡CSiMe3}-κ2-N,N] (4). The reactions of 1 and 2 with two equivalents of PdCl2 yielded rare chloropalladated tetranuclear complexes [Pd4(μ-Cl)4(PhC=C(Cl)CH2NC4H8NCH2(Cl)C=CPh)2] (5) and [Pd4(μ-Cl)4(Me3SiC=C(Cl)CH2NC4H8NCH2(Cl)C=CSiMe3)2] (6), respectively, resulting from the trans nucleophilic addition of chloride ion onto the electrophilic CC bond. The reactions of 1 and 2 with two equivalents of CuI produced 2-D coordination polymers [{Cu2(μ-I)}2(PhC≡C–CH2NC4H8NCH2C≡CPh)]n (7) and [{Cu2(μ-I)}2(Me3SiCCCH2NC4H8NCH2C≡CSiMe3)]n (8), respectively. Similar reactions in 1:1 M ratios produced dimeric complexes [Cu2(μ-I)2(PhC≡CCH2NC4H8NCH2C≡CPh)2] (9) and [Cu2(μ-I)2(Me3SiCCCH2NC4H8NCH2C≡CSiMe3)2] (10), respectively. The structures of compounds 3, 5 and 7 have been established by single crystal X-ray analysis.

SERS, XPS and DFT Study of Xanthine Adsorbed on Citrate-Stabilized Gold Nanoparticles.

We have studied the adsorption of xanthine, a nucleobase present in human tissue and fluids that is involved in important metabolic processes, on citrate-reduced gold colloidal nanoparticles by means of surface-enhanced Raman scattering (SERS), absorption, and X-ray photoelectron spectroscopy (XPS) measurements, along with density functional theory (DFT) calculations. The citrate anions stabilize the colloidal suspensions by strongly binding the gold nanoparticles. However, these anions do not impair the adsorption of xanthine on positively-charged active sites present on the metal surface. We have obtained the Fourier transform (FT)-SERS spectra of adsorbed xanthine by laser excitation in the near infrared spectral region, where interference due to fluorescence emission does not usually occur. In fact, the addition of chloride ions to the Au/xanthine colloid induces the aggregation of the gold nanoparticles, whose plasmonic band is shifted to the near infrared region where there is the exciting laser line of the FT–Raman instrument. Hence, this analytical approach is potentially suitable for spectroscopic determination of xanthine directly in body fluids, avoiding fluorescence phenomena induced by visible laser irradiation.

Electrochemical Comparative Characteristics of La(Fe,Si)13 Type Materials with Different Content of Co in Acidified Phosphate Environment in Presence of Cl- Ions

In the paper the electrochemical characteristics of alloys based on La(Fe,Si)13 phase have been presented. The material for research was the LaFe11.8-xCoxSi1.2 alloy with different cobalt content. Presented electrochemical characteristics provide information about pitting corrosion. This kind of corrosion is one of the most common local corrosion, it is especially undesirable for multi-phase alloys based on rare earth elements, as it contributes to the sudden and unexpected destruction of the surface of the material in working conditions. In the paper the results of potentiokinetic corrosion tests determined for LaFe10.72Co1.08Si1.2 and LaFe11.00Co0.8Si1.2 alloys in acidified phosphate solution (pH = 3) with different addition of chloride ions (Cl-) have been presented. Also analysis of alloys surface before and after corrosion measurement have been presented. The surface analysis have been carried out on the basis of profilometric roughness tests and optical microscopy observation. The studies have shown low resistance of LaFe10.72Co1.08Si1.2 and LaFe11.00Co0.8Si1.2 alloys to pitting corrosion, which, however, increases with Co content increase. DOI: http://dx.doi.org/10.5755/j01.ms.25.3.19536