Chloride Media Research Articles

Comparison of the Antimony Cementation from Chloride Media Using Various Cementators

Comparison of the Antimony Cementation from Chloride Media Using Various Cementators

Superior corrosion resistance of mild steel coated with graphene oxide modified silane coating in chlorinated simulated concrete solution

The corrosion of steel bars is the main reason for the premature failure of reinforced concrete structures, and coating reinforcement is considered to be an effective method to protect steel bar from chloride attack. In this work, we have developed a graphene oxide (GO) modified silane composite coating (isobutyl triethoxysilane combined with tetraethyl orthosilicate) for the corrosion protection of reinforcement bar. The physicochemical characteristics and corrosion resistance performances of mild steel coated with this composite coating was detailed studied by scanning electron microscopy, Fourier transform infrared spectroscopy, thermogravimetric, Raman analyses, and electrochemical measurements. The results indicate that the coating with a thickness of about 45 μm exhibits substantial corrosion resistance effect with a maximum protection efficiency of about 99.36% at chloride media. The superior corrosion protection performance is attributed to the formed covalent bonds between GO and silanol, which strengthens the three-dimensional network structure of the coating. Besides, the uniformly distributed GO immensely slows down the degradation of silane coating structure and improves the stability of the coating, and thus delays the corrosion.

Examination and study of (thiazole-5-carboxylic acid) as inhibitor in sodium chloride medium for a mild steel corrosion

Examination and study of (thiazole-5-carboxylic acid) as inhibitor in sodium chloride medium for a mild steel corrosion

Recovery of Palladium by Extraction-electrodeposition Using N, N, N’, N’, N”, N”- Hexaoctyl-nitrilotriacetamide

ABSTRACT It is essential to develop solvent extraction (SX), and electrodeposition (ED) processes for palladium to reduce the volume of acid and organic media. In this study, the extraction reaction of Pd(II) in chloride media using of N, N, N’, N’, N”, N”-hexaoctyl-nitrilotriacetamide (NTAamide(C8)) as a novel extractant has been demonstrated. Three diluents with high dielectric constants (acetophenone (AP), 1,2-dichloroethane (DCE), and 1-octanol (OC)) were used for the solvent extraction reaction. The slope analysis indicated that the anion exchange extraction reaction of Pd(II) was consistent with an approximately 2:1 stoichiometry for the NTAamide(C8)/AP and NTAamide(C8)/DCE systems, and 1:1 for NTAamide(C8)/OC. Moreover, the ED behavior of the extracted Pd(II) complex was investigated using cyclic voltammetry (CV). Palladium reduction was found to be an irreversible process based on analysis of the standard rate constant. A semi-integral analysis of the voltammogram determined the diffusion coefficients of the extracted Pd(II) complex in the AP, DCE, and OC systems to be 3.7 ± 0.1 × 10−10, 2.8 ± 0.1 × 10−10 and 1.5 ± 0.2 × 10−10 m2 s−1, respectively. Furthermore, consecutive extraction-electrodeposition processes using the NTAamide(C8)/AP system were carried out for five cycles. High extraction percentage (E > 91%) and current efficiency (ε > 83.1%) were attained in all cycles. The electrodeposits recovered from the extraction-electrodeposition process were identified as Pd metal through X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) analyses.

Anion exchange separations to produce a suitable electrolyte for the electrodeposition of pure zinc

Anion exchange separations have been devised to purify model solutions of the usual pickling liquor (SPL) obtained from hot dip galvanization to produce a suitable ZnCl2 electrolyte for electrodepositing pure Zn. The method was based on the established anion-exchange distribution functions in chloride media. Both the simple batch and the more accurate chromatographic methods of separation were examined. The loaded solutions contained Zn, Fe, Mn, Ni and Pb of different concentrations with 1.8 - 2 M NaCl or HCl as the background. The resin bed primarily retained Zn while divalent Fe, Mn and Ni were removed in the loading and the continued rinsing steps with the mobile phase at the initial level of Cl- ion concentration. The elution of Zn was carried out by a significantly reduced Cl- ion concentration. The preliminary reduction of the iron to its divalent state was found of utmost importance. The only difficulty arises from the separation of Pb, which has an equilibrium distribution function comparable to the anion exchange of Zn, however in Europe this minor impurity should not be present at disturbing levels. Kinetic examination of the batch process revealed that Zn sorption is virtually complete within 20 minutes, however despite the low distribution coefficients, some 10 % of iron is also sorbed. Almost 90 % of the retained iron could be in the Fe(III) state caused by aerial oxidation. It was also found that the elution of Zn in the batch technique was not possible by just lowering the Cl- ion concentration. Therefore, the chromatographic method is the only possible way if only chloride media are to be applied.

Development of an analytical model for copper heap leaching from secondary sulfides in chloride media in an industrial environment

In multivariate analysis, a predictive model is a mathematical/statistical model that relates a set of independent variables to dependent or response variable(s). This work presents a descriptive model that explains copper recovery from secondary sulfide minerals (chalcocite) taking into account the effects of time, heap height, superficial velocity of leaching flow, chloride concentration, particle size, porosity, and effective diffusivity of the solute within particle pores. Copper recovery is then modelled by a system of first-order differential equations. The results indicated that the heap height and superficial velocity of leaching flow are the most critical independent variables while the others are less influential under operational conditions applied. In the present study representative adjustment parameters are obtained, so that the model could be used to explore copper recovery in chloride media as a part of the extended value chain of the copper sulfides processing.

Selective Extraction and Separation of Gallium from Indium in Chloride Medium by Di(2-Ethylhexyl) (N, N’-Di(2-Ethylhexyl) Amino Methyl) Phosphonate

Selective Extraction and Separation of Gallium from Indium in Chloride Medium by Di(2-Ethylhexyl) (N, N’-Di(2-Ethylhexyl) Amino Methyl) Phosphonate

Reverse Pulse Plated Ni-La-Cr-Fe High Entropy Alloy as a Conversion Coating for Use in Chloride Media

Reverse Pulse Plated Ni-La-Cr-Fe High Entropy Alloy as a Conversion Coating for Use in Chloride Media

Studies on the stress corrosion behaviour of aluminium 6061 / red mud metal matrix composites

Composite materials are very much popular nowadays with respect to their decreased density and improved corrosion and mechanical characteristics. They are in demand in many engineering and manufacturing fields. In this work composite materials of aluminium 6061 reinforced with Two, Four and Six weight percentage of red mud particulates are developed by stir casting process. They were subjected to studies on stress corrosion behaviour in hydrochloric acid and sodium chloride mediums at different temperature and exposure timings with different concentrations using specimens machined from castings as per ASTM standards. In all the mediums it was found that composite materials exhibit improved corrosion resistance on comparison with matrix alloy. Hence composite materials are having extensive applications than matrix alloy.

Experimental Investigation of Inhibition Efficiency of Crocin for Chloride-Induced Corrosion of Aluminum Alloys

The use of Crocin, derived from the flowers of Crocus sativus, is investigated as corrosion inhibitor for the AA1050, AA5083, AA5754 and AA6082 aluminum alloys in chloride ions environment. Aluminum and aluminum alloys are subjected to corrosion in the aggressive environment of chlorides, so several green corrosion inhibitors, mostly of plant origin, with minimum impact on health and the environment have been examined. In this study, the inhibition efficiency of 1.25 mM Crocin in a 0.01 M NaCl corrosive solution was assessed via electrochemical corrosion techniques and gravimetric mass loss measurements of the aluminum alloys. The surface of the specimens was examined using Scanning Electron Microscopy, Energy Dispersive Spectroscopy, Stereomicroscopy and Glossiness measurements. Experimental results reveal the protective anticorrosive action of Crocin for all aluminum alloys in the sodium chloride medium.

Effect of temperature on corrosion inhibition by ethanolic extract of Eriobotrya Japonica seeds in chloride medium 1M

This work investigated the effect of temperature on corrosion of C38 steel in a hydrochloric medium (1M) in the absence and presence of the ethanolic extract from Eriobotrya Japonica (ERJ) seeds treated by maceration. For a better understanding of the corrosion process, electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization techniques had applied by increasing the temperature from 303.15 K to 333.15 K. Moreover, studying adsorption isotherms and determining thermodynamic parameters to understand the mechanism adopted in the adsorption of ERJ molecules on the metal surface. The results reveal that the inhibition efficiency increases with higher inhibitor concentration and decreases slightly with increasing temperature. Thus, the Langmuir model is the best model to fit the data obtained, and the adsorption follows a spontaneous physisorption process. According to the evolution of enthalpy, entropy, and activation energy, the inhibition capacity decreases is associated with a slow endothermic dissolution due to forming an active complex on the surface of C38.

Fabrication of Cobalt-Based Nano-Composite Film for Corrosion Mitigation of Copper in Flow Chloride Medium

Corrosion of metals leads to high maintenance costs, as well as potential threats to structural health and safety. Here, we demonstrate the coating of cobalt tungstate (CoWO4) nanoparticles (NPS)/5-mercapto-1-phenyl-1 H-tetrazole derivative (MPT) used as a nano-composite film on Cu surface for the blocking of micropores to hinder the propagation of metastable pits in an aggressive NaCl medium. The mechanism of interaction between the nanoparticles and tetrazole derivative, in addition to the mode of anchoring to the metal surface and blocking the penetration of chloride ions (Cl−), are all investigated. In this investigation, CoWO4 is synthesized via a wet chemical route and thereafter, is combined with MPT at an optimized ratio thus formulating a nano-composite corrosion inhibitor which in solution gets coated on Cu surface. Atomic force and scanning electron microscopic images of the bare Cu reveal dip pits, which by the coating of the nano-composite are suppressed at the nucleation stage during exposure to the aggressive 3.5% NaCl electrolyte under flow conditions. Electrochemical analysis shows high protection of Cu up to 97% efficiency in the presence of the newly formulated nano-composite inhibitor film.

Synergistic effects of Ionquest 801 and Cyanex 572 on the solvent extraction of rare earth elements (Pr, Nd, Sm, Eu, Tb, and Er) from a chloride medium

A binary mixture of Ionquest 801 and Cyanex 572 was employed to study their synergistic effect on the solvent extraction and separation of rare earth elements (praseodymium (Pr), neodymium (Nd), samarium (Sm), europium (Eu), terbium (Tb) and erbium (Er)) dissolved in a chloride solution. The results demonstrated a significant synergistic effect of 50% vol. Ionquest 801 and 50% vol. Cyanex 572 at pH of 1.5 in the extraction of heavy rare earth elements (HREEs). The maximum percentage extraction of the HREEs, Er3+ and Tb3+, under the optimized condition, were 95.7% and 71.7%, respectively; also, their distribution coefficient was improved, DEr (22.61) and DTb (2.54). Under that optimum condition, the extraction efficiencies of Nd (light rare earth element, LREE), Pr (LREE), Eu (middle rare earth element, MREE), and Sm (MREE) were 28%, 27%, 40%, and 38%, respectively. Additionally, the distribution coefficients of the HREEs to those of LREEs and MREEs were improved. For example, the measured separation factor for some of the couples were: Er/Pr: 61.31, Er/Nd: 57.77, Er/Sm: 36.44, Er/Eu: 33.19, Tb/Pr: 6.88, Tb/Nd: 6.48, Tb/Sm: 4.09 and Tb/Eu: 3.72. Both extractants individually showed similar performance in the extraction of HREEs. However, the highest efficiencies of the extraction of LREEs and MREEs were obtained solely with Cyanex 572. In contrast, Ionquest 801 showed little tendency towards extracting LREEs and MREEs, especially towards LREEs. Overall, the addition of Ionquest 801 to Cyanex 572 resulted in increased extraction of HREEs compared to the same in the sole Cyanex 572 and Ionquest 801. Additionally, the selectivity of the separation of HREEs from LREEs and MREEs was improved. The synergistic effect was concluded to result from changes in the phosphinic and phosphonic acids ratio in the extractant. By plotting McCabe-Thiele diagrams, it was confirmed that the complete extraction of Er3+ and Tb3+ occurred at the 3rd and 6th extraction stages, respectively. Stripping REE3+ from the loaded organic solution, using HCl with different concentrations, was investigated and the maximum stripping percentages reached were 92.2% for Er3+ and 55.8% for Tb3+ using a 4 M HCl solution.

Extraction and separation of rare earths using mixtures of sec-nonylphenoxy acetic acid and alkylated phosphine oxides

The increasing demand for high-purity rare earths and their compounds promoted the separation technology of rare earths. In this work, the mixtures of sec-nonylphenoxy acetic acid (CA100) and alkylated phosphine oxides (Cyanex923 and Cyanex925) were used as extractants instead of single CA100 for high-efficiency extraction of rare earths from chloride medium. Compared with single CA100 , the mixture of CA100 and Cyanex923/Cyanex925 could improve the selectivity of yttrium (Y) extraction from the lanthanoids based on their separation factors. The synergistic effects of CA100 and Cyanex923 on lanthanum (III) extraction were investigated by using the methods of slope analysis and constant mole to determine the extraction reaction. The reaction product, equilibrium constants, formation constants, and the thermodynamic functions were determined. The synergistic extraction of lanthanum (III) with CA100 and Cyanex923 was proved to be endothermically driven.

Influence of silane functionalized nanoclay on the barrier, mechanical and hydrophobic properties by clay nanocomposite films in an aggressive chloride medium

The surface alteration of silica clay by a silane coupling agent was done to improve the compatibility with epoxy polymer matrix. It can be attained with ethoxy based silanes namely (3-mercaptopropyl) triethoxysilane (MPTES), propyltriethoxysilane (PTES) and 3-aminopropyl(diethoxy)methylsilane (APDES) in order to enhance the anticorrosion potential of epoxy coatings on mild steel. The structural and thermal properties of the functionalized clay nanoparticles are studied by X-ray diffraction (XRD) and thermogravimetric analysis (TGA). The morphological features of the functional nanoclay were also described by employing field emission scanning electron microscopy with energy dispersive x-ray analysis (FE-SEM/ EDX) and TEM (Transmission electron microscopy) analysis. These analyses showed the well functionalization of nanoclay by silanes. The well dispersion of functionalized nanoclay in the epoxy resin produces better nanocomposites which are coated on the mild steel. The coated steel samples were analyzed in terms of microstructure and corrosion resistant properties in 3.5% NaCl solution. Electrochemical impedance spectroscopy (EIS), scanning electrochemical microscopy (SECM), salt spray analysis, and analysis of oxygen and water permeability were applied to assess the barrier properties against water permeation, oxygen penetration and protectiveness of silane-modified epoxy coatings. It was found that all the modified coatings showed higher barrier resistance and superior corrosion resistance than pure epoxy coating, which were described by higher charge transfer resistance (Rct) 6815.36 kΩcm2 and lower double-layer capacitance (Cdl) 405.51 µF at the electrolyte/metal interface. The tensile strength was found to be 113 MPa for EP-MPTES/clay nanocomposite while the value of pure epoxy coated specimen was 41 MPa. Therefore, the silane grafted clay nanoparticles results in slower diffusion processes, which specifically slow down the anodic reaction, thus blocking the overall corrosion path. Modified clay-epoxy nanocomposite displays good thermostability, better dispersion, outstanding mechanical property and superior water resistance property. Among the examined silanes, MPTES shows an effective functionalization of nanoclay, followed by the APDES and PTES. A possible mechanism has also been proposed.

Enhanced protection of hybrid polyetherimide-ZnO or CuO bilayer composite coatings against mild steel corrosion in chloride media

Protective bilayer composite coatings based on polyetherimide (PEI) containing ZnO or CuO particles were applied on mild steel (MS) by the sol-gel dip coating method and exposed to aggressive NaCl solutions. Scanning electron microscopy (SEM) analysis revealed the formation of homogenous coatings and X-ray diffraction (XRD) and energy dispersive spectroscopy (EDS) analysis confirmed the presence of ZnO or CuO. Although attenuated total reflectance (ATR) proved that the polymer structure was not affected by the presence of the oxide particles, water contact angle revealed that PEI-CuO fallen within the hydrophobic range, whereas PEI alone and PEI-ZnO presented a hydrophilic behaviour. Upon immersion, the PEI-CuO coating was preserved, whereas the PEI and PEI-ZnO coatings were more susceptible to damage and the exposed MS presented different corrosion profiles, depending on being previously coated with blank PEI or PEI-ZnO coatings. The corrosion resistance was investigated by electrochemical impedance spectroscopy (EIS) and demonstrated that the barrier properties of the composite coating and the corrosion resistance of MS, over a short period of immersion, were improved with PEI-CuO. The coating modified with CuO particles, immersed for 8 days in NaCl, presented impedance values above 5 × 105 Ω.cm2, and represented a protective efficiency greater than 99% compared to PEI alone, or to the coating modified with ZnO for which the impedance was in the order of 103 Ω.cm2.Therefore, the most protective composite coating, due to the presence of CuO, brings potential to be explored as an anti-biofouling solution.

Comparative study of the removal of direct red 23 by anodic oxidation, electro-Fenton, photo-anodic oxidation and photoelectro-Fenton in chloride and sulfate media

This study aims to compare the efficiency of anodic oxidation with electrogenerated H2O2 (AO-H2O2), electro-Fenton (EF), and their association with UV irradiation (photo anodic oxidation (PAO), and photo electro-Fenton (PEF) for the removal of Direct Red 23 from wastewater using a BDD/carbon felt cell in chloride and sulfate medium and in their combination. The effect of the supporting electrolyte was investigated in AO-H2O2 and EF processes. High discoloration efficiency was obtained in chloride media while a higher mineralization rate was achieved in sulfate media. The EF process reached higher total organic carbon (TOC) removal efficiency than AO-H2O2. 90% TOC removal rate was achieved by the EF against 82% by AO-H2O2 in sulfate media. The influence of using the mixt supporting electrolyte formed of 75% Na2SO4 + 25% NaCl was found to have beneficial effect on TOC removal, achieving 89% and 97% by AO-H2O2 and EF, respectively. High currents led to higher mineralization rates while low currents yielded to a higher mineralization current efficiency (MCE%) and lower energy consumption (EC). UV irradiation enhanced process efficiency. Mineralization efficiency followed the sequence: AO-H2O2 < PAO < EF < PEF. The PEF process was able to remove TOC completely at 5 mA cm−2 current density and 6 h of electrolysis with a MCE% value of 16.57% and EC value of 1.29 kWh g−1 TOC removed.

Synthesis of some metal nanoparticles using the effective media of choline chloride based deep eutectic solvents

Nanoparticles are potential candidates for numerous biological as well as chemical applications due to their exotic properties 1 - 3. Low lattice energy ions are found in deep eutectic solvents (DES). A quaternary ammonium salt is frequently complexed with a metal salt or hydrogen bond donor to produce these compounds (HBD) 4 - 6. The green synthesis of nanoparticles using DESs is always eco-friendly and attractive. The current study focuses on the synthesis of mercuric sulphide, Zirconium oxide, Manganese oxide and Copper oxide nanoparticles using the Choline Chloride - Ethylene Glycol DES as the solvent in presence of a reducing agent, hydrazine hydrate. The UV-Visible, FTIR spectra, XRD, SEM and EDAX analysis were carried out on these metal nanoparticles. The average sizes of these metal nanoparticles were found to be 50 to 150 nm. Hence the green synthesis of metal nanoparticles using Ch. Cl – EG can be considered as an alternative route in chemical synthesis of metal nanoparticles.

Leaching Chalcocite in Chloride Media—A Review

Chalcocite is the most abundant secondary copper sulfide globally, with the highest copper content, and is easily treated by conventional hydrometallurgical processes, making it a very profitable mineral for extraction. Among the various leaching processes to treat chalcocite, chloride media show better results and have a greater industrial boom. Chalcocite dissolution is a two-stage process, the second being much slower than the first. During the second stage, in the first instance, it is possible to oxidize the covellite in a wide range of chloride concentrations or redox potentials (up to 75% extraction of Cu). Subsequently, CuS2 is formed, which is to be oxidized. It is necessary to work at high concentrations of chloride (&gt;2.5 mol/L) and/or increase the temperature to reach a redox potential of over 650 mV, which in turn decreases the thickness of the elemental sulfur layer on the mineral surface, facilitating chloride ions to generate a better porosity of this. Finally, it is concluded that the most optimal way to extract copper from chalcocite is, during the first stage, to work with high concentrations of chloride (50–100 g/L) and low concentrations of sulfuric acid (0.5 mol/L) at a temperature environment, as other variables become irrelevant during this stage if the concentration of chloride ions in the system is high. While in the second stage, it is necessary to increase the temperature of the system (moderate temperatures) or incorporate a high concentration of some oxidizing agent to avoid the passivation of the mineral.

Stoichiometry of the Nickel Complex Formed with LIX 63 Hydroxyoxime under Acidic Chloride Conditions

ABSTRACT The extraction of nickel by LIX® 63 hydroxyoxime (‘hydroxyoxime’) under acidic (10–100 g/L hydrochloric acid) chloride conditions was investigated with the intent of determining the stoichiometry of the resulting complex in solution. Maximum loading and continuous variation tests indicate that nickel is extracted as a cationic salt with chloride counter-ions, the resulting complex exhibiting octahedral coordination with 1:3:2 nickel:hydroxyoxime:chloride stoichiometry. This species is also observed to readily form under mildly acidic (pH 1–4) chloride conditions, with the extent of formation being independent of pH. Nickel extraction kinetics were moderately fast, equilibrium being reached in 10 minutes. The behaviour of this system helps to provide clarity in relation to complex stoichiometry and the role of different ligands in synergistic systems utilising LIX 63 and an organic acid such as Versatic 10, opening up the possibility of nickel extraction from acidic chloride media using LIX 63.