•Polyaniline in the form of base and salt was prepared chemically and electrochemically.•Corrosion of mild steel with different composite coatings were investigated.•Chemically prepared emeraldine ...salt posses good anticorrosion properties.•Anticorrosion properties were connected with the content of oligomers in the samples.•It was proposed that polyaniline acts as active barriers.
The protective abilities of composite coatings based on electrochemically and chemically formed polyaniline powder against the corrosion of mild steel were investigated. A polyaniline powder has been prepared in the form of an emeraldine base and benzoate salt through chemical dedoping and doping. The composite coatings using polyaniline powders, which were obtained through different routes, and base coatings, which were not corrosion-resistant, with different formulations were prepared and applied on mild steel samples. The corrosion was investigated using an electrochemical impedance technique in 3% NaCl, and the atmospheric corrosion was assessed in a humidity chamber. Emeraldine–benzoate salts, which are a chemically synthesized polyaniline, offer the best protection with an optimal polyaniline concentration of approximately 5wt%. The different corrosion behaviors were assessed relative to the presence of aniline oligomers in the samples after characterization using UV–vis spectrophotometry. Upon comparison between the corrosion behavior in 3% NaCl with commercial primer paint for iron and that with a paint containing 5wt% PANI, the composite coating has superior anticorrosion characteristics. The mechanism for the protection of mild steel from corrosion through composite polyaniline coatings was also considered.
Electrochemical oxidation of iodide on DSA (Ti/RuO
2) anode was investigated in laboratory cell and semi-industrial electrochemical reactor. Anodic polarization curves in the laboratory cell were ...obtained in solutions contained 0.10, 0.25 and 0.40
mol
dm
−3 KI in order to determined current densities for electrolysis in the semi-industrial electrochemical reactor. Parameters of the electrolysis were estimated using semi-industrial electrochemical reactor in which concentration of KI and current density were varied. pH and reactor voltage, were measured as a function of time, as well. The electrolysis was carried out until stationary concentration of equivalent iodine was reached. It was concluded that optimal electrolysis conditions based on current efficiency, concentrations of equivalent iodine, and the other parameters, was achieved in solution contained 0.40
mol
dm
−3 KI and with current density of 10
mA
cm
−2. Based on the theoretical analysis of the iodine–iodide–water equilibria, it was concluded that at pH 11.6 main electrolysis products were triiodide, hypoiodite and IOH
2
−.
Electrochemical behavior of zinc and polyaniline (PANI) electrode polymerized from 0.1
M HCl and 0.1
M aniline on graphite electrode, in 0.2
M ZnCl
2 and 0.50
M NH
4Cl (chloride electrolyte) and with ...addition of 0.33
M Na-citrate (chloride/citrate electrolyte) were investigated. In the chloride/citrate comparing with chloride containing electrolyte for the zinc electrode negative shift of the open circuit potential of 150
mV, decreases of exchange current density for more than order of magnitude and increase of cathodic Tafel slope, due to the zinc ions complexation, were observed. In citrate/chloride electrolyte zinc dendrite formation were completely suppressed. PANI electrodes show better discharge characteristic in chloride/citrate electrolyte with determined maximum discharge capacity of 164
mAh
g
−1.
Polyaniline electrode (PANI) was formed electrochemically at graphite electrode. Electrochemical polymerization was performed at constant current density of 2.0
mA
cm
−2 from aqueous solution of 1.0
...mol
dm
−3 HCl with addition of 0.25
mol
dm
−3 aniline monomer. Electrochemical characterization of the PANI electrode in chloride and chloride/citrate electrolyte was performed using cyclic voltammetry and galvanostatic measurement in order to study the influence of citrate ions on charge/discharge capability and cycling efficiency. It was observed that, for anodic potential 0.32
V, higher electrode capacity of PANI electrode in chloride/citrate electrolyte was obtained, comparing to chloride electrolyte, indicating positive effect of citrate ions on cycling characteristics. On the other hand, for higher anodic potential limit of 0.50
V, faster decrease of the electrode capacity in chloride/citrate electrolyte was observed. It was suggested that influence of both chloride and citrate anions had exhibited influence on electrochemical behavior of PANI electrode in citrate containing electrolyte.
Electrochemical properties of RuO2-based electrode, particularly the oxygen evolution and anodic dissolution of RuO2 have been investigated in 0.5 mol dm-3 H2SO4 solution by means of polarization ...measurements and product analysis. It has been demonstrated that it is possible to determine very low concentration of dissolved ruthenium species (8 x 10-10 mol dm-3 Ru) by a sensitive spectrophotometric method based on the ruthenium-catalyzed ceric-arsenite reaction.
Electrochemical behavior of zinc and thin polyaniline (PANI) polymerized from 0.1
M HCl to 0.1
M aniline on graphite electrode, in 0.2
M ZnCl
2 and 0.50
M NH
4Cl (chloride electrolyte) and with ...addition of 0.33
M Na-citrate (chloride/citrate electrolyte) were investigated. In the chloride/citrate comparing with chloride containing electrolyte zinc electrode shows negative shift of the open circuit potential of ∼130
mV, decreases of exchange current density for more than order of magnitude and increase of cathodic Tafel slope, due to the zinc ions complexation. In citrate/chloride electrolyte zinc dendrite formation were suppressed. In the range of investigated charge/discharge current densities of 0.25–1
mA
cm
−2, initially obtained specific capacity was in the range of 140–85
mAh
g
−1, respectively. In cycling regime specific capacity and columbic efficiency were affected with anodic potential limits. For anodic potential limits of 0.32
V (SCE) citrate/chloride electrolyte shows better characteristic than chloride electrolyte, due to the influence of citrate ions on negative shift of doping reaction. Increasing anodic potential limit to 0.5
V (SCE), leads to faster decrease of specific capacity in citrate/chloride than in chloride electrolyte, which was. explained by higher hydrophilic effect of citrate anions.
Electrochemical behavior of zinc and thin polyaniline (PANI) electrodes in citrate/chloride-contained electrolyte has been investigated by the means of electrolyte composition optimization. ...Electrolyte contained 0.8 M sodium citrate, 0.3 M ammonium chloride, and ~0.3 M zinc chloride has been found to be an optimum electrolyte for the further applications in the real zinc–polyaniline citrate/chloride-based secondary cell.
Electrochemical properties of RuO
2-based electrode, particularly the oxygen evolution and anodic dissolution of RuO
2 have been investigated in 0.5 mol
dm
−3 H
2SO
4 solution by means of ...polarization measurements and product analysis. It has been demonstrated that it is possible to determine very low concentration of dissolved ruthenium species (8
×
10
−10 mol
dm
−3 Ru) by a sensitive spectrophotometric method based on the ruthenium-catalyzed ceric-arsenite reaction.
Finally, the probable mechanism of anodic dissolution of RuO
2-based electrode, has been proposed.
The conductivity and the state of the surface of supports are of vital importance for metallization via electrodeposition. In this study, we show that the metallization of a carbon fiber-reinforced ...polymer (CFRP) can be carried out directly if the intermediate graphene oxide (GO) layer is chemically reduced on the CFRP surface. Notably, this approach utilizing only the chemically reduced GO as a conductive support allows us to obtain insights into the interaction of rGO and the electrodeposited metal. Our study reveals that under the same contact current experimental conditions, the electrodeposition of Cu and Ni on rGO follows significantly different deposition modes, resulting in the formation of three-dimensional (3D) and free-standing metallic foils, respectively. Considering that Ni adsorption energy is larger than Ni cohesive energy, it is expected that the adhesion of Ni on rGO@CFRP is enhanced compared to Cu. In contrast, the adhesion of deposited Ni is reduced, suggesting diffusion of H+ between rGO and CFRP, which promotes the hydrogen evolution reaction (HER) and results in the formation of free-standing Ni foils. We ascribe this phenomenon to the unique properties of rGO and the nature of Cu and Ni deposition from electrolytic baths. In the latter, the high adsorption energy of Ni on defective rGO along with HER is the key factor for the formation of the porous layer and free-standing foils.
•The corrosion behavior of stainless steel 316Ti in 12–15 NaOCl is investigated.•SS 316Ti is used as a transport tank for NaOCl.•Corrosion product based on metal oxides decompose NaOCl to oxygen.•The ...main process is metastable pitting corrosion provoked by increased concentrations of the oxygen.
The corrosion of the transport tank materials made of stainless steel 316Ti is investigated in a solution containing 12–15% of the commercial sodium hypochlorite solution. Using the electrochemical techniques, weight loss measurements, and optical microscope, it is shown that corrosion occurs due to the metastable pitting. It is proposed that formed metal oxides corrosion product could catalyzed chemical decomposition of hypochlorite solution to oxygen, which provokes the positive shift of the corrosion potentials into the region of metastable pitting.
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