The corrosion inhibition by 5-(Phenyl)-4H-1,2,4-triazole-3-thiol (PTT) on mild steel in 0.5M H2SO4 solution has been investigated by weight loss, electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization techniques at various concentrations and temperatures. The results obtained revealed that this compound performed excellently as corrosion inhibitor for mild steel in 0.5M H2SO4 solution. It was found that the inhibition efficiency increased with inhibitor concentration reached a maximum of 91.6 % at 0.5 mM. The addition of potassium iodide to PTT in solution increased the inhibition efficiency of this latter. A synergistic effect was observed between KI and inhibitor with optimum of concentration of 0.5 mM/PTT + 0.2% potassium iodide. Potentiodynamic polarization studies have shown that PTT inhibitor acts as a mixed-type inhibitor retarding the anodic and cathodic corrosion reactions with predominant effect on the cathodic reaction. Adsorption of inhibitor alone or in combination with potassium iodide on the metal surface obeyed the Langmuir adsorption isotherm. The effect of temperature on the inhibition efficiency was also determinated, some thermodynamic parameters such as apparent activation energy and adsorption free energy have been calculated and discussed. Results obtained with different methods are in good agreement. Scanning electron microscopy (SEM) study confirmed that the inhibition of corrosion of mild steel is through adsorption of the extract molecules on surface of metal. Quantum chemical parameters were also calculated to characterize adsorption mechanism. Acceptable correlations were obtained between experimental (inhibition efficiencies, ΔGads, Ea) and quantum calculation parameters (dipole moment, EHOMO, ELUMO). The high inhibition efficiency was declined in terms of strongly adsorption of protonated inhibitor molecules on the metal surface and forming a protective film. Originality/value–Electrochemical techniques have been used for the first time to study synergistic effect of PTT inhibitor and potassium iodide on inhibition of corrosion of mild steel in 0.5M H2SO4 solution. The results suggest that the mixture (PTT + KI) could find practical application in corrosion control in aqueous acidic environment. The effect of molecular structure on the inhibition efficiency has been investigated by quantum chemical calculations. The electronic properties of inhibitor were calculated and are discussed. The theoretical results were found to be consistent with the experimental data reported.
The aim of the present work was to search a convenient, simple and inexpensive method to determine the metals in electroplating hydroxide sludges. The analytical methods are characterized by sensitivity, selectivity and accuracy but for economic reasons and of course the availability of equipments and products, the UV-visible spectrophotometry was used. We have undertaken the study of the influence of different cations present in the same solution on the determination of metal. After conducting several tests on solutions prepared in the laboratory and then on the solutions used to dissolve different samples of industrial waste, the result revealed that it is possible to use spectrophotometric method to assess the amount of metals in electroplating sludges, provided that we followed a well-defined scheme so as to avoid all the possible interference.
The aim of the present work was the recovery of nickel and copper from metal finishing hydroxide sludge by kinetic acid leaching. The study was divided into two main parts: First, a kinetic model of precipitate leaching with the presence of acid was developed and subjected to theoretical approach so as to determine optimal leaching conditions (pH and time). Next, the study was conducted experimentally on pure metals hydroxides and then on electroplating sludges. The leaching operation was performed at atmospheric pressure with constant stirring. pH and solubility versus time at different temperature values and different amounts of sludge were carried out. The resulting filtrate was found to contain more than 99% of nickel and copper.
Ammodaucus belongs to the family Apiaceae (Umbelliferae), subfamily Apioideae, trib Caucalideae, and comprises one species in Algeria (Quezel and Santa, 1962).
The biological importance of members of this genus promoted us to reinvestigate the volatile constituents of the fruits of Ammodaucus leucotricus Coss. et Dur., and to carry out a biological study as far as the antibacterial activity is concerned. The present work deals with the chemical composition and antibacterial activities of the hydrodistilled oils. After extraction, the oil was analyzed by gas chromatography–mass spectrometry to afford 14 components. The major components were found to be, 1-cyclohexene-1-carboxaldehyde (56.40%), d-limonene (28.82%), and 2-pentanone-4-hydroxy-4-methyl (5.73%). Moreover, the antimicrobial activities of the volatile oils were evaluated by disk diffusion method against Gram-positive and Gram-negative bacteria. The results showed a strong antibacterial activity against Staphylococcus aureus, Escherichia coli and Klebsiella pneumonia.
The aim of the present work was the recovery of nickel and copper from metal finishing hydroxide sludges by ammoniacal leaching. Actually the study was split into two main parts. First, the recovery of the metals in the presence of ammonia was subjected to theoretical approaches followed by numerical and computer calculations to determine optimal leaching conditions (pH and total concentration). In this part the solubility diagrams were plotted versus two parameters: pH and [NH3]T. second, the study was carried out experimentally. The work was performed on pure metals hydroxides and then on electroplating sludges. The solubility variation versus pH at various ammonia concentrations and versus ammonia concentration at various pH values was conducted keeping the free ammonia concentration on the diagram to show the stability regions of soluble metal species. Optimal ammonia concentration for leaching [NH3]total at pH58 to 11 was found to be less than 6 mol L21, and a recovery experimental flowsheet was proposed.
In present studies, the synthesis of 2-chloroquinoline-3-carbaldehyde derivatives from acetanilide as starting materials, to prepare macroheterocycles and their reaction with heavy metals to test the selectivity of extracting them from their mixtures in the industrial residues are reported.
The effect of aqueous extracts of Zygophyllum album on the corrosion of X52 mild steel in 1M sulphuric acid was investigated by Weight-loss determinations and electrochemical measurements. Potentiodynamic polarization curves indicated that the plant extracts behave as mixed-type inhibitors. The corrosion rates of steel and the inhibition efficiencies of the extract were calculated. The results show that the extract solution of the plant could serve as an effective inhibitor for the corrosion of steel in sulphuric acid medium. Inhibition was found to increase with increasing concentration of the plant extract up to a critical concentration.
The main aim of this research work is to determine optimal leaching conditions: Eh, pH and total ammonia concentrations, for recovery of copper and nickel from electroplating hydroxide sludges containing iron, chrome, copper and nickel hydroxides. This has been preceded by a theoretical approach and numerical and computer calculation. By maintaining total dissolved metal and total ammonia constant, all equilibriums are taken into consideration simultaneously. The diagrams then show stable domains for the solution and solids. Solubility curves and potential-pH diagrams for the copper-water-ammonia and nickel-water-ammonia systems at different total metal and different total ammonia concentrations have been presented. This analysis has practical value in interpreting the process conditions required to conduct hydrometallurgical process.
The main aim of this research is to determine optimal leaching conditions; Eh, pH and complexing agent concentrations, for recovery of Copper from hydroxide sludges such as those produced by electroplating shops, metal finishers, treatment of acid mine drainage, and industrial wastewater in general. This has been preceded by a theoretical approach and numerical and computer calculation. Potential-pH diagrams for the copper-water-ammonia, copper-watercyanide, copper-water-glycine, copper-water-ethylenediamine (En) and copper-water-ethylenediaminetetracetic acid (EDTA) systems are derived at different total copper and complexing agent concentrations. The originality of our method is the introduction of a rigorous calculating method; we don’t neglect any equilibrium or species for Eh-pH diagrams and with the free concentration of complexing agent (pL-pH) diagram to show the stable regions of soluble copper species.
Calculations and computations are applied to find the optimal conditionts (pH, [NH3], ...) of a selective recovery of metal values from the electroplating sludges.
This study compares a classical and approximate method, based on the superposition of solubility-pH-complex diagrams, and our rigorous approach, The studied example is the selective recovery of Ni++ and Cu++ from their hydroxide sludges by an ammoniacal leaching.
We introduce also a direct relation between the solubility and the total concentration of NH3, [NH3]T