查看更多>>摘要：Electrochemical reduction of imides i.e., N-phenyl phthalimide and substituted N-phenyl phthalimide (3-methyl and 3-chloro) has been studied on glassy carbon electrode under different pH condition using cyclic voltammetric technique. The kinetic parameters like cathodic peak potential E_(pc), cathodic peak current (i_(pc)), diffusion coefficient (D_o) and heterogeneous rate constant (ko) have been evaluated. Single irreversible/quasireversible reduction/oxidation waves were observed under different pH conditions due to the reduction/oxidation of >C=O moiety. The effect of sweep rate, concentration of the electroactive species were evaluated. The electrode process was shown to be diffusion controlled and irreversible involving adsorption effects. Cationic surfactant cetyltrimethyl ammonium bromide inhibited the reduction process. Effect of cationic surfactant on E_(pc), i_(pc), D_o and k_0 has been discussed. The effect of dielectric constant is studied in dimethyl sulphoxide, dimethyl formamide, acetonitrile. The electrolytic products were characterized/identified by controlled potential electrolysis.
查看更多>>摘要：The inhibition effect of benzoic hydrazide on the corrosion of mild steel in acid medium has been studied by mass loss and polarization techniques between 303K and 333K. The inhibition efficiency increased with concentration of inhibitor and temperature. At 333K the inhibition efficiency decreased. The corrosion rate increased with temperature and decreased with increase in concentration of inhibitor. The adsorption of this compound has been found to obey Temkin's adsorption isotherm. Potentiostatic polarization revealed that benzoic hydrazide is a mixed type inhibitor. The values of activation energy (E_a) and free energy of adsorption (triangle open G_(ads)) were also calculated.
查看更多>>摘要：This paper gives an outlook of how microbiologically influenced corrosion (MIC) led to the corrosion of stainless steel pipelines (which are generally considered corrosion resistant) used widely in many chemical process industries and power plants. The paper highlights the causes and effects of MIC through a case study. The paper also discusses some corrective measures that can be applied.
查看更多>>摘要：Electrodeposition of zinc on steel was obtained from chloride bath containing condensation product of a polymer Chitosan and Vanillin. The effect of bath constituents, pH, current density and temperature on deposit nature was studied by Hull cell experiments. The bath composition and operating parameters were optimized. The metallurgical properties and corrosion resistance of deposits were discussed. Throwing power and current efficiency values under different plating conditions were measured. SEM photomicrographs of the deposit were used for the study of surface morphology. The inclusion of addition agent in the deposit was inferred from the IR spectrum of the scraped deposit.
查看更多>>摘要：The inhibitive effect of glycine on the corrosion of aluminium in 1IN HCl and 1N H_2SO_4 were studied at 303K, 348K and 358K by weight loss method. The weight loss data were confirmed by potentiostatic polarization method. The inhibition efficiency of glycine increased with increase in concentration of inhibitor (0.1 percent to 1.0 percent) and decreased with rise in temperature from 303K to 358K. The adsorption of this compound on the aluminium surface from the acid has been found to obey Temkin's adsorption isotherm. The potentiostatic polarization results revealed that glycine is a mixed type inhibitor. The values of activation energy (Ea) indicated physical adsorption of this compound on the metal surface.
查看更多>>摘要：Electrocatalytic activity of the Pt microparticles dispersed into polyfuran (PFu) films on platinum (Pt), glassy carbon (GC) and graphite (Gr) electrodes towards methanol oxidation in acid medium has been investigated using cyclic voltammetry, potentiodynamic polarization and impedance spectroscopic techniques. The results show that PFu films obtained on these electrodes serve as good host matrices for the dispersion of Pt microparticles and exhibit good catalytic activity towards the electrooxidation of methanol. The maximum electrocatalytic activity was observed on Pt modified PFu films on Pt substrates followed by those obtained on GC and Gr substrates respectively.
查看更多>>摘要：Paper making is experiencing significant changes because of several reasons. Important one among them being the pollution control measures. One option is to cook the wood chips, so as to delignify selectively, by cooking them in liquor of higher sulfidity. This liquor, therefore, has higher concentration of sulfur compound e.g. S~(2-), S_2O_3~(2-), SO_3~(2-), SO_4~(2-) and S_x~(2-) etc. because of the process conditions in different stages of paper making. It seems the corrosion in digesters depends very strongly on the relative amount of the different sulfur species in cooking liquor, which is likely to differ from one mill to another. To tackle the problem of corrosion in digesters, therefore, it was planned to understand the basics of the reactions and their dependence on liquors' composition. This is to be followed by comparing the performance of steels and stainless steels currently being used and likely to be used in fabrication of future digesters. All these aspects are discussed in this paper.
Hassan Ali ZamaniMohammad Reza GanjaliParviz Norouzi
7页
查看更多>>摘要：A novel Dy(III) ion-selective PVC membrane sensor has been introduced, based on 6-Hydrazino-3-methyl-1,5-diphenyl-4H-pyrazolo[3,4-d]pyrimidine-4-imine (HMDPPI), as an excellent sensing material. The electrode performance includes a Nernstian slope of 19.5 + - 0.4 mV per decade across a wide concentration range between 1.0 X 10~(-1) and 1.0 X 10~(-6) M and a detection limit of 6.4 X 10~(-7) M. The sensor possesses the advantages of short conditioning time, fast response time (<10 s) and, especially, great selectivity towards transition and heavy metal and some mono, di and trivalent cations. The recommended electrode was effectively used as an indicator electrode in the potentiometric titration of Dy(III) ions with EDTA. The membrane sensor was also applied to the F" ions determination in some mouth washing solutions and to the Dy~(3+) determination in binary mixtures.
查看更多>>摘要：The electrochemical oxidation of catechol has been studied in the presence of azide ion (N3~-) as nucleophile in aqueous solution with various pU values using cyclic voltammetry and differential pulse voltammetry. Cyclic voitammetry of catechol in the buffered solution (pH < = 9.0) shows one anodic and corresponding cathodic peak which corresponds to the transformation of catechol to, corresponding o-benzoquinone and vice versa within a quasi-reversible two electron transfer process. Although cyclic voltammogram of catechol in the presence of azide ion shows one larger anodic peak compared in the absence of azide, but, the corresponding cathodic peak disappears and a new cathodic peak appears at the more negative potential. Also, in the subsequent scans of potential, two new anodic peaks and corresponding cathodic peaks appear. On the basis of these observations, we propose an ECECE mechanism for the electrochemical oxidation of catechol in the presence of azide ion.
查看更多>>摘要：Ferrocement is a type of thin walled reinforced concrete commonly constructed of cement mortar reinforced with closely spaced layers of continuous and relatively small size wire mesh. Durability of a structure is its resistance to weathering action, chemical attack, cracking or any other process of destruction. The durability of ferrocement depends on the quality of ferrocement, mesh type, depth of cover over the mesh and its resistance to corrosion. Ferrocement structures are made more durable by controlling the factors such as mortar composition, permeability, corrosion of reinforcement, attack of chemicals etc. Earlier workers have recommended galvanizing or use of an inhibitor admixture to prevent the mild steel network in ferrocement. This paper discusses the durability of polymer-modified ferrocement and flyash modified ferrocement with conventional ferrocement. In this work, polymer ferrocement was prepared with various polymer-cement ratios and flyash modified ferrocement were prepared with various replacement levels of cement. In order to find out the permeability of cement mortar, 12 numbers of cylinders of height 120mm and diameter 105mm were cast. The permeability of the cement mortar was determined experimentally with the help of 6 cell permeability apparatus. To study the corrosion performance of mesh reinforcement, 36 beams of size 300mm long, 50mm width and thickness 25mm were cast by varying the number of layers of mesh. In order to accelerate corrosion, impressed current voltage test was conducted and the corrosion process was monitored continuously. The corrosion performance in conventional ferrocement is compared with that of polymer ferrocement and flyash modified ferrocement.
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