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71.
72.
S.A.Abd El-Maksoud 《Electrochimica acta》2004,49(24):4205-4212
Phthalazin derivatives were tested as corrosion inhibitors of copper in 1 M H2SO4 using electrochemical polarization and weight loss techniques. This study monitored the evolution of the inhibitory effect of the phthalazin derivatives, according to their substituents. A significant decrease in the corrosion rate of copper was observed in the presence of the investigated inhibitors. The inhibition efficiency (%I) increases with increasing inhibitor concentration. The potentiodynamic polarization data indicated that, the inhibitors were of mixed type, but the cathodic effect is more pronounced. The slopes of the cathodic and anodic Tafel lines are approximately constant and independent on the inhibitor concentration. The mechanism of inhibition was discussed in the light of the chemical structure of the undertaken inhibitors. The adsorption on the copper surface follows the Langmuir isotherm model. 相似文献
73.
The corrosion and inhibition behavior of mild steel in 1 M HCl in the presence of poly(4-vinylpyridine)(P4VP) and potassium iodide (KI) was investigated using weight loss measurements, potentiodynamic polarization studies and impedance measurements. The inhibition efficiency increased with increasing P4VP concentration. The inhibiting action of P4VP is considerably enhanced by the addition of potassium iodide. The adsorption of this compound either alone or in combination with iodide ions on the metal surface is found to obey Lamgmir's adsorption isotherm. The experimental results suggest that the presence of iodide ions in the solution increases the surface coverage and, therefore, indicate the joint adsorption of P4VP and iodide ions. On the other hand, it was found that the inhibiting effect of P4VP and (P4VP + KI) increased with increasing temperature of the corrosion medium. The presence of these species in the solution decreases the double layer capacitance and increases the charge transfer resistance, both derived from Nyquist plots obtained from a.c. impedance studies. The variation of charge transfer resistance with time suggests that the inhibitive action of (P4VP + KI) depends mainly on the protective inhibitor film formed on the steel surface. 相似文献
74.
The catalytic activity of Pt catalysts supported on high surface area tin(IV) oxide in the complete oxidation of CH4 traces under lean conditions at low temperature was studied in the absence and in the presence of water (10 vol.%) or H2S (100 vol.ppm). Their catalytic properties were compared to those of Pd/Al2O3 and Pt/Al2O3. In the absence of H2S in the feed, Pt/SnO2appears as a very promising catalyst for CH4 oxidation, being even significantly more active under wet conditions than the best reference catalyst, Pd/Al2O3. Catalysts steamed-aged at 873 K were also studied in order to simulate long term ageing in real lean-burn NGV exhaust conditions. To this respect, Pt/SnO2 is slightly less resistant than Pd/Al2O3. In the presence of H2S, Pt/SnO2catalysts are rapidly and almost completely poisoned, comparably to Pd/Al2O3and the catalytic activity is hardly restored upon oxidising treatment below 773 K. A synergetic effect between Pt and specific surface SnO2sites active in CH4oxidation is proposed to explain the superior catalytic behaviour of Pt/SnO2. 相似文献
75.
In recent years, polymer amines have been studied as an efficient corrosion inhibitor for iron in acid media. In this article, the performance of water soluble polyaniline as corrosion inhibitor for iron in 0.5M H2SO4 has been evaluated by potentiodynamic polarization, linear polarization, and electrochemical impedance spectroscopy and compared with the performance of the aniline monomer. It has been found that polyaniline is an efficient inhibitor, since the maximum efficiency of 84% has been observed at a concentration of 100 ppm, whereas the monomer has accelerated the corrosion. FTIR studies have shown that the polyaniline is strongly adsorbed on the iron surface and inhibits the corrosion effectively. However, aniline has been found to improve the passivation tendency of iron at higher concentrations. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 2144–2153, 2006 相似文献
76.
77.
B. Lotina-Hennsen E. Bernal-Morales A. Roo De Vivar A. L. Perez-C A. Castro-R M. Aguilar-Martinez 《Journal of chemical ecology》1992,18(11):1891-1900
The inhibition of ATP synthesis, proton uptake, and electron transport (basal, phosphorylating, and uncoupled) from water to methylviologen by zaluzanin C indicates that it acts as an electron transport inhibitor. Uncoupled photosystem I electron transport rate was not affected by zaluzanin C; however, uncoupled photosystem II electron flow from water to 2,3,5,6-tetramethyl phenylenediamine and from water to silicomolybdate was inhibited, but electron transport from diphenylcarbazide to silicomolybdate was not affected. We conclude that the site of inhibition by zaluzanin C is located at the oxygen evolution level. 相似文献
78.
Nabel?A.?NegmEmail author Salwa?M.?I.?Morsy 《Journal of surfactants and detergents》2005,8(3):283-287
A weight loss technique was used to determine the corrosion inhibition efficiency of synthesized alkyl mono-and dibenzoate
triethanolammonium bromide derivatives (TEAMB, TEADB) in an acidic medium (2 N HCl) at different doses (50, 100, and 200 ppm).
The results showed that monoderivatives had a higher corrosion inhibition efficiency than diderivatives. The results were
correlated with several factors, including the alkyl chain length of the hydrophobic chains, interfacial tension (IT), critical
micelle concentration (CMC), and adsorption free energy of these inhibitors. Increasing the geometric length of the alkyl
chains in the synthesized inhibitors had an increasing effect on their corrosion inhibition efficiency, whereas decreasing
the CMC and IT had an increasing effect on their tendency toward corrosion inhibition. The number of hydrophobic chains attached
to the inhibitor molecules had a vital influence on their efficiency as corrosion inhibitors. 相似文献
79.
Dendroctonus jeffreyi andD. ponderosae are morphologically similar sympatric species of pine bark beetles over portions of their geographic ranges; however,D. jeffreyi is monophagous onP. jeffreyi whileD. ponderosae is highly polyphagous. Both species carry a species of mycangial fungi that are also very similar in appearance. Growth of the two mycangial fungi and of the fungusLeptographium terebrantis (associated with the polyphagous and non-tree-killingDendroctonus valens) in the presence of oleoresin constituents of host and nonhost conifers was tested by placing individual chemicals on agar growth medium and by growing the cultures in saturated atmospheres of the chemicals. The fungus associated withD. jeffreyi showed greater tolerance for chemical constituents placed on the growth medium than the other two fungi, and growth after three days was enhanced by heptane, the dominant constituent ofP. jeffreyi oleoresin. Growth of all three species of fungi was reduced by the resin constituents when the chemicals were presented as saturated atmospheres. The results suggest that the influence of the tree on growth of the symbiotic fungi of the bark beetles during the initial attack process may be different than after colonization by the beetles is complete. The difference in the responses of the apparently related species of mycangial fungi may provide some new insight into the evolutionary history of these beetle/mycangial fungus/host tree systems. 相似文献
80.