Some phthalazin derivatives as non toxic corrosion inhibitors for copper in sulphuric acid

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.     

Synergistic Influence of Poly(4-Vinylpyridine) and Potassium Iodide on Inhibition of Corrosion of Mild Steel in 1M HCl

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.     

Complete Oxidation of Methane at Low Temperature over Pt Catalysts Supported on High Surface Area SnO2

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.     

Polyaniline as corrosion inhibitor for iron in acid solutions

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     

MA-AM-AA三元共聚物的制备及阻垢性能

以马来酸酐(MA)、丙烯酸(AA)和丙烯酰胺(AM)为原料,研制出环保型三元共聚阻垢剂PMAA,并通过研究其阻垢性能确定了产品的最佳工艺配方。实验结果表明,当单体的质量配比m(AA)∶m(AM)∶m(MA)=2∶3∶0·5,引发剂用量为单体总质量的1.5%,反应温度为80℃,单体质量分数为15%时,得到的聚合物PMAA的用量为5mg/L时,用国标法测得其对碳酸钙的阻垢率达94·15%,对磷酸钙的阻垢率达80·93%。     

Inhibition of oxygen evolution by zaluzanin C

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.     

Corrosion inhibition of triethanolammonium bromide mono- and dibenzoate as cationic inhibitors in an acidic medium

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.     

Influence of oleoresin constituents fromPinus ponderosa andPinus jeffreyi on growth of mycangial fungi fromDendroctonus ponderosae andDendroctonus jeffreyi

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.     

聚天冬氨酸的合成与阻垢缓蚀性能评述

主要介绍了聚天冬氨酸的合成工艺，包括：单体合成、单体聚合以及产物的处理等。同时，对聚天冬氨酸的阻垢与缓蚀性能做了阐述。     

The allelopathic mechanisms of dominance in bracken (Pteridium aquilinum) in Southern California

Bracken,Pteridium aquilinum, exerts a strong dominance over associated plants throughout much of its worldwide range. Associated plants are often severely inhibited or even excluded from dense stands of the fern. This study investigated the various aspects of herb suppression in bracken stands and assessed the contribution of the various forms of interference between plants to the establishment and maintenance of bracken dominance. It was shown that competition for soil moisture, light, and nutrients could not account for the lack of herbs in bracken stands. Further, uniformity of soil pH, texture, water-holding capacity, and organic matter content ruled out variability in physical factors as a cause. Baiting and trapping experiments showed that the higher concentration of animal activity inside the bracken stands contributed significantly to the pattern of herb suppression, but only against select species. The maintenance of this pattern in the animal-free Santa Cruz Island stands indicates the importance of another factor, allelopathy. It was found that phytotoxins leached from the dead, standing bracken fronds with the first few rains of the wet season were largely responsible for herb suppression. These toxins were isolated in raindrip and from soil inside the fern stands. Removal of the fronds from the stand before the rains could leach them resulted in reinvasion by the herbs after several seasons, and, conversely, placing fronds over the herbs in the grassland brought about herb inhibition. A number of known allelopathic chemicals were tentatively identified from bracken leachates. The importance of the interaction of allelopathy with other factors of plant interference is illustrated by bracken.