Investigating the Acid Failure of Aluminium Alloy in 2 M Hydrochloric Acid Using Vernonia amygdalina

The acid failure of aluminium alloy in 2 M hydrochloric acid solution in the presence of Vernonia amygdalina extract was investigated using gasometric technique. Aluminium alloy coupons of dimension 4 cm by 1 cm were immersed in test solutions of free acid and also those containing extract volumes of 2, 3, 4 and 5 cm3 at ambient temperature for 30 minutes. The volumes of hydrogen gas evolved as a result of the rate of reaction were recorded and analyzed. Analysis revealed that maximum inhibitor efficiency which corresponds to the lowest corrosion rate was obtained at optimum inhibitor volumes of 5 cm3, with reduction in the corrosion rate observed to follow in order of increasing extract volumes. Adsorption study revealed that Temkin isotherm best described the metal surface interaction with the extract phytochemicals, with 12 minutes becoming the best exposure time for the phytochemicals to adsorb to the metal surface at all volumes. Statistical modelling of the corrosion rate yielded an important relationship suitable for estimating corrosion rate values once volumes of the extract is known. Microstructural studies, showed an indirect relationship between crack growth rates and extract volumes, while consistency of the irregular intermetallic phases increases with increasing extract volumes

Aniline effect on concrete steel rebar degradation in saline and sulfate media

Electrochemical potential monitoring experiments were performed on mild steel rebars embedded in concrete admixed with aniline inhibitor and fixed amount of sodium chloride salt partially immersed in sulfuric acid and sodium chloride solution. The open circuit potential corrosion monitoring technique was employed and potential readings were taken in accordance with ASTM C 876. Repressive attribute and consistency of the inhibitor was then estimated by the Weibull probability density distribution as an extreme value statistical modeling approach to study performance effectiveness and predict the most efficient inhibitor concentration in each media. Aniline effect on the compressive strengths of the reinforced concrete samples was also investigated and reported. Varying concentrations of the inhibitor were used and its performance improved as concentration changed in NaCl medium, while no particular order of performance was noted in sulfuric medium. In the statistically analyzed experimental results for each of the inhibitor concentrations employed, 0.34 and 0.41 M aniline admixed samples are identified as exhibiting the best inhibiting quality in sodium chloride while 0.14 M aniline was predicted as showing the lowest probability of corrosion risk in sulfuric acid medium. The overall effective inhibitive performance in sulfuric acid was less when compared to the sodium chloride medium. Concrete sample admixed with 0.41 M aniline had the highest improvement in compressive strength in both media

Investigating Concrete Steel Rebar Degradation Using Some Selected Inhibitors in Marine and Microbial Media

Potential monitoring investigations were conducted on concrete steel rebar samples premixed with selected inhibitors accompanied by fixed amount of sodium chloride salt and partially immersed in sulphuric acid and sodium chloride solution. Varying concentration of potassium dichromate, potassium chromate and sodium nitrite inhibitors were used individually and synergistically in this study. The potential readings were taken in accordance with ASTM C 876 through the open circuit potential corrosion monitoring technique. Suppressive quality and dependability of the inhibitor was then assessed by the Weibull probability density distribution as an extreme value statistical modeling approach to study performance effectiveness and forecast the most effective inhibitor concentration in each media. Inhibitor effect on the compressive strengths of the reinforced concrete samples was also examined and reported. Results showed that 0.15M potassium chromate inhibitor had the best overall and individual performance in its inhibiting ability in the H2SO4 medium, while 0.68M sodium nitrite admixture was predicted as showing the lowest probability of corrosion risk in NaCl medium. Also, the best synergistic performance was shown by sample admixed with 0.06M K2Cr2O7, 0.15M K2CrO4 and 0.27M NaNO2 partially immersed in the NaCl medium. The compressive strength of concrete sample admixed with 0.03M K2Cr2O7 and 0.10M K2CrO4 was the highest amongst samples admixed with inhibitor in both media, though the control sample partially immersed in the NaCl medium had the highest overall compressive strength value

Acid Failure of Mild Steel in 2 M Sulphuric Acid in the Presence of Vernonia amygdalina

The degradation of mild steel in 2 M sulphuric acid solution in the presence of Vernonia amygdalina extract was investigated using gasometric technique. Mild steel coupons of dimension 4 cm by 1.5 cm were immersed in test solutions of uninhibited acid and also those containing extract concentrations of 60,100 and 140 cm3 at a temperature of 333K for 60 minutes. The volumes of hydrogen gas evolved from the reaction were recorded and examined. The results showed that while extract concentration was increasing, H2 evolution and % I.E increased, with a reduction in corrosion rate. The reduction in corrosion rate was observed to follow in order of increasing extract concentration. Also, phytoconstituent-metal interaction mechanism was best explained by Freundlich isotherm, with the 4 minutes curve becoming the best contact time for the extract phytochemicals to properly adsorb to metal surface across all concentrations used. Furthermore, an expression suitable for estimating corrosion rate values once concentration is known was also obtained. The microstructural studies however, revealed that increasing the extract concentration led to considerable reduction in the dominant coarsening of the oxide of iron phase, while the pearlite and ferrite phases were highly dispersed

Aniline effect on concrete steel rebar degradation in saline and sulfate media

Electrochemical potential monitoring experiments were performed on mild steel rebars embedded in concrete admixed with aniline inhibitor and fixed amount of sodium chloride salt partially immersed in sulfuric acid and sodium chloride solution. The open circuit potential corrosion monitoring technique was employed and the potential readings were taken in accordance with ASTM C 876. Repressive attribute and consistency of the inhibitor was then estimated by the Weibull probability density distribution as an extreme value statistical modeling approach to study performance effectiveness and to predict the most efficient inhibitor concentration in each media. Aniline effect on the compressive strengths of the reinforced concrete samples was also investigated and reported. Varying concentrations of the inhibitor were used and its performance improved as concentration changed in NaCl medium, while no particular order of performance was noted in sulfuric medium. In the statistically analyzed experimental results for each of the inhibitor concentrations employed, 0.34 and 0.41 M aniline admixed samples were identified as exhibiting the best inhibiting quality in sodium chloride while 0.14 M aniline was predicted as showing the lowest probability of corrosion risk in sulfuric acid medium. The overall effective inhibitive performance in sulfuric acid was less when compared to the sodium chloride medium. Concrete sample admixed with 0.41 M aniline had the highest improvement in compressive strength in both media

Rauvolfia vormitoria Effect on the Degradation of Aluminium Alloy in 2.5 M Hydrochloric Acid Solution

The deterioration of aluminium alloy in 2.5 M hydrochloric acid in the presence Rauvolfia vormitoria extract was examined using both gasometric and gravimetric techniques. Aluminium coupons measuring 4 cm by 1 cm were introduced into test solutions of uninhibited acid and also those containing extract quantities of 10, 20, 30 and 40 cm3 at ambient temperature of 250C for a total cumulative period of 117 minutes. The volumes of hydrogen gas evolved and weight loss readings were recorded and analyzed to obtain weight loss and corrosion rate for each coupon at specific time intervals. The results however, showed that while extract quantity was increasing; weight loss measurements increased but inhibitor efficiency decreased. Also, the metal surface-phytoconstituent interaction mechanism was consistent with the Temkin adsorption isotherm and the 3 minutes curve showed the best exposure time for phytochemicals to adsorb to alloy surface. Furthermore, microstructural studies showed an indirect relationship between metallic degradation and extract quantity, while uniformity of the irregular intermetallic phases increased with increasing extract quantity

Environment Induced Failure of Mild Steel in 2 M Sulphuric Acid Using Chromolaena odorata

Failure investigation of mild steel sample in 2 M sulphuric acid solution in the presence of Chromolaena odorata extract was conducted using the gasometric method. Mild steel coupons, each measuring 4 cm by 1.5 cm were completely immersed in test solutions of free acid and also those containing extract quantities of 60, 100 and 140 cm3 at a temperature of 333K for 60 minutes. The volumes of hydrogen gas evolved from the experiment were recorded and analyzed. The result showed that maximum inhibitor efficiency which has a relationship with lowest corrosion rate was obtained at the highest inhibitor concentration of 140 cm3, with reduction in the corrosion rate observed to follow in order of increasing extract volume. Temkin isotherm best described the metal surface interaction adsorption mechanism. Once concentration of the acid is known, an expression for estimating corrosion rate values in the presence of the extract was obtained. Also, the photomicrograph study showed a direct relationship between the extract quantity and the extent of corrosion. Sample immersed in the 140 cm3 extract quantity showed no trace of the third phase but rather the presence of a finely distributed pearlite phase indicating that increased inhibitor concentration led to a reduction in the deterioration of the metal

Inhibition effect of potassium dichromate on the corrosion protection of mild steel reinforcement in concrete

The inhibition of potassium dichromate on the corrosion protection of mild steel embedded in concrete and partially immersed in sulphuric acid and sodium chloride environments was evaluated at ambient temperatures. The experiments were performed using electrochemical potential monitoring method. Varying quantities of the inhibitor was used. In the NaCl test medium, the effectiveness of the inhibitor improved as higher concentration was used. The best inhibition was achieved in the reinforced concrete sample admixed with 9 g potassium dichromate. Steel-reinforced concrete sample admixed with 3 and 9 g potassium dichromate inhibitor had the highest improvement in compressive strength. The potassium dichromate inhibitor was most effective amongst other inhibitor concentrations used when 7.5 g was admixed with the sample in the H2SO4 medium. The sulphuric acid medium had a deleterious effect on the strength of concrete test specimens

Embryogenesis of Heterobranchus longifilis (Curvier and Valenciennes, 1840)

Studies on development of H. longifilis (Curvier and Valenciennes, 1840) were conducted at a temperature of 25EC ( 1Ec) in aquaria tanks continuous development were monitored with the use of wild Heerbrugy photomacroscope and length of yolk and larva were monitored using Stereo Olympus microscope with ocular micrometer. The division into animal and vegetal poles was observed 22 minutes after activation. The first cleavage occurred 65 minutes after activation while the second division which was perpendicular to the first line of division occurred 74 minutes after activation. This was quickly followed by the third and fourth cleavage at 80th and 82nd minutes after activation respectively. Morular stage was reached at 4 hours 20 minutes with formation of optic bud at 14 hours 35 minutes. (DBO) Developing embryo hatched after 27 hours of activation at a mean length of 6.63 and mean yolk length of 2.17. Yolk size decrease at an average rate of 38.5 % till the 5th day of total absorption. Growth of larvae proceeded faster in tail-anus region than in anus-snout portion of the body. The rate of yolk absorption and larva development (survival) as monitored in this work gives important information in Research and development programme for H. longifilis larva - an important aspect of Research development and implementation of appropriate technologies in small scale fisherie