Inhibition Effect of Extracts of Carica Papaya and Camellia Sinensis Leaves on the Corrosion of Duplex (α β) Brass in 1M Nitric Acid

The effect of C. Papaya (pawpaw) leaves and C. Sinensis (tea) extracts as an organic „green‟ inhibitor on the corrosion of α β (duplex) brass (65-35% Cu-Zn alloy) in 1MHNO3 (nitric acid) was studied at ambient temperature. Weight loss/corrosion rate and potential measurement techniques were used for the experimental work. The tea extract was obtained from the green tea leaves. The results obtained showed effective corrosion inhibition of the extracts on the brass test specimens in the 1M nitric acid used. The different combined extracts concentrations also gave good corrosion inhibition performance. They also exhibited effective corrosion reactions synergism. The test specimen (duplex brass) gave some appreciable corrosion resistance in the test environmen

Corrosion Inhibition of Thiourea and Thiadiazole Derivatives : A Review

The continuous search for better corrosion inhibitors, due to vast differences in the media encountered in industry remains a focal point in corrosion control. The use of organic compounds to inhibit corrosion has assumed great significance due to their application in preventing corrosion under various corrosive environments. These compounds have great potential to inhibit aqueous corrosion due to film formation by adsorption on the metal surface. This paper reviews the inhibitive effect of thiourea and thiadiazole derivatives. This group of organosulphur and heterocyclic compounds and derivatives has important theoretical and practical applications, but their inhibition mechanism is not fully understood, despite extensive study. The effect of these compounds on the corrosion of metallic alloys was evaluated through assessment of various journals and experimental techniques. The corrosion rate was found to be a function of different variables. Due attention was paid to the systematic study of inhibitor action of derivatives with much emphasis on the functional groups of the molecular structure. From the comprehensive discourse presented, it is concluded that the derivatives fulfill the basic requirements for consideration as an efficient corrosion inhibito

Synergistic Effect of Tobacco and Kola Tree Extracts on the Corrosion Inhibition of Mild Steel in Acid Chloride

The corrosion inhibition effect of extracts of kola plant and tobacco in mixed form on the protection of mild steel specimens immersed in acid chloride solution was studied at ambient temperature by gravimetric and potential monitoring methods. The electrode potential monitoring was performed using a digital voltmeter and a saturated calomel electrode (SCE) as the reference electrode. Extracts of kola plant and tobacco in different concentrations and combinations were used as ‘green’ inhibitors. There was significant reduction in the weight loss and in the corrosion rate of the test samples, particularly at the added extracts concentration of 100%. Some very good inhibitor efficiency values were obtained which suggested good corrosion inhibition performance of the added extracts at the concentrations used. Potential measurement values recorded showed in most cases, a reduction in active corrosion reactions for some combinations of the extracts. This behavior was attributed to the protective film provided on the steel’s surface by the complex chemical constituents of the plants extracts. The best corrosion inhibition performance for mild steel was obtained using the combined extracts of kola leaf and tobacco at100% concentration with an inhibitor efficiency of 91.27%. The combination of kola leaf, nut and tobacco at the same concentration was effective at an inhibitor efficiency of 82.78%

Pyrimidine Derivatives as Environmentally-Friendly Corrosion Inhibitors: A Review

The perpetual quest for more efficient and environment friendly corrosion inhibitors remain a focal point in corrosion control. The use of organic compounds to inhibit corrosion has assumed great significance due to their vast applications in counteracting wastage of ferrous alloys. These compounds have shown great effectiveness for inhibiting aqueous corrosion due to film formation by adsorption on the metal surface. This paper reviews the inhibitive effect of pyrimidine derivatives as corrosion inhibitor. This class of heterocyclic aromatic organic compound has very important theoretical and practical applications. Their effect on the corrosion of metallic alloys was evaluated through assessment of various techniques and articles on their use in various investigations. The corrosion rate was found to be a function of different variables. Due attention was paid to the systematic study of inhibitor action of derivatives with much emphasis on the inhibitor type and functional groups of the molecular structure. The comprehensive discourse presented concludes, that the pyrimidine derivatives fulfill the basic requirements for consideration as an efficient corrosion inhibito

Inhibition Effect of Vernonia amygdalina Extract on the Corrosion of Mild Steel Reinforcement in Concrete in 3.5M NaCl Environment

The inhibition effect of Vernonia amygdalina (bitter leaf) extract on the corrosion behaviour of embedded mild steel rebar in concrete has been investigated by electrochemical potential measurement, pH and gravimetric (weight loss) methods. The results were further analysed using the two-factor ANOVA test. The experiments were performed using bitter leaf extract as a green inhibitor in 3.5% sodium chloride solution. Inhibitor extracts concentrations of 25, 50 75, and 100% were prepared from the fresh leaves of Vernonia amygdalina with distilled water. The voltage (potential) measurements were recorded with a digital voltmeter and a copper-copper sulphate electrode as the reference electrode. The pH of the test medium was measured by a pH meter. Compressive strength of each of the block samples was determined after the experiments. Weight loss values were obtained from the weight loss method (gravimetric) and the inhibitor efficiency was computed from the corrosion rate of each of the tested samples. Results showed that varied concentration of Vernonia amygdalina and the test exposure time significantly affect both the corrosion potential of embedded steel rebar in concrete and the pH of the medium. The outcome of the ANOVA test confirmed the results at 95 % confidence, and further showed that concentration of Vernonia amygdalina had greater effect on potential measurements, whereas, exposure time had greater effect on pH measurements. Vernonia amygdalina extract gave good corrosion inhibition performance of the embedded steel rebar in concrete at 25%, 50% and 75% concentrations in NaCl test medium. The highest inhibition efficiency of 90.08 % was achieved at 25% concentration, the lowest inhibitor concentration used

Corrosion Polarization Behaviour of Type 316 Stainless Steel in Strong Acids and Acid Chlorides

The corrosion resistance and/or susceptibility of Type 316 austenitic stainless steel was separately performed at ambient temperature in different concentrations (the intermediate and the concentrated) of sulphuric acid, H2SO4, and phosphoric acid, H3PO4. Similar tests were also performed by the addition of 2% (20g/l) sodium chloride, NaCl, to each of the specified acid concentrations to form their acid chlorides. Potentiostatic polarization method was used for the corrosion investigation. The electrochemical corrosion reactions exhibited both the passive and active corrosion reactions characteristics. The acids at the intermediate concentrations show more obvious active corrosion reactions; while in the concentrated form they were relatively passive – the passivity that was associated with the oxidizing nature of the concentrated acids. The addition of 2% NaCl to each of the test medium concentration gave increased active corrosion reactions that could be due to the test electrodes’ surface protective film rupture by anodic dissolution. In all the tests, however, the magnitude of corrosion could be considered to be lo

ANTIMICROBIAL EFFICACY OF THYMOL IN THE MANAGEMENT OF BACTERIAL WILT OF TOMATO

Bacterial wilt (BW), caused by Ralstonia solanacearum, is a devastating disease of tomato world-wide. The disease is responsible for more than 60% reduction of tomato yield in Nigeria. Volatile plant essential oil, thymol, was evaluated against BW in artificially-inoculated potted plants.  Twenty milliliter of 108 cfu/ml suspension of Ralstonia solanacearum was introduced into 5 kg pot of sterilized soil and 20 ml each of three concentrations of thymol (0.2, 0.4, 0.6 g/L) applied as pre-plant soil drench 2 hours after bacterial inoculation.  Eight tomato genotypes were transplanted into the pots five days after thymol application.    The experiment was laid in a completely randomized design (CRD) with three replicates.  At 0.2 g/L thymol application, disease severity index was 1.50-4.00 at 5 Weeks After Transplanting (WAT).  Disease severity index was reduced significantly (p<0.05) by 77.78% in tomato variety Delila upon 0.4 g/L application of thymol. At 0.6 g/L thymol application, tomato varieties Delila, Perfect Pee and Kerewa each had 0 (zero) disease severity index, while tomato lines NG/AA/MAY/09/030, NG/TB/AUG/09/006 and NG/AA/SEP/09/037 had disease severity index of 1 (one) each.  These results indicated that application of thymol (0.6 g/L concentration, 1:250, thymol:soil, v:w) in potted experiment was effective in reducing the severity index of bacteria wilt of tomato caused by Ralstonia solanacearum, and is therefore recommended for management of the disease

Inhibition Effect of Deanol on Mild Steel Corrosion in Dilute Sulphuric Acid

The influence of deanol on the corrosion behaviour of mild steel in dilute sulphuric acid with sodium chloride addition was studied by means of mass-loss, potentiodynamic polarization, electrode potential monitoring, scanning electron microscopy and statistical analysis.Results show that deanol performedexcellently with amaximuminhibition efficiency of 97.9%obtained from the mass loss technique and 98.23%fromthe potentiodynamic polarization tests at themaximumdeanol concentration evaluated. Polarization studies show that the amino alcohol is a cathodic type inhibitor. Adsorption of deanol on the steel surface was observed to obey the Langmuir and Frumkin adsorption isotherms. Scanning electron microscopy studies confirmed the corrosion protection property of deanol to be through adsorption on the mild steel surface while statistical evaluation showed the overwhelming influence and significance of inhibitor concentration on inhibition efficiency compared with exposure time

Corrosion and plants extracts inhibition of mild steel in HCl

Corrosion and plants extracts inhibitive protection of mild steel specimens immersed in 0.5 M hydrochloric acid was investigated at ambient temperature by gravimetric and metallographic methods. Extracts of kola plant and tobacco in different concentrations were used as ‘green’ inhibitors. This paper reports the results obtained from the weight loss method, calculated corrosion rates, inhibitor efficiencies and the metallographic observations from metallurgical microscopy. Addition of different concentrations of the plants extracts gave considerable reduction in the weight loss and in the corrosion rate of the test samples. This apparent corrosion inhibition was associated with the protective film provided on the steel’s surface by the complex chemical constituents of the plants extracts. Effective protection of the mild steel was achieved more from the tobacco extract and also from the extract of kola leaf

An investigation of carburization resistance performance of ethylene furnace tube alloys

Carburization tests and analysis were performed on some samples of radiant tube alloys of ethylene furnaces at three petrochemical plants. These tubes had undergone carburization in service with some losing their structural integrity. This study evaluates and compares the carburization resistance performances of some of these tubes in service and identifies the cause of their degradation. The polished surfaces of the test samples were visually observed. The depth of carburization zones for each test sample was measured. Scanning electron microscopy and energy dispersive x-ray spectroscopy were used to examine the carburization zones and the rest part of the specimens and to characterize the microstructure and elemental composition of the tubes’ material. Optical microscope (Image analyzer) was used to examine the etched surface of each of the test samples. Microhardness testing was performed to determine their mechanical strength. Visual inspection revealed the sagging in some of the tubes. Metallurgical assessment indicated that the selected furnace tubes showed relative greater depths of carburized zones when compared with other tube materials tested. Microstructure of the tubes showed coarse Cr-carbide precipitation and continuous carbide networks at austenite grain boundarie