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Performances of Alkaloid Extract from Rauvolfia macrophylla Stapf toward Corrosion Inhibition of C38 Steel in Acidic Media.

ABSTRACT: Alkaloid extract from Rauvolfia macrophylla Stapf (AERMS) was studied as the corrosion inhibitor for C38 steel in 1 M HCl and 0.5 M H2SO4 using electrochemistry and surface analysis. The corrosion inhibition was efficient and proceeds via adsorption of AERMS on the steel surface due to the active functional groups present in the molecules. AERMS acts as a mixed inhibitor in HCl and as a cathodic inhibitor in H2SO4. In H2SO4 corrosive medium, the presence of iodides improves the adsorption of the alkaloid molecules by reducing the surface charge of the electrode and thus substantially decreases the corrosion rate. Two pure alkaloids (tetrahydroalastonine (THA) and perakine (PER)) were quantitatively isolated from AERMS, and their anticorrosive properties for C38 steel in 1 M HCl and 0.5 M H2SO4 were evaluated. THA showed the highest efficiency while the performance of PER was less important compared to the extract. This confirms that the efficiency of AERMS was the result of the complementary action of the chemical compounds present in the extract.

SUBMITTER: Ngoune B

PROVIDER: S-EPMC6648148 | biostudies-literature | 2019 May

REPOSITORIES: biostudies-literature

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Performances of Alkaloid Extract from Rauvolfia macrophylla Stapf toward Corrosion Inhibition of C38 Steel in Acidic Media.

Ngouné Bertrand B Pengou Martin M Nouteza Armel Megha AM Nanseu-Njiki Charles Peguy CP Ngameni Emmanuel E

ACS omega 20190523 5

Alkaloid extract from Rauvolfia macrophylla Stapf (AERMS) was studied as the corrosion inhibitor for C38 steel in 1 M HCl and 0.5 M H2SO4 using electrochemistry and surface analysis. The corrosion inhibition was efficient and proceeds via adsorption of AERMS on the steel surface due to the active functional groups present in the molecules. AERMS acts as a mixed inhibitor in HCl and as a cathodic inhibitor in H2SO4. In H2SO4 ...[more]

PMID: 31459996

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Project description:Food contamination due to metal corrosion and the consequent leakage of metals into foods is a problem. Understanding the mechanism(s) of metal corrosion in food media is vital to evaluating, mitigating, and predicting contamination levels. Fruit juices have been employed as model corrosive media to study the corrosion behaviour of metallic material in food media. Carbon steel corrosion in fresh juices of tomato, orange, pineapple, and lemon, as well as dilute hydrochloric acid solutions at varied pH, was studied using scanning electron microscopy, gravimetric and spectrophotometric techniques, and comparisons made between the corrosivity of these juices and mineral acids of comparable pH. The corrosion of carbon steel in fruit juices and HCl solutions manifests as a combination of uniform and pitting corrosion. Gravimetric data acquired after one hour of immersion at ambient temperature (22 °C) indicated corrosion rates of 0.86 mm yr-1 in tomato juice (pH ≈ 4.24), 1.81 mm yr-1 in pineapple juice (pH ≈ 3.94), 1.52 mm yr-1 in orange juice (pH ≈ 3.58), and 2.89 mm yr-1 in lemon juice (pH ≈ 2.22), compared to 2.19 mm yr-1 in 10-2 M HCl (pH ≈ 2.04), 0.38 mm yr-1 in 10-3 M HCl (pH ≈ 2.95), 0.17 mm yr-1 in 10-4 M HCl (pH ≈ 3.95), and 0.04 mm yr-1 in 10-5 M HCl (pH ≈ 4.98). The correlation of gravimetrically acquired corrosion data with post-exposure spectrophotometric analysis of fruit juices enabled de-convolution of iron contamination rates from carbon steel corrosion rates in fruit juices. Elemental iron contamination after 50 h of exposure to steel samples was much less than the values predicted from corrosion data (≈40%, 4.02%, 8.37%, and 9.55% for tomato, pineapple, orange, and lemon juices, respectively, relative to expected values from corrosion (weight loss) data). Tomato juice (pH ≈ 4.24) was the least corrosive to carbon steel compared to orange juice (pH ≈ 3.58) and pineapple juice (pH ≈ 3.94). The results confirm that though the fruit juices are acidic, they are generally much less corrosive to carbon steel compared to hydrochloric acid solutions of comparable pH. Differences in the corrosion behaviour of carbon steel in the juices and in the different mineral acid solutions are attributed to differences in the compositions and pH of the test media, the nature of the corrosion products formed, and their dissolution kinetics in the respective media. The observation of corrosion products (iron oxide/hydroxide) in some of the fruit juices (tomato, pineapple, and lemon juices) in the form of apparently hollow microspheres indicates the feasibility of using fruit juices and related wastes as "green solutions" for the room-temperature and hydrothermal synthesis of metal oxide/hydroxide particles.

Dataset Information

Performances of Alkaloid Extract from Rauvolfia macrophylla Stapf toward Corrosion Inhibition of C38 Steel in Acidic Media.

Publications

Performances of Alkaloid Extract from <i>Rauvolfia macrophylla</i> Stapf toward Corrosion Inhibition of C38 Steel in Acidic Media.

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