Evaluation of the protective effectiveness of aqueous plant extracts in the composition of corrosion inhibitor extract

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1 Kryvyi Rih Central City Lyceum

2 Kryvyi Rih State Pedagogical University

Evaluation of the protective effectiveness of aqueous plant extracts in the composition of corrosion inhibitor extract

N.О. Bondarenko1, A.O. Yuchynska1,

T.V. Selivanova2, P.P. Nechipurenko2

Abstract

An urgent scientific and technical task is the study of corrosion processes and finding cheap and effective methods of protection. As a result of corrosion destruction, about 10% of annual metal production is lost. Therefore, considerable attention is paid to anti-corrosion measures. Rust inhibitors are an effective way to remove rust and protect against corrosion. Recently, the so-called “green inhibitors” have aroused increased interest. Many plants are a source of such inhibitors, a complex of compounds -- alkaloids, polysaccharides, proteins, mucous and tannins. All of them, although to varying degrees, have the ability to be adsorbed on a metal surface and fixed on it. We conducted research on the possibility of protecting metals from corrosion with extracts: Tomato edible Lycopersicum, Celandine Chelidonium majus L, Althaea Althaea officinalis L., Yarrow Achillea millefolium.

Key words: green inhibitors, corrosion inhibitors, metal corrosion, plant extracts.

Introduction

Many corrosion inhibitors are now available. All of them, entering into a chemical reaction of the products of thinking on the surface of the metal, which determines the appearance of moisture through the creation of a dense protective film that changes the metal base. The use of all these mixtures, depending on which solution is used, can slow down or stop oxidative processes [1, 3].

A new generation of environmental regulations requires the replacement of toxic chemicals with so-called “green inhibitors”. The choice of inhibitor for a particular application is limited by several factors, including increased environmental awareness and the need to encourage environmentally friendly processes in conjunction with the specific actions of most acid inhibitors, which often require the combined action of compounds to achieve effective corrosion inhibition.

For this reason, in recent years, great efforts have been made in this area to develop new environmentally friendly inhibitors [2-6].

From the point of view of environmental friendliness, promising components of protective materials can be products of plant origin, one of the main advantages of which is relative cheapness and fast renewability. In the last two decades, research has been carried out to find and obtain the so-called “green” inhibitors: cheaper, readily available and reducing the risk of environmental impact [7]. Sources of such substances can be non-toxic and renewable plant waste. Sources describe extracts of a number of plants that exhibit inhibitory properties to various metals, but the mechanism of their action is practically not studied [8-10]. An extract is a solution consisting of active substances from the whole plant or its parts (roots, leaves, flowers, fruits) and a liquid part that acts as a solvent. The concentration of the extract depends on the solvent and its polarity, the method of extraction. The solvent is most often water or ethyl alcohol. Various substances have been used since ancient times to prevent corrosion processes. In the Middle Ages, gunsmiths, removing scale from steel, added starch and brewer's yeast to acid solutions. In the 1900s and 1930s, patented inhibitors were starch, dextrin, gelatin, casein, cake, molasses, carbohydrates, and extracts of wood and coal resins. There are now many developments to protect various alloys with aqueous or alcoholic plant extracts. In table 1. presents some plant extracts as inhibitors that have been studied over the past 10 years. These extracts have been proposed to protect certain metals and alloys.

Table 1. Extracts of plant origin which are created to protect metals

Reagents and equipment

During the research the following utensils and equipment were used: volumetric flasks, beakers, spatulas, filter paper, petri dishes, laboratory electronic analytical scales VLA-200 (d = 0.001 g), drying cabinet, multifunctional device EZODO.

The following reagents were used in the course of work: natural sea salt, sea salt solution with a concentration of 16%oof distilled water, aqueous solution of 2 mol /1 hydrochloric acid. All solutions were prepared on distilled water. For the study, we also used extracts in two different solvents. The solvents were water and ethyl alcohol. Extracts were also prepared in two ways: from fresh raw materials and from dry raw materials. The extraction was performed directly. First, the plants were weighed and crushed. Then poured the solvent and defended for 5 days in a dark place, periodically stirring the contents.

Experiment techniques

The following research methods and calculations were used during the research. Method of obtaining pickling solutions (Holgin method): plant raw materials (leaves and stems) of wild or domestic plants were crushed with a knife and filled with a weak, concentration of not more than 5%, hydrochloric acid solution. Left for extraction for 7 days. 8 samples were made: option A from fresh plants, option B from dry raw materials. When the extract was ready, a pickling solution was prepared to study its effectiveness. The protective effect of inhibitors, ie their ability to inhibit the corrosion rate, is evaluated by the inhibition coefficient (g) and the degree of protection (Z). The density of the inhibitor solution was taken equal to the solvent. Corrosion losses were evaluated by the gravimetric method on the weight loss of the sample during corrosion. The values of the protective effect of the coating were calculated by the formula:

where Km -- corrosion rate, g/ (cm2 * h); m1 -- mass of the sample before the test, g; m2 -- mass of the sample after the test, g; S -- surface area of the sample, cm2; t -- duration of the study, (hour).

The film thickness was estimated gravimetrically, assuming that the layer is evenly distributed:

where h is the film thickness, pm, m is the mass of the sample with the film, g, m0 is the mass of the sample without the film, g, p is the density of the composition, g/cm, S is the area of the sample, cm.

The effectiveness of the protective action of the corrosion inhibitor was evaluated by the degree of protection:

where Km, K'm -- corrosion rate of the metal without inhibitor and with inhibitor, respectively, g/ (cm2 * hour).

The presence of the effect of “aftereffect” was checked after treatment of steel samples with a disinfectant solution of 1 mol /1 hydrochloric acid with the addition of test inhibitors at the optimal concentration of 0.5 g/l for some time. Untreated control plates were immersed in a corrosive working medium without inhibitor, kept. After exposure, the plates were washed with water, weighed and calculated the degree of corrosion protection. The anti-corrosion effect provides the presence of a film on the metal surface formed by adsorption of the inhibitor.For the experiment, samples were taken from steel (composition, wt.% Fe -- 98; C -- 0.17-0.24; Si -- 0.17-0.37; As -- 0.08). Plates in the size of 50 mm*100 mm, 1 mm thick. To assess the protective effectiveness of the solutions, steel samples were polished, degreased with ethyl alcohol, weighed. The film was applied by immersing the samples in the test pickling solution at room temperature for 1 minute, followed by drying in an upright position for 10 minutes in an oven. Corrosion losses were evaluated by gravimetric method on the loss of mass of the sample during corrosion. We studied the effectiveness of the inhibitory effect of aqueous extracts of plants: edible tomato, yarrow, celandine.

Studies on corrosion resistance were performed at a temperature in the range of 19-23° C. Weight loss and hydrogen evolution are most often used to assess corrosion inhibition and the effectiveness of experimental “green inhibitors”. The values of the protective effect of the coating were calculated by the formula:

Results and its discussion

Having received the results and analyzing them, we can say that the proposed extracts are quite good at protecting the metal from aggressive environments. The effectiveness of the protective action of the proposed inhibitors shown in tables 2-4.

Table 2. The magnitude of the protective effect of the coating in an acidic environment

References

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Анотація

Оцінка захисної ефективності водних рослинних екстрактів у складі екстракту-інгібітора корозії

Н.О. Бондаренко1, А.О. Ючинська1 Т.В. Селіванова2, П.П. Нечипуренко2

¹Криворізький Центрально-Міський ліцей КМР, м. Кривий Ріг, Україна

²Криворізький державний педагогічний університет, м. Кривий Ріг, Україна

Актуальним науково-технічним завданням є вивчення корозійних процесі i пошук дешевих та ефективних методів захисту. Унаслідок корозійного руйнування втрачається близько 10% річного виробництва металу. Тому антикорозійним заходам приділяється значна увага. інгібітори іржі є ефективним способом її видалення та захисту від корозії. Останнім часом підвищений інтерес викликають так звані «зелені інгібітори». Багато рослин є джерелом таких інгібіторів, комплексу сполук алкалоїдів, полісахаридів, білків, слизових і дубильних речовин. Усі вони, хоча і в різному ступені, здатні адсорбуватися на металевій поверхні та закріплюватися на ній. Проведені дослідження демонструють можливості захисту металів від корозії за допомогою екстрактів рослин: томата їстівного Solanum lycopersicum, чистотілу Chelidonium majus L., Althaea officinalis L., деревію Achillea millefolium L.

Ключові слова: зелені інгібітори, інгібітори корозії, корозія металів, рослинні екстракти.

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