Corrosion is a natural process that was done by some metallic materials and energy considerations. It can be viewed as a universal phenomenon, omnipresent and omnipotent and also It has been categorized into different methods like; Low and high-temperature corrosion, Electrochemical and chemical, and also Wet and Dry corrosion. Some materials inhibit a preventive measure against corrosive attacks that they called Corrosion inhibitors. These materials have been frequently studied and used as a simple extract for the protection of elements against corrosion in an aqueous environment. Inhibitors are employed in industrial and commercial plans to minimize both metal loss and acid using .
There are growing concerns about the use of corrosion inhibitors because some of these inhibitors are not only toxic to living organisms but also cause environmental damage although some may be helpful and non-toxic, they are probably less effective. When choosing an inhibitor, it is important to consider the cost of the inhibitor, access to the inhibitor (materials are often expensive if access is limited), and its environmental friendliness. Inhibitors are volatile, inactive (anodic), precipitated, cathodic, organic and inorganic compounds that prevent corrosion through adsorbing ions or molecules from the metal surface, increasing or decreasing anodic or cathodic reaction, reducing penetration rate of reactants on metal surface and electrical resistance of metal surface [2-4].
Inhibitors are generally substances which reduce the level of chemical reactions at appropriate concentrations. Corrosion inhibitors are active chemical species which help to slow down, delay or prevent corrosion, via different mechanisms, such as adsorption onto the metal surface that blocks active surface sites [5, 6]. These substances can inhibit the growth of biological agents and stop the physiological processes. The word “inhibitor” is rooted in the Latin word of “inhibere”, which means to prevent, protect or preserve. The inhibitor at low concentrations in corrosive medium delays the corrosion of metals [7, 8]. These substances can be solid, liquid or gas, and used in closed, gaseous, and aqueous mediums [9, 10].
Corrosion inhibitors reduce the rate of corrosion in several ways: (i) reduce the adsorption of ions/molecules on the metal surface; (ii) increase or decrease the anodic and/or cathodic reaction; to the metal surface, (iv) reduce the electrical resistance of the metal surface .
The effective techniques possible for the protection are modification of metal, design, corrosive environment, metal environment potential, surface, and also the Use of inhibitors. Inhibitors are categorized into some methods like: mechanism (anodic, cathodic and mixed inhibitors), environment (acid, alkali and neutral inhibitors) and mode of protecion (chemical, adsorption, film forming and vapor phase inhibitors)
Much attention has been paid to the use of corrosion inhibitors in protecting metal works [12-14] [10-12]. Corrosion inhibitors in the form of non-soluble compounds on metal surfaces can provide better stability for metal corrosion. Using corrosion inhibitors is very common in protecting metal works. By forming a thin impermeable layer of the work, inhibitor compounds slow down the anodic and cathodic activities . This protection method can be used as the last and most common solution to fight bronze disease and get rid of this problem.
The inhibitory effect of BTA (Benzotriazole) and AMT (5-ami- no-2-mercapto-1, 3, 4-thiadiazole) on historical bronze art works has been proved previously [16-19]. While these inhibitors have high efficiency, they have toxic and cancerous impacts on the environment. For this reason, green inhibitors such as honey, fig juice , the extract of salvia  and green tea extract  have been examined and evaluated in recent years.
Most organic corrosion inhibitors have heteroatoms. P, O, N and S are known as active centers (O <N <S <P) for the adsorption process on the metal surface and have a higher electron density. These elements act as a corrosion inhibitor. The use of organic compounds containing oxygen, sulfur and especially nitrogen to reduce the corrosion attack on steel has been studied in detail. Most organic inhibitors have been shown to be adsorbed by displacing water molecules on the metal surface and forming a compact barrier. In addition, the availability of non-bonded electrons (single pair) and p in inhibitor molecules facilitates the transfer of electrons from the inhibitor to the metal.
Corrosion control of metals is of technical, economic, environmental and aesthetic importance. The use of corrosion inhibitors is one of the best options for protecting metals and alloys. Organic corrosion inhibitors are somewhat toxic, so green corrosion inhibitors have been shown to be biodegradable because they are biodegradable and do not contain heavy metals or other toxic compounds. In addition to being environmentally friendly, plant products have acceptable environmental effects, are cheap, and are readily available and renewable. As a result, the corrosion inhibitory abilities of tannins, alkaloids, amino acids and organic dyes of plant origin are considered. Although significant research has been devoted to the inhibition of corrosion by plant extracts, reports on the exact mechanisms of the adsorption and identification process of the active substance are still scarce.
Rosemary leaves were investigated as corrosion inhibitor for the Al + 2.5Mg alloy in a 3% NaCl solution at 25°C , and El-Etre studied natural honey as a corrosion inhibitor for copper  and studied opuntia extract on aluminum . The inhibitive influence of the extract of khillah (Ammi visnaga) seeds on the corrosion of SX 316 steel in HCl solution was determined utilizing weight loss amounts as well as the potentiostatic method. Delonix regia extracts inhibited the corrosion of aluminum in hydrochloric acid extracts .
One of the most important causes of damage to historical monuments is bronze disease, one of the most important causes of this damage is chlorine ion. Therefore, in the present study, following various other researches, chloride medium has been used to study the corrosion process and also based on previous research that the Robinia pseudoacania L fruit extract was used for anti-corrosion effect on mild steel [28-30]. The aim of this experiment, Robinia pseudoacania L fruit extract was used to evaluate the inhibitory effect on bronze alloy (Cu-10Sn).
The acacia plant, scientifically named Robinia pseudoacacia L from the Papilionaceae family, is one of the two-celled plants whose beautiful and ornamental flowers are cultivated by beekeepers to produce fragrant honey.The flowers also have a soothing, stomach tonic effect and astringent and biliary properties . The acacia plant (robina psudoacacia) is a fast growing tree. It has a broad crown with leaves consisting of 11-23 dark green oval leaflets. In the roots, bark, and seeds of the Robinia pseudoacacia L tree, there is a substance called Description Robin, and in the leaves and flowers, there is also a glucoside called Description Robinin. Robinia pseudoacacia L wood is hard and durable. For these reasons, it is of industrial and commercial importance and is used to build columns and scaffolding for mines, as well as to make sofas and chairs .
Mineral inhibitors such as chromate (hexavalent chromate, oxidizing) are stable in most systems but are known to be carcinogenic and have been implicated in bone, skin, kidneys and spleen and then they may even enter red blood cells in very small amounts [32, 33].
The phenomenon of bronze disease is considered to be the most important factor in the destruction of bronze objects. So far, various methods have been proposed to deal with it. The specific inhibitors used for this purpose are BTA and AMT. The combination of BTA with AMT improved the inhibitive efficiency at lower concentrations with ethanol or deionised water as a solvent . These inhibitors are toxic and carcinogenic during inhibitory control. Ideally, these inhibitors may be able to activate chlorine ions, but after treatment they may have some side effects [20, 35].
Safety and environmental issues when using corrosion inhibitors in industry have always been a global concern. Because inhibitors are often toxic and carcinogenic. In addition, these toxic compounds are widely used in the protection of historical metal artifacts and some of them cause harmful effects on human health. These inhibitors may damage living tissue such as kidneys and liver. These toxic effects have led to the use of natural products (alternative corrosion inhibitors) as anti-corrosion agents, to reduce the dangerous effects on humans and the environment, which are environmentally friendly and range from rare earth elements to organic compounds [36-39].
Industrial and consumer interests in the development of green materials from abundant renewable resources have increased as they are readily available, are of low cost, and are nontoxic and biodegradable [40, 41].
But one of the most important drawbacks of these inhibitors is that they are toxic. Although green inhibitors have less inhibitory efficiency than organic inhibitors, their performance can also be optimized by re-treating these environmentally friendly inhibitors and making these inhibitors available.
The general compounds of The Robinia pseudoacania L fruit extract contain the natural sugars of ramenoz, arabinose, and galactose, as well as gluconic acid, 4 methoxygluconic and rubinin [42-44].