TECHNICAL FIELD

The invention relates to the addition of the inhibitor "Boronium-doped corrosion inhibitor (synthesized product)" obtained from the product boron to the system as corrosion preventer for the required applications and to increase the corrosion resistance of the metal by increasing the amount of concentration in the system.

STATUS OF THE TECHNICAL ASPECTS

Corrosion is the damage to the metals due to chemical and/or electrochemical interaction with the environment in which the metals are present. There are various types of corrosion according to environmental conditions, metallic properties and mechanism of effect. Nonetheless, different corrosion prevention methods are applied to eliminate these undesirable effects which may cause technical, economic and environmental consequences. Another effective corrosion preventer method for the required applications is the use of inhibitors. Inhibitors are additives that are doped to the corrosion environment to reduce or prevent corrosive effects.

Currently, as stated in the study for "Recent Patents on Corrosion Science", 2010, 2, 6-12, there are many inhibitors (organic and inorganic) in the fight against corrosion. "Boronium-doped corrosion inhibitor (synthesized product)" molecule, has been synthesized for the first time by ourselves. It has been searched using electrochemical methods as shown in Figure 1 , as it can be used as a corrosion inhibitor for low carbon steel in acidic medium. The Dynamic Electrochemical Impedance Spectroscopy (DEIS) method, which is considered to be one of the most effective methods for inhibitor activity determination, has been extensively used in this patent study. The most important distinctions are that the product we synthesized is dissolved in water and contains boron element which is found abundant in our country. An inhibition effect of up to 87% has been determined using 0.0025 Molar product, which we specified as the maximum concentration. In this context, the product precludes the patents set out in other literature.

2009/07228 are natural tannin inhibitors for metals and relates to inhibitors which are one of the methods used to prevent corrosion. The inhibitor subject of the invention includes the valex obtained from the oak barrel, the extract obtained from valex and the pomegranate shell extract to prevent corrosion.

2011/04039 is the corrosion inhibitor and biocide for the tannin-based chemicals in the cooling water conditioning and relates to the use of human / environmentally friendly tannin-based chemicals as the sole product instead of phosphate or polymer-based corrosion inhibitors dispersants and biocides and chlorinated compounds used in the cooling water conditioning. The amount of cooling water used in the industry is considerably high. Therefore, the costs of the chemicals used in cooling water conditioning and the effects on the environment and on human health are crucial. The objective of this invention is to use environmentally friendly tannin-based chemicals as the sole product instead of chlorinated compounds and phosphate-based chemicals in the cooling water conditioning. Tannin-based powder formulation is prepared in water solution and dosed in cooling water. 2015/15107 are corrosion-protective methacrylate adhesives for galvanized steel and other metals and bonding compositions for galvanized surfaces have been described. The compositions may include either (i) at least one (meth) acrylate component, one free radical inhibitor component and one phosphate ester component and one accelerator component in the second part or (ii) one first piece including at least one (meth) acrylate component and one accelerator and one phosphate ester compound together with one second part including one first part, and a carrier component, and a free radical initiator and a phosphate ester compound. Preparation methods and uses for the utilization of such pharmaceutical compositions, such as corrosion preventive treatment of galvanized surfaces, have been disclosed.

Corrosion inhibitors in the patent literature, including the known state of the art, are set forth above and do not have any relation with the product subject of invention.

DEFINITION OF THE INVENTION

The invention is concerned with the synthesis of a boronium cation-doped corrosion inhibitor developed to remove the above-mentioned disadvantages and bring new advantages to the related technical field.

Currently, there are many inhibitors (organic and inorganic) in the fight against corrosion, as stated in the study for "Recent Patents on Corrosion Science", 2010, 2, 6-12. An article titled "A Review on Recent Patents in Corrosion Inhibitors" (2010, 2, 6-12) published in 2010, in the journal titled "Recent Patents on Corrosion Science", specifically highlighted acidic corrosion inhibitors and emphasized acidic environment inhibitors and patents. According to the article, in particular, iron and steel erosion inhibitors were used in different sectors (e.g. oil and gas sector with widespread use). Thus, many patent applications have been observed recently. For instance; Khomyakova et al. referred to the use of metals on etching and on equipment acid treatment and their effects in a patent they received for a chemical composition. In the patent the content of nbrominebenzal-m-nitroaniline, 2- chlorine-6-diethylamino-4- methyl pyridine, 1 ,3-bis(carbamoyltio)-2-(N,N-diemethylamine) propane hydrochloride, and urotropine were mentioned to be used in food industry etc. This content composition gave good results for the protection of steel, Al and Ni and also provided for reduction of steel hydrogenation. Kurochkin et al. described the effect of the combination of 5-nitrosalycylalsulphathiazole, 3-dodecylbenzimidazole iodide, and polyethylene-polyamine for protection of steel, Ti and Al, as well as for hydrogen inhibition. Besides, a combination of alpha-oxynaphthalisonicotine hydrazide, 2,4,6-tris (2-isothioureido) -s-triazine hydroiodide, 2- (thiazolyl-4) -benzimidazole and urotropine was described to reduce the effect of Al, In and hydrogen to steel.

Li et al. on the other hand reported in the patent the content of 1-amino-2-mercapto-5- [1 - (1 ', 2', 4'-triazol) - methylene] -1 H-1 ,3,4-triazole and / or 1-phenyl-2- (5- [1 ', 2', 3 ', 5'-tetrazole-methylene] -1 ,3,4-furodiazole) thioalkyl ethyl ketone they produced environmentally friendly as an inhibitor in the cleaning of the carbon steel in acidic environment.

Taking into account of the above-mentioned developments, the necessity of continuing the studies in this direction has been taken into consideration and the studies related to the invention in question have been carried out. The most important distinctions regarding the invention in question are that the product we synthesized is dissolved in water and contains boron element which is found abundant in our country. An inhibition effect of up to 87% has been determined using 0.0025 Molar product, which we specified as the maximum concentration. In this context, the product precludes the other patents set out in literature.

Inhibitors are used in virtually every area of the industry. The total economic value of the inhibitors used in the world in 2013 is estimated to be 2.4 billion dollars. Various organic and inorganic corrosion inhibitors are used for this purpose.

Studies similar to our proposed ecological inhibitor have become more important nowadays that it has been found that toxic effects of many organic compounds used as corrosion inhibitors. Usability of the synthesized molecule as a corrosion inhibitor has also been demonstrated in the morphological examination of the metal surface. Scanning Electron Microscopy (SEM) and Energy Dispersive X-Ray Spectroscopy (EDS) analyzes have shown that the corrosive effect on the metal surface is reduced due to the use of the synthesized molecule.

Explanation of Figures Figure 1. Electrochemical methods used,

Table 1. Main sectors in which inhibitors are used, Industries using inhibitors,

Table 2. Chemical composition of the used metal (wt.%),

Figure 2. Preparation form of the electrodes used in the experiment,

Figure 3. [(1) Ag / AgCI Electrode, (2) Pt Electrode, (3) Working Electrode], Figure 4. Inhibitor concentrations used in 0.1 M HCI,

Figure 5. Graph of the inhibitor effect synthesized to St37 corrosion in the invention in the medium of 0.1 M HCI obtained by EIS method

Figure 6. R (QR) and R (Q (R (QR))) circuits,

Table 3. Data obtained by the EIS method of the effect of boronium cation-doped corrosion inhibitor (product synthesized in combination) on St37 corrosion in 0.1 M HCI medium,

Figure 7. Graph obtained by TP method of the inhibitor effect of metal (e.g. St37 metal) boronium cation-doped corrosion inhibitor (product synthesized in combination) in 0.1 M HCI medium.

Table 4. Data obtained by the TP method of the inhibitor effect of boronium cation-doped corrosion inhibitor (product synthesized in invention) on St37 corrosion in 0.1 M HCI medium, Figure 8. Graph obtained by DEIS method of the inhibitor effect of boronium cation-doped corrosion inhibitor (product synthesized in invention) on metal (e.g. St37) corrosion in 0.1 M HCI medium,

(a) Spectrum obtained by the DEIS method for the corrosion of metal (e.g. St37 metal) in 0.1 M HCI medium,

(b) Spectrum obtained by the DEIS method of the corrosion inhibitor effect of 0.001 M boronium cation-doped corrosion inhibitor (product synthesized in invention) on metal (e.g. St37 metal) corrosion in 0.1 M HCI medium, (c) Spectrum obtained by the DEIS method of the corrosion inhibitor effect of 0.0015 M boronium cation-doped corrosion inhibitor (product synthesized in invention) on metal (e.g. St37 metal) corrosion in 0.1 M HCI medium,

(d) Spectrum obtained by the DEIS method of the corrosion inhibitor effect of 0.002 M boronium cation-doped corrosion inhibitor (product synthesized in invention) on metal (e.g. St37 metal) corrosion in 0.1 M HCI medium,

(e) Spectrum obtained by the DEIS method of the corrosion inhibitor effect of 0.0025 M boronium cation-doped corrosion inhibitor (product synthesized in invention) on metal (e.g. St37 metal) corrosion in 0.1 M HCI medium,

Figure 9. 3D representation of the DEIS result of the inhibitor effect of "Boronium-doped corrosion inhibitor (synthesized product)" on metal (e.g. St37) corrosion in 0.1 M HCI medium [a); (b); (c); (d)], Table 5. Data obtained by the DEIS method of inhibitor effect of boronium cation-doped corrosion inhibitor (product synthesized in combination) on metal (e.g. St37 metal) corrosion in 0.1 M HCI medium,

In Figure 10, pre-experimental SEM images

(a) SEM images of pre-experimental metal surface (b) SEM image of the metal surface after the Potentiodynamic Polarization Resistance Method in 0.1 M HCI medium,

(c) SEM image of inhibitor effect of 0.001 M "Boronium-doped corrosion inhibitor (synthesized product)" on metal corrosion after the Potentiodynamic Polarization Resistance Method in 0.1 M HCI medium,

(d) SEM image of inhibitor effect of 0.0015 M "Boronium-doped corrosion inhibitor (synthesized product)" on metal corrosion after the Potentiodynamic Polarization Resistance Method in 0.1 M HCI medium,

(e) SEM image of inhibitor effect of 0.002 M "Boronium-doped corrosion inhibitor (synthesized product)" on metal corrosion after the Potentiodynamic Polarization Resistance Method in 0.1 M HCI medium,

(f) SEM image of inhibitor effect of 0.0025 M "Boronium-doped corrosion inhibitor (synthesized product)" on metal corrosion after the Potentiodynamic Polarization Resistance Method in 0.1 M HCI medium, In Figure 10, pre-experimental SEM images

(a) Pre-experimental result of metal EDS analysis

(b) EDS analysis result of the metal after the Potentiodynamic Polarization Resistance Method in 0.1 M HCI medium,

(c) EDS analysis result of inhibitor effect of 0.0025 M "Boronium-doped corrosion inhibitor (synthesized product)" on metal corrosion after Potentiodynamic Polarization Resistance Method in 0.1 M HCI medium,

Figure 11. EDS images [(a), (b), (c)],

DETAILED DESCRIPTION OF THE INVENTION

In this detailed description, preferred alternatives to the synthesis of the boronium cation-doped corrosion inhibitor subject of invention are disclosed only regarding the better understanding of the subject and without any restrictive effect.

The corrosion inhibitor activity of our original compound named "boronium-doped corrosion inhibitor (synthesized product)" synthesized by our research group for the first time, which is not available in the literature, has been searched using the methods shown in Figure 1. The method followed in the research and the results obtained from the methods used are presented below. The product subject of invention is a first-time synthesized molecule, and according to the data obtained by electrochemical methods, it has been proven that it protects the low carbon steel extensively used in the industry against corrosion in a 0.1 M HCI acid medium, with a percent inhibition of up to 87%. The fact that the inhibitor is semi-metal sourced, which is mostly found in Turkey and has the potential to be used in a rather expensive industry such as corrosion makes this patent even more important. With obtaining the patent, it will be a new alternative area of use for boron element which is exported from our country very cheaply in an unprocessed state.

1. Preparation of Experimental Setup

The composition of the low carbon steel used extensively in the industry due to its excellent mechanical properties and low cost maintenance is shown in Table 2. The sample, except only one of the base areas of the cylinder exposed, is put in the insulated tube so that a thick polyester layer is formed on and around it (Fig. 2). All electrochemical methods are performed using the experimental setup shown in Figure 3.

2. Findings and Discussion

2.1. Electrochemical Impedance Spectroscopy (EIS) Method

The corrosion behavior of the metal (e.g. St37 metal) in the 0.1 M HCI solution is made at the end of the open circuit potential for two hours. The Nyquist diagrams obtained by adding "Boronium-doped corrosion inhibitor (synthesized product)" (Figure 4) to different concentrations of 0.1 M HCI solution for metal (e.g. St37 metal) are given in Figure 5. EIS data are analyzed using the R (QR) and R (Q (R (QR)) circuits (Figure 6). The results demonstrate the formation of a barrier on the metal surface.

From Table 3, it can be seen that the Rs resistance of the metal (e.g. St37 metal) increases from 10.54 Ω to 17.19 Ω, the value of "n" representing the metal roughness increases from 0.82 to 0.88 and similarly the Ret value increases from 240 Ω.αη2 to 1526 Ω. cm2. The data obtained show that the Ret value (charge transfer resistance) increases as the amount of inhibitor used for the metal (e.g. St37 metal) is increased. That is, the synthesized molecule tends to protect the metal against corrosion in its environment. The calculated corrosion inhibition (% IE) percentage based on the use of 0.0025 M "boronium-doped corrosion inhibitor (synthesized product)" is 84.27%.

2.2. Potentiodynamic Polarization Resistance Method Potentiodynamic Polarization Resistance Method is adopted after Dynamic Electrochemical Impedance Spectroscopy (DEIS) method and Electrochemical Impedance Spectroscopy (EIS) method. The corrosion potential of low carbon steel put in a 0.1 M HCI solution is made in the GAMRY PC3/600 potentiostat/ galvanostat/ZRA system, and the data are analyzed with Gamry CMS-5.30 software. To obtain the polarization curves, the equilibrium potential of the working electrode is measured for 100 seconds against the reference electrode, followed by a scan at 1 mV/s velocity in the cathodic and anodic directions at ± 250 mV interval. In the corrosion potential measurements, Ag/AgCI electrode is used as the reference electrode and Pt wire is used as the counter electrode. The potentiodynamic polarization curves obtained at room temperature of the metal (e.g. St37 metal) in 0.1 M HCI are shown in Figure 7.

Table 4 shows the data obtained by the TP method of inhibitor effect of "Boronium-doped corrosion inhibitor (synthesized product)" on metal corrosion in 0.1 M HCI medium. When the table is examined, it is determined that as the concentration of the "Boronium-doped corrosion inhibitor (synthesized product)" is increased, the corrosion current density value (lcorr) decreases. This change demonstrates that our group synthesized "Boronium-doped corrosion inhibitor (synthesized product)" molecule can be used as an inhibitor. It is seen that the anodic Tafel constant value increases due to the increase in the inhibitor amount, while the cathodic Tafel constant changes less in this context. Depending on the amount of inhibitor, the cathodic and anodic zone shift of the corrosion potential (Ecorr) suggests that our inhibitor possesses the feature of a mixed inhibitor.

2.3. Dynamic Electrochemical Impedance Spectroscopy (DEIS) Method

The Ret graph obtained by the DEIS method with the addition of Boron-Doped Corrosion Inhibitor at different concentrations to the 0.1 M HCI medium for the metal (e.g. St37 metal) is shown in Figure8. The 3D representation of the DEIS result of the inhibitor effect of Boron-Doped Corrosion Inhibitor on corrosion of the metal (e.g. St37 metal) in 0.1 M HCI medium is given in Fig 9. 30 minutes after the experiment start, "Boronium-doped corrosion inhibitor (synthesized product)" is doped, which is prepared in different concentrations with 0.1 M HCI, in a drop of burette to the corrosion cell. So, instantaneous potential and impedance changes occurring in the metal are recorded.

The impedance spectrum obtained for the St-37 as a result of 2-hours experiments conducted in 0.1 M HCI medium is shown in Figure 9. (a). The time-dependent increase in Re[Z]/Qcm2 and lm[Z]/Qcm2 of the impedance spectrum with the addition of the "Boronium-doped corrosion inhibitor (synthesized product)" to the system after half an hour is shown in Figure 9 (b). As the concentration of "Boronium-doped corrosion inhibitor (synthesized product)" in the system increases, the time-dependent impedance spectrum increases more in Re[Z]/ Qcm2 and lm[Z]/Qcm2 as shown in Figure 9. (c), (d) and (e). It is understood from these graphs that when the "Boronium-doped corrosion inhibitor (synthesized product)" is doped to the system and the amount of concentration in the system is increased, an increase in the corrosion resistance of the metal (e.g. St37 metal) occurs and thus, indicates that "Boronium- doped corrosion inhibitor (synthesized product)" has an inhibitor effect. When Table 5 is analysed, it is seen that the Rs resistance of the metal rises from 13.79 Ω to 17.73 Ω, and the value of "n" representing the metal roughness increases from 0.86 to 0.89 and similarly the Ret value increases from 407.4 Q.cm2 to 2588 Q.cm2. The data obtained show that as the amount of inhibitor used for the metal increases, the Ret value increases, that is, the corrosion resistance increases and thus it has an inhibitor effect. The corrosion inhibition percentage calculated for the "Boronium-doped corrosion inhibitor (synthesized product)" by the DEIS method is 84.26%.

2.4. Research on Surface Morphology

Changes in the metal surface after the Potentiodynamic Polarization Resistance Method experiments are explored by SEM and EDS images. The surface change of our sample in 0.1 M HCI acid solution prepared with the addition of 0.1 M HCI, 0.001 M, 0.0015 M, 0.002 M and 0.0025 M "Boronium-doped corrosion inhibitor (synthesized product)" before the experiment is shown in Figure 10. Oxides and pits, which are corrosion products on the metal surface, are formed in 0.1 M HCI acid medium. When the inhibitor is used, it is seen that these pits formed on the surface disappear. Surface morphological changes after addition of 0.0025 M inhibitor on 0.1 M HCI are shown in Figures 10 and 11.

SEM images of the metals obtained after the Potentiodynamic Polarization Resistance Method of the "Boronium- doped corrosion inhibitor (synthesized product)" prepared in 0.1 M HCI medium and at different concentrations are seen in Figures 10 and 11. At each concentration studied, formation of deteriorations and pitting on the metal surface are seen in the SEM images of the metal (e.g. St37 metal) at the end of 2 hours. According to EDS results, it is observed that the ratio of "Fe" element in the structure of metal (e.g. St37 metal) decreases with the addition of 0.1 M HCI and "Boronium-doped corrosion inhibitor (synthesized product)", while "O" ratio increases. In the same way, it is observed that "B" and "N" on the metal surface are adsorbed to the metal surface and close the distortions formed on the metal surface. 2.5 Process Steps of Synthesis

After L-leucine silver salt (1 g, 0.0042 mol.) is dissolved in 20 ml of polar protic solvent (e.g. methanol) per gram of substance, Bis (1-methyl-1 H-imidazol-3-il) dihydroboronium iodide (1.27 g, 0.0042 mol), which is dissolved in 10 ml of polar protic solvent (e.g. methanol) per gram of substance, is slowly added. The reaction is stirred at room temperature (min 25° C) and vigorously in the dark environment on a magnetic stirrer. The reaction is followed by thin layer chromatography (TLC). The reaction is complete after 12 h at minimum. The separation of the product from the reaction mixture is carried out by filtration. The subsided white Agl solid is first washed with 2x10 ml of methanol and then with 2x10 ml of ethanol solvents. The liquid fractions are combined and with the aid of a solvent evaporator, are removed under vacuum. The crude product is eluted by column chromatography in a solvent mixture of EtOAc/hexane (1 :4) and the green and viscous product structure is illuminated by ¹ H-NMR and ¹³ C-NMR analysis. The insulation yield of the obtained material is >90%.

¹ H NMR (600 MHz, CD ₃ OD): δ 8.44 (s, 2H), 7.35 (s, 2H), 7.26 (s, 2H), 3.84 (s, 6H), 3.28 (dd, J=8.3,5.8 Hz, 2H), 1.63-1.57 (m, 1 H), 0.9 (d, J=6.6 Hz, 6H). ¹³ C NMR (150 MHz, CD ₃ OD): 180.6, 138.7, 125.0, 123.0, 54.4, 44.2, 34.0, 24.6, 22.9, 20.9. IR (cm ^"1 ): 3061 , 2954, 2870, 2421 , 2125, 1599, 1576, 1341 , 1405, 1128

Waenumber (cm-1)

IR spectrum of Bis(1-methyl-1H-imidazol-3-il) dihydroboronium 2-amino-4-methylpentanoate

¹ H-NMR and ¹³ C-NMR spectra of Bis(1-methyl-1 H-imidazol-3-il) dihydroboronium 2-amino-4- methylpentanoate