The present study relates to preparation corrosion inhibiter from caster oil for carbon steel pipeline by two steps; the first step includes sulfonation of caster oil and the second step includes amination the sulfonic caster oil with ammonia solution the final product characterized by FTIR. The effectiveness of the synthesized compounds is studied as corrosion inhibitors for carbon steel; in formation, water was investigated by electrochemical techniques using Tafel plot methods. The synthesized compounds showed enhancement in inhibition efficiencies, and then studied the effect of temperatures on inhibition efficiency.
Corrosion is the destructive attack of a material by reaction with its Environment [
The use of chemical inhibitors to decrease the rate of corrosion processes is quite varied. In the oil extraction and processing industries, inhibitors have always been considered to be the first line of defense against corrosion. A great number of scientific studies have been devoted to the subject of corrosion inhibitors. However, most of what is known has grown from trial and error experiments, both in the laboratories and in the field. Rules, equations, and theories to guide inhibitor development or use are very limited. Inhibitors have been classified by their chemical functionality into: inorganic inhibitors, organic inhibitors [
Organic inhibitor are applied extensively to protect metals from corrosion in many aggressive acidic media (e.g., in the acid pickling and cleaning process of metals). Different kinds of organic compounds are used as corrosion inhibitors for iron alloys in various acid media such as aromatic compounds with positively charged amine groups, Sodium sulfonates, phosphonates, or mercaptobenzotriazole (MBT) are used commonly in cooling waters and antifreeze solutions [
Caster oil, sulfuric acid, ammonia solution, mechanical stirring, bath, evaporation rotary, viscometer, IR spectra, RP 6000, carbon steel (C1010) standard strips and potentiostat.
In a 500 ml three-neck round bottom flask, 250 ml of castor oil and 75 ml of sulfuric acid were charged and the whole were stirred for 24 h at room temperature. At the end of reaction, the reaction was cooled to room temperature and then, ethyl acetate (50 mL) was added to the reaction mixture with stirrer for 30 min, followed by filtration to separate the precipitate from the mixture medium. The precipitate obtained was purified by column chromatography (silicagel, petroleum ether/ethyl acetate (100/1, v/v) as eluent) to give sulfonated castor oil (SC). Then the (SC) dissolved in distilled water and neutralized with ammonium solution to give ammonium sulfonated castor oil (ASC) [
A standard strip of carbon steel alloy (C1010) is shown in
by emery cloth paper to 400 micron. Then specimens degreased with acetone, and are washed with distilled water and ethanol. Hot air were used to dry the sample and stored in a desiccators containing silica gel during the period in between polishing and Tafel measurements. The composition of these alloys was illustrated in
In present study, we use formation water from Iraqi southern oil Company as corrosive environment. The compositional analyses of formation waters carried out in south oil company―Basrah, as shown in
The new compounds were characterized, by FTIR Spectroscopy―technique, as a viscous solution by using sodium chloride disc. Spectra [
A potentiostat was used to measure current density vs electric potential in order to calculate the corrosion rates. The electrochemical results obtained from polarization experiments through “Tafel plots” performed in corrosive environment (formation water) in the absence and presence of different specified concentration of (ASC) (from 5 ppm to 30 ppm) are showed in
Alloy | Composition % w/w | |||||||||
---|---|---|---|---|---|---|---|---|---|---|
Carbon steel (C1010) | C | Mn | P | S | Si | Ni | Cr | Cu | As | Fe |
0.08 - 0.13 | 0.3 - 0.5 | 0.04 | 0.05 | 0.17 - 0.37 | 0.3 | 0.1 | 0.3 | 0.08 | Residue |
Total suspended Solid TSS (ppm) | Salinity (ppm) | Conductivity (semen) | TDS (ppm) | pH |
---|---|---|---|---|
160.8 | 374,000 | 4,340,000 | 217,000 | 6.6 |
Ca2+ | Mg2+ | Na+ | K+ | Cl− | ||
---|---|---|---|---|---|---|
150 | 2975 | 471 | 110 | 11,260 | 82 | 200 |
−S | N-H abs cm- | SO3− abs cm- | C-H abs cm- | CH2 abs cm- | IR spectrum |
---|---|---|---|---|---|
- | - | - | 680, 1450 | 2995, 2880 | Caster oil |
1650 | 315, 350 | 1220, 1050 | 680, 1450 | 2995, 2880 | Ammonium Sulfonated Caster oil |
Tafel plots employed for rapid evaluation inhibitors in order to determine their effectiveness on the corrosion rates of carbon steel. From
Conc (ppm) | Ecorr (V) | Icorr (A) E − 6 | CR (mm/year) E − 3 | CR (mpy) | βc (A/V) | βa (A/V) | Rct (ohm) E + 3 |
---|---|---|---|---|---|---|---|
0 | −0.94 | 224.0 | 241.5 | 9.5078 | −9.191 | 7.117 | 0.1147 |
5 | −0.5 | 4.468 | 4.818 | 0.1896 | −5.369 | 5.060 | 5.750 |
10 | −0.44 | 15.09 | 16.28 | 0.6409 | −6.265 | 5.879 | 1.702 |
15 | −0.44 | 12.89 | 13.90 | 0.5472 | −6.324 | 5.234 | 1.994 |
20 | −0.44 | 12.65 | 13.64 | 0.5370 | −6.480 | 5.208 | 2.032 |
25 | −0.49 | 3.138 | 3.383 | 0.1331 | −6.337 | 6.367 | 8.189 |
30 | −0.47 | 8.668 | 9.347 | 0.3679 | −7.100 | 5.277 | 2.964 |
rate, Ecorr and Icorr of carbon steel in formation water after added various concentrations. From these results, the corrosion rate reduced as concentration increases. The compound (ASC),
The effect of temperature on inhibition efficiency of the inhibitors on carbon steel (CS) alloy can be studied depending on two principles, the first principle includes increasing the efficiency as it decreases in temperature; this due to physical adsorption mode for the inhibitor on the surface of metal or alloy, and the second principle includes increasing the efficiency as temperature increases; it results from chemical adsorption mode for the inhibitor on the surface of metal or alloy [
The present study of the effect of temperature on inhibitor properties and corrosion inhibitor for CS and alloy was studied at range (30˚C - 50˚C) as is shown in
This table showed that this inhibitor have some effects on both, the cathodic and anodic processes. This indicates a modification of the mechanism of cathodic hydrogen evolution as well as anodic dissolution of iron, which suggests that the above inhibitors can be used to inhibit the corrosion process of CS and their suppression of cathodic process by the covering of CS surface with monolayer is due to the adsorbent of inhibitors molecules. It can also be the anodic Tafel constant (βa) slopes which has variable values between increasing and decreasing values whereas the decreasing may be described to the changes in charge transfer
Temp (˚C) | Ecorr (V) | Icorr (A) E−5 | CR (mm/year) E−2 | CR (mpy) | βc (A/V) E+0 | βa (A/V) E+0 | Rct (ohm) E+3 |
---|---|---|---|---|---|---|---|
30 | −0.46 | 0.9178 | 0.9897 | 0.3896 | −6.356 | 4.016 | 2.800 |
35 | −0.448 | 2.537 | 2.736 | 1.0771 | −5.888 | 5.515 | 1.013 |
40 | −0.413 | 2.604 | 2.808 | 1.1055 | −5.832 | 5.486 | 0.986 |
45 | −0.388 | 1.089 | 0.9534 | 0.3753 | −6.146 | 5.923 | 2.906 |
50 | −0.409 | 2.128 | 2.294 | 0.9031 | −6.331 | 5.567 | 1.208 |
resistance. From
The inhibition characteristics of compound (ASC) were studied for iron corrosion in formation water. Electrochemical (Tafel polarisation and EFM) method was applied. Polarisation measurements showed that the compound (ASC) acted as cathodic inhibitor. The surfactants chemisorbed on the electrode surface without modifying the mechanism of anodic and cathodic reactions. The cathodic process is activation controlled even in the presence of surfactant. The inhibition efficiency of the surfactants generally increases with the increasing in surfactant concentration. From these results the ammonium sulfonated castor oil (ASC) can be used as anti-corrosion inhibitor for pipeline of crude oil.
Ali, H.A (2017) Modification of Caster Oil and Study Its Efficiency as Corrosion Inhibitors in Formation Water Media. Engineering, 9, 254- 262. https://doi.org/10.4236/eng.2017.93013