Corrosion inhibition of carbon steel pipelines by some novel Schiff - - PowerPoint PPT Presentation
Corrosion inhibition of carbon steel pipelines by some novel Schiff base compounds during acidizing treatment of oil wells studied by electrochemical and quantum chemical methods Presented by Ahmed M. Abu-Dief Chemistry Department, Faculty of
Corrosion inhibition of carbon steel pipelines by some novel Schiff base compounds during acidizing treatment of oil wells studied by electrochemical and quantum chemical methods
Presented by Ahmed M. Abu-Dief
Chemistry Department, Faculty of Science, Sohag University, 82524 Sohag, Egypt
Ackn knowledgment
The electrochemical properties of carbon steel are the subject of many studies due to its wide applications in industry such as heat exchange and boiler systems, construction material for chemical reactors, storage tanks, and oil and gas transport pipelines
processes, such as: industrial acid cleaning, acid pickling, oil well acidizing, acid descaling and in petrochemical processes
corrosion protection of the equipments and vessels is one of chief concerns of the maintenance and design engineers
لورتبلا لقن بيبانأو طوطخ ىلع هرارضأو أدصلا
The use of organic molecules as corrosion inhibitors to decrease the corrosion rate processes has been the focus of very many efforts within the chemical process industry especially in acidic environments
Characterization of the investigated inhibitors and electrochemical reactions
(a) (a) (a)
4-bromo-2-{(Z)-[(3, 5-dimethylphenyl) imino]methyl}phenol (HA-1) 1-{(Z)-[(4, 6-dimethylpyridin-2-yl) imino] methyl} naphthalen-2-ol (HA-2) 1-{(Z)-[(2-methoxy-4-nitrophenyl)imino] methyl}naphthalen-2-ol (HA-3)
(b) (b) (b)
Optimized (a) and chemical (b) structures of the investigated Schiff base inhibitors.
250 300 350 400 450 500 550 600 650 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 2.2
(a)
max=443 nm max=480 nm max=379 nm
II I
Absorbance
Wavelength/ nm I HA-1 II [Fe(II)-HA-1]
UV/vis absorption of (I) HA-1 and (II) [Fe(II)–HA-1] complex at 298
HA-1 HA-2 HA-3 (a) (a) (a) (b) (b) (b)
ORTEB diagram showing atomic numbering scheme (a) and close packing structure (b) for HA-1, HA-2 and HA-3 compounds. The molecular structures and the packing arrangements
the molecules with hydrogen bonds of compounds HA-1, HA-2 and HA-3
Compounds HA-1 HA-2 HA-3 Empirical formula C15H14BrNO·C15H14BrNO C18H16 N2O C18 H14 N2 O4· H2O Formula weight 608.34 276.33 339.44 Temperature/K 100.0 293.0 293.0 Crystal system Orthorhombic Monoclinic Triclinic Space group Pn21a P21 P-1 a/Å 21.8290 (3) 8.8848(2) 7.2885(4) b/Å 16.9484 (3) 6.3713(1) 8.8646(5) c/Å 7.11447 (13) 12.6507(2) 14.0050(8) α/° 90.00 90 95.660 β/° 90.00 94.429(2) 100.258 γ/° 90.00 90 112.670 Volume/Å3 2632.11 (7) 713.99(2) 807.54 (9) Z 4 2 2 ρcalcmg/mm3 1.533 1.285 1.369 F(000) 1228 292 355 Crystal size/mm3 0.54 × 0.19 × 0.13 0.78 × 0.51 × 0.38 0.32 × 0.17 × 0.10 2Θ range for data collection
5.47 to 70.7° Reflections collected 12770 5753 11870 Independent reflections 2533[Rint= 0.11 ] 2091[Rint= 0.019] 3088 [Rint=0.034] Data/restraints/paramete rs 2583/1/326 2014/1/195 3033/0/223
Crystal data and structure refinement of the investigated inhibitors
(a)
Blank 0.01 mM 0.05 mM 0.10 mM 0.50 mM 1.00 mM
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(b)
log I, A cm
Blank 0.01 mM 0.05 mM 0.10 mM 0.50 mM 1.00 mM
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(c)
Blank 0.01 mM 0.05 mM 0.10 mM 0.50 mM 1.00 mM
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E/ mV vs. (SCE) log I/ A cm
log I/ A cm
log I/ A cm
Polarization curves for carbon steel in 15 % HCl solution in the absence and presence of various concentrations of (a) HA-1, (b) HA-2 and (c) HA-3 inhibitors at 45 °C.
Aliaga-Alcalde, J. Electroanal. Chem. 743 (2015) 120–133.
Effect of inhibitor dose
significantly minimize in the rate of corrosion, i.e. shifts the catholic curves to more negative potentials and the anodic curves to more positive potentials . This may be ascribed to adsorption of the inhibitors over the metal surface
The surface coverage (θ) and the inhibition efficiency (P %)
T/ ºC Systems Icorr/ mAcm-2 Ecorr/ mV (vs. SCE) βa/ mV dec -1
θ P/ % 45 15 % HCl 93.75±9.1
90 180
59.84±5.2
94 179 0.361 36.1 15% HCl+0.05 mM HA-1 42.18±4.7
92 190 0.552 55.2 15% HCl+0. 10 mM HA-1 31.25±4.1
87 193 0.666 66.6 15% HCl+0.50 mM HA-1 21.86±2.6
93 170 0.766 76.6 15% HCl+1.00 mM HA-1 10.12±1.8
97 185 0.892 89.2 60 15 % HCl 203.50±16.4
92 185
15.46±1.1
89 176 0.924 92.4 45 15 % HCl 93.75±9.1
90 180
52.49±4.9
95 175 0.441 44.1 15% HCl+0.05 mM HA-2 38.51±3.3
86 171 0.589 58.9 15% HCl+0. 10 mM HA-2 27.81±2.6
94 177 0.703 70.3 15% HCl+0.50 mM HA-2 16.13±1.5
97 181 0.827 82.7 15% HCl+1.00 mM HA-2 7.83±0.80
93 186 0.916 91.6 60 15 % HCl 203.50±16.4
92 185
12.01±1.0
91 187 0.941 94.1 45 15 % HCl 93.75±9.1
90 180
48.94±4.4
98 177 0.477 47.7 15% HCl+0.05 mM HA-3 34.14±3.1
92 181 0.635 63.5 15% HCl+0. 10 mM HA-3 22.12±2.3
94 187 0.764 76.4 15% HCl+0.50 mM HA-3 11.94±1.1
97 185 0.872 87.2 15% HCl+1.00 mM HA-3 3.51±0.5
96 171 0.962 96.2 60 15 % HCl 203.50±16.4
92 185
5.08±0.4
95 183 0.975 97.5
Polarization parameters for carbon steel 15 % HCl containing different concentrations of the inhibitors at 45 °C and 60 °C.
The θ value found to be near unity (θ=0.96), indicates almost a whole coverage of the steel surface with the adsorbed inhibitor molecules.
There is a clear acceleration of both the cathodic and anodic reactions with an increase in temperature
log I/ A cm
E/ mV vs. (SCE)
15 % HCl- 45
15 % HCl- 60
15 % HCl+1.0 mM HA-1- 45
15 % HCl+1.0 mM HA-1- 60
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Potentiodynamic polarization curves carbon steel 15% HCl solution in the absence and presence of 1.0 mM HA-1 inhibitor at 45 °C and 60 °C.
The inhibition efficiency and surface coverage degree increased with the rise of temperature, indicating chemical adsorption of the Schiff base molecule on the metal surface
2 1 ) 1 ( ) 2 (
1 1 303 . 2 log T T R E I I
a corr corr
( 2 )
1 2 2 1 1 1 2 2
The decrease in activation energy after the addition of inhibitors could be interpreted as a chemical adsorption of the inhibitors on the steel surface The obtained positive values indicated that, the adsorption of the inhibitors on the metal surface was endothermic
Calculating Thermodynamic Parameters
2 4 6 8 10 12 14 16 18 20 22 24 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 6.5
(a)
Immersion time / hour
Corrosion rate/ mm year
Blank (15% HCl) 15% HCl + 1.0 mM HA-1 15% HCl + 1.0 mM HA-2 15% HCl + 1.0 mM HA-3
2 4 6 8 10 12 14 16 18 20 22 24 76 78 80 82 84 86 88 90 92 94 96 (b)
15% HCl + 1.0 mM HA-1 15% HCl + 1.0 mM HA-2 15% HCl + 1.0 mM HA-3
Inhibition efficiency/ P% Immersion time / hour
Variation of (a) corrosion rate and (b) inhibition efficiency with immersion time for carbon steel immersed in 15% HCl in the presence of 1.0 mM of different Schiff base inhibitors at 45 °C
The inhibition efficiency of the investigated inhibitors was increased with increasing immersion time until 2 h which may be attributed to the formation of strong inhibitor layer which prevents the attack of corrosive media on the metal surface
These compounds can provide good protection to the carbon steel substrate even after 24 h exposure to this highly corrosive media
0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1 1.2 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1 1.2 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1 1.2 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0
Cinh./ (mM) Cinh./ (mM)
Cinh./ (mM)
R
2=0.99883
(a) HA-1 (b) HA-2
R
2=0.99969
(c) HA-3
R
2=0.99936
Curve fitting of the corrosion data obtained from EIS measurements for carbon steel in 15% HCl containing various concentrations of inhibitors (a) HA-1, (b) HA-2 and (c) HA-3 according to Langmuir adsorption isotherm model at 45 °C.
Aliaga-Alcalde,, J. Electroanal. Chem. 743 (2015) 120–133.
The investigated Schiff base inhibitors give larger Kads values at 45 °C, imply more efficient adsorption and hence better inhibition efficiency.
مدع يف بطقلا حطس طبثملا دوجو
0.01.53.04.56.07.59.010.512.013.515.0 0.0 1.5 3.0 4.5 6.0 7.5 9.0 10.5 12.0 13.5 15.0
050100150200250300350400450500 50 100 150 200 250 300 350 400 450 500
Z
/ Real/ cm 2
Im ag/ cm2
Blank
Z
/ Real/ cm 2
Im ag/ cm2
200 ppm
200 ppm CHOGS-16
5kV ×2,000 10µm 0000 JSM-5500LV 5kV ×2,000 10µm 0000 JSM-5500LV
يف بطقلا حطس طبثملا دوجو
Aliaga-Alcalde,, J. Electroanal. Chem. 743 (2015) 120–133.
LOMO LOMO LOMO HOMO HOMO HOMO
(a) (a) (b) (b) (c) (c) Frontier molecular orbital density distributions of the synthesized Schiff bases (a) HA-1, (b) HA-2 and (c) HA-3.
Sañudo, N. Aliaga-Alcalde,, J. Electroanal. Chem. 743 (2015) 120– 133.
The relationship between quantum chemical indices and inhibition efficiency was inspected the EHOMO for the investigated imines decreases in the order; (HA-3> HA-2>HA-1), which is in agreement with the experimental results of inhibition efficiency (P%).
Schematic representation of the mode of adsorption and inhibition mechanism of HA-2 onto the carbon steel surface.
Aliaga-Alcalde,, J. Electroanal. Chem. 743 (2015) 120–133.
The positively charged of cationic forms of molecule has been formed an electrostatic bond with the Cl- ions already adsorbed on carbon steel surface. The physical adsorption, these molecules are also adsorbed through the chemisorption mechanism that may be formed between the lone pair electrons of the unprotonated imine and d oribital of metal surface
0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6
(b)
0.68
Absorbance
[L]/([L]+[Fe
2+])
HA-1 HA-2
Continuous variation plots for the prepared complexes in aqueous-alcoholic mixture at [Fe2+] = [L] = 1.0 mM and 298 K.
The suggested structures for the complexes which formed on the steel surface (a) [Fe (HA-1)2] and (b) [Fe (HA-2)2].
Aliaga-Alcalde,, J. Electroanal. Chem. 743 (2015) 120–133.
molecular structure has been confirmed with support of X-ray single crystal, 13CNMR, 1HNMR, mass, UV-Vis, FTIR spectra and elemental analyses
dose and temperature, and attains a maximum value at 1.0 mM.
to 24 h of immersion.
cathodic and anodic reactions.
inhibitor layer provided the protective property against corrosion.
quantum chemical parameters (ELUMO, gap energy (∆E) and dipole moment (μ)).
Ackn knowledgme
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