Experimental and Theoretical Studies of Tailor-made Schiff Bases as Corrosion Inhibitors for Carbon Steel in HCl

Furtado, Luana B.; Leoni, Gabriel B.; Nascimento, R. C.; Santos, Pedro Henrique C.; Henrique, Fábio J. F. S.; Guimarães, Maria José O. C.; Brasil, Simone L. D. C.

doi:10.1590/1980-5373-MR-2022-0398

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Articles • Mat. Res. 26 • 2023 • https://doi.org/10.1590/1980-5373-MR-2022-0398 copy

Experimental and Theoretical Studies of Tailor-made Schiff Bases as Corrosion Inhibitors for Carbon Steel in HCl

Authorship SCIMAGO INSTITUTIONS RANKINGS

Abstract

Strong acids used in industrial applications as cleaning, descaling, among others, can severely damage metallic structures, requiring corrosion inhibitors to diminish or avoid these issues. Since many conventional compounds used for this purpose may result in environmental and human health issues, eco-friendly compounds such as Schiff bases have been recently investigated. The synthesis of three novel Schiff bases (SBs) was confirmed by infrared spectroscopy (FTIR) and hydrogen nuclear magnetic resonance (¹H-NMR). Weight loss measurements were carried out in 1 M HCl over 303K-333K. Furthermore, the combination of these compounds with a surfactant improved the efficiencies, reaching an efficiency of 93%. Optical and scanning electron microscopies confirmed the reduced roughness and pit depths of carbon steel samples. Density-functional theory calculations for neutral forms of SBs revealed that the geometrical and the energetical parameters are similar for the three studied SBs. The geometrical results exhibited more planar structures of protonated species, improving the chemical and physical interactions between aromatic rings and metallic atoms.

Keywords:
Weight Loss; Acid inhibition; Schiff bases; Surfactants

Test	Concentration (ppm)	303 K		318 K		333 K
Test	Concentration (ppm)	CR (mm/y)	IE_WL (%)	CR (mm/y)	IE_WL (%)	CR (mm/y)	IE_WL (%)
Blank	0	7.37 ± 0.53	-	25.90 ± 1.37	-	79.89 ± 1.67	-
SB1	100	1.14 ± 0.06	84.49	5.53 ± 0.15	78.63	15.28 ± 1.24	79.32
SB1	600	1.12 ± 0.11	84.79	2.00 ± 0.19	92.28	8.65 ± 0.15	88.30
SB2	100	1.22 ± 0.16	83.48	5.03 ± 0.63	80.59	16.15 ± 0.95	78.14
SB2	600	0.76 ± 0.03	89.73	3.25 ± 0.52	87.46	11.03 ± 0.31	85.07
SB3	100	1.87 ± 0.18	74.69	7.42 ± 0.36	71.36	25.87 ± 1.29	64.98
SB3	600	0.94 ± 0.05	87.28	3.36 ± 0.26	87.01	11.70 ± 0.33	84.16

Inhibitor/Concentration	IE(%)			Reference
Inhibitor/Concentration	298 K		333 K	323-333 K
SB1 / 600ppm	84.79	88.30		This work
SB2 / 600 ppm	89.73	85.07
SB3 / 600 ppm	87.28	84.16
B2 / 300 mg/L	96.50	85.90		³⁵35 Shahabi S, Hamidi S, Ghasemi JB, Norouzi P, Shakeri A. Synthesis, experimental, quantum chemical and molecular dynamics study of carbon steel corrosion inhibition effect of two Schiff bases in HCl solution. J Mol Liq. 2019;285:626-39.
PASP/SB / 80 mg/L	88.97	84.86		³⁹39 Wang C, Chen J, Han J, Wang C, Hu B. Enhanced corrosion inhibition performance of novel modified polyaspartic acid on carbon steel in HCl solution. J Alloys Compd. 2019;771:736-46.
DMAHB / 5x10^-3 M	87.30	89.92		⁴⁰40 Badr EA, Bedair MA, Shaban SM. Adsorption and performance assessment of some imine derivatives as mild steel corrosion inhibitors in 1.0 M HCl solution by chemical, electrochemical and computational methods. Mater Chem Phys. 2018;219:444-60.
BPT / 2.13 mmol/L	81.40	94.20		⁴¹41 Fernandes CM, Alvarez LX, dos Santos NE, Maldonado Barrios AC, Ponzio EA. Green synthesis of 1-benzyl-4-phenyl-1H-1,2,3-triazole, its application as corrosion inhibitor for mild steel in acidic medium and new approach of classical electrochemical analyses. Corros Sci. 2019;149:185-94.
DBB / 5x10^-4M	85.69	92.60		⁴²42 Bedair MA, Soliman SA, Bakr MF, Gad ES, Lgaz H, Chung IM, et al. Benzidine-based Schiff base compounds for employing as corrosion inhibitors for carbon steel in 1.0 M HCl aqueous media by chemical, electrochemical and computational methods. J Mol Liq. 2020;317:114015.

Compound (s)	Inhibitor concentration (ppm)	Surfactant concentration (ppm)	Total concentration (ppm)	Corrosion rate (mm/y)	Efficiency (%)	Synergism parameter (S)
A1	-	15	15	23.93 ± 1.33	67.61	-
A2	-	15	15	13.70 ± 2.11	81.46	-
SB1	600	-	600	8.65 ± 0.15	88.30	-
SB1 + A1	585	15	600	5.94 ± 1.10	91.97	1.70
SB1 + A2	585	15	600	7.10 ± 0.69	90.40	1.89
SB2	600	-	600	11.03 ± 0.31	85.07	-
SB2 + A1	585	15	600	5.17 ± 0.90	93.00	1.65
SB2 + A2	585	15	600	7.55 ± 0.61	89.78	1.86

Test	Concentration (ppm)	E_a (kJ mol^-1)	R²
Blank	0	64.51	0.9994
SB1	100	72.78	0.9906
SB1	600	56.72	0.9279
SB2	100	72.37	0.9992
SB2	600	74.98	0.9995
SB3	100	73.56	0.9999
SB3	600	70.58	0.9996

Inhibitor	Langmuir			Temkin		El Awady		Freundlich
Inhibitor	K_ads (L mg^-1)	R²	Slope	R²	Slope	R²	Slope	R²	Slope
SB1	0.0302	0.9976	1.0460	0.8443	0.0693	0.7721	0.5846	0.8589	0.0817
SB2	0.0752	0.9999	1.1238	0.9999	0.0384	0.9981	0.2869	0.9999	0.0458
SB3	0.0353	0.9999	1.1002	0.9658	0.0894	0.9782	0.5622	0.9622	0.1132

Sample	R_s (Ohm.cm²)	R_CT (Ohm.cm²)	Y₀ (CPE) (Sⁿ.Ω^-1.cm^-2)	n (0<n<1)	IE (%)
Blank	0.787±0.129	5.360±0.909	7.93x10^-4 ±1.53x10^-4	0.866±0.003	-
SB1 (100 ppm)	0.922±0.074	10.200±1.302	6.41x10^-4 ±2.45x10^-5	0.804±0.001	47.45
SB1 (600 ppm)	0.888±0.325	35.990±7.269	1.53x10^-4 ±4.24x10^-6	0.766±0.016	85.11
SB2 (100 ppm)	0.833±0.020	8.593±3.007	8.19x10^-4 ±1.42x10^-4	0.791±0.017	37.63
SB2 (600 ppm)	0.911±0.067	34.075±5.678	4.59x10^-4 ±2.89x10^-5	0.727±0.030	84.27
A2 (15 ppm)	0.744±0.009	8.713±0.982	3.80x10^-4 ±1.77x10^-5	0.851±0.000	38.48
SB1 (585 ppm) + A2 (15 ppm)	0.886±0.002	57.420±3.620	2.80x10^-4 ±2.47x10^-5	0.681±0.002	90.67
SB2 (585 ppm) + A2 (15 ppm)	0.733±0.218	48.145±4.009	3.36x10^-4 ±9.55x10^-5	0.671±0.034	88.89

Sample	-E_corr (mV)	I_corr (mA/cm²)	βc (mV/dec)	βa (mV/dec)	IE_PDP (%)
Blank	497.68	6.08	149.52	139.06	-
SB1 (100 ppm)	466.72	1.17	122.60	-	80.76
SB1 (600 ppm)	558.91	0.39	216.40	-	93.48
SB2 (100 ppm)	449.00	1.19	109.71	-	80.43
SB2 (600 ppm)	543.04	1.12	291.80	-	81.50
A2 (15 ppm)	517.94	2.75	115.60	-	54.66
SB1 (585 ppm) + A2 (15 ppm)	500.44	0.49	189.31	-	91.81
SB2 (585 ppm) + A2 (15 ppm)	499.66	0.80	201.77	-	86.76

Tests	Pitting depth (µm)
Blank	-
A2	-
SB1	111.30
SB2	228.40
SB1 + A2	203.70
SB2 + A2	-

Quantum properties	E_HOMO (eV)	E_LUMO (eV)	ΔE (eV)	μ (D)	X (eV)	$η$ (eV)	$σ$ (eV^-1)	Reference
SB1	-5.09	-1.10	3.99	4.55	3.09	2.00	0.50	-
SB2	-5.07	-1.08	3.99	4.76	3.07	2.00	0.50	-
SB3	-5.02	-1.06	3.96	4.15	3.04	1.98	0.51	-
Peumus boldus	-5.28	-0.52	4.76	2.33	2.90	2.38	0.42	⁶³63 Furtado LB, Nascimento RC, Guimarães MJOC, Henrique FJFS, Rocha JC, Seidl PR, et al. Cleaner corrosion inhibitors using Peumus boldus Molina formulations in oil well acidizing fluids: gravimetric, electrochemical and DFT studies. Sustain Chem Pharm. 2021;19:100353.
Schiff Base^* * 2-methoxy-4-(((2-(methylthio)phenyl)imino)methyl)phenol	-5.25	-1.42	3.82	2.93	3.34	1.91	0.52	⁷¹71 Furtado LB, Nascimento RC, Henrique FJFS, Guimarães MJOC, Rocha JC, Ponciano JAC, et al. Effects of temperature, concentration and synergism on green Schiff bases synthesized from vanillin in applications as corrosion inhibitors for carbon steel in well stimulation. J Petrol Sci Eng. 2022;213:110401.

Quantum properties	E_HOMO (eV)	E_LUMO (eV)	ΔE (eV)	μ (D)	X (eV)	$η$ (eV)	$σ$ (eV^-1)	ΔE_prot (kcal/mol)
SB1(imine)	-9.00	-5.81	3.19	3.24	7.41	1.60	0.63	-249.86
SB1(tertiary amine)	-8.46	-4.93	3.53	16.52	6.69	1.77	0.57	-208.89
SB2 (imine)	-8.95	-5.75	3.20	4.02	7.35	1.60	0.63	-242.78
SB2 (tertiary amine)	-8.28	-4.91	3.37	17.70	6.60	1.69	0.59	-209.10
SB3 (imine)	-8.83	-5.71	3.12	6.22	7.27	1.56	0.64	-256.19
SB3 (tertiary amine)	-8.20	-4.84	3.36	13.87	6.52	1.68	0.59	-214.38

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