<p> Supplementary Material</p><p>Synthesis and inhibition effect of novel Tri-cationic surfactant on</p><p> carbon steel corrosion in 0.5 M H2SO4 solution</p><p>A.S. El-Tabeia, M.A. Hegazy a, *, A. H. Bedairb, M.A. Sadeqb</p><p> aEgyptian Petroleum Research Institute (EPRI), Nasr City, Cairo, Egypt</p><p> bFaculty of Science, Al-Azhar Univ., Chemistry Dept., Nasr City, Cairo, Egypt</p><p>*Corresponding author. Tel.: +20 1002653529; fax: +20 222747433.</p><p>E-mail address: [email protected] (M.A. Hegazy).</p><p>1 Caption of figures </p><p>Fig. 1: 1HNMR spectrum of N-((pyridin-2-ylamino)(pyridin-3-yl)methyl)pyridin-</p><p>2-amine.</p><p>Fig. 2: Mass spectrum of N-((pyridin-2-ylamino)(pyridin-3-yl)methyl)pyridin-2-</p><p> amine.</p><p>Fig. 3: FITR spectrum of 2,2'-(((1-dodecylprydinium bromide)-3-</p><p> yl)methylene)bis(azanediyl)bis(1-dodecylprydinium bromide). </p><p>Fig. 4: 1HNMR spectrum of 2,2'-(((1-dodecylprydinium bromide)-3-</p><p> yl)methylene)bis(azanediyl)bis(1-dodecylprydinium bromide</p><p>Fig. 5. Suggested equivalent circuit model for the studied system.</p><p>Fig. 6: Effect of temperature on the inhibition efficiency obtained by weight loss</p><p> method for carbon steel in 0.5 M H2SO4 in presence of different</p><p> concentrations of the synthesized Tri-cationic surfactant at various</p><p> temperatures.</p><p>Fig. 7: Langmuir isotherm adsorption model of the synthesized Tri-cationic</p><p> surfactant on the carbon steel surface in 0.5 M H2SO4 at different</p><p> temperatures.</p><p>Fig. 8: The relationship between (ln Kads and 1/T) for carbon steel in different</p><p> concentration of the synthesized Tri-cationic surfactant.</p><p>2 Fig. 9: Arrhenius plots (ln k vs. 1/T curves) for carbon steel dissolution in absence</p><p> and presence of different concentrations of the synthesized Tri-cationic</p><p> surfactant in 0.5 M H2SO4 solution.</p><p>Fig. 10: Relationship between ln k/T and the reciprocal of the absolute</p><p> temperature of carbon steel in different concentration of the synthesized</p><p>Tri-cationic surfactant. </p><p>3 4 Fig. 1</p><p>5 Fig. 2</p><p>6 Fig. 3</p><p>7 Fig. 4</p><p>8 Fig. 5</p><p>Fig. 6</p><p>9 Fig. 7</p><p>Fig. 8</p><p>10 Fig. 9</p><p>Fig. 10</p><p>11 Table 1</p><p>Activation parameters for carbon steel in 0.5 M H2SO4 in the absence and presence of different concentrations of Tri-cationic surfactant</p><p>* * Conc. of inhibitor Ea ∆H ads ∆S ads</p><p>M kJ mol-1 kJ mol-1 J mol-1 K-1 0.00 35.12 32.53 -76.64 1x10-5 28.68 26.09 -102.76 5x10-5 27.77 25.18 -110.27 1x10-4 25.40 22.81 -121.93 5x10-4 25.19 22.60 -129.33 1x10-3 19.59 17.00 -149.71</p><p>3. Results and discussion</p><p>The chemical structure confirmation of the synthesized Tri- cationic surfactant</p><p>N-((pyridine-2-ylamino)(pyridine-3-yl)methyl)pyridine-2-amine </p><p>FTIR spectra</p><p>12 FTIR spectrum of N-((pyridin-2-ylamino)(pyridin-3-yl)methyl)pyridin-2-amine showed the characteristic bands (cm-1) at 3248 (N-H), 3091, 3059, 3022 (py-H), 2925,</p><p>2853, (C-H aliphatic), 1605 (C=N).</p><p>1HNMR spectra</p><p>1 HNMR spectrum (DMSO – d6) spectrum (Supplementary material, Fig. 1) showed δ, ppm at : 5.81 (2H, 2C-H) and (24 py-H + 4N-H), 6.3825, 6.5751 (4H , 2d, J=5.04</p><p>Hz), 6.40695 (1H, d, J= 5.33 Hz), 6.4933 (2H, t, J= 7.65), 6.912 (1H, t, J=7.65 Hz),</p><p>7.18265 (2H, d, J= 7.65 Hz ), 7.3722 – 7.3034 (6H, m), 7.5433 (1H), 7.8055 (2H, d,</p><p>J= 8.4 Hz), 7.8444 (1H, d, J=4.55 Hz), 7.8857 (1H), 7.9166 (2H, d, J=5.35 Hz),8.3744</p><p>(1H, d, J=9.2 Hz), 8.4268, 8.7141 (2H, 2d, J=4.6 Hz), 8.49175 (1H, d, J=3.85), 8.6331</p><p>(1H, s).</p><p>Mass spectra </p><p>Mass spectrum of N-((pyridin-2-ylamino)(pyridin-3-yl)methyl)pyridin-2-amine</p><p>(Supplementary material, Fig. 2) showed a molecular ion peak M+2 at m/z 279 (66.64</p><p>%), 185 (55.82 %, M-C5H4N2), 171, (48.82 %, M-C5H4N2-CH2).</p><p>According to the data FTIR, 1HNMR, Mass spectroscopy, the product is a mixture of two compounds: N-((pyridin-2-lamino)(pyridin-3-yl)methyl)pyridin-2-amine (major) and N-((2-iminopyridin-1(2H)-yl)(pyridin-3-yl)methyl)pyridin-2-amine (trace).</p><p>2,2'-(((1-dodecylprydinium bromide)-3-yl)methylene)bis(azanediyl)bis(1-</p><p> dodecylprydinium bromide)</p><p>FTIR spectra</p><p>FTIR spectrum of 2,2'-(((1-dodecylprydinium bromide)-3- yl)methylene)bis(azanediyl)bis(1-dodecylprydinium bromide) (Supplementary</p><p>13 material, Fig. 3) showed characteristic bands (cm-1) at 2924, 2853, (C-H aliphatic),</p><p>1663.30 (C=N+).</p><p>1HNMR spectra</p><p>Comparing the 1HNMR spectrum of 2,2'-(((1-dodecylprydinium bromide)-3- yl)methylene)bis(azanediyl)bis(1-dodecylprydinium bromide) presented in</p><p>(Supplementary material, Fig. 4) and 1HNMR spectrum of N-((pyridin-2-ylamino)</p><p>(pyridin-3-yl)methyl)pyridin-2-amine presented in Fig. 2. Fig. 5 showed the same peaks in Fig. 2 in addition to other peaks δ, ppm at: 0.8150 (9H, CH3), 1.19 (m, 60H,</p><p>+ (CH2)30), 3.3218 (6H, NCH2).</p><p>The above data of FTIR and 1HNMR spectra confirmed the proposed structure of the synthesized Tri-cationic surfactant (2,2'-(((1-dodecylprydinium bromide)-3- yl)methylene)bis(azanediyl)bis(1-dodecylprydinium bromide)).</p><p>14</p>