Papers by Keyword: Inhibitor

Abstract: Applications of harmless fluid derivative for the sustenance of carbon steel in corrosive environments are more appropriate for environmental sustainability and safety of personnel. Admixture of grapefruit and lemongrass distillates was assessed for their protective performance on plain carbon steel within 0.5 M of H₂SO₄ and HCl solution through weight loss analysis and optical macroscopy studies. Results shows the plant extracts effectively stifled corrosion in both acids with inhibition value range (lowest to highest) of 98.65%-99.5% in H₂SO₄ solution and 96.31%- 98.39% in HCl. PCS in H₂SO₄ and HCl electrolyte at 0% extract concentrate were 5.330 mm/y and 2.701 mm/y. Inclusion of the distillate to the electrolyte significantly reduced the corrosion rates in both acids to midpoint values of 0.0448 mm/y and 0.072 mm/y at 240 h of test. The oil extract strongly adsorbed unto the steel surface by means of chemisorption with midpoint Gibbs free energy value above -44 Kjmol^-1 signifying strong covalent bonding. The extract adsorption aligned with Langmuir and Frumkin adsorption isotherms with interaction coefficient above 0.9. Optical images of steel surface without inhibitor showed a severely corroded morphology and significant reduction in thickness. The protected steel substantially differs the earlier observation due to the presence of the oil extract which passivated the steel exterior.

Abstract: Application of plant extracts for the corrosion protection of engineering materials is an ongoing research to replace the conventional toxic, costly and unsustainable chemical derivatives. Data on the corrosion inhibition performance of rosemary oil extracts on high carbon steel in 0.5 M C₆H₈O₇, 0.5 M H₂SO₄ and 3.5 wt.% NaCl solution was studied and the inhibition efficiency data statistically analysed. The oil extract performed poorly in C₆H₈O₇ solution with optimal inhibition efficiency of 49.21% at 1.5% extract concentration. However, the extract performed effectively in H₂SO₄ and NaCl solution with optimal inhibition efficiency of 78.45% at 2.5% extract concentration and 97.87% at 1.5% extract concentration. Inhibition efficiency varied significantly with exposure time and concentration. The oil extract exhibited chemisorption type adsorption mechanism in all the solutions in consonance with Langmuir, Frumkin and Freundlich adsorption isotherms. Statistical data on standard deviation showed the variation of extract inhibition efficiency with respect to mean inhibition value and exposure time was relatively significant in C₆H₈O₇ solution due to instability of inhibitor molecules, compared to the relatively low values obtained in H₂SO₄ and NaCl solution. Data from numerical variation showed extract concentration is the dominant statistically relevant inducing inhibition performance of rosemary oil extract in C₆H₈O₇ and NaCl solution with statistical relevance factor of 63.40% and 70.36% compared to the corresponding values obtained in H₂SO₄ solution were extract concentration and exposure time were statistically relevant. Data showed 30%, 19% and 90% of inhibition efficiency data in C₆H₈O₇, H₂SO₄ and NaCl solution are above 70% inhibition value at margin of error of +0.09, +0.077 and +0.059.

Abstract: Rutin flavonoid compounds have been isolated from cassava leaves and tested for their corrosion resistance against mild steel. Inhibition efficiency and adsorption properties were studied using the weight loss method at temperature variations of 303K, 313K, 323K and 333K and concentration variations of 0.1; 0.5; 1.0; 5.0; and 10 g/L. Potentiodynamic polarization was used to determine the inhibitor type of Cassava Leaf Routine (RCL). The results showed that RCL can reduce the corrosion rate and increase the corrosion inhibition efficiency of mild steel. The thermodynamic parameters have been calculated and the result is that the adsorption corrosion mechanism by physisorption takes place spontaneously with increasing temperature. Based on potentiodynamic polarization, the efficiency of corrosion inhibition by RCL with a concentration of 10 g//L on mild steel was 81.58%. RCL as a mixed corrosion inhibitor.

Abstract: Grain-oriented electric steel is hot rolled at different hot rolling temperature, and subsequent thermal maintained. Precipitation features of MnS and Cu₂S were observed under different process conditions using thermal field emission scanning electron microscopy. The results show that Cu is precipitate out in the form of a composite precipitate with MnS during hot rolling, The hot rolling temperature and the postrolling maintain time had no obvious effect on the precipitation of MnS, The lower the hot rolling temperature, the faster the Cu₂S precipitation. And the insulation process after high temperature hot rolling can make a large number of the Cu₂S diffusion precipitation, There was no significant effect on the precipitation of Cu₂S after low temperature hot rolling, still remain in the precipitate state after hot rolling.

Abstract: The protection performance Aloe vulgaris (AV) and Nicotiana tabacum (NT) leaf extracts on 1070 aluminum (Al) were separately studied while the combined admixture of the extracts (AVNT) on mild steel (MS) was also studied in 3.5% NaCl solution by gravimetric analysis. Data output showed AV and NT effectively stifled the redox reaction process responsible for Al corrosion in NaCl with protection performance data above 98% throughout the exposure hours signifying strong resilience of the extract molecules withstanding the corrosive anions and thermodynamic stability with respect to exposure time. AVNT performed effective on mild steel at relatively lower efficiency, but with final values above 80% efficiency. Statistical data for standard deviation shows the degree of variation of protection performance data for AV, NT and AVNT extracts from mean value is minimal signifying consistent data value with respect to exposure time. Data also showed 100% of AV and NT protection performance data are above 98% efficiency value at +0% margin of error while 14.29% of AVNT protection performance data are above 95% efficiency at margin of error of +14.97%. Data from analysis of variance shows AV extract concentration and observation time strongly influences the performance out of AV at rated value of 42.06% and 29.41%. NT extract concentration solely dominated the performance output of NT at 95.37% while the performance of AVNT was independent of its concentration with values below threshold significance. However, AVNT performance varied significantly with observation time signifying progressive improvement in performance in over time.

Abstract: The protection performance of admixed Lavandula latifolia and Ricinus communis (LLRC) oil distillates on low carbon steel in 0.5 M H₂SO₄ and HCl was performed by gravimetric measurement. Data output shows LLRC distillate effectively stifled the corrosion of the carbon steel with peak protection performance of 96.35% at 1% LLRC concentration in H₂SO₄ solution and 88.72% at 6% LLRC concentration in HCl solution. LLRC performed more effectively in H₂SO₄ solution than in HCl. The performance of LLRC in H₂SO₄ exhibited significant non dependence on observation time while LLRC concentration strongly influenced its performance. In HCl solution observation time and LLRC concentration influenced the performance output of LLRC distillate in different proportions. Statistical evaluation rated the influence of LLRC concentration the protection performance of LLRC at 90.66% compared to 2.22% for observation time, while the corresponding values in HCl are 55.37% for LLRC concentration and 21.04% for observation time. Calculated data for standard deviation shows relatively minimal variation from mean values with respect to LLRC concentration and observation time at lower LLRC concentration in H₂SO₄ solution. At higher LLRC concentration, the degree of variation increases due to relative instability with respect to exposure time. The standard deviation values in HCl are significantly and relatively higher than the values obtained in H₂SO₄ solution due to significant deviation from mean values which signifies extensive instability with respect to exposure time. The margin of error shows 91.7% and 93.3% of LLRC protection performance data in H₂SO₄ and HCl solution are greater than 80% inhibition efficiency at margin of error of +6.99% and +6.31%.

Abstract: The corrosion mitigation effect of aminophen (an organic fluid derivative) on 1070 aluminum alloy was studied in 1 M HCl solution by potentiodynamic polarization and weight loss analysis. Data obtained showed aminophen performed poorly at low concentrations (2.5%, 5% and 7.5%) with optimal value of 49.9% and 30% (potentiodynamic polarization and weight loss analysis) at 7.5% aminophen concentration. At 10% concentration, significant improvement in inhibition efficiency value was observed (53% and 61.33%), but the value is below the threshold minimum for effective inhibition. Effective inhibition efficiency occurred at 12.5% and 15% aminophen concentration with values of 71% and 81.67% at 12.5% concentration, and 89% and 70.77% at 15% concentration. Plots from weight loss indicated stable thermodynamic behavior throughout the exposure hours. Aminophen demonstrated anodic-cathodic type inhibition characteristics with dominant cathodic inhibition action. Corrosion inhibition behavior of aminophen aligned with Frumkin and Freundlich adsorption isotherm models. However, thermodynamic calculations show adsorption did not occur. Inhibition behavior of aminophen on 1070 aluminum occurred through modification of the corrosive media.

Abstract: Oxypeucedanin hydrate is a furanocoumarin widely found in various fruits and vegetables so it may interact with prescribed drugs leading to pharmacokinetic interaction. This study was conducted using in vitro cell culture model to investigate the role of oxypeucedanin hydrate on P-gp function. To evaluate the role of oxypeucedanin hydrate as a P-gp substrate, the bidirectional transport studies of oxypeucedanin hydrate were performed in LLC-PK₁ and LLC-GA5-COL300. The corrected efflux ratio of oxypeucedanin hydrate was 3.3 ± 0.7, indicating that it was a P-gp substrate. Calcein AM uptakes performed in comparison between LLC-PK₁ and LLC-GA5-COL300 as well as daunorubicin transport across Caco-2 cell monolayer were conducted to examine the inhibition effect of oxypeucedanin hydrate on P-gp. The results exhibited that oxypeucedanin hydrate significantly increased calcein accumulation in LLC-GA5-COL300 in a concentration dependent manner and, moreover, the b-a daunorubicin transport across Caco-2 cell monolayer was decreased from 7 to 5, implying the role of the compound on P-gp inhibition, although the effect was quite minimal. Collectively, the results suggested that oxypeucedanin hydrate could act as P-gp substrate and be likely to inhibit P-gp function.

Abstract: Comparative study of the corrosion inhibition effect of specific concentrations of cedrus atlantica (CA) and azadirachta indica (AI) oil distillates was performed on low carbon steel in 3M of C₆H₇O₈ by coupon analysis. Data obtained showed both distillates performed adequately at all concentrations assessed with principal inhibition value of 94.31% and 99.59%. The performance of CA oil distillate was concentration dependent compared to AI distillate which showed limited variation with respect to concentration. Statistical computation by analysis of variance shows inspection time and inhibitor concentration influences the inhibition performance of both compounds. The margin of error values shows the performance values of both compounds above 70% inhibition efficiency is 100% (+0%). Results from standard deviation shows the inhibition efficiency data varied positively with respect inspection time.

Abstract: The corrosion inhibition reaction of plant distillates and their synergistic combination effect was studied. Atlas cedarwood distillate (ACW), and admixture of sage and Jojoba distillates (SJA), and admixture of jojoba and lavender distillates (JLD) were evaluated at minimal concentrations to for their corrosion inhibition effect on mild steel in 1 M H₂SO₄ solution. Results showed ACW reacted poorly at 1% and 2% inhibitor concentration. However, from 3% - 6% ACW concentration the final corrosion rate of 94.73%, 94.77% and 95.61% was attained at 240 h signifying effective inhibition performance. SJA inhibitor compound exhibited optimal performance at all concentrations (1% - 6% SJA) with maximum inhibition value of 98.44% at 5% SJA concentration. JLD exhibited optimal performance at all concentrations studied after 2% JLD with maximum inhibition value of 91.07% at 3% JLD concentration and 240 h exposure time. The mean values for ACW and JLD inhibition efficiency appreciated with increase in inhibitor concentration while the value for SJA compound was generally constant. Results shows the extent of variation from mean values (standard deviation) for ACW and JLD was significantly high compared to the values obtained for SJA compound where the deviation from mean value is below 2. The Margin of error values for ACW and JLD compound shows that 65% and 60% of inhibition efficiency data have values above 70% inhibition efficiency compared to SJA where 100% of its inhibition efficiency data have values above 70% inhibition at +12.07%, +13.58% and +0% and +13.58%. Statistical analysis ANOVA only inhibitor concentration of the compounds significantly influenced their inhibition performance with values of 66.61%, 70.29% and 93.07% (ACW, SJA and JLD compound) compared to exposure time which had no influence. However, confirmation comparison of the mean square ratio of the compounds with the theoretical statistical tables shows the inhibitor concentration for JLD only is statistically relevant.