Corrosion inhibition and statistical data of low carbon steel in HCl media by admixed organic compounds

Corrosion inhibition of carbon steels with organic compounds exhibiting effective corrosion inhibition is an on-going research. The corrosion inhibition of low carbon steel in 1M HCl solution by the combined admixture of vanillin and benzonitrile (VBN), and salvia officinalis with lavendulan officinalis (SLV) was studied by weight loss method. Results obtained show that VBN and SLV performed effectively with maximum inhibition efficiency 91.03% at 1.5% VBN concentration and 97.89% at 5% SLV concentration. The inhibition efficiency of VBN increased with concentration but decreased with exposure time compared to the values obtained for SLV which showed non-dependence on concentration and exposure time after 1% SLV concentration. Correlation plots of inhibition efficiency versus inhibitor concentration show VBN to be more concentration dependent in performance. Calculated data for standard deviation shows the degree of variation from mean values for both compounds is significant at low inhibitor concentration due to time dependence action. Statistical analysis through ANOVA shows inhibitor concentration overwhelmingly influences the inhibition performance of the despite even though exposure time is statistically relevant to minimal degree

Heavily polluted mechanic workshop soil and its phenanthrene-degrading Bacillus thuringiensis

Mechanic workshops in residential areas are sites referenced for small-scale chronic contamination with petroleum hydrocarbons (HC) and associated pollutants like heavy metals. The main aim of this study was to isolate from a mechanic workshop soil in Lagos a novel indigenous bacterium with potential for degradation of phenanthrene, a model polyaromatic compound. Gas chromatographic analysis revealed concentrations of HC (20,055 mg kg-1), lead (156.19 mg kg-1) and zinc (202.005 mg kg-1) in excess of regulatory limits in the soil. Continuous enrichment resulted in the isolation of a bacterium strain ALSL2, which was identified by 16S rRNA gene sequencing as Bacillus thuringiensis. Strain ALSL2 showed broad specificity for a range of HCs including phenanthrene, anthracene, biphenyl, dibenzothiophene, crude oil, diesel and kerosene and also showed biosurfactant production with emulsification index 55.2 %, 65.7 % and 58.7 % on crude oil, kerosene and vegetable oil respectively. The isolate showed evidence of dioxygenase activity and utilized metabolites of aromatic hydrocarbon degradation including 1-naphthol and O-phthalate. At the end of 10 days 51.45 % of phenanthrene was degraded at the rate of 7.922 mg l−1 d−1, degradation constant 0.073 d−1, and half-life 9.864 d. The corresponding values for anthracene were 69.11 %, 9.92 mg l−1 d−1., 0.11 d−1, and 5.924 d respectively. Our findings represent a remarkable addition to available indigenous bioresources with potential for application in bioremediation, and further highlight mechanic workshop soils as veritable source of such isolate

Synergistic Combination Effect of Salvia officinalis and Lavandula officinalis on the Corrosion Inhibition of Low-Carbon Steel in the Presence of SO42−- and Cl−-Containing Aqueous Environment

The corrosion inhibition of low-carbon steel in 1 M H2SO4 and HCl solutions by the admixture of Salvia officinalis and Lavandula officinalis essential oil extracts was studied through potentiodynamic polarization analysis, coupon measurement and optical microscopy. The carbon steel undergoes severe surface deterioration in H2SO4, while the morphology of the steel from HCl showed selective deterioration with numerous corrosion pits in the absence of the oil extracts. The extracts performed effectively in the acid media with optimal inhibition efficiency of 86.92 and 96.90% in H2SO4, and 84.68 and 97.59% in HCl from potentiodynamic polarization and coupon analysis. The oil extract displayed anodic inhibition properties in H2SO4 due to surface coverage of the steel and cathodic inhibition in HCl due to selective precipitation of extract molecules. Thermodynamic calculations show the extracts adsorbed onto the steel surface, effectively suppressing the corrosion reactions through chemisorption mechanism according to the Langmuir, Frumkin and Freundlich adsorption isotherms