Inhibition of mild steel corrosion using Jatropha Curcas leaf extract

Jatropha Curcas leaf was investigated as a green inhibitor on the degradation of mild steel in 4 M HCl and 4 M H2SO4 aqueous solutions using gasometric technique. Mild steel coupons of dimension 2 × 1.5 cm were immersed in test solutions of uninhibited acid and also those with extract concentrations of 4 ml, 6 ml, 8 ml and 10 ml at 30 oC, for up to 30 minutes. The results showed that as the concentration of the extract increases, there was reduction in the corrosion rate. As the extract concentration increased from 4 ml to 10 ml at 30 minutes exposure, the volume of hydrogen gas evolved decreased from 19.1 cm3 to 11.2 cm3 in H2SO4 medium, while it reduced to 5 cm3 from 9 cm3 in HCl medium. Also, the metal surface-phytoconstituent interaction mechanism showed that 6 minutes is the best exposure time for the adsorption of the extract in both acidic media. The Jatropha Curcas leaf extract was adsorbed on the mild steel surface to inhibit corrosion, while the experimental data obtained at 30 minutes exposure in both acidic media were well fitted with the Langmuir adsorption isotherm. Hence, Jatropha Curcas leaf extract is a good and safe inhibitor in both acidic solutions

Corrosion Inhibition Efficacy of Hybrid Organic Extracts from Prosopisafricana and Citrulluslanatus on Mild Steel in Acidic Medium

Each of Prosopis Africana pod extract (PAPE) and Citrulluslanatus (WMPE) performed quite well as green inhibitors in the electrochemical corrosion in acidic solution at ambient temperature in previous research. However, the hybridization of these compounds was varied with the concentration ratio in this study to optimize the efficiency of the green inhibitor in a hydrochloric acid medium using mild steel. The extraction process of the inhibitor samples was carried out with the Soxhlet apparatus using n-hexane as the solvent. Furthermore, the potential inhibition efficiency was monitored using various corrosion measurement techniques at room temperature. The inhibitive response of the extracts could be attributed  to the adsorption of the extracts’ components on mild steel surface by physisorption mechanism according to the Langmuir adsorption isotherm model. The results revealed that inhibition efficiency (IE%) depends on the concentration of the extracts. The peak IE% values were obtained with a hybrid ratio of 3:1 (PAPE: WMPE) for gravimetric technique. The Tafel polarization and gasometrical measurement technique is 96.7%, 98.5% and 83.1% respectively at the concentration of 1.0 g/L, which are above the peak IE% for PAPE (93.7%, 80.96% and 77.8%) and WMPE (92.7%, 80.5% and 75.6%)

Corrosion of food grinding discs in gastro-intestinal environment

The need for food size reduction before consumption has led to the use of motorized grinding machine which operates on energized rubbing of two grooved cast-iron discs, and this unintentionally results in tribological degradation and corrosion of grinding discs into the ground food. The objective of this study was to carry out an assessment of corrosion susceptibility of grinding discs from different manufacturing methods in simulated gastro-intestinal environment. Six grinding discs from three states in Nigeria were selected for this study, based on manufacturing methods namely: rotary, cupola, and pit furnaces. Experimental techniques used for the study included: X-Ray Fluorescence spectroscope for determination of chemical composition and X-Ray Diffractometer was used for phase identification. Corrosion susceptibility of grinding discs on interaction with pseudo-body fluid was studied using potentiodynamic polarization scan and product analysis (gasometric) methods in simulated gastro-intestinal environment, typical of human stomach, as electrolyte. The electrolyte contained 2 g/L NaCl acidified to pH of 1.7 with HCl and regulated at 37 °C. Optical microscopy of the electrochemical samples was done for corrosion damage assessment. The key finding from the study was that all the grinding discs contain iron and silicon as dominant alloy elements, which existed predominantly as iron carbide and ferrosilicon phases. Corrosion of the discs in simulated gastric solution was well profound irrespective of the manufacturing method, though, with varying degree among the discs. The outcome of this study is applicable to food industries where cognitive measures may have to be taken on materials selection to minimise the risk of food contamination from materials corrosion