Cyclic voltammetric studies of carbon steel corrosion in chloride-formation water solution and effect of some inorganic salts

AbstractThe influence of sulfide, sulfate and bicarbonate anions on the pitting corrosion behavior of carbon steel in formation water containing chloride ions were analyzed by means of cyclic voltammetry technique and complemented by X-ray diffraction (XRD) investigation. The anodic response exhibits a well-defined anodic peak A, followed by a passive region. A pronounced increase in the anodic current density is observed in the passive region at pitting potential (Epit). On the other hand, the cathodic sweep shows two cathodic peaks CI and CII. The data show that the presence of chloride ions causes pitting corrosion of carbon steel in formation water. It was found that both the pitting potential Epit and the repassivation potential (Epro) decreased with increase in Cl− ions concentration. Data clearly show that the presence of Na2S with 0.3M of chloride ions has a strong accelerating effect on the active dissolution and pitting corrosion of carbon steel in formation water, while the presence of Na2SO4 and NaHCO3 with chloride ions has an inhibiting effect on the active dissolution and pitting corrosion

Castor oil biodiesel production and optimization

Biodiesel is evolving to be one of the most employed biofuels for partial replacement of petroleum based diesel fuel, especially in recent years. The most widely used feedstocks for biodiesel production are vegetable oils. In this work, biodiesel production from castor oil has been synthesized by homogenous alkaline transesterification. The influence of catalyst concentration, methanol:oil molar ratio, reaction temperature and reaction time in the methyl ester content reached by castor oil transesterification have been evaluated. A yield of 95 wt% biodiesel was achieved at 1 wt% KOH, 60 °C, 9:1 methanol:oil ratio and 30 min reaction time. Transesterification at temperature 30 °C gave a yield compatibles with that obtained at 60 °C. The composition of the fatty acid methyl ester was determined by Gas Chromatography. The castor oil biodiesel produced was blended with different concentrations of petrodiesel to obtain B5, B10 and B20. The biodiesel properties and its blends were determined according to the standard test methods of analysis. The results showed that Castor oil biodiesel in the blends could lower the cloud point value, but simultaneously, increases the viscosity of the diesel–biodiesel blends. Thus, castor oil biodiesel with its very low cloud and pour points is suitable for using in extreme winter temperatures. Keywords: Biodiesel fuel, Castor oil, Transesterification, Gas chromatography, Biodiesel propertie