Abstract The aim of this study was to evaluate the quantity of vanadium removed through electrokinetic remediation applied to catalyst waste used in a fluid catalytic cracking process. In excess, vanadium affects process efficiency by reducing the catalyst’s activity, causing deactivation and reducing its useful life in petroleum cracking during refining. The electrochemical reactor used was composed of an extra cathode chamber coupled with an ion-selective cation exchange membrane, Nafion ®. The function of the cathode chamber was to increase the overpotential for a hydrogen reduction reaction (HRR) and the electric field to favour metal ion removal. Sodium citrate was used for electrolyte remediation (complexing vanadium) at 0.5 mol/L with an 11.0 V (ε =0.5 V/cm) potential applied. The treatment efficiency was analysed based on the vanadium ion concentration in the electrolyte collected. The results show that electrokinetic remediation using the dual cathode chamber yielded more metal removal and lower energy consumption.

The formation of a protective layer of iron carbonate (FeCO3) can reduce the rates of corrosion and prolong the useful life of carbon steel. However, turbulent flow conditions in this layer can easily be damaged and thus compromise the protection of the steel. In this work, will be presented a methodology based on the chemical aspects of the mechanism of formation of iron carbonate layer in a Thin Channel Flow Cell (TCFC). Electrochemical techniques were used to measure the corrosion rate and corrosion potential on the surface of steel API X65 exposed to aqueous solution of 1 wt.% NaCl purged with CO2 at 2 atm, pH 6.6 and 80°C in turbulent flow conditions. The surfaces and cross sections of the samples were characterized by means of Scanning Electron Microscopy (SEM) and Energy-Dispersive X-ray (EDS) analysis. The results confirm the nucleation and growth of iron carbonate layer: the extension of supersaturation of the solution and the corrosion rate have decreased, and the corrosion potential has increased. The surface analysis showed dense and uniform FeCO3 layer with c.a. 20 µm thick after 120 hours in turbulent flow conditions.