Portugaliae
Electrochimica Acta

Concrete is one of the most commonly used construction materials, but there is a need to develop a new and sustainable technology to make it more affordable. With the advancement in technology, concrete is no longer seen as a composite of three elements (binder, aggregate, and water). The distinctive workability properties of SCC make it unique in the concrete industry. This review has assessed the materials, strength and rheological properties of agricultural waste, industrial waste and mineral additives in SCC production. The effect of the utilization of these additives and replacements on structural, mechanical and rheological properties of SCC has been studied. This review has revealed that the use of both industrial and agricultural waste enhances the strength properties of SCC. Additionally, the use of agricultural waste improves the rheological properties of fresh concrete. The utilization of expansive materials should be discouraged in SCC production. This review has revealed that SCC developments ensure a good balance between deformability and stability. It is therefore recommended that SCC is utilized in pavement construction, particularly when high axle load is expected.

In this study, Fenton, photo-Fenton, electro-Fenton, anodic oxidation and heterogeneous photocatalysis advanced oxidation processes (AOPs) have been applied to degrade reactive yellow 17 (RY17) dye in an aqueous solution. Comparison of these techniques for oxidation efficiency was undertaken. The results showed better performance with the use of a heterogeneous photocatalysis process. Degradation efficiency was observed in the order: heterogeneous photocatalysis > photo-Fenton = electro-Fenton > anodic oxidation > Fenton. Even though complete RY17 dye degradation has been observed with heterogeneous photocatalysis, photo-Fenton and electro-Fenton processes, the heterogeneous photocatalysis process has showed complete RY17 dye removal within 30 min, whereas in the case of photo-Fenton and electro-Fenton processes, no RY17 was detected after 60 min. Fenton and anodic oxidation processes have required more time for complete RY17 degradation. The RY17 degradation kinetics was studied and compared in all processes. The results showed higher rate constant values for heterogeneous photocatalysis (kapp = 0.2 min−1), photo-Fenton (kapp = 0.126 min−1) and electro-Fenton (kapp = 0.122 min−1) processes.

The chemical composition of Jatropha curcas seeds oil was determined using chromatography gas (GC/MS) analysis after the esterification of fatty acids to methyl ester (FAME). The obtained results show that the average yield of Jatropha curcas seeds oil reached a maximum value of 50%. The seeds oil fatty acids carbon chain was composed of palmitic, oleic and linoleic acids. The percentage of unsaturated fatty acids reached a value of 77%.The new developed formulation containing Jatropha curcas seeds oil (labeled as JAC) was tested as a friendly iron corrosion inhibitor in an acidic medium by potentiodynamic polarization and Electrochemical Impedance Spectroscopy (EIS) techniques. The surface analysis was performed using Scanning Electron Microscopy (SEM). The electrochemical measurements show that the JAC formulation is a mixed type inhibitor. The obtained inhibition efficiency results increase with higher inhibitor concentrations, to attain a maximum value of 97% at 250 ppm. Furthermore, the protective effect is reinforced by increasing the immersion time and the rotation speed of the working electrode.

Experimental electrochemical methods, combined with Monte Carlo simulations, have been employed to investigate the possibility of using 1-decyl-2-(decylthio)-1H-benzimidazole (T2) as corrosion inhibitor for mild steel in a 1 M HCl medium. This inhibitor was found to be of the mixed type. The results derived from EIS indicate that the charge transfer resistance has increased with the increase in the inhibitor concentration. The inhibitory mechanism was explored by the potential of zero charge (Epzc) measurement at the solution/metal interface. The inhibitor adsorption has followed Langmuir adsorption isotherm. Surface morphology results showed the compound adsorbed film on a mild steel surface. The molecule interactions with the mild steel surface were simulated based on Monte Carlo simulation approach using Fe(111) crystal surface as a representative metallic surface.

An expired drug with non-toxic characteristics has been evaluated as a corrosion inhibitor for mild steel alloy. The corrosion inhibition efficiency of the expired ethambutol drug in a 0.5 M HCl solution has been studied using weight loss, electrochemical impedance spectroscopy (EIS), electrochemical polarization, scanning electron microscopy (SEM) and molecular dynamics (MD) techniques. The results showed that the drug provides appreciable inhibition efficiency, more than 95% at the higher concentration, i.e., 1000 ppm. The Tafel polarization plots have shown that the expired drug acted as a mixed type inhibitor. Langmuir adsorption isotherm, along with physiochemical mode of interaction, has proved that the corrosion inhibition process accords with the isotherm. The outcomes obtained from all the experimental techniques and theoretically obtained information are in good correlation. MD simulations reveal that the studied compound adsorbs onto the surface of mild steel in the planar orientation.