Evaluation of Phosphopolyoxometalates with Mixed Addenda (Mo, W, V) as Corrosion Inhibitors for Steels

Abstract

Nowadays, choosing a corrosion inhibitor is not only based on efficiency, but must also consider the toxicity of the compound, the impact on the environment, and, obviously, the regulations in the field. In the last two decades, a special class of substances has begun to be studied, namely polyoxometalates (POMs). Their electronic properties and redox characteristics make the polyoxometalates potential candidates to be used in many electrochemical processes, and as potential corrosion inhibitors. Electrochemical methods such as a Tafel extrapolation plot, chronopotentiometry, or gravimetry have been used to establish the capacity of corrosion inhibition of S235 and SS304 steels in the presence of phosphovanadomolibdate acid (@PMoV) and phosphovanadotungstate acid (@PWV) in 0.5 M sulphuric acid solution. The inhibition efficiency for S235 steel is about 90.6% for @PMoV, and 69.5% for @PWV after 24 h of immersion. In the case of SS304 steel, polyoxometalates have similar effects: the inhibition degree, as a function of Flade potential, is 4.66 for @PMoV; better than 3.26 for @PWV, with both proving the passivant effect.

Inhibition Effect of Triphenylmethane Dyes for the Corrosion of Carbon Steel in CO2-Saturated NaCl Corrosion Medium

“…It can be seen from the figures that the addition of the corrosion inhibitor results in a shift in both the cathodic and anodic polarization curves to the left to various extents, and the reduction in polarization current density indicates that the corrosion inhibitor has a significant inhibitory effect on both the anodic dissolution and the reduction in cathodic hydrogen ions in the corrosion process of carbon steel [ 18 ]. Additionally, the figures reveal that the corrosion potential of this inhibitor does not show significant differences at different concentrations, indicating that CV is a mixed-type corrosion inhibitor [ 30 ].…”

Research on the Synthesis of Zinc–Ammonium Phosphate Using Galvanic Waste Sludge as a Source of Zinc

“…While zinc-ammonium phosphate has various industrial applications, its use should be mindful of environmental impacts. Proper disposal and management practices are essential to minimize any potential ecological effects [2][3][4][5][6][7][8][9][10].…”