Characteristics of Air Nanobubbles in Circulating Cooling Water and Their Corrosion Inhibition Mechanism on Stainless Steel: The Role of Temperature

The influence of temperature on the physicochemical properties of air nanobubbles (A-NBs) in a complex salt solution is crucial for their application in corrosion inhibition within circulating cooling systems. The variation patterns of the physicochemical properties, the corrosion inhibition of A-NBs on stainless steel and their underlying mechanisms in the temperature range of the circulating cooling system were investigated. Results indicated that increasing temperature led to a decrease in the number concentration of A-NBs, their average particle size, and the absolute value of the zeta potential gradually. Weight loss measurements, electrochemical analyses, and morphological characterizations of corrosion specimens demonstrated that A-NBs exhibited effective corrosion inhibition, particularly at concentrations on the order of 107 particles/mL and temperature ≤50 °C. Electrical conductivity, impedance, and surface characterizations of the corrosion specimens revealed that elevated temperatures were detrimental to the stability of A-NBs and the bubble layer. The binding effect of A-NBs on corrosive ions, as well as the protective roles of the passive film, calcium carbonate scale, and bubble layer on the stainless steel surface, were weakened, leading to an accelerated corrosion rate. This study provides insights into the industrial application of A-NBs as an environmentally friendly corrosion inhibition technology.