Mechanisms of scale formation and inhibition

Scaling is a very common and serious problem in industries. The formation of scale is enabled by the presence of dissolved salts in a supersaturated solution. The precipitation of a crystalline substance from a solution onto the site of scale formation requires three simultaneous factors: supersaturation, nucleation, and adequate contact time. The scaling rate is influenced by the supersaturation level, retention time, temperature, hydrodynamic conditions (velocity, pipe diameter, Reynolds number), surface roughness, and the type of the surface material. Scale formation can be reduced or completely inhibited by many types of chemical additives, coined scale inhibitors. which have different efficiency on different scalants. The effectiveness of the inhibitors depends on various factors such as contact time, temperature, solution pH, as well as the additive structure and concentration. The Langmuir isotherm can be used effectively to predict the efficiency of scale inhibitors.