The Effects of Detergent Pollution on the Corrosion of Iron and Aluminium

Corrosion of metals depends on the kind of metal and the prevailing conditions in the medium (temperature, pH, pressure, concentration, etc.) as well as the type of ions such as CO3 , NO − 3 , Cl − and NO2 present in the medium. It will be useful to briefly discuss the effects of some ions on metals. The ions mentioned above have different effects on metals. For example, CO3 is adsorbed on the metal surface and produces insoluble carbonates with iron. As a result, the metal is isolated from the medium and corrosion is prevented . Having an oxidizing character, NO3 increases the dissolution of the metal, and the protective effect of the oxide phase which is formed, similar to the effect of carbonate precipitations, decreases the corrosion . On the other hand, ions such as Cl− , Br− and F− which are adsorbed selectively on the metal surface, prevent the formation of the oxide phase on the metal surface, thus allowing continuous corrosion on the naked surface1−10 . The chloride ion produces metal chlorides in stationary parts of the metal and corrosivity of the medium increases as a result of hydrolysis. In short, chloride ions increase corrosion on many metals6−10 . It is claimed that nitro compounds or nitrite ions adsorbed on metal surfaces decrease the free energy of the system, thus inducing the onset of passivity . Organic substances as well as inorganic ones affect the corrosion rate. It is claimed that if organic molecules have groups like -OH, -CHO, -COOH, -CN, -SCN, -CO, -NH2 , -SO3 , double or triple bonds or unpaired electrons, the substance and the metal interac easily, and charging the zero charge potential, an effective protection is provided .