In order to remove pigment soil, it is necessary to reduce the attraction between pigment and underlying materials as much as possible. You must therefore try to introduce a corresponding repulsion so that the pigment spontaneously or with the help of mechanical energy can be made to leave the surface. Most particles and surfaces are given a negative surface potential in an air or water current. Increasing this potential should therefore increase the repulsion. This is easiest obtained by increasing the concentration of OH-, i.e. increasing the pH. In practice, this has been known for a long time and for instance soda has been used as alkali for washing.
However, for effective cleaning it is not enough to only increase the negative surface potential. This is where the surfactants come in. The surfactants are adsorbed to the pigment an to the different underlying materials. The negatively charged anionic surfactants are here increased with repelling energy and the pigment removal is further improved. The anionic surfactants have a good pigment removing capacity on certain materials, e.g. textiles. On the other hand, on hard surfaces that are to be cleaned, anionic surfactants can make pigment removal more difficult. Certain cationic surfactants in combination with nonionic surfactants have a considerably better pigment removing capacity on hard surfaces. This must be the explantion: different surfaces have different charges.
Nonionic surfactants often have good pigment removing capacity on all surfaces. The nonionic surfactant is adsorbed with its hydrophobic part on both the pigment and the surface, and removes the pigment from the surface with ist large hydrophilic part that ist surrounded by water molecules. In this way water enters between the pigment and the surface, and the pigment is easily released.
Whether heat exchangers, refrigeration and air conditioning systems, or cleaning as a pre-treatment before electroplating, enamelling and finishing is our daily bread. Experience of 55 years is our capital. Whether tape, screws or operational maintenance, we develop the right processes for all areas. Ecological and economic aspects are at the top of the list of priorities.
Want to join the discussions?
Log in to read, write and comment on group posts.