1; Adsorption residue problem

In the washing process, surfactants that are difficult to dissolve in water instead of dirt are adsorbed on the surface of the cleaning object, and it is often difficult to remove it by washing with water. It is theoretically analyzed that washing with a large amount of water for multiple times to dissolve and dissolve can completely remove the adsorbed surfactant. However, under actual rinsing conditions, there will always be trace amounts of surfactants that form a covering film on the surface of the object and remain. In the precision cleaning process prior to the painting, electroplating and vacuum coating process, it is required to solve the problem of removing the surfactant coating film adsorbed on the surface with a thickness of only about 0.1 nm. If a degreasing surfactant (a surfactant with a low HLB value) is used for decontamination, it is also difficult to remove with water. The use of higher temperature water improves the rinsing ability, so the method of raising the temperature of the rinsing water is generally used to reduce the residual surfactant on the surface. When it is required to completely remove the residual surfactant, the method of soaking in ethanol or isopropanol is required, because alcohols have a good solubility for surfactants. Or after removing dirt with a degreasing surfactant, wash with a hydrophilic surfactant to remove the lipophilic surfactant, and then rinse with water to remove the hydrophilic surfactant .
In short, we must pay attention to solving the residual problem of surfactants, especially in the field of precision industrial cleaning is more important.

2; Environmental pollution issues

Many wastes generated during the cleaning process and discharged into the environment will cause pollution. In particular, the surfactant mixed into the washing waste liquid and flows into natural waters is an important factor that causes environmental damage. There are many surfactants that are difficult to be biodegraded, such as sodium branched alkylbenzene sulfonate, so it should be avoided as much as possible to reduce environmental pollution. So far, it has been replaced by sodium benzene sulfonate, a stubborn disease, which is biodegradable. In addition, the non-ionic surfactants of the alkylphenol polyoxyethylene ether series are also poor in biodegradability. At present, it is required that the wastewater containing them must be treated by activated sludge before being discharged. Moreover, their usage has been reduced and other types of nonionic surfactants have been used.

From the point of view of biodegradation, all products of natural origin or substances with similar structures are easily degraded. For example, surfactants synthesized from high-carbon alcohols, fatty acids, and glucose have good biodegradability, and the environment is compatible with such substances. Sex is good.