Pure alkali degreasing? - The principle of pure alkali degreasing

In life, the biggest problem mothers often encounter in the kitchen is the oil stain problem. Oil stains in life are usually in the kitchen, mainly splashed when cooking or frying food. Many repair shops also encounter this tricky problem. So what is the most effective way to remove oil stains? The most effective way to remove grease is to use pure alkali, because the main component of grease is ester, which will turn into water when it meets pure alkali.

Pure alkali degreasing? - The principle of pure alkali degreasing

In actual production processes, pure alkali is not used alone to remove oil stains, especially when there are both oil stains and dirt (the former is mainly organic, and the latter is mainly inorganic). Instead, the so-called alkaline detergent is used. Its decontamination principle includes not only saponification reaction, but also emulsification, dispersion, solubilization, diffusion, mechanical action and electrochemical action, etc. Sometimes the role of the latter is decisive for the degree and effect of decontamination.

Alkaline cleaning liquid is widely used in wet coating, metal material heat treatment and other technologies, and is divided into chemical degreasing and electrochemical degreasing according to whether external current is applied during the purification process. Typical alkaline detergent formulations generally include sodium hydroxide, sodium carbonate, sodium phosphate, and sodium silicate.

Chemical alkaline liquid degreasing mainly uses the sodium hydroxide component in the alkaline liquid to remove vegetable oil through saponification, and removes mineral oil with the help of the emulsification effect of sodium silicate or surfactant. Its advantage is that it has a wide cleaning range for common industrial pollutants and can obtain a hydrophilic surface after purification. It is particularly suitable for degreasing before wet coating and surface conversion treatment.

Compared with organic solvents, it has the advantages of being non-toxic, non-flammable, easy to operate, simple in equipment, and economical. However, alkaline cleaning liquid is corrosive to metals, takes a long time to clean, usually requires heating, and the waste liquid needs to be treated before it can be discharged.

Electrochemical degreasing is also called electrolytic degreasing. Its basic principle is: in an alkaline electrolyte, with the workpiece as the cathode or anode and the iron plate or nickel-plated plate as the anode or cathode, when power is turned on, hydrogen or oxygen is electrolytically precipitated on the surface of the workpiece. The precipitated hydrogen or oxygen bubbles have a strong mechanical tearing and impact effect on the oil stains on the surface of the workpiece, prompting the oil stains to separate from the surface of the workpiece. At the same time, the stirring effect of the solution near the surface of the workpiece also accelerates the saponification and emulsification of the alkaline solution. Depending on the polarity of the workpiece, electrochemical degreasing can be divided into anodic degreasing and cathodic degreasing.

In addition, hot alkaline liquid degreasing has actually been eliminated in advanced countries and some important manufacturing companies in my country (such as Shanghai Volkswagen). The more environmentally friendly, energy-saving and efficient industrial cleaning technologies include the use of aqueous cleaning agents, organic steam cleaning, high-pressure jet cleaning and ultrasonic cleaning.