Common cleaning agents can be classified in different ways. For example, according to their chemical composition, they can be divided into inorganic chemical cleaning agents and organic chemical cleaning agents [2]; according to some cleaning agents may have different effects on different dirt, or have two or more effects on the same dirt, they should be classified according to their important effects under normal circumstances.
1. Water and non-aqueous solvents
The solvent of dirt refers to those substances that can strip off the dirt of the cleaning object in the form of dissolution or dispersal without generating new substances with stable and definite chemical composition. It includes water and non-aqueous solvents.
(1) Water: Water is the most important solvent that exists in nature. In industrial cleaning, water is both the solvent for most chemical cleaning agents and the solvent for many dirt. In cleaning, wherever the dirt can be removed with water, non-aqueous solvents and various additives are not used.
(2) Non-aqueous solvents: Non-aqueous solvents include hydrocarbons and halogenated hydrocarbons, alcohols, ethers, ketones, esters, phenols, etc., and their mixtures. They are mainly used to dissolve organic dirt such as oil dirt and certain organic compound dirt.
2. Surfactants
Their molecules simultaneously have hydrophilic polar groups and lipophilic non-polar groups. When a small amount is added, it can greatly reduce the surface tension and liquid interface tension of the solvent (usually water), and has lubricating, solubilizing, emulsifying, dispersing and washing functions.
Surfactants have many classification methods. They are widely classified according to their ionization state in the solvent and the type of hydrophilic group ions. The most commonly used are anionic surfactants, cationic surfactants, amphoteric surfactants, and non-ionic surfactants. The first three are ionic surfactants.
Surfactants have a wide range of uses in household life and industrial production cleaning.
3. Acid-base cleaning agent
A cleaning agent that changes dirt into soluble or dispersed in the cleaning solution by means of acid-base reaction with the dirt (sometimes accompanied by oxidation-reduction reaction), mostly organic acids, inorganic acids, alkalis and salts that are acidic or alkaline after hydrolysis.
Most acid-base cleaning agents are composed of aqueous solutions of acids and alkalis plus necessary additives. Another type of acid or alkali that acts on dirt in a molten state under high temperature conditions, which converts dirt that is originally insoluble or difficult to dissolve in the cleaning medium into easily soluble compounds. This kind of acid and alkali is usually called a flux. This cleaning agent has good results when dealing with dirt that is difficult to remove with solvents or solutions.
4. Oxidation-reduction agent
A preparation that removes dirt by means of oxidation-reduction reaction with dirt is an oxidant or reductant for cleaning, including flux.
Oxidants are used to remove reducing dirt, such as many organic dirt. Reductants are used to remove oxidizing dirt, such as rust dirt.
5. Metal ion chelating agent
By means of complex reaction with metal ions in dirt, the dirt is changed into chelates that are easily soluble in cleaning agents, and this cleaning agent or additive is a chelating agent. It is often used in the cleaning of rust dirt and inorganic salt dirt.
6. Adsorbents
Substances that remove dirt through physical adsorption or chemical adsorption of dirt are adsorbents for cleaning. Adsorbents with strong affinity for dirt should be selected for cleaning.
Membrane cleaning Scale inhibitor Scale inhibitor