1.The Nature of Soap
- Crystallinity. Pure anhydrous soap is white crystal. The white fibrous crystals of water-containing soap are produced by evaporation of water under different conditions. This phenomenon is more common in the storage process. The longer the storage time is, the drier the crystallization is. It has no effect on the inherent quality of soap and should not be regarded as deterioration.
- Surface activity. When soap dissolves in water, it can reduce the surface tension of water, which is called the surface activity of soap.
The surface activity of soap is due to the amphoteric structure of the water-soluble hydrophilic group (oleophilic group) and water-insoluble hydrophobic group (oleophilic group). One end of hydrophilic group is easily adsorbed by water molecule, while the other end of hydrophobic group is repulsed by water molecule and affinity to water-insoluble objects (such as grease scale), so that soap molecules have the properties of adsorption, wetting, penetration, emulsification and so on, and play the role of washing and descaling. - Hygroscopicity and solubility. Soap has the ability to absorb water in a humid environment, which is called the moisture absorption of soap. When soap absorbs moisture, it dissolves into gelatinous substance with the increase of water content.
Soap hygroscopicity and dissolution are caused by the presence of hydrophilic groups in molecules. The shorter the carbon chain and the more double bonds, the stronger the hydrophilicity, the higher the hygroscopicity and the greater the solubility. - Wettability. Soap refers to the property of soap that makes water adsorb insoluble substances and diffuse and penetrate between and inside solids. It helps to separate the dirt from the fabric and disperse the dirt particles, thereby improving the ability to remove dirt.
- Emulsification and turbidity. Emulsifying property refers to the property that soap can mix water with water-insoluble substances and turn them into emulsions. The suspension is the property that soap liquor can make solid particles insoluble in water form suspension in water. The emulsification and turbidity of soap are the results of the comprehensive action of surface activity, wettability, adsorption and dispersion of soap.
- bubble. When soap is dissolved in water, a large amount of foam can be produced by stirring, and it will disappear slowly. This property is called foaming or foaming. The formation of foam helps to increase the surface-active area of soap solution and to bring dirt into it, which can promote the detergency of soap.
2.Scaling Principle of Soap
Soap descaling is a complex process in which various properties of soap interact, permeate and synthesize. It can be expressed as Fabric, Dirt and Soap Solution-Fabric, Dirt and Soap Solution
- First of all, the moisture absorption and dissolution of soap make the soap body molecules have surface activity in the soap solution, which can reduce the interfacial tension between water and dirt. The wetting and penetration of soap make the soap body molecules adsorb between dirt and fabric and penetrate into the dirt particles, thus reducing the attraction between dirt and fabric and loosening the dirt. Fabrics are easy to take off and roll off.
- Secondly, by mechanical scrubbing, hydrophobic dirt can be removed from the fabric and involved in the soap solution. Soap has good emulsification, dispersion, and turbidity, so that dirt particles are dispersed into fine particles and suspended in the washing solution. In addition, the solubilization of micelles can enhance the effect of fouling dissolution.
- Finally, due to the foaming property of soap and the action of carboxymethyl cellulose in soap, the dirt will not be deposited on the fabric again due to the aggregation, and it will be removed by rinsing and foam together with dirt to clean the fabric and achieve the purpose of descaling.