A wetting agent is a substance that reduces the surface tension of water, it spreads water on the surface and increases the ability of liquid dispersion. Reducing the surface tension will reduce the energy required to distribute the droplets onto the film, thereby weakening the cohesion of the liquid and enhancing its adhesion. An example of how wetting agents work is the formation of micelles. The micelle consists of a hydrophilic head, which forms an outer layer around the lipophilic tail. When it is in water, the tail of the micelle can surround the oil drop and draw its head into the water.
Dishwashing soap is a good example of a wetting agent. For all food oils and the cohesion on the board, it is difficult for water to disperse and clean the board. Soap dissolves all these unwanted particles, showing us a clean surface. Soap can also reduce the surface tension of water and make it evenly distributed on the whole surface.
There are four types of wetting agents: anionic wetting agent, cationic wetting agent, amphoteric and non-ionic wetting agent.
1. When mixed with water, anionic, cationic and amphoteric wetting agents will ionize.
2. Anionic wetting agent
has negative charge, while cationic wetting agent has positive charge.
3. According to the acidity of the solution, amphoteric wetting agents can act as anions or cations.
4. Nonionic wetting agents will not ionize in water. The possible advantage of using a non-ionic wetting agent is that it does not react with other ions in the water, which may lead to the formation of precipitates.
How to identify if a liquid contains a wetting agent
One way to identify if a liquid contains a wetting agent is to spread the liquid over a greased surface. If the liquid does not contain a wetting agent, its cohesion will overwhelm the adhesion, resulting in the formation of droplets on the surface. If the liquid does contain a wetting agent, the grease will be dissolved and the surface tension of the liquid will be reduced, resulting in the adhesion force exceeding the cohesion force, which will cause the liquid to spread evenly along the surface.