Deinking Agent
An anionic surfactant derived from oleic acid acts as a wetting and dispersing agent to release print ink from cellulose fibres during the paper recycling process. Incorporating sodium oleate in the pulper slurry reduces the surface tension of the wash water, which allows the chemical to penetrate the ink layer and detach it from the paper substrate. This chemical compound is one of the most widely used industrial soaps for froth flotation.
Calcium Interaction
The efficiency of the surfactant depends on its ability to react with calcium ions dissolved in the process water. This reaction forms insoluble calcium soap flakes that bind with the dispersed ink particles, creating hydrophobic agglomerates that easily attach to rising air bubbles. If the water lacks calcium, the surfactant remains in its soluble form, causing excessive foam that disrupts the flotation cell and fails to remove the ink.
Correct balance of the soap dosage and hardness levels is required to maintain deinking efficiency.
Foam Generation
Control of the bubble volume and stability in the flotation cell is essential for preventing the loss of usable wood pulp. Overdosing the soap results in a thick, stable foam that traps healthy fibres and carries them into the reject stream. This issue increases the waste generated by the recycling mill and reduces the overall yield of the deinking line.
