The application of waste paper deinking chemicals

- The most important thing in waste paper deinking chemicals is deinking agent. Deinking agent is mainly a series of surfactant compound formulations, anionic, cationic, amphoteric and non-ionic, the choice of surfactant depends on the paper printing conditions and deinking process may be;

- In the flotation deinking process, the most commonly used deinking agent is sodium soap, which is actually a mixture of sodium soap and other surfactants. The use of sodium soap in the pulper is mainly due to its dispersion. The best operating effect is to add a portion of the sodium soap to the pulper and part of the sodium soap to the flotation device.

- The role of NaOH is to saponify or hydrolyze the ink resin. NaOH not only swells and emulsifies the fiber, speeds up the release of ink from the surface, but also prevents the ink from breaking.

- Na2SiO3 as a wetting agent can be adsorbed on the surface of the colloidal particles to reduce the surface tension of the liquid, improve the dispersibility of the printing ink, and prevent the ink particles from re-precipitating onto the fibers. Na2SiO3 is usually used together with H2O2 to passivate metal ions and act as a buffer at the same time so that the H2O2 bleaching can be carried out at a desirable pH.

- Chelating agents: Currently used chelating agents for waste paper pulp treatment are inorganic polyphosphate (NTP), organic ethylenediaminetetraacetic acid (EDTA) and diethylenetriaminepentaacetic acid (DTPA), It can effectively remove the heavy metal ions (Fe, Mn, and Cu) in the deinking process of waste paper, improve the bleaching ability of H2O2 and prevent fouling of equipment and pipelines.

The role of H2O2 in repulping is to decolorize the chromophoric groups contained in waste pulp containing mechanical pulp under alkaline conditions.