How to remove fluorescent brightener?

I often hear people ask how to remove fluorescent brightener from fabrics. I've compiled some of my own methods and would like to share them with you.

Why do we need to remove fluorescent brightener? Most cases involve accidental addition or staining of fabrics with fluorescent brighteners, as in the case of baby products or IKEA products, where the customer didn't request it. Another common problem is that fluorescent brighteners cause uneven coloring, requiring removal.

Chlorine Dioxide Removal Method

Fluorescent brighteners for cotton generally have the following properties:

1. Alkali resistance

2. Acidic conditions may cause color change, but this does not affect the removal of the fluorescent brightener

3. Resistant to hydrogen peroxide bleaching, allowing for simultaneous whitening with oxygen bleaching

4. Resistant to reduction with hydrosulfite

5. Intolerant to chlorine bleaching6. Compatible with common anionic and nonionic surfactants

Therefore, acid-base, oxygen bleaching, hydrosulfite, and surfactants cannot remove fluorescent brighteners. Only chlorine dioxide, widely used in the paper industry for fluorescent brightener removal, can oxidize and decompose them.

Chlorine dioxide (ClO₂) is a yellow-green to orange-yellow gas. How is it used in printing and dyeing? Sodium chlorite and sodium hypochlorite. Sodium chlorite is a solid powder, while sodium hypochlorite is commonly known as chlorine water. Both oxidants react under acidic conditions to release chlorine dioxide.

When I was working as a dry dyeing operator, I often encountered uneven color spots of the whitening agent. The solution at that time was to put the whitening fabric into a bleaching tank for bleaching, and then the fluorescent whitening agent was removed very cleanly.

UV Absorber Method

When encountering fabrics or situations that cannot be treated with chlorine or chlorine bleach, or when using fluorescent brighteners that are resistant to chlorine bleaching, we recommend the second method: the UV absorber method. Let's first review the whitening principle of fluorescent brighteners:

Fluorescent brighteners absorb invisible ultraviolet light (wavelength 300-400nm), causing molecules to become excited. When they return to their ground state, some of the UV energy is lost and converted into lower-energy blue-violet light (wavelength 420-480nm).

How UV absorbers work:

UV absorbers strongly and selectively absorb high-energy UV light and dissipate the absorbed energy as heat or harmless low-energy radiation, thereby avoiding skin damage and preventing the excitation of polymers due to the absorption of UV energy, which can lead to photophysical and photochemical decomposition.

So my principle is to add enough UV absorber so that the fluorescent whitening agent can't absorb enough UV light and can't emit blue-violet light. This method is not to remove it, but to cover it up and eliminate it.

If you have more problem about the remove fluorescent brightener ,you can contact us :info@tiankunchemical.com