Types of Bleaching in Textile | Oxidizing and Reducing Bleaching Agent

What is Bleaching in Textile?

The process by which the natural color of a fiber can be removed and make the textile materials pure white and bright is termed as bleaching.

Textile bleaching process
Fig: Textile bleaching process

Objectives of Textile Bleaching:

There are some key purposes of bleaching in the dyeing industry which are mentioned below:

  1. To remove the natural color of textile fiber,
  2. To make the fabric permanent white and bright,
  3. To increase the absorbency power of the fabric,
  4. To make the fabric compatible for the next subsequent process,
  5. To ensure the level of dyeing property.
What Types of Bleaching Process in Textile?

Bleaching is classified based on the bleaching system, bleaching agent, and chemical.

a. According to the Bleaching Agent:

It includes-

  1. Hand bleaching,
  2. Machine bleaching,
  3. Continuous bleaching system,
  4. Pad roll batch-wise agent.
b. According to the Bleaching Agent:

It includes-

  1. Bleaching by oxidizing agents,
  2. Bleaching by reducing agents.
c. According to the Chemical Used:

It includes-

  1. Hypochlorite bleaching (HOCL),
  2. Hydrogen peroxide (H2O2) Bleaching,
  3. Sodium Chlorite (NaU) bleaching,
  4. Potassium Nitrate (KNO3).
List of Oxidizing Bleaching Agent Used in Textile Industry:

All the oxidizing bleaching agents have presented in the following:

  1. Oxygen (O2),
  2. Ozone (O3),
  3. Potassium Nitrate (KNO3),
  4. Potassium Phosphate (K2PO4),
  5. Potassium Permanganate (KMNO4),
  6. Potassium Chlorate (KCLO3),
  7. Sodium per Oxide (Na2O2),
  8. Sodium Dichromate (Na2Cr2O3),
  9. Sodium Hypochlorite (NaOCl),
  10. Calcium Hypochlorite {Ca(OCl)2},
  11. Bleaching Powder ({Ca(OCl)Cl},
  12. Hydrogen Peroxide (H2O2),
  13. Halogen (X2),
  14. Hypochlorous Acid (HClO2),
  15. Manganese Dioxide (MnO2),
  16. Per Acetic Acid,
  17. Led Dioxide (PbO2),
  18. Nitric Acid (HNO3),
  19. Sulphuric Acid (H2SO4),
  20. Potassium Hypochlorite (KCLO),
  21. Potassium Sulphate (K2SO4),
  22. Aqua Resia (Con. HNO3+Con. 3hCL) etc.
List of Reducing Bleaching Agent Used in Wet Processing:

All the reducing bleaching agents have listed the below:

  1. Hydrogen (H2),
  2. Hydrogen Sulphide (H2S),
  3. Carbon (C),
  4. Carbon Mono Oxide (CO),
  5. Sodium Sulphate (Na2SO4),
  6. Sodium Bi-Sulphate (NahSO4),
  7. Sodium Sulphite Formaldehyde,
  8. Zinc Dist (Zn),
  9. Zinc Oxide (ZnO),
  10. Sulfur Dioxide (SO2),
  11. Stannous Chloride (SnCl2),
  12. Ferrous Sulphate (FeSO4),
  13. Titanous Chlorite (TnCl2),
  14. Hydrogen Iodide (HI) etc.

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