Types and Application Methods of Bleaching Agents

Bleaching Agents

The bleaching agent is the most important part of wet processing. Bleaching is done to remove the natural color of the textile materials. During the pre-treatment of the textile materials, the different parameters are maintained strictly. These bleaching is done by different types of bleaching agents.

Bleaching Agents Types

Bleaching agents are applied to different types of fiber. Textile fiber may be natural or synthetic. Depending on fiber types bleaching agents also differ. Bleaching agents are mainly classified as follows:

1. Oxidizing Agents
2. Reducing Agents

Oxidizing Agents

The following are the oxidizing bleaching agents. They are-

1. Ozone (O₃)
2. Bleaching Powder
3. Hydrogen Per Oxide (H₂O₂)
4. Sodium Hypochloride (NaOcl)
5. Sodium Chlorite (NaclO₂)
6. Potassium Dichromate (K₂Cr₂O₇)
7. Potassium Permanganate (KmnO₄)
8. Per Acetic Acid (CH₃COOH)
9. Sodium Per Oxide (Na₂O₂)
10. ETC

It is mentioned that;

• Above no. 1 and 2 agent uses for home purpose.
• 3, 4 and 5 Above no. agent uses for industrial purpose.
• Above no. 6, 7, 8 and 9 agent uses for washing purpose.

Reducing Agent

1. Ferrose Sulphate (FeSO₄)
2. Zinc Dust (ZnO)
3. Stannous Chloride (SnCl₂)
4. Sulpher Dioxide (SO₂)
5. Sodium Hypo Sulphite (Na₂S₂O₂)
6. Glucose
7. Hydrogen Sulphide (H₂S)
8. ETC

Applicability and Application Methods of Bleaching Agents

Bleaching agents have different applicability depending on fiber types. Different types of bleaching agents use on different fibers. Among all of the bleaching agents, hydrogen peroxide is called a universal bleaching agent. There have some reasons behind this specialty. They are as follows:

• Firstly, hydrogen per oxide is a very gentle bleaching agent.
• Secondly, it is very easy for application.
• Thirdly, permanent treatment is possible with hydrogen per oxide.
• Lastly, it is ease to apply with any types of fiber.

Methods of Bleaching Process

Bleaching agents are applied to fiber by two processes. They are:

1. Discontinuous or Semi-Continuous Process: In this method bleaching agent is applied to fiber discontinuously or semi-continuously. Bleaching tank, Jigger, Padder, Kier, and many others use for treatment with bleaching agents.

2. Continuous Process: In this process, bleaching treatment is performed as per the sequence of treatments. J-Box is used for continuous process.

Materials for Bleaching Process

During bleaching; the following points must be considered to get better performance:

1. Bleaching Agent
2. Wetting Agent
3. Sequestering Agent
4. Stabilizer
5. Alkali
6. Materials and Liquor ratio
7. Temperature
8. Application time

Different types of machine manufacturing companies manufacture this type of machine. The machine should have enough properties which are required for performing the operation.

Anyhow, when we will select the chemicals we have to ensure the chemical properties, which is required. Well-known chemical manufacturing companies also supply guidelines for chemical use. We will use the right bleaching agent for the right fiber.