Peroxide Bleaching

Summary

Hydrogen peroxide is a versatile bleaching chemical widely used in both chemical and mechanical pulp processing. Unlike other bleaching agents, it can be applied directly without specialized equipment to increase pulp brightness by two to three points. It plays a key role in elemental chlorine-free (ECF) and total chlorine-free (TCF) bleaching sequences, enhancing brightness while reducing chlorine dioxide consumption. Peroxide can also replace final chlorine dioxide stages, further minimizing chemical use. This module highlights its essential function in achieving target brightness levels and demonstrates its flexibility and efficiency in modern pulp bleaching operations.

Takeaways

• 🧪 Hydrogen peroxide is a versatile bleaching chemical with multiple applications in pulp processing.
• ⚙️ Unlike other bleaching chemicals, peroxide does not require any special equipment for application.
• 💧 Peroxide can be added directly to pulp storage chests to increase brightness by 2–3 points.
• 🌿 It is often used to reinforce extraction stages in Elemental Chlorine Free (ECF) bleaching sequences.
• ✨ Adding peroxide in ECF sequences increases pulp brightness and reduces chlorine dioxide consumption.
• ♻️ Replacing a final chlorine dioxide stage with a peroxide stage can further reduce chlorine dioxide use.
• 🎯 Peroxide is essential for achieving target brightness in Total Chlorine Free (TCF) bleaching sequences.
• 📊 Its use contributes to more environmentally friendly bleaching by reducing reliance on chlorine compounds.
• 📝 While this module focuses on chemical pulp, peroxide is also extensively used for mechanical pulp bleaching.
• 🔬 Overall, peroxide provides flexibility, efficiency, and environmental benefits in modern pulp bleaching operations.

Q & A

What makes hydrogen peroxide a unique bleaching chemical?

Hydrogen peroxide is versatile, can be used for general brightening without special equipment, and is suitable for multiple applications in both chemical and mechanical pulp bleaching.

How can hydrogen peroxide be applied directly in the pulp bleaching process?

It can be added directly to a pulp storage chest, where it increases the brightness of the pulp by 2–3 points.

Why is peroxide often used in the extraction stages of ECF bleaching sequences?

Peroxide reinforces the extraction stages, increasing pulp brightness and reducing the consumption of chlorine dioxide.

How can chlorine dioxide use be further reduced in ECF bleaching sequences?

By replacing the final chlorine dioxide stage with a peroxide stage, chlorine dioxide consumption can be significantly reduced.

What is the role of hydrogen peroxide in Total Chlorine-Free (TCF) bleaching sequences?

Peroxide is essential in TCF bleaching to achieve the target brightness, as no chlorine-based chemicals are used in these sequences.

Is special equipment required for using hydrogen peroxide in bleaching?

No, hydrogen peroxide can be used directly without any special equipment, making it a convenient bleaching agent.

What types of pulp commonly use hydrogen peroxide for bleaching?

Hydrogen peroxide is primarily used for chemical pulp but is also extensively applied in mechanical pulp bleaching.

What are the environmental benefits of using hydrogen peroxide in bleaching?

Using peroxide reduces the need for chlorine dioxide, lowering the formation of harmful chlorinated compounds and making the process more environmentally friendly.

How much brightness increase can typically be achieved by adding peroxide to the pulp storage chest?

A brightness increase of approximately 2–3 points can be achieved.

Why is hydrogen peroxide considered flexible compared to other bleaching chemicals?

Other bleaching chemicals have specific uses and requirements, whereas hydrogen peroxide can be used for a wide range of bleaching purposes, including general brightening and reinforcement of different stages.