Ozone Technology in Denim Washing Industry: Easy Mechanism

Introduction

Ozone technology is a new technique used in denim washing. Ozone technology is used to address sustainability issues. The world is concerned about environmental pollution. So, denim washing industries are searching for an alternative denim washing process that requires less chemicals, less water, and less energy, as are buyers. In the traditional denim washing process, each jeans needs about 70 L of water, 1 kWh of power, and 150 grams of chemicals. So, it is a huge amount of water, chemicals, as well as energy.

A cleaner-production assessment of a Bangladesh denim washing factory reported about 72.36 L of water, 0.181 kWh of electricity, and 4.34 kg of steam required per kg of denim garment washing. One day, the world will face clean water. Hence, it is crucial to find an alternative to water in case of garment washing. The article will brief the mechanism of ozone technology, how ozone reacts with indigo dye of denim as well as the mechanism of an ozone machine. The article will help textile professionals select a suitable process for denim washing. From here, they can learn how to do denim washing in a sustainable way.

Read: Jeans Acid Wash Guide: 13 Easy Steps for Perfect Results

What is ozone?

Ozone is a molecule containing three oxygen atoms. It is represented chemically as O₃. Ozone is a strong oxidizing agent. It is less stable than ordinary oxygen (O₂). Ozone is naturally formed in the atmosphere through photochemical reactions. But in the denim washing industry, ozone gas is prepared through an ozone generator. Generally, ozone is generated on-site because ozone gas cannot be stored easily for long periods.

Why is ozone technology used in the denim washing industry?

Mainly, ozone technology is used in the denim washing industry to reduce environmental impact. Conventional denim washing can consume large amounts of water, chemicals, and energy. The conventional denim washing process is costly as well as it impacts the environment. Hence, ozone technology is used to reduce the environmental impact. To clear the question why ozone technology is used in the denim washing industry, read the following points:

• Ozone technology reduces water consumption in denim washing. Ozone gas is a strong oxidizing agent. Hence, it works as a bleaching agent. In the denim bleaching process, about 30-40 L of water is needed to wash one pair of jeans. But in ozone technology, there is no need for a single amount of water.
• About 30 gm of KCl bleaching agent is required to complete the bleaching process of a jeans pant. After the bleaching process, water is discharged into the environment which create unavoidable problem. But in ozone technology, there no need any bleaching agent to get the same shade as after the shade after bleaching process. So, ozone technology saves chemicals in the denim washing industry.
• Additionally, In ozone technology, denim pants are treated within a short time. This technology also uses less heat. Hence, it saves energy compared to conventional denim washing process.

To cut the long story in short, ozone technology requires less water, fewer chemicals, and less energy compared to the conventional denim washing process. Hence, the denim washing industry uses this technology. It is also called a sustainable washing process.

Ozone Generator Mechanism: Ozone(O₃) from Oxygen (O₂)

This section will discuss how an ozone generator works as well as the mechanism of ozone washing machine. From this section, one can learn how ozone (O₃) gas produces from oxygen(O₂). Behind the ozone washing machine, there are four oxygen(O₂) cylinder. First no cylinder collect oxygen from the environment; second no, the second cylinder dispels other compound from air; fourth no cylinder collects pure oxygen from 2, 3 no cylinder. Finally, the fourth no cylinder supplies to the ozone generator.

1. Initially, pure air is pulled into the ozone generator from the oxygen cylinder.
2. Then, the air comes into contact of a filter. A filter prevents dust.
3. Next step, a fan accelerates air through the unit for ozone generation. 
4. Now, the air comes into contact with a high-voltage area. When oxygen from the air is subjected to a high-energy pulse, the usually diatomic molecules break down into single atoms and recombine. Some of these recombined molecules contain three oxygen atoms instead of two. This new compound is called Ozone.
5. Then, ozone gas is supplied to the ozone washing machine.

You can read: Denim Bleach Wash Process with Recipe : 7 Easy Steps

How does ozone destroy indigo?

1. The chemical formula of indigo is C₁₆H₁₀N₂O₂ [2-(1,3-dihydro-3-oxo-2H-indol-2-ylidene)-1,2-dihydro-3H-indol-3-one]. The formula is composed of two indole rings joined by a central double bond. This double bond creates a highly conjugated π-electron system. This conjugated structure is responsible for the deep blue color of indigo dye.
2. Ozone is a powerful oxidizing agent. This agent reacts with the double bonds of the indigo dye.
3. Ozone breaks the double bond of indigo dye and produces two major oxidation products. One is phenylglycine, which is colorless. Another is Isatin (C₈H₅NO₂), a yellow-colored compound. Hence, jeans become yellowish after ozone washing.

Ozone Washed Denim

Factors affecting ozone washing

Several process variables influence the final results of ozone washing

1. The first and most important is ozone concentration. Higher ozone concentration generally increases the oxidation process, but excessive exposure creates damage.
2. Another factor is treatment time. Longer treatment time increases color reduction. But treatment times need to be maintained to get repeatable shades.
3. Moisture may influence ozone reaction behavior.
4. Dye characteristics are also a factor. But ozone works well in indigo dye.

Advantages of ozone washing

1. Ozone technology reduces water requirement.
2. Additionally, it reduces color faster.
3. It also reduces chemical requirements.
4. Overall, it reduces the production cost of the factory.

Limitations of ozone washing

1. Ozone is highly reactive. Hence, process control is essential.
2. It is difficult to get repeatable shade.
3. Equipment and maintenance costs are high.
4. It is hazardous for worker.

Ozone washing vs conventional washing

S/N	Ozone washing	Conventional washing
1.	The ozone washing process doesn’t need an aqueous chemical bath.	Conventional washing needs a chemical bath.
2.	It does not need water	It needs water
3.	It reduces chemical requirements	It requires chemicals. For example: desizing agent, enzyme, bleaching agent etc.
4.	It reduces energy by reducing heating and wet processing steps.	It requires more energy for water heating and washing steps.
5.	Generally, this process has a lower impact on the environment.	But this process has a higher impact on the environment.
6.	It requires control of ozone concentration, moisture, and time.	It requires control of the amount, temperature, pH, and time.
7.	This process is called a sustainable process owing to the less water, less chemicals and less energy uses.	This process is not a sustainable process.

Conclusion

Ozone technology is used in denim washing to modify the garment appearance, like vintage. This article tries to present an easy way to understand how ozone gas is produced, how it works with indigo dye, as well as advantages and limitations. This article also presents a comparison between ozone washing and conventional garment washing. However, if you have any questions about ozone technology regarding garment washing, let me know in the comments below.

Reference

1. Guinesi AS, Andolfatto C, Bonetti Filho I, Cardoso AA, Passaretti Filho J, Farac RV. Ozonized oils: a qualitative and quantitative analysis. Braz Dent J. 2011;22(1):37-40. doi: 10.1590/s0103-64402011000100006. PMID: 21519646.
2. Khan MKR, Jintun S. Sustainability Issues of Various Denim Washing Methods. Textile& Leather Review. 2021. https://doi.org/10.31881/TLR.2021.0
3. Atav, Riza & Gündüz, Öner & Yaz, Sercan & Çakan, Gizem & Sevgili, Bahadırhan. (2024). Eco-Friendly Ozone Process for Denim Garments as an Alternative to Conventional Bleaching. Fibers and Polymers. 25. 2661-2667. 10.1007/s12221-024-00589-2.

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