Twelve azo dyes are found in the ink mixture 

Twelve azo dyes are found in the ink mixture 

 

All twelve dyes have different chemical structures, which are responsible for the different colours. Certain properties can be assumed based on these structures, and there are a few similarities between the twelve dyes. For example, Reactive Black 5. The sodium sulphonate salt is present in all the dyes and it is responsible for adhesion of the dye to the fabric.

Chemical structure of azo dye Reactive Black 5 

Chemical structure of azo dye Reactive Black 5 

 
 
 
Enzymes like azoreductases can degrade azo dyes into aromatic amines. The azo bond cleavage involves a transfer of four electrons, which proceeds through two stages at the azo-linkage. Credit: Environment and Climate Change Canada

Enzymes like azoreductases can degrade azo dyes into aromatic amines. The azo bond cleavage involves a transfer of four electrons, which proceeds through two stages at the azo-linkage. Credit: Environment and Climate Change Canada

Another common component is the azo bond. Azo bond is present in ten out of twelve dyes and is primarily responsible for showing the colour. Finally, the presence of sulphonyl groups, benzene rings and hydrophilic side groups on these benzene rings will alter the colour. Knowing that there are similarities between the dyes makes it easier to create a treatment process.

Several physical and chemical methods exist for treating dyes. However, some processes are expensive and produce a lot of waste. Treatment by microbes offers an interesting alternative. Some Microalgae, bacteria and fungi contain proteins which can break the azo bond and form intermediate products. Unfortunately, additional expensive products are needed when using these proteins, and the intermediates are often toxic. However, the good news is that intermediates with sulphonate groups are normally harmless to human. 

 
 
 
We worked with our academic advisor on enzyme, yeast and microalgae decolourisation. More details:  Microalgae   Bacteria   Fungi .

We worked with our academic advisor on enzyme, yeast and microalgae decolourisation. More details: Microalgae Bacteria Fungi.