Tahmid Mahmud Rahin
Department of Textile Engineering, Khulna University of Engineering & Technology
* This paper won the 3rd position in “1st Inter University Innovative Research & Idea Competition 2018” organized by Department of Textile Engineering, Dhaka University of Engineering Technology (DUET)
Textile dyeing industries are the most highly water consuming sectors of the world. Almost 17-20% of today’s industrial pollution are caused by the chemicals used by the textile industries for coloring, bleaching and other treatments. More than 72 toxic chemicals can be mixed to the water bodies through textile dyeing. These chemicals just don’t pollute water, but also damage the whole ecosystem. It also makes us prone to chemical exposure and health hazards. A new technology has been developed to reduce water application and contamination in textile dyeing sector named “Air-Dye”. This system uses 95% less water than conventional dyeing system and ultimately saves 86% energy in the process. This technology is still developing. However only synthetic fiber like polyester can be dyed in this process. But natural fibers like cotton is more common to the people of our sub-continent. Air dyeing technology can also be used in cotton fiber by applying some modification into the chemical structure. In the following project some ways of modification of the structure of cotton is discussed to make it available for the air dyeing process.
Problem and Context
The limitation of this revolutionary technology is that it can only be used at synthetic fibers. The textile industries of Bangladesh are heavily depended on cotton. Bangladesh is one of the leading countries in importing cotton. On the other hand production of synthetic based product is very rare compared to the cotton. So utilizing the air dye technique vastly in context of our country is impossible unless a developed method has been introduced for cotton based textile materials.
Mainly this technology is based on transfer printing theory. Dyes are first applied on a paper carrier. Then heat is applied to transfer the dye from paper to the fiber. Now in case of synthetic fiber like polyester; on 200-210 C temperature, fiber opens up. This is because of the thermoplastic behavior of the synthetic fibers. When polyester fiber opens up, the dyes enters in the fiber in gas form. After removing heat, the fiber gets cold and the bond is reunited, as a result of which dye particles get stuck inside of the polyester and dye it in the molecular level. As we know, thermoplastic behavior is only showed by the synthetic fibers. Natural fibers like cotton do not show this thermal property and that’s the reason air dye technology is not still available for cotton fiber.
Thermoplastic molecules do not chemically bond with each other. They held with each other with weak van der walls force in a chain formation like a ball thread. So when they heated up, the chain that hold the bond just melts more like opens up. After removing the heat, the chains remolded closing the created gap. The molecular structure of polyester is a chain structure. It has the thermoplastic property.
But Cotton has a ring structure. The chemical composition of cellulose is simple, consisting of glucose units joined by β-1, 4-glucosidic bonds to form linear polymeric chains. The individual chains adhere to each other along their lengths by hydrogen bonding and Van der Waals forces. There are delocalized electrons in this ring structure of cotton. When cotton is heated up, delocalized electrons moves to and fro and after prolonged heating, these electrons break the chemical bond. That’s why it cannot retains its original structure after removal of heat.
The main principle of air dyeing is to opening up the structure, pass the dye in gaseous form in the structure and then close the structure. So to make cotton dye-able in this process, we have to open up the structure of cotton, and then return it into its original state. Solution to this problem is genome sequencing.
A genome is all of a living thing’s genetic material and it is the entire set of hereditary instructions for building, running, maintaining an organism, and passing life on to the next generation. Genome sequence is the process to find out the complete DNA sequence of any organism. DNA sequence is the secret ingredient behind every characteristic property that every living organism shows. Think of it like a math equation. If we want to solve the problem, we have to know where to solve. By knowing the complete genome sequence we can bring change in the structure and produce modified version for our own purpose.
It is possible to change structure by modifying the DNA map. There is already various modified version of jute is in our country produced by genome sequencing. So it can be possible to bring change in the molecular structure of cotton by bringing change in the DNA map. At first we have to find the whole genome sequence of cotton. After that we need to figure out in which part of DNA we need to modify to introduce the required thermoplastic behavior. If we are able to bring change preciously, then our modified version of cotton will effectively show thermoplastic behavior and we will be able to apply air dye process in cotton. That is a possible solution to our problem.
Genome sequencing is being done in many prospects. Bangladeshi scientist Professor Dr. Maqsudul Alam have successfully decoded the genome sequence of the golden fiber jute. Experts and Agriculturalist said that this gene sequencing would help improve the fiber length and quality, including colors and strength; and develop high yielding, saline soil- and pest-tolerant jute varieties through genetic engineering. As a result of this success, we can now produce genetically modified disease free version of jute. Similar research to find out the genome sequencing of rice plant is going out inspired by the success of late Dr. Maqsudul Alam. Also many genetically modified crops are now being cultivated around the world. Genome sequencing is becoming more and more popular in the scientist community nowadays.
The main challenge in modifying cotton by applying genome sequencing is to maintain the fundamental properties of cotton fiber. Very cautious steps must be taken to maintain the certain quality that normal cotton fiber possess. Another challenge is the available technology. Modern technology required for tracking down DNA map is very costly and rare. So this process will require large fund and backup from proper division.