Discharge printing is a method where the pattern is produced by the chemical destruction of the original dye in the printed areas. The discharging agents used can be oxidizing or reducing agents, acids, alkalis and various salts. But, most important methods of discharging are based sulphoxylates formaldehyde & Thiourea dioxide.
Recently, the environmental and industrial safety conditions increased the potential for use of enzymes in textile processing to ensure eco-friendly production. In Discharge printing, Sulphoxylate Formaldehyde (NaHS02.CH2o.2H20) is one of the powerful discharging agent used commercially, however, it is considerably toxic and evolves formaldehyde known as a human carcinogenic associated with nasal sinus cancer and nasopharyngeal cancer.
In this article we have discussed about replacement of this hazardous chemical with eco- friendly enzymes in textile discharge printing. Enzymatic discharging printing carried out with Phenol oxidizing enzyme such as Peroxidase with hydrogen peroxide by selectively discharged reactive dyes from the cotton fabric at selected areas creating a printed surface.
Textile discharging printing is the most versatile and important of the methods used for introducing design to textile fabrics. Considered analytically it is a process of bringing together a design idea, one or more colorants, and a textile fabric, using a technique for applying the colorants with some precision.
Biotechnology has dramatically increased the scope for application of enzyme systems in all areas of textile processing. Enzymes can be tailored to implement specific reactions, such as decomposition, oxidation and synthesis, for a variety of purposes. There is a growing recognition that enzymes can be used in many remediation processes to target specific purpose in textile industry. In this direction, recent biotechnological advances have allowed the production of cheaper and more readily available enzymes through better isolation and purification procedures.
The enzymes are used in textile industry because it operates under mild conditions of temperature and pH, it replaces non-selective harsh chemicals. A Bleaching enzyme such as Peroxidases together with hydrogen peroxide is capable of oxidizing organic compounds containing phenolic groups.
Bacterial system present (Peroxidase) in activated sludge, they catalyses the oxidative cleavage of Azo dyes.
Enzymes are specific that is, they control only one particular chemical change or type of change, quotes New Junior Encyclopedia.