Ozone: An Alternative Oxidant for Textile Applications

Abstract

Ozone is a triatomic form of oxygen (O3) with an outstanding oxidation potential. Ozone is generated via ozone generators; two main types of ozone generators are corona discharge units and ultraviolet lamps. Either air or oxygen may be used as the feeding gas, but an oxygen generator is required if the feeding gas is air. The ozone concentration in the outlet gas mixture of an ozone generator increases as the purity of oxygen gas inlet increases. The high oxidation potential of ozone gas has encouraged research studies on the utilization of ozone for textile applications. Oxidative agents are used in desizing, bleaching, dyeing, clearing, surface modification, and wastewater treatments for applications in textile sector. The main oxidative agent used in the textile sector is hydrogen peroxide. Use of an activator, generally caustic soda, and high temperatures are required for hydrogen peroxide bleaching. On the other hand, ozone is usually applied at room temperature because of its decreasing solubility at high temperatures, and ozone is active in the whole pH range compensating the requirement of pH adjustment chemicals. Of course, the pH of the aqueous solution affects the reactions of ozone, but ozone is capable of giving oxidation reactions in neutral, acidic, or alkaline solutions. In textile industry, ozone is utilized in various processes such as: denim applications, cotton pretreatments, dyeing and finishing, polyester dyeing and clearing, treatment of various textile fibers (wool, polylactic acid, etc.), and textile wastewater and color removal treatment. In this chapter, potential uses of ozone as an alternative oxidant for textile applications are reviewed in detail. It is important to point out that ozone utilization may result in chemical substitution, waste reduction, and energy conversation in textile processes, leading to more sustainable world for future generations.