Concurrent desizing and bleaching of greige cotton fabric, using KMnO4

The purpose of preparing loomstate cotton fabric is to remove the non-cellulosic impurities fromthe cellulosic fibers and increase the wettability and whiteness of the fabric. This improves dyeingperformance and subsequent processing steps such as printing and finishing. Conventional timeconsuming methods, using hypochlorite and hydrogen peroxide, used in scouring and bleaching ofcellulose-based textile material use large amounts of chemicals, energy, and water, so to avoidenvironmental damages, and achieving waste water BOD to the ISI tolerance , the effluents requireneutralization or dilution prior to discharge. In order to economizing process pretreatment stagesshould be combined as much as possible to reduce consumption of water and energy. Oxidativecombined process gives lower pollution than caring out these three stages (desizing, scouring, andbleaching) separately. Since, KMnO4 is a powerful oxidizing agent, the ability of this agent forcombined desizing, scouring and bleaching of loomstate cotton fabric was investigated[1,2,3].Permanganate is known as a versatile oxidizing agent. Depending on the requirements of agiven substrate MnO4- oxidizes inorganic or organic compounds under neutral, acid and alkalineconditions in aqueous or non aqueous media. Under more extreme pH conditions such as very highacidity, which converses MnO4- ions to the much more vigorous HMnO4- molecule, is the reactivebehavior of the permanganate itself is significantly influenced by the H+ concentration. Morepermanganate oxidation is carried out under alkaline oxidation alkaline, neutral or moderately acidconditions. The traditional formulation of KMnO4 oxidation under acid condition applied to alimited number of organic substrates since only few can reduce the intermediate MnO2 to Mn+2: