Abstract


Bleaching tests were conducted to study the efficacy ofperacetic acid as a replacement of hydrogen peroxide in bleaching processes of100% cotton fabric. The criteria chosen for assessing bleaching performances ofperacetic acid and hydrogen peroxide were whiteness index, tensile strength,absorbency and fluidity values. The CIE whiteness index value of fabrics wasmeasured by a spectrophotometer using appropriate computer software. UniversalStrength Tester (Titan) was used to measure tensile strength. Ostwald-FenskeCuen viscosimeter was used to determine chemical degradation of cotton fabricby measurement of its fluidity and embroidery hoop was used to determineabsorbency. The results of this research showed that the peracetic acid is moreeffective as a bleaching agent than hydrogen peroxide. An acceptable degree ofwhiteness (CIE whiteness index 80) can be obtained with minimum loss of tensilestrength. This study has also provided valuable information for industrialapplication of the developed bleaching systems.


Key words: Cotton, Bleaching, Peracetic acid, Hydrogen peroxide


Introduction


The art of bleaching has been practiced since beginning ofcivilization. Bleaching is the process of removing colored impurities from thegriege fabric as efficiently as possible, with minimum or no damage to thefiber and leaving in a perfect white state.


Nowadays, consumers increasingly demand more environmentallyfriendly products. This also effect the textile industry, and thus, aspectssuch as control of water, energy and chemicals consumption should be taken intoaccount in wet textile processes. Hydrogen peroxide (H2O2) is the most widelyused bleaching agent for textiles and came into use around 1878. Hydrogenperoxide is suitable for most fibers and it can be used in a wide range ofmachines under different conditions. Reaction products are non-toxic andnon-dangerous but hydrogen peroxide is a highly corrosive compound and degradesto oxygen and water. Hydrogen peroxide is however, damaging to fiber, becauseit is applicable in strongly alkaline medium and it requires a high temperatureto give the most effective bleaching.


Paracetic Acid (PAA) as a bleaching agent has manyadvantages compared to hydrogen peroxide. It does not produce any toxic byproduct in bleach reaction, it is less corrosive, it is biologically totallydegradable and it causes no AOX (absorbable halogenated organic compounds) loadin the waste water.


ReadFull Article



Theauthor is associated with the Department of Textile Science, Textile Instituteof Pakistan, Karachi