International Journal of Textile Science 2014, 3(3): 51-58 DOI: 10.5923/j.textile.20140303.03 Study on the Performance of Eco-Alkali in Dyeing of Cotton Fabric with Reactive Dyes Mohammad Gias Uddin 1,* , Nayon Chandra Ghosh 2 , Md. Shamim Reza 3 1 Department of Textile Engineering, Faculty of Engineering, Ahsanullah University of Science and Technology, Dhaka, Bangladesh 2 Department of Textile Engineering, Primeasia University, Dhaka, Bangladesh 3 Aswad Composite Mills Ltd., Shreepur, Bangladesh Abstract Dyeing was carried out on cotton fabric using Novacron Blue FN-R and Novacron Brilliant Red FN-3GL dyes in 0.5%, 1.5% and 4% shades using soda ash and eco-alkali. One-half, one-fourth, one-sixth and one-eighth amount of eco-alkali was used to analyze the performance of eco-alkali in comparison to the required amount of soda ash for the three shade%. Then color yield (K/S value), fixation efficiency (%), pH of wash liquor after dyeing, washing fastness and color uniformity results of dyed fabrics were analyzed and compared. Color yield was found better using one-fourth amount of eco-alkali in 0.5% and 1.5% shades and using half amount of eco-alkali in 4% shade. Fixation efficiency was found better using one-fourth amount of eco-alkali. pH of the wash liquor after dyeing was found less in case of using eco-alkali. Washing fastness and color uniformity of dyed fabrics were also comparable using lower amount of eco-alkali. Keywords Cotton, Reactive dye, Eco-alkali, pH, Color yield, Fixation efficiency, Color uniformity 1. Introduction Reactive dyes are the widely used dyes all over the world. Most of the dyeing operations of cellulosic fibers are done by reactive dyes which have the worldwide acceptance to the dyeing technologists. This water soluble dyes get exhausted on the cellulosic fiber in the presence of glauber’s salt at neutral pH. Under alkaline conditions fixation is carried out in which covalent bond forms between reactive sites of fiber and cellulosic material [1]. But this alkaline condition also facilitates the reaction of reactive group with the dye liquor, resulting in deactivation or hydrolysis of the dye [2]. Normally soda ash is used as the most commonly used alkali in the dyeing bath. The important point is not the type or amount of alkali, but the pH of the bath. However, dye fixation on cellulosic fibers is generally low (Often less than 70%) [2]. This results in a highly colored dye house effluent which is not favorable for the environmental grounds. As much as 50% of the total cost of a reactive dyeing process is attributed to the washing off stages to remove unfixed or hydrolyzed dyes and treatment of the resulting effluent [1]. Furthermore, the higher concentrations of alkali required in cellulosic dyeing may pose additional effluent problems. Under this circumstance, eco-alkali can be used in place of soda ash in dyeing of cotton fabric with reactive dyes. Due to * Corresponding author: giasdtt@gmail.com (Mohammad Gias Uddin) Published online at http://journal.sapub.org/textile Copyright © 2014 Scientific & Academic Publishing. All Rights Reserved having higher fixation%, it can produce better color yield on cotton fabric, hence dye wastage can be less in reactive dyeing and consequently can create less effluent problem. Furthermore, as less amount of eco-alkali can be used to produce better color yield, the pH of wash liquor after dyeing can be reduced which facilitates the post-dyeing neutralization process. The unfixed and hydrolized dyes causes difficulities if not washed and neutralized properly, as a result, in the soaping process, soaping bath will act as a dyeing bath in the presence of alkali and high temperature which can cause color change in the dyed fabric.That is why, pH of wash liquor need to be measured after dyeing in both cases using soda ash and eco-alkali. In this study, cotton fabric was dyed with reactive dyes using soda ash and its lower amount of eco-alkali; then color yield and fixation efficiency were compared. After dyeing, pH of the wash liquor was compared in both cases. Color uniformity and washing fastness test of the dyed fabric were also compared in both cases. 2. Materials and Methods 2.1. Materials 2.1.1. Fabric The grey 100% cotton knit fabric (Single Jersey) of about 164 gm/m 2 , procured from Dulal Brothers Limited, Nayapara, Kashimpur, Gazipur, Bangladesh was used throughout the present study.