Application of Multifunctional Reactive Dyes on the Cotton Fabric and Conditions Optimization by Response Surface Methodology Umme Habibah Siddiqua a , Shaukat Ali a , Tanveer Hussain b , Munawar Iqbal c , Nasir Masood d , and Arif Nazir c a Department of Chemistry, University of Agriculture, Faisalabad, Pakistan; b Department of Textile Processing, National Textile University, Faisalabad, Pakistan; c Department of Chemistry, The University of Lahore, Lahore, Pakistan; d Department of Environmental Sciences, COMSATS University Islamabad, Sub Campus Vehari, Punjab, Pakistan ABSTRACT This study presents optimization of dyeing variables for dyeing 100% cotton fabric with two novel bifunctional reactive dyes D-1 and D-2. These dyes have sulfatovinylsulfone and monochlorotriazine functional moieties. The impact of diferent variables, including dyeing temperature, salt concentration, and alkali, was investigated and optimized using response surface methodology (RSM). In spite of an exploring structural diference between both of these dyes, the dyeing temperature was optimized at the same value (61.68°C). The optimized conditions of salt (43.33 g/L) and alkali (29.50 g/L) for D-1 were resulted in 72.29% (±3) of exhaustion and 67.45% (±3) fxation. Similarly, D-2 showed 69% (±3) of exhaustion and 62.5% (±3) fxation at optimum value of salt (44.05 g/L) and alkali (33.87 g/L) concentration. Results showed better fxation and exhaustion of D-1 than dye D-2 which may be attributed to its more structural planarity and lower steric hindrance. The diferent fastness behaviors of dyes were found good to excellent for both dyes. The results attained were useful and suitable for commercial dyeing processes. 摘要 研究了两种新型双功能活性染料D-1和D-2对100%纯棉织物染色工艺参数 的优化. 这些染料具有磺基乙烯基砜和一氯三嗪的官能团. 采用响应面 法（RSM）研究了染色温度、盐浓度、碱浓度等因素对染色效果的影响. 尽管这两种染料的结构差异很大，但在相同的染色温度（61.68℃）下对 染色温度进行了优化. 在盐（43.33g/L）和碱（29.50g/L）条件下，D-1的 耗竭率为72.29（±3）%，固色率为67.45（±3%）. 同样地， 在盐（44.05g/L）和碱（33.87g/L）的最佳浓度下，D-2表现出69（±3）% 的衰竭和62.5（±3）%的固定. 结果表明，D-1比染料D-2具有更好的固色 性和上染率，这可能是由于其具有更高的结构平面度和较低的位阻. 结果 表明，两种染料的染色牢度表现从好到优. 所得结果可用于工业染色. KEYWORDS Response surface methodology; optimization; steric hindrance; reactive dyes; cotton fabric 关键词 响应面法; 优化; 空间位阻; 活性染料; 棉织物 Introduction Reactive dyes comprise the most commonly used class of dyestuffs for dyeing cotton and other cellulosic materials. This is the only dye class which is capable of forming covalent bond with the substrate molecules, resulting in superior fastness properties in broad range of colors. Dyeing is a complex process (Baaka et al., 2019a; Baaka, Mahfoudhi, and Mhenni 2019b; Bouatay et al. 2016; Kamel, Abdelghaffar, and El-Zawahry 2011; Tronci 2017; Yin, Fei, and Wang 2018; Zhang, Zheng, and Zheng 2018) and for reproducible results requires careful control of several variables including dye concentration, pH of dye solutions, dyeing temperature, time of dyeing, and concentration of salt and alkali used during the process of dyeing (Mahilrajan et al. 2014; Mazumder and Haque 2011; Singla, CONTACT Arif Nazir anmalik77@gmail.com Department of Chemistry, The University of Lahore, Lahore, Pakistan JOURNAL OF NATURAL FIBERS https://doi.org/10.1080/15440478.2020.1789532 © 2020 Taylor & Francis