8 Physico-chemical Aspects of Wool Dyeing: Adsorption, Kinetics and Thermodynamics LUQMAN JAMEEL RATHER 1 *, MOHD SHABBIR 1 AND FAQEER MOHAMMAD 1 ABSTRACT Dyeing of textiles and textile materials has been going parallel to the human life since time immemorial. With the development of new technologies, domestic and overseas textile market have developed a variety of new functional fibers which not only fulfill the demand of the traditional textile industry but also improve quality of our life, meets the requirement of textile industrial sectors in terms of environmental protection levels, comfort, and health. In order to manipulate the process of natural dyeing efficiently and to get maximum color yield in economical way, it is essential to develop knowledge based on dye chemistry, various aspects of dyeing process variables, rate of dyeing and chemical kinetics of dyeing for different dyes and fiber combinations. In this chapter, physical and chemical aspects of wool dyeing processes were discussed with the focus on the effect of chemical modifications of textile materials on the adsorption characteristics. A comparative analysis of various textile substrate surfaces were discussed in relevance to the dyeing process parameters responsible for dye stickiness towards textile materials. Key words: Dyeing, Textiles, Thermodynamics, Kinetics, Adsorption isotherm 1. INTRODUCTION Significant advancements have been achieved since last few decades in natural dye applications, but still insufficient scientific studies and systematic reports render full exploitation of these dye yielding flora and fauna with lot of natural products untouched (Islam et al., 2013; Shahid et al., 2013). Thus there is need of improving research methodologies to build a database of knowledge with generation of cost-effective processes for modern textile coloration. Endeavour to textile industry is to have maximum flexibility in terms of proper coloration, augmentation of easy monitoring techniques, replenishment of stocks with newer trend and meeting fashion demands of consumers (Shahid et al., 2013). Eventually, large number of factors involved in the natural dyeing process needs proper standardization of dyeing parameters for achieving broad spectrum of colors and special performance characteristics on wide range of natural as well as synthetic textile materials (Rather et al., 2016a, Shabbir et al., 2016a). 1 Department of Chemistry, Jamia Millia Islamia, New Delhi-110025, India. *Corresponding author: E-mail: luqmanjameel123@gmail.com