The effect of temperature on the adsorption of lac dye on cotton was investigated. It was found that a higher dyeing temperature resulted in higher initial dye adsorption rate (hi) on
cotton before equilibrium as shown in Fig. 1. These results are similar to those observed for lac dyeing of silk in our previous work [12]. The mobility of the large dye ions would be
increased at higher temperature and subsequently the rates of dyeing would be enhanced. A similar observation was also reported in the study on the adsorption of a basic dye on crosslinked cotton [17]. At the equilibrium time, the dye adsorbed by the cotton decreased with increasing temperature, indicating an exothermic process. As can be observed from
Fig. 1(a), the time required to reach equilibrium was shorter at higher dyeing temperatures, i.e., 120, 60 and 5 min at 10,30 and 60 C, respectively. The dyeing condition of pH 3.0, initial dye concentration of 480 10 mg/L and MLR of 1:100 was subsequently used to study the adsorption kinetics of lac dye on cotton.