Study on the dyeing and kinetics of reactive yellow 145 in the salt-free and low-water dyeing system
Reactive dyes have been widely used in cotton fabrics'dyeing due to their excellent application performance such as color diversity and simple use.Traditional dyeing of reactive dyes/cotton fabrics is carried out under water bath conditions,which consumes a large amount of energy and dyeing auxiliaries,and generates a large amount of dyeing wastewater.The non-aqueous medium(decamethylcyclopentasiloxane)dyeing system of reactive dyes has attracted attention due to its significant advantages of zero salt and low water content in the dyeing process,high dye utilization rate,and energy conservation and environmental protection.It can effectively solve the problems of low dye utilization,high electrolyte consumption,and large sewage discharge in traditional reactive dyes'water bath dyeing.The dye solution is completely insoluble in the non-aqueous phase,but has a strong affinity for cotton fibers,so that more of the dye is rapidly distributed to the fibers with a small amount of water in a non-aqueous medium.However,in the dyeing system,polar aqueous solutions are tightly encapsulated by organic non-polar non-aqueous media,forming a high concentration of dye solution,resulting in poor dispersion of dyes in non-aqueous media.This may also cause aggregation or precipitation of dye molecules and uneven dyeing.The research on the adsorption mechanism of a reactive dye solution in salt-free and low-water dyeing systems is limited.In particular,the comprehensive information on the effects of media on the diffusion and adsorption models of reactive dyes has not been systematically studied.In order to study the dyeing properties and dyeing kinetics of reactive dyes in the traditional water bath system and siloxane system,and to explore the key factors affecting the dyeing of reactive dyes in non-aqueous medium salt-free and low-water dyeing systems,the reactive dye of cyanuric acid-vinyl sulfone(reactive yellow 145)was selected.The dyeing of reactive yellow 145 in the non-aqueous medium dyeing system and the traditional water bath dyeing system was investigated,and an adsorption kinetic model of reactive dyes was established to explore the key factors affecting the dyeing of reactive dyes in non-aqueous medium salt-free and low-water dyeing systems.The intrinsic relationship between the diffusion behavior of reactive yellow 145 in non-aqueous dyeing systems was successfully determined,and the adsorption kinetics and mechanisms of reactive dyes in non-aqueous dyeing systems and water bath systems were revealed.The experimental results show that the absorption rate of active yellow 145 is higher(＞95％)and the fixation rate is also higher(72％-84％for non-aqueous dyeing and 43％-71％for traditional dyeing)in the non-aqueous medium salt-free and low-water dyeing system.The K/S value of cotton fabric after dyeing is higher(5.97-26.63 for non-aqueous dyeing and 4.35-21.92 for traditional dyeing).The dyeing kinetics of reactive yellow 145 in the two dyeing systems can be described by using a quasi-second-order kinetic model.As the dye concentration increases,the difference between the final adsorption amount of reactive dyes in the non-aqueous medium salt-free and low-water dyeing system and the final adsorption amount in the water bath system gradually increases.When the dye dosage is 8％,the final adsorption capacity of the traditional water bath system(68.32)is more than twice compared to 29.20.The half dyeing time distribution of the water bath dyeing system is between 16.60 and 7.48.The half dyeing time distribution of the water bath dyeing system is between 16.60 and 7.48.The distribution of semi staining time in non-aqueous media is between 2.03 and 2.58.These results indicate that the dyeing speed of reactive dyes in salt-free and low-water systems is much higher than that in traditional water bath systems,and the dye utilization rate is high.The K/S value of the dyed fabric is also high.Non-aqueous dyeing technology provides an innovative method to increase dye uptake at low energy consumption,in addition to saving large amounts of water.This study provides theoretical guidance for the dyeing of cotton fabrics with different dyeing depth requirements in the salt-free and low-water dyeing system,and it is of great significance to improve the practical application of reactive dyestuffs in non-aqueous medium salt-free and low-water dyeing system as well as industrial production.
salt-free and low-water dyeingreactive dyesdyeing performancedyeing ratehalf-dyeing time
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