Natural tea pigment dyeing of cotton fibers with Fe~(2+) as a mordanting agent

The aqueous tea solution extracted from green tea was used to dye cotton fibers with FeSO4 as mordanting agent.The effect of pre-mordanting,meta-mordanting and post-mordanting on dyeing property of fibers was studied.In the case of the post-mordanting,the effect of dye concentration,dyeing temperature,pH value of dye bath and mordant concentration on the dyeing of fibers were analyzed.FTIR was used to characterize the microstructure of fiber samples,and the strength and elongation of fibers before and after dyeing were also tested.The results showed that post-mordanting method exhibited the best effect of dyeing with the maximum K /S value.The optimum conditions for the post-mordanting dyeing method with natural tea pigment using Fe2 + as mordant were as follows: dye concentration 10 g /L,dyeing temperature 100 ℃,pH = 4,and mordant concentration 5%(o.w.f).The hydrogen bond of cellulose reacted with Fe2 + to form metal complex.In comparison with the cotton fibers before dyeing,the breaking strength decreased slightly and breaking elongation increased considerably for the dyed fibers.