Chitosan/bentonite composite as a green mordant for Alkanna tinctoria root dyeing of wool fabrics

Chitosan/bentonite (CS/BT) composite material was used to pretreat wool fabric to optimize its dyeing performance. CS/BT composite was prepared and XRD patterns showed that chitosan intercalated between bentonite layers. The wool was pretreated with chitosan (CS) and CS/BT before dyeing with Alkanna tinctoria (AT) root. FTIR and SEM indicated that CS/BT can increase the positive surface charge of wool and be more evenly and densely distributed on wool fibers than CS. After treating wool with CS/BT, exhaustion rate of AT root increased from 40% to 80%, delta E value decreased from 3.79 NBS to 0.62 NBS. At the same time, there is no loss of color fastness and tensile strength while CS treated wool has varying degrees of loss in both aspects. In summary, BT/CS can be used as a green mordant for AT root dyeing wool to improve dyeing performance.