Simultaneous dyeing and wastewater treatment in one bath by constructing cationic polyelectrolyte self-assembled coating onto cellulosic fabrics

In this study, we present a simple yet effective strategy for simultaneous textile dyeing and wastewater treatment in a single bath. Fabrics were first treated with polyhexamethylene biguanide (PHMB) through self-assembly coating and subsequently dyed with bromophenol blue (BPB) and C.I. Acid Red 127 (AR). The color yield exhibited a strong dependence on PHMB concentration, with optimal color strength achieved at 1 % (v/v) PHMB, independent of the liquor-to-goods ratio. For wastewater treatment, the phase separation efficiency varied depending on dye type and processing conditions. The BPB dyebath showed the best phase separation effect at 2 % (v/v) PHMB, particularly at a 30:1 liquor-to-goods ratio. In contrast, the acid dye AR required a higher PHMB concentration (3 %, v/v) for optimal separation, with the best performance observed at 35:1 and 40:1 ratios. Notably, a 2 % (v/v) PHMB concentration at the 30:1 ratio still provided acceptable separation for AR. This one-pot process successfully combined high-quality dyeing with efficient wastewater treatment. Additionally, the dyed fabrics showed excellent antibacterial activities. Our findings demonstrate that PHMB-based self-assembled coating enables simultaneous dyeing and wastewater purification within a single bath, eliminating the need for additional wastewater collection and treatment. This integrated approach significantly reduces operational costs while minimizing the environmental impact of conventional dyeing processes.