The potential of cetyltrimethylammonium bromide-treated Phragmites australis powder (CTAB-PA) as a novel polymeric sorbent for Eriochrome Black T (EBT) removal was studied. CTAB impregnation process increased adsorption sites availability that led to a better interaction of EBT dye and CTAB-PA. CTAB impregnation process increased the PA monolayer adsorption capacity from 57.14 to 89.93 mg g(-1). Adsorption data were modeled using chemical reaction-based kinetic models (pseudo-first-order, pseudo-second-order, and Elovich models) and diffusion-based kinetic models (Weber-Morris and Boyd models). EBT sorption kinetics could be described by the pseudo-second-order model having film diffusion as the main rate-limiting step. Adsorption data for both adsorbents were fitted to Langmuir, Freundlich, Temkin, and Dubinin-Radushkevich models, and best fitting was obtained with Langmuir model. Thermodynamic functions indicated that EBT adsorption onto PA and CTAB-PA was an exothermic and physical process. CTAB-PA burning behavior showed that this novel adsorbent can be considered as flame-retarding material. Adsorption-desorption experiments revealed that CTAB-PA could be reused up to five cycles with recovery percentage values maintained higher than 71%. CTAB-PA, a low-cost, durable, flame-retarding, and reusable material, was found to be an attractive candidate for EBT removal from water.