Novel bentonite/zeolite-NaP composite efficiently removes methylene blue and Congo red dyes

Synthetic dyes are common water contaminants that impair water quality and cause diseases such as dermatitis, cancer and dysfunction of kidneys. There is therefore a need for adsorbent materials to remove dyes from water. Here a bentonite/zeolite-NaP composite was synthesized by alkaline treatment of bentonite at 150 °C for 4 h. The composite exhibits nearly cubic zeolite-NaP crystals dispersed throughout bentonite aggregates. This composite has 512 m 2 /g surface area, 387 meq/100 g cation exchange capacity and 5.4 nm average pore diameter. The composite shows high removal efficiency for methylene blue, of 94%, and Congo red, of 93%, after 720 min at an initial concentration of 5 mg/l.