Efficient Adsorptive Removal of Toxic Amaranth Dye from Water using a Zeolitic Imidazolate Framework

Adsorbents reported to remove a toxic acidic azo dye, Amaranth (AMR) are very limited, and their typical adsorption capacities are quite low. Recently, a zeolitic imidazolate framework (ZIF-67) has been proposed as a novel adsorbent as ZIF-67 possesses high surface area, superior chemical stability in water and positive charges, making it a promising adsorbent for AMR. Nevertheless, no studies have been conducted to investigate the adsorption of AMR to ZIF-67. Herein, ZIF-67 is employed for the first time to remove AMR from water via adsorption. Adsorption behaviors are investigated via determining the adsorption kinetics and isotherm. ZIF-67 also exhibits a significant higher maximum adsorption capacity (qmax = 121 mg g-1 at 30 °C) than most of the reported adsorbents. ZIF-67 can be also regenerated by washing it with NaCl solutions and the regeneration efficiency remains effective over multiple cycles, demonstrating that ZIF-67 is a promising adsorbent for AMR.