Hierarchical mesoporous ZIF-67@LDH for efficient adsorption of aqueous Methyl Orange and Alizarine Red S.

Abstract Metal-organic frameworks (MOFs) are traditional porous materials considered as efficient and low-cost for the removal of organic dyes from polluted water. In this study, we report a new type of hierarchical porous zeolitic imidazole frameworks −67@ layered double hydroxide (ZIF-67@LDH) consisting of nanocubes decorated with nanosheets. The prepared ZIF-67@LDH contains versatile functionalities which exhibit superior adsorption efficiency and adsorption rate for Methyl Orange (MO) and Alizarine Red S (ARS). The influence of pH, temperature, and contact time were analyzed in detail. The kinetics study revealed that the adsorption of MO and ARS over ZIF-67@LDH followed pseudo-second order (PSO) kinetic model, and adsorption isotherms were best described by the Langmuir isotherm model. Adsorption isotherms confirm the monolayer adsorption of MO and ARS over ZIF-67@LDH. The prepared material also shows outstanding recyclability with negligible loss. Thus ZIF-67@LDH presented a promising candidate for treating MO and ARS containing wastewater.