Flower-like hierarchical Ni-Zn MOF microspheres: Efficient adsorbents for dye removal

Water pollution has become a great problem and aroused worldwide concern. As a new class of materials, metal-organic frameworks (MOFs) exhibit significant potential for wastewater treatment due to their high surface area, porosity, stability and tunability. In this work, flower-like hierarchical Ni-Zn MOF microspheres were synthesized via a facile solvothermal method. The mole ratio of Ni to Zn had a great influence on the morphology and microstructure of the final products. With the increase mole ratio of Zn to Ni, the morphology of MOFs gradually changed from spheroidal structure to rod-like structure. Using the Congo red (CR) experiment to evaluate the adsorption performance, Ni-Zn MOF displayed superior adsorption capacity towards CR (460.90 mg g(-1)) compared with Ni MOF (276.70 mg g(-1)) and Zn MOF (132.20 mg g(-1)). Besides the tuned morphology and pore structure, electron transferring from Zn species to Ni species would also favor the physicochemical adsorption of Ni-Zn MOF towards CR.