Flower-Shaped Ni/Co MOF with the Highest Adsorption Capacity for Reactive Dyes

Reactive dyes are widely used in textile industry, but their excessive use has caused several water pollution problems. In order to reasonably treat printing and dyeing wastewater, the highly efficient adsorbent for reactive dyes employed in this study is a new type metal-organic framework (MOF) material. Ni/Co MOF (NCM) was synthesized using the solvothermal method; then, the materials were analyzed by a series of characterization methods. This study mainly investigated the adsorption properties of NCM toward reactive dyes, and the adsorption capacities of NCM toward reactive red 218 were up to 200 mg·g^-1. The results were found to conform to the Langmuir isotherm model, and the pseudo-second-order kinetic model by performing kinetic and isotherm studies on the adsorption process of reactive red 218 on NCM. The results of the intraparticle diffusion model suggest that the binding of reactive red 218 to NCM was mainly divided into three steps: adsorption, diffusion, and saturation. Moreover, it was concluded by thermodynamic fitting of the adsorption process that the adsorption of reactive red 218 by NCM proceeded spontaneously and was accompanied by an endothermic reaction, in which the adsorption of both occurred mainly by electrostatic attraction. The NCM has good reusability and still has good adsorption performance after being reused 5 times. Therefore, NCM is a very promising and excellent adsorbent for the treatment of dye wastewater because of its high efficiency and reusability.