Application of a new metal-organic framework of [Ni2F2(4,4′-bipy)2(H2O)2](VO3)2.8H2O as an efficient adsorbent for removal of Congo red dye using experimental design optimization

Abstract

The new metal-organic framework of [Ni2F2(4,4′-bipy)2(H2O)2](VO3)2.8H2O was synthesized by a sonochemical method for the adsorptive removal of Congo red (CR) in a batch system. It was characterized by infrared spectroscopy (FT-IR), field emission scanning electron microscopy (FESEM), thermogravimetric (TGA), and elemental analyses. Box-Behnken design (BBD) was applied to obtain an appropriate regression model for removal percent (R%) of CR dye. The optimized conditions for three effective factors: adsorbent dosage, temperature, and CR concentration were m = 0.0107 g, T = 45 °C, and Cd = 50 mg.L−1, respectively, while maximum removal percent is 96%. Langmuir isotherm shows that the maximum monolayer adsorption capacity (qmax) is 242.1 mg.g−1. The pseudo-second-order kinetic model better describes the adsorption kinetics behavior. Thermodynamic parameters illustrate that the adsorption process is endothermic and spontaneous chemisorption. The aim of this study is the introduction of a new metal-organic framework that can adsorb Congo red with high adsorption capacity. Therefore, due to synthesis of the new metal-organic framework as a high efficient adsorbent for Congo red removal, and also multivariate optimization of removal conditions, this study outright is novel.