The adsorption of cationic dye onto ACPMG@ZIF-8 core-shell, optimization using central composite response surface methodology (CCRSM)

Abstract

The massive parts of commercial dyes are interring to our environment and are considered danger for humans and animals. The aim of this study is to fine an effective adsorbent for the removal of cationic days such as Safranin o (SO). The activated carbon prepared from Persian mesquite grain (ACPMG) and zeolitic imidazolate frameworks (ZIF-8) have used to form ACPMG@ZIF-8 core-shell by the solvothermal method. Several techniques such as Fourier Transform Infra-Red, X-ray Diffraction, Scanning Electron Microscope, Elemental mapping analysis, Energy-dispersive X-ray, Transmission Electron Microscopy, thermogravimetric analysis, and Pore Size Distribution have been used for characterizing of the adsorbents. The results of these techniques show essential changes in porosity that happened on the material surface after the modification process. The essential factors on the removal, the amount of AC on ZIF-8, the initial concentration of SO, contact time, and pH, were optimized by the central composite response surface methodology (CCRSM). The equal adsorption capacity of 1250 mg. g-1 is attained at 24.20 wt% loading amount, the initial concentration of SO 109.609 mg. L-1, contact time of 44.631 min, and pH of 5.686. The experimental data were investigated by some famous kinetic and isotherm models, which the removal of SO by the ACPMG@ZIF-8 core-shell is correlated with the Langmuir isotherm model and follow the quasi-second-order kinetic model. According to the results of thermodynamics, the adsorption process is exothermic and spontaneous.