Facile Synthesis of MIL-۵۳(Fe) by Microwave Irradiation and its Application for Robust Removal of Heavy Metals from Aqueous Solution by Experimental Design Approach: Kinetic and Equilibrium

MIL-۵۳(Fe) with huge porosity has been synthesized by microwave radiation in the different ‎conditions: various powers (۸۰, ۱۰۰W) and time (۵, ۱۰ min). Nano-sized crystals were ‎characterized by using X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier ‎transform infrared spectroscopy (FTIR) and specific surface area analysis. After performing the characterization, MIL-۵۳(Fe)-۱ with the best porous structure for Pb (II) and Cd (II)‎ removal was used for all tests from aqueous solution. The best condition for synthesis was ۵ min and ۸۰ W. Then the best porous structure was selected for removal of Pb (II) / Cd (II) from aqueous solution. The ‎response surface methodology (RSM) based on central composite design (CCD) was applied to ‎optimize the removal capacity. In these experimental designs, four independent variables were studied and the best condition was evaluated as ‎‎pH(in the range of ۶-۸), temperature (۴۰-۵۰◦C), contact time (۵۰ min), and adsorbent amount (۰.۱-۰.۳ g.L-۱). The removal efficiency and ‎capacity of MIL-۵۳(Fe) for Pb (II) and Cd (II) was further surveyed. Langmuir equation was the ‎best isotherm to describe the adsorption manner of Pb (II) and Cd (II) ions (qmax values ( ۱۷۸.۵۷ and ۷۱۴.۲۸ mg g−۱) for Pb (II) and Cd (II)). The adsorption ‎process was confirmed by a pseudo-second-order kinetic pattern. The result of thermodynamic ‎studies displayed that the sorption process was spontaneous and exothermal.

Keywords:

MIL-۵۳(Fe) , microwave radiation , Nano-sized crystals , Response surface ‎methodology (RSM) , heavy metals , Removal