Microwave-assisted synthesis of MIL–53(Fe)/biochar composite from date palm for ciprofloxacin and ofloxacin antibiotics removal

Abstract

Removing hazardous materials such as pharmaceutical compounds from wastewater has become a significant global concern. The development of new materials with high efficiency, eco–friendly nature, and low–cost to address such situation is, therefore, a significant environmental challenge. In the present study a novel porous composite based on biochar derived from date palm rachis and MOFs MIL–53(Fe) has been successfully prepared using an uncomplicated and controllable microwave–assisted approach. Structural and physicochemical properties of the resulting photocatalysts were explored through several characterization methods; namely, X–Ray diffraction (XRD), Scanning electron microscopy (SEM), Energy dispersive Xray spectroscopy (EDS), Fourier transform infrared spectroscopy (FTIR), Thermogravimetric Analysis (TGA) and Brunauer–Emmett–Teller (BET). The developed composite was applied to remove ciprofloxacin and ofloxacin fluoroquinolone antibiotics, as persistent elements most found in wastewater. Results concluded that the composite prepared with the synergistic effect of biochar and MOF combination exhibited excellent adsorption activity, with maximum monolayer adsorption capacities of 218.29 and 223.89 mg/g based on the Langmuir isotherm model for OFX and CPX respectively. Kinetic and isotherm studies show that pseudo–second–order and Langmuir models best describe the adsorption process. The reusability up to five consecutive adsorption–desorption cycles was tested. Thermodynamic parameters show that the absorption of both fluoroquinolone antibiotics is spontaneous and endothermic. The regeneration efficiency can still reach up to 92.74 and 93.64% for OFX and CPX, respectively. The mechanism of adsorption was elucidated. It has been suggested that OFX and CPX molecules were captured on the MIL–53(Fe)/biochar composite through electrostatic interactions, hydrogen interactions, hydrophobic interactions and π-π EDA interactions are responsible for scavenging of MB by the synthesized materials. Consequently, MIL–53(Fe)/biochar composite derived from date palm can be used as a potential sorbent for removing antibiotics from aqueous environments.