Adsorption of Tetracycline by Magnetic Mesoporous Silica Derived from Bottom Ash-Biomass Power Plant

In recent years, the contamination of the aquatic environment with antibiotics, including tetracyclines, has drawn much attention. Bottom ash (BA), a residue from the biomass power plant, was used to synthesize the magnetic mesoporous silica (MMS) and was utilized as an adsorbent for tetracycline (TC) removal from aqueous solutions. The MMS was characterized by Fourier transform-infrared (FTIR), X-ray diffraction (XRD) pattern, and scanning electron microscopy (SEM). Optimum conditions were obtained in overnight incubation at 60 degrees C, a pH of 6-8, and an adsorption capacity of 276.74 mg/g. The isotherm and kinetic equations pointed to a Langmuir isotherm model and pseudo-first-order kinetic optimum fitting models. Based on the very low values of entropy changes (Delta S degrees), the negative value of enthalpy changes (Delta H degrees) (-15.94 kJ/mol), and the negative Gibbs free-energy changes (Delta G degrees), the adsorption process was physisorption and spontaneous.