Enhanced decontamination of Levofloxacin residuals from water using recycled glass based a green zinc oxide/mesoporous silica nanocomposite; adsorption and advanced oxidation studies

Abstract

Glass solid wastes were recycled in the synthesis of green zinc oxide/mesoporous silica (MCM-41) composite with significant surface area (661 m2/g) and bandgap energy (2.43 eV). It was assessed as a potential adsorbent and photocatalyst for Levofloxacin. The Levofloxacin adsorption reaction is of First-order kinetic (R2 = 0.99) and Langmuir isotherm properties (R2 > 0.95). A monolayer model with two energy sites was applied for more details about the adsorption process (R2 = 0.999). Considering the steric parameters, the adsorbed Levofloxacin molecules (n) are higher than 1 on both sites (n1 (2.6–5.15) and n2 (2.99–3.18)). This suggested vertical adsorption of several Levofloxacin molecules per site by a multimolecular mechanism. The active site densities of zinc oxide as the first site (Nm1) and saturation capacity (Qsat1) increased with temperature up to 45 °C (Nm1 = 17.8 mg/g and Qsat1 = 57.49 mg/g). The reverse occurred for the second sites (MCM-41) and the best values were reported at 25 °C (Nm2 = 23.35 mg/g and Qsat2 = 69.8 mg/g). The adsorption energy (−8.16 to −25.9 kJ/mol) and thermodynamic functions declare physical Levofloxacin uptake mechanisms of spontaneous and exothermic properties. G.Zn/MCM as photocatalyst (0.5 g/L) achieved 100% oxidation of Levofloxacin (50 mg/L) and 100% mineralization after 160 min and 240 min, respectively.