Adsorption of levofloxacin onto mechanochemistry treated zeolite: Modeling and site energy distribution analysis

Adsorption of antibiotic levofloxacin from aqueous solution to humic acid treated zeolite has been studied. The equilibrium isotherm model was calculated and the site energy distribution was determined. Within the test range (initial concentration 5.5-67 mg/L, pH 2-12), adsorption performance for levofloxacin showed two maximum total uptakes at acid and alkali conditions. The uptake capacities are 33.93 mg/g and 35.98 mg/g at pH 4.85 and pH 9.44, respectively. Due to the equilibrium isotherm model, the theoretical maximum value of adsorbent capacities of levofloxacin are 35.45 mg/g and 47.68 mg/g at pH 4.85 and pH 9.44. The site energy distribution of the adsorbent for levofloxacin molecules adsorption was estimated. The higher average site energy of the adsorbents is 28.01 kJ/mol at pH 4.85. The methods of site energy distribution analysis could be transferable to extend other organics and inorganics adsorption.