Carboxylated cellulose nanofiber/montmorillonite nanocomposite for the removal of levofloxacin hydrochloride antibiotic from aqueous solutions

Herein, we report the facile two-step synthesis of an effective carboxylated cellulose nanofiber/montmorillonite nanocomposite (CMNFs–MMT) adsorbent for levofloxacin hydrochloride (Levo-HCl). CMNFs–MMT was characterized using scanning electron microscopy, energy dispersive X-ray spectrometry, Brunauer–Emmett–Teller measurements, X-ray photoelectron spectroscopy, X-ray diffraction, and Fourier transform infrared spectroscopy. Based on the central composite design, the effects of various factors on the removal of Levo-HCl by the CMNFs–MMT were explored, wherein the effect of pH was the most significant. To gain a clearer perspective on the adsorption process of Levo-HCl onto CMNFs–MMT, the adsorption kinetics and isotherms were also measured, revealing that the reaction is pseudo-second-order and the Sips models provide the best fit with experimental data. Comparing the adsorption in pure water with the removal in river water, the rate of river water removal (90.37%) was slightly lower than that of pure water (93.97%) when adsorption equilibrium was reached, confirming that CMNFs–MMT is not easily influenced by environmental conditions. Reusability experiments indicate that CMNFs–MMT can maintain a certain adsorption capacity for Levo-HCl after six uses. Overall, this work indicates that CMNFs–MMT is an effective adsorbent for eliminating Levo-HCl from aqueous media in future engineering applications.