Adsorption of selective fluoroquinolones by cysteine modified silane magnetic nanocomposite from the aqueous phase

Elevated levels of pharmaceutical pollutants in the aquatic environment have caused detrimental effects on water quality and biodiversity. Nanomaterials are among the most promising technologies to detect, adsorb, and remove these pollutants from the aqueous systems. The current work explores the applicability of nickel ferrite nanocomposite functionalized with L-cysteine attached 3-glycidyloxypropyltrimethoxysilane to remove a selective class of antibiotics known as fluoroquinolones (Lomefloxacin, Ciprofloxacin, and Norfloxacin). 20 mg of this nanocomposite achieve maximum removal efficiencies of 61%, 67%, and 75% for 40 mg L−1 of lomefloxacin, norfloxacin, and ciprofloxacin, respectively. The nanocomposites also show good regeneration capacity with negligible reduction in the efficiencies up to three cycles. Furthermore, adsorption isotherms such as Langmuir and Freundlich isotherms were used to characterize the removal of fluoroquinolones from the aqueous phase by the nanocomposites. The results show that the adsorption process was in good agreement with the Langmuir isotherm, thus confirming its monolayer sorption process and also reveals that adsorption kinetics follows a pseudo-second-order model. The maximum adsorption capacity of functionalized nickel ferrite nanocomposites are 122 mg g−1, 135 mg g−1, and 150 mg g−1 for lomefloxacin, norfloxacin, and ciprofloxacin, respectively. Overall, all the results obtained indicate that the nickel ferrite nanocomposite functionalized with L-cysteine attached 3-glycidyloxypropyltrimethoxysilane is an effective adsorbent to remove fluoroquinolones from the aqueous systems and could be potentially incorporated in water treatment processes under well-defined parameters.