Adsorptive Removal of Fluoroquinolones from Water by Pectin-Functionalized Magnetic Nanoparticles: Process Optimization Using a Spectrofluorimetric Assay

The efficiency of adsorption of two photosensitive fluoroquinolones; Ciprofloxacin (CIP) and Moxilloxacin (MOX), on the surface of synthesized magnetite/pectin nanoparticles (MPNPs) and magnetite/silica/pectin nanoparticles (MSPNPs) was studied from aqueous solution under varying experimental conditions. A validated spectrofluorimetric assay was developed for monitoring of CIP and MOX intact drugs and their photodegraded molecules concentrations. To optimize the working conditions which influence the drugs sorption, a 2(4) full factorial experimental design was implemented. The maximum percentage of removal was attained as 89% (type of sorbent = MSPNPs, pH = 7.0, initial drug concentration = 5 mg/L, and contact time = 30 min). The studied factors-pH, NPs loading initial drug concentration, and contact time-were significant for both types of sorbents. The most significant variable was pH, and the highest CIP and MOX adsorption occurred at pH = 7.0. Equilibrium isotherm data were fitted to Langmuir, Freundlich, and Sips equations, and the Sips model showed the best fit with equilibrium isotherm data. Furthermore, pseudo-first- and pseudo-second-order kinetic models were used to analyze sorption kinetics, and it was found that adsorption of the investigated fluoroquinolones followed pseudo second-order kinetics. We believe that our synthesized NPs can be used as effective adsorbents for fluoroquinolones and their photodegraded molecules removal from aqueous solutions.