Arabic Gum-Grafted-Hydrolyzed Polyacrylonitrile@ZnFe 2 O 4 as a Magnetic Adsorbent for Remediation of Levofloxacin Antibiotic from Aqueous Solutions.

The Arabic gum- grafted -hydrolyzed polyacrylonitrile/ZnFe 2 O 4 (AG- g -HPAN@ZnFe 2 O 4 ) as organic/inorganic adsorbent was obtained in three steps using grafted PAN onto Arabic gum in the presence of ZnFe 2 O 4 magnetic nanoparticles and then hydrolysis by alkaline solution. Fourier transform infrared (FT-IR), energy-dispersive X-ray analysis (EDX), field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), thermogravimetric analysis (TGA), vibrating sample magnetometer (VSM), and the Brunauer-Emmett-Teller (BET) analysis analyses were used to characterize the chemical, morphological, thermal, magnetic, and textural properties of the hydrogel nanocomposite. The obtained result demonstrated that the AG- g -HPAN@ZnFe 2 O 4 adsorbent showed acceptable thermal stability with 58% char yields and superparamagnetic property with magnetic saturation (Ms) of 24 emu g -1 . The XRD pattern showed that the semicrystalline structure with the presence of ZnFe 2 O 4 has distinct peaks which displayed that the addition of zinc ferrite nanospheres to amorphous AG- g -HPAN increased its crystallinity. The AG- g -HPAN@ZnFe 2 O 4 surface morphology exhibits uniform dispersion of zinc ferrite nanospheres throughout the smooth surface of the hydrogel matrix, and its BET surface area was measured at 6.86 m 2 /g, which was higher than that of AG- g -HPAN as a result of zinc ferrite nanosphere incorporation. The adsorption effectiveness of AG- g -HPAN@ZnFe 2 O 4 for eliminating a quinolone antibiotic (levofloxacin) from aqueous solutions was investigated. The effectiveness of adsorption was assessed under several experimental conditions, including solution pH (2-10), adsorbent dose (0.0015-0.02 g) contact duration (10-60 min), and initial concentration (50-500 mg/L). The maximum adsorption capacity ( Q max ) of the produced adsorbent for levofloxacin was found to be 1428.57 mg/g (at 298 k), and the experimental adsorption data were well explained by the Freundlich isotherm model. The pseudo-second-order model satisfactorily described the adsorption kinetic data. The levofloxacin was mostly adsorbed onto the AG- g -HPAN@ZnFe 2 O 4 adsorbent via electrostatic contact and hydrogen bonding. Adsorption-desorption studies demonstrated that the adsorbent could be efficiently recovered and reused after four consecutive runs with no significant loss in adsorption performance.