Arabic Gum-Grafted-Hydrolyzed Polyacrylonitrile@ZnFe2O4 as a Magnetic Adsorbent for Remediation of Levofloxacin Antibiotic from Aqueous Solutions

The Arabic gum-grafted-hydrolyzed polyacrylonitrile/ZnFe2O4 (AG-g-HPAN@ZnFe2O4) as organic/inorganic adsorbent was obtained in three steps using grafted PAN onto Arabic gum in the presence of ZnFe2O4 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@ZnFe2O4 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 ZnFe2O4 has distinct peaks which displayed that the addition of zinc ferrite nanospheres to amorphous AG-g-HPAN increased its crystallinity. The AG-g-HPAN@ZnFe2O4 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 m2/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@ZnFe2O4 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 (Qmax) 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@ZnFe2O4 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.

Automated summary

The AG-g-HPAN@ZnFe2O4 organic/inorganic adsorbent was synthesized by grafting polyacrylonitrile onto Arabic gum with the addition of ZnFe2O4 magnetic nanoparticles and subsequent hydrolysis. The adsorbent exhibited thermal stability, superparamagnetic property, and improved crystallinity compared to AG-g-HPAN. It effectively adsorbed levofloxacin from aqueous solutions through electrostatic contact and hydrogen bonding, with a maximum adsorption capacity of 1428.57 mg/g. The adsorbent could be easily recovered and reused without significant loss in adsorption performance.