چكيده لاتين
The provision of safe drinking water has become a global challenge due to population growth, industrial development, and the emergence of new pollutants such as pharmaceuticals. In this study, to improve performance and overcome the limitations of recovery and agglomeration of ZIF-8 in drug adsorption as well as to create a synergistic effect, a nanocomposite of ZIF-8 and halloysite nanotubes (HNTs) was used. Halloysite is a natural mineral material with a nanoscale tubular structure. Its advantages include biocompatibility, low cost, and non-toxicity. Moreover, halloysite, as a nanocarrier, prevents the agglomeration of ZIF-8.
Initially, the ZIF-8@HNTs nanocomposite was synthesized using the in-situ growth method and employed for the adsorption of the pharmaceuticals cefixime, ciprofloxacin, and ofloxacin from aqueous solutions. The influencing factors, including temperature, contact time, pH, adsorbent dosage, and solvent concentration, were optimized. Under optimal conditions, the adsorption efficiencies of cefixime, ofloxacin, and ciprofloxacin by the HNTs@ZIF-8 adsorbent were 95%, 93.6%, and 97%, respectively.
In the next stage of the study, to improve and facilitate the recovery of the adsorbent, the aforementioned nanocomposite was grown in situ on polyvinyl alcohol nanofibers. Under optimal conditions, the adsorption efficiencies of cefixime, ofloxacin, and ciprofloxacin by this adsorbent reached 85%, 87%, and 88%, respectively. The reusability of both adsorbents was investigated for up to six cycles, and both exhibited good stability. Furthermore, for both synthesized composites, the pseudo-first-order, pseudo-second-order, intraparticle diffusion, and Elovich kinetic models were examined. The thermodynamic parameters and the Langmuir, Freundlich, and Temkin isotherm models were also analyzed. Based on the results, the adsorption processes of the mentioned drugs by both adsorbents were spontaneous and exothermic.
All samples used in this research including ZIF-8 powder, halloysite nanotubes, and the synthesized composites were characterized using various techniques such as XRD, FT-IR, UV-vis, BET, TGA, ICP, FESEM, EDX, and tensile testing.