Biobased biodegradable hydrogel containing modified cellulosic nanofiber-ZnO nanohybrid as efficient metal ions removers with recyclable capacity

Abstract

In the past decades, immense attention has been paid to the development of biobased hydrogel nanocomposite (HNC) to remove metal ions from wastewater owing to their high adsorption capacity, biodegradability, and reusability. In this work, we have demonstrated the fabrication of a nanohybrid using modified cellulose nanofiber and zinc oxide nanoparticles using an eco-friendly and non-toxic approach and subsequently incorporated it into a starch/itaconic acid/acrylic acid-based hydrogel matrix. The structure and morphology of the prepared nanohybrid and HNC were characterized by different spectroscopic and microscopic techniques. The resulting HNCs were employed for the removal of metal ions (Cu(II) and Fe(II)) from aqueous solution and manifested noteworthy adsorption ability. With the incorporation of 0.25 wt% nanohybrid, the HNC showed the highest water swelling capacity of 580 g/g. Besides, the incorporation of the nanohybrid enhanced the metal ion adsorption ability of the HNC, and the removal capacity of 122 and 70 mg/g was obtained for Cu(II) and Fe(II) ions, respectively. The adsorption kinetics followed the pseudo-second-order model and isotherms were found to be fitted well with the Freundlich model. Additionally, the prepared nano-structural adsorbent can be removed easily and could be used for 3 repeated purification cycles without significant loss of efficiency. Thus, this work leads to the development of nanohybrid-containing biobased HNC as a promising candidate for the removal of toxic metal ions with remarkable reusability as well as adsorption capacity.