Superparamagnetic cobalt ferric nanoparticles incorporated biopolymers extracted from dragon fruit (hylocereus undatus) peels for nickel(II) removal

Low-cost adsorbents derived from agricultural by-products incorporated magnetic nanoparticles (NPs) are promising and novel adsorbents for water/wastewater treatment due to their outstanding performance and easy separation. This study reports a nanocomposite of cobalt superparamagnetic (CoFe2O4) NPs incorporated biopolymers extracted from a dragon fruit (hylocereus undatus) peel, called bp-CoFe2O4, to potentially remove Ni(II) ions from aqueous solutions. Morphologic and structural properties of the bp-CoFe2O4 were successfully characterized using a scanning electron spectrometry, X-ray diffraction, Fourier transform infrared spectrometry, and vibrating sample magnetometer (VSM). The bp-CoFe2O4 particles exhibited soft and superparamagnetic properties, which can be easily recycled using an external magnet. Ni(II) adsorption on the bp-CoFe2O4 was attributed to both the components including CoFe2O4 particles and coated biopolymers. Indeed, the bp-CoFe2O4 adsorbing Ni(II) ions reached optimal at pH ∼6 (∼88% of Ni(II) removal at an adsorbent dose of 1 g/l and Ni(II) concentration of 171.1 mg/l). The bp-CoFe2O4 can maintain the effective treatment of Ni(II) ion (only ∼10% of efficiency loss) up to three cycles of the regeneration. Owing to retaining the magnetic property through the regeneration cycles, this bio-adsorbent would promise a high potential for long-term treatment of Ni(II) ions from polluted waters with easy separation. [Display omitted] •A magnetic composite of CoFe2O4 nanoparticles incorporated biopolymer was prepared.•This nanocomposite showed effective adsorption of Ni(II) ions at optimal pH ∼6.•Easy separation/recycle of the nanocomposite from the solution using a magnet.•Good reusability of the nanocomposite in repeated Ni(II) adsorption–desorption runs.