Copper (II) removal by pectin–iron oxide magnetic nanocomposite adsorbent

This study describes an effective copper removal method using pectin-coated iron oxide magnetic nanocomposite as an adsorbent. The nanocomposite adsorbent was synthesized with the iron salt co-precipitation method followed by direct encapsulation with pectin coating without cross linking with calcium ions. Scanning electron microscopy (SEM) images showed pectin–iron oxide magnetic nanocomposite (PIOMN) adsorbent was spherical in shape and 77 ± 5 nm in diameter. Fourier transform infrared spectroscopy (FTIR) spectra provided the evidence that pectin was successfully coated on the surface of iron oxide nanoparticle. The interaction between copper ions and pectin on PIOMN surface was elucidated from energy dispersive analysis system of X-ray (EDAX) spectra. The amount of adsorbed Cu(II) by PIOMN adsorbent increased with increasing pH, followed by decreased pH value after copper uptake, attesting to the ion exchange and electrostatic force mechanism during the adsorption process. Sorption kinetic data were well fitted with a pseudo second-order model, and sorption isotherms were described by both Langmuir and Freundlich equation with maximum adsorption capacity of 48.99 mg/g. Furthermore, the adsorbents can be regenerated using 0.01 M EDTA, remaining 93.70% of its original capacity after the first regeneration cycle, and still reaching 58.66% of the original capacity after the fifth cycle.

► Pectin–iron oxide magnetic nanocomposite (PIOMN) adsorbent was easily synthesized.
► PIOMN is low-cost, environmental friendly and can be separated conveniently.
► PIOMN exhibits favorable adsorption capacity for copper ions removal.