Chitosan Grafted with Biobased 5-Hydroxymethyl-Furfural as Adsorbent for Copper and Cadmium Ions Removal

Mariza Mone; Dimitra A Lambropoulou; Dimitrios N Bikiaris; George Kyzas

doi:10.3390/polym12051173

Chitosan Grafted with Biobased 5-Hydroxymethyl-Furfural as Adsorbent for Copper and Cadmium Ions Removal

Polymers (Basel). 2020 May 20;12(5):1173. doi: 10.3390/polym12051173.

Authors

Mariza Mone¹, Dimitra A Lambropoulou², Dimitrios N Bikiaris¹, George Kyzas³

Affiliations

¹ Laboratory of Polymer Chemistry and Technology, Department of Chemistry, Aristotle University of Thessaloniki, GR-541 24 Thessaloniki, Greece.
² Laboratory of Environmental Pollution Control, Department of Chemistry, Aristotle University of Thessaloniki, GR-541 24 Thessaloniki, Greece.
³ Department of Chemistry, International Hellenic University, GR-654 04 Kavala, Greece.

Abstract

This work investigates the application of 5-hydroxymethyl-furfural (HMF) as a grafting agent to chitosan (CS). The material produced was further modified by cross-linking. Three different derivatives were tested with molecular ratios CS/HMF of 1:1 (CS-HMF1), 2:1 (CS-HMF2) and 10:1 mol/mol (CS-HMF3)) to remove Cu²⁺ and Cd²⁺ from aqueous solutions. CS-HMF derivatives were characterized both before, and after, metal ions adsorption by using scanning electron microscopy (SEM), as well as Fourier-transform infrared (FTIR) spectroscopy thermogravimetric analysis (TGA), and X-Ray diffraction analysis (XRD). The CS-HMF derivatives were tested at pH = 5 and showed higher adsorption capacity with the increase of temperature. Also, the equilibrium data were fitted to Langmuir (best fitting) and Freundlich model, while the kinetic data to pseudo-first (best fitting) and pseudo-second order equations. The Langmuir model fitted better (higher R²) the equilibrium data than the Freundlich equation. By increasing the HMF grafting from 130% (CS-HMF1) to 310% (CS-HMF3), an increase of 24% (26 m/g) was observed for Cu²⁺ adsorption and 19% (20 mg/g) for Cd²⁺. By increasing from T = 25 to 65 °C, an increase of the adsorption capacity (metal uptake) was observed. Ten reuse cycles were successfully carried out without significant loss of adsorption ability. The reuse potential was higher of Cd²⁺, but more stable desorption reuse ability during all cycles for Cu²⁺.

Keywords: 5-hydroxymethyl-furfural; adsorption; biobased polymers; cadmium; chitosan; copper; derivatives; wastewaters.