In this study, alginate extracted from marine algae biomass was used for the functionalization of iron oxide particles obtained in situ. This procedure ensured a complete recovery of the alginate from the aqueous solution obtained after extraction and allowed the preparation of a new biosorbent. The obtained iron oxide microparticles functionalized with alginate (Alg-Fe3O4-MPs) were analyzed (FTIR spectrometry, energy dispersive X-ray spectroscopy and scanning electron microscopy), and their biosorptive performance was tested for the removal of Cu(II), Co(II) and Zn(II) ions. The optimal conditions were established as pH = 5.4, adsorbent dosage of 2 g/L, contact time of minimum 60 min and room temperature (23 ± 1 °C). The retention of metal ions was quantitative (99% for Cu(II), 89% for Co(II) and 95% for Zn(II)) when the concentration of metal ions was less than 0.80 mmol M(II)/L. The Langmuir model was found to be the best fitted model for the equilibrium data, while biosorption kinetics followed the pseudo-second order model. Biosorption processes were spontaneous (ΔG0 < 0), endothermic (ΔH0 > 0), and accompanied by an increase in entropy (ΔS0 > 0). The high maximum biosorption capacity of Alg-Fe3O4-MPs and its good regeneration highlight the potential of this biosorbent for applications in decontamination processes.
Keywords: alginate; biosorption; functionalized iron oxide particles; metal ions retention.