Adsorption of AR114 onto humic acid-modified Fe3O4 nanoparticles

In this study, Fe3O4 and humic acid-modified Fe3O4 (Fe3O4@HA) magnetic nanoparticles were synthesized and used for the removal of Acid Red 114 (AR114) dyestuff from aqueous. The batch adsorption method was used for the experiments. The magnetic nanoparticles, synthesised by an inexpensive and environmentally friendly precipitation process, were characterised by FTIR, SEM-EDX, BET surface area, and XRD analyses. The optimum pH values determined for Fe3O4 and Fe3O4@HA were the original pH (6.4) and 4, respectively. The equilibrium state was reached after 60 minutes for both adsorbents. The values for Fe3O4 and Fe3O4@HA were determined as 3.4 mg/g and 3.1 mg/g, respectively, when 10 mg/l initial dyestuff concentration and 2 g adsorbent were used. The results obtained in the adsorption experiments performed for both adsorbents were compatible with the Freundlich isotherm and pseudo-second-order kinetic model. Fe3O4 was found to be more efficient than Fe3O4@HA in terms of reuse and Fe3O4 can be used 5 times without any significant loss of adsorption capacity. The results showed that Fe3O4 and Fe3O4@HA can be environmentally friendly alternative adsorbents for the removal of hazardous azo dyestuffs from water, and have regeneration possibilities.