Cobalt(ii) Schiff base chemically grafted onto magnetic amino-functionalized reduced graphene oxide nanosheets for highly rapid and selective removal of methyl orange

Abstract

In this paper, a new magnetic reduced graphene oxide functionalized with a Co(II) Schiff base complex (Co(SB)-rGO/ZnFe₂O₄) was synthesized and characterized by means of FT-IR, Raman, XRD, FE-SEM, EDX, BET, TGA, zeta potential and VSM measurements. All analyses confirmed the successful immobilization of the Co(II) Schiff base (∼10.2 wt%) into the magnetic GO nanosheets. The adsorption abilities of the synthesized nanocomposite were tested towards cationic methylene blue (MB) and rhodamine B (RhB), and anionic methyl orange (MO) dyes. From the results, this magnetic hybrid nanomaterial exhibited excellent adsorption ability for anionic organic pollutants; it could absorb 100% of methyl orange (MO) from an aqueous solution within only 2 min. Moreover, the magnetic nanocomposite demonstrated the fast and selective adsorption of anionic dyes from mixed dye solutions. The removal rate was up to 100% for MO from MO + MB and MO + RhB mixed solutions within 5 minutes. The influences of the initial concentration of dye, amount of adsorbent and pH on the adsorption ability were examined in detail. The kinetics of the adsorption process followed the pseudo-second-order model and the Langmuir isotherm model provided the best fit for the adsorption of MO onto the Co(SB)-rGO/ZnFe₂O₄ composite. The adsorbent was readily recovered from the reaction mixture by a usual magnet and reused at least four times without any observable change in structure and adsorption capability. Therefore, this novel magnetic nanomaterial demonstrates great potential in the applications of water treatment and recovery of valuable organic compounds from wastewater.