Synthesis of Dendritic Magnetic Graphene Oxide by Radical Polymerization as Adsorbent for Rapid Removal of Dye from Aqueous Solutions

Abstract

Disposal of dyes containing dyes from related industries has caused global concern. Therefore, removing dyes from aqueous solution is very important and necessary. In this work, a novel magnetic glycodendrimer is introduced as effective adsorbent for malachite green adsorption. Firstly, magnetic graphene oxide was prepared by co-precipitation method and then modified with ethylenediamine to generate amine group on the surface which was further reacted with mercaptoacetic acid to provide polymerizable MGO nanosheets. Thereafter, Allylamine was grafted onto nanosheets and subsequently, reacted with methacrylate in a Michael type reaction to generate methyl ester groups. Finally, amidation of the terminal methyl ester groups with chitosan resulted in the formation of glycodendrimer. The properties of the synthesized adsorbent were investigated using XRD, FTIR, BET, FESEM and TEM. The results showed that pH=5, temperature of 40 °C, initial concentration of 600 mg/mL and contact time of 10 min as optimal values for removing malachite green dye with nanosorbent (MGD) were obtained. The maximum adsorption capacity of green malachite was 452.97 μg/mg. The high correlation coefficient (R2=0.9947) for the Freundlich model confirms that the Freundlich model is suitable for fitting laboratory data. According to the compliance model, the heat absorption for malachite green is B=8.1447 j/mol and indicates that the process of dye adsorption with nanosorbent is physical. According to the results of fitting the kinetic models of dye adsorption kinetics by nanosorbent shows that Hu and McKay model with higher correlation coefficient (R2=0.994) than other models is more consistent with experimental data. Due to the fact that a large decrease in dye removal is not observed in 10 consecutive recovery cycles and therefore nanosorbent has a high stability and can be used several times.

Keywords

• magnetic graphene oxide
• dendrimer
• radical polymerization
• green malachite