Comparison of magnetic properties and adsorption capability of synthesized magnetic Graphene oxide Nano-composite via co-precipitation and solvo-thermal methods

Abstract

Background and Objective: Nano-sorbents are suitable for pollutants removing from aqueous environment. Therefore, the aim of this study was to compare magnetization of magnetic graphene oxide nano-composite by using co-precipitation and solvothermal methods. In addition, the capability of nano-adsorbent was conducted in order to examine removal efficiency of Cd (II) from aqueous solution. Method: Graphene oxide (GO) was synthesized by modified Hummers method and magnetized using co-precipitation and solvothermal procedures. The amine functionalization of as-prepared magnetic graphene oxide was performed by reflux method in the presence of ethylenediamine as functional group and cold synthesis method in the presence of dichloromethane as reaction solvent. The synthesized adsorbents were used for Cd (II) removal from aqueous solutions and the effects of pH, amount of adsorbent, contact time, initial concentration of Cd (II) ions and temperature were investigated. Findings: According to FTIR, XRD and VSM analyses, the synthesized magnetic graphene oxide with co-precipitation showed higher magnetization values than that of from the solvothermal method. The adsorption results displayed that the synthesized adsorbent with solvothermal and reflux processes of amination has the highest adsorption capacity of 207 mg.g-1. But it is only 82 mg.g-1 with co-precipitation and cold amination process. Kinetic data showed better correlation with pseudo-second-order equation and the Freundlich model was found to fit for the isotherm data. Discussion and Conclusion: The magnetization values of adsorbent in co-precipitation method was better while the adsorption capacity reduced. The loss of adsorption capacity was due to high loading of magnetic particles under surface of GO, which leads to block the carboxyl functional groups. This was also confirmed by elemental analysis. The amount of nitrogen was lower in co-precipitation process comparing to solvothermal method. In batch adsorption, the adsorption process was found to be endothermic and spontaneous in nature. The results suggest that the solvothermal and reflux procedures was more efficient in amine functionalization and adsorption process.