Electrosorption Of Methylene Blue From Aqueous Solution On Graphene-titanium Electrode

Graphene(Gr) is a piece of carbon atoms which arrange into benzene-ringstructure, which was isolated from pyrolytic graphite first time in2004. Unlike otherallotropes of arbon, graphene showed both special surface and excellent mechanical,optical, thermal and electronic properties. It can be used in sensor application,high-efficiency solar cell and effective electrodes. In addition, titanium sheet hasgreat electrical conductivity and plasticity, so we selected titanium as the material ofsubstrate. In the past study, there were few research about Gr used as the material ofelectrode in electrosorption, particularly used for removing dyes from solution.By using the method of Hummers and hydrazine monohydrate, a new electrode(Gr/Ti) was prepared by graphene and titanium (Ti) substrate, it was effective inelectrosorption of methylene blue (MB) from aqueous solution. Cyclicvoltammogram, SEM and FTIR spectrum were used to characterize Gr and Gr/Ti.The testing parameters of electrosorption were potential, initial concentration ofelectrolytes, initial pH and temperature. The results indicate that the maximumadsorption capacity research60.68mg·g-1under the condition of-600mV, pH of7.5,293K and0.01M electrolyte. And it was3.06times than open circuit in10mg·L-1MB solution. Compare with the same situation under OC, the maximum adsorptioncapacity is19.83mg·g-1, so the effect of potential improve the ability of Gr/Ti inelectrosorption. In addition, with the result of opposite potential, it indicated that it iseffective reuse of the Gr/Ti.Adsorption isotherm of MB on Gr/Ti was decided with Langmuir andFreundlich isotherm equations. Pseudo-first-order model, pseudo-second-order model,and intra-particle diffusion model were applied to depict the adsorption kinetics.Thermodynamic parameters were Gibb’s free energy, enthalpy and entropy. Theelectrosorption of MB preferably fits Langmuir isotherm, which shows single-layeradsorption. Adsorption kinetics of MB follows pseudo-second-order model. And electrosorption of MB on Gr/Ti was found to be spontaneous and endothermic. Andthere were not any oxidation-reduction reactions appeared in MB and solution.Furthermore, the results of electrosorption showed that the Gr/Ti performed a highadsorption capacity and great electrochemical performance, which could be a highefficient and environment friendly adsorbent with low energy consumption.