Efficient and Enhanced Adsorption of Methylene Blue on Triethanolamine-Modified Graphene Oxide

Triethanolamine-graphene oxide composite material (TEOA-GO) is prepared by the successive modification of GO with epichlorohydrin and TEOA. Several characterization methods including Fourier transform infrared spectra, Raman spectrometry, scanning electron microscopy, X-ray photoelectron spectroscopy, and thermogravimetric analysis are employed to confirm the structure of the resulting composite. With methylene blue (MB) as the adsorbate, TEOA-GO has a much higher adsorption capacity (similar to 457.15 mg/g) than GO (similar to 331.87 mg/g), and the possible adsorption mechanism suggests that pi-pi interaction and electrostatic interaction between adsorbent and dye molecules may lead to a higher adsorption capacity. The adsorption of MB on TEOA-GO follows the pseudo-second-order kinetic model and Langmuir isotherm model. From the viewpoint of thermodynamic analysis, the adsorption is spontaneous and endothermic (Delta H degrees = 7.865 kJ mol(-1)). In addition, the positive value of Delta S degrees (56.451 J mol(-1) K-1) confirms the increased randomness on the surface of adsorbent during the adsorption process. After five runs, the removal efficiency of MB hardly decreases, which indicates that reusable efficient TEOA-GO has potential applications in the treatment of dye wastewater.