Ethylenediamine-Functionalized Graphene Oxide Nanosheets for Modifying Chitosan/Polyvinyl Alcohol Membrane Adsorbents for RB19 Removal from Wastewater

Abstract

Graphene oxide (GO) was covalently functionalized with ethylenediamine (ED-GO) and characterized by Fourier transform infrared spectroscopy, X-ray diffraction, Raman spectroscopy, and field emission scanning electron microscopy techniques. Afterward, ED-GO-embedded chitosan/polyvinyl alcohol membrane adsorbents (CP/ED-GO) were fabricated by incorporating different amounts (0–1 wt %) of ED-GO, and the resultant membrane adsorbents were applied for the adsorption of reactive blue 19 dye (RB19) from water. According to the batch adsorption results, the adsorbent containing 0.25 wt % ED-GO possessed the best performance in RB19 removal. Adsorption of RB19 dye onto the CP/ED-GO-0.25 wt % membrane was also optimized using the response surface methodology. The solution pH, initial dye concentration, and adsorbent mass were selected as independent variables. The dye removal of 95% was achieved under the optimized conditions, close to the experimentally measured value, indicating the reliability of the optimization. Isothermal adsorption experiments revealed that RB19 dye adsorption onto CP, CP/ED-GO-0.25 wt %, and CP/GO-0.25 wt % could be well described by the Freundlich isotherm model. The adsorption kinetic of RB19 dye using CP, CP/ED-GO-0.25 wt %, and CP/GO-0.25 wt % membrane adsorbents followed the pseudo-second-order kinetic pattern. The adsorption capacity values of 333.331, 303.03, and 256.41 mg g–1 were obtained for CP/ED-GO-0.25 wt %, CP, and CP/GO membrane adsorbents, respectively. In summary, the CP/ED-GO-0.25 wt % membrane was found to be a promising adsorbent for wastewater decoloring.