Optimization of Conditions for Removal Phenolic Compounds from Water by a Graphene Oxide Aerogel

摘要

In this study, graphene oxide (GO) was prepared from graphite by improved Hummers' method. Graphene oxide aerogel (GOA) was synthesized via the ice segregation induced self-assembly method. Various modern analytical methods were utilized to characterize GOA. The results revealed the aerogel structure with a pore size of 100-150 mu m, a specific surface area of 515.21 m(2)/g, and a pore volume of 2.08-2.16 cm(3)/g. The synthesized GOA was applied as an adsorbent for the removal of phenol (PN) and bisphenol A (BPA) with a maximum adsorption capacity of 117.65 and 70.17 mg/g, respectively. Response surface methodology involving a rotating central composite design was applied to investigate simultaneously the effects of adsorption variables including adsorption time, pH, and initial concentration on the removal efficiency of GOA for PN or BPA. The results showed that the optimal adsorption efficiency for PN was 92.15 with an adsorption time of 208.52 min, a pH of 6.08, and an initial PN concentration of 30 mg/L. Regarding BPA, the optimal adsorption efficiency was 95.27 with an adsorption time of 352.79 min, a pH of 4.91, and an initial BPA concentration of 20 mg/L. The adsorption of both PN and BPA onto GOA was appropriate with the Langmuir model, in which the maximum adsorption capacity of GOA for PN and BPA was 117.65 and 70.175 mg/g, respectively. The results confirmed that the adsorption of PN and BPA onto GOA was monolayer adsorption on a homogeneous surface. The adsorption mechanism of GOA for PN or BPA depended mainly on the electrostatic interaction and hydrogen bonding between -OH of PN, BPA, and oxygen-containing functional groups of GOA. Besides, pi-pi interaction between carbon rings of GOA and PN or BPA also contributed to the enhancement of adsorption performance. The results showed that GOA exhibited potential application in the treatment of organic pollutants. Besides, the evaluation of the morphology of the GOA and the simultaneous effects of different factors can contribute to the advancement of graphene-based materials and the improvement of wastewater treatment.