Binary adsorption of 17β-estradiol and bisphenol A on superpararnagnetic amino-functionalized graphene oxide nanocomposites

Two types of graphene oxide (GO), namely, superparamagnetic GO (SM-GO) and chemically modified superparamagnetic amino-functionalized GO (SM-NGO), were prepared in this study. The adsorption of 17 beta-estradiol (E2) and bisphenol A (BPA) by the two types of GO composites was investigated. SM-NGO showed better adsorptive performance than SM-GO in adsorbing E-2 and BPA. Moreover, E-2 was suitably removed by both adsorbents, which indicated the stronger interaction of E-2 with the composites than BPA. The performance of the sorbents was examined through pH, kinetic, and isotherm experiments. The adsorption of E-2 and BPA was favorable under neutral condition. The rate-limiting step in the adsorption process was chemisorption for both adsorbents, which fit well with the pseudo-second-order kinetic model. The adsorption isotherms were described by the Langmuir model. Moreover, the theoretical maximum adsorption capacity (Q(max)) of E-2 by SM-NGO and SM-GO reached 106.38 and 52.91 mg g(-1), respectively, and the corresponding Q(rnax) values for BPA were 41.32 and 18.11 mg g(-1). Both nanocomposites can be easily separated by a commercial magnet within a few seconds. Therefore, SM-NGO is a promising magnetic adsorbent of heterogeneous organic chemicals. (C) 2016 Elsevier B.V. All rights reserved.