Fabrication of β-cyclodextrin/poly (l-glutamic acid) supported magnetic graphene oxide and its adsorption behavior for 17β-estradiol

A novel adsorbent, namely, β-cyclodextrin/poly (l-glutamic acid) supported magnetic graphene oxide (CGMG), was synthesized through a facile chemical route and its application as excellent adsorbent for 17β-estradiol (E2) removal from aqueous solution was also demonstrated. The characteristics of CGMG were investigated via using Fourier transform infrared spectrometer, X-ray photoelectron spectroscopy, Raman spectra, X-ray diffraction, vibrating sample magnetometer and Brunauer-Emmett-Teller surface area, respectively. Results indicated that CGMG was successfully prepared and the saturated magnetization could reach up to 0.09043 emu/mg. Meanwhile, investigation of adsorption behavior illustrated that the adsorption process could be better fitted by the pseudo-second-order and Langmuir models. Analysis of intraparticle diffusion model demonstrated that intraparticle diffusion was not the only rate-limiting step; however, both film diffusion and intraparticle diffusion were involved in the diffusion process. Thermodynamic study indicated that adsorption of E2 onto CGMG was spontaneous and endothermic. The E2 uptake by CGMG decreased in high pH values. However, it was insensitive to ionic strength variation (0.0-0.1 M). Moreover, the regeneration experiments illustrated that CGMG could be recovered, and it showed good recycling ability with ca. 88.7% of the initial sorption capacity after being used for sixth cycles.