▎ 摘　　要

In this study, a kind of magnetic graphene oxide/ cationic hydrogel nanocomposite (MGO-CH) was synthesized and characterized for acid red 88 (AR88) removal. SEM and HRTEM-EDS show that the magnetic graphene oxide nanoparticles were effectively dispersed on the cationic hydrogel matrix. The adsorption kinetics, isotherms, and effects of pH on AR88 uptake by MGO-CH were evaluated. The results show that MGO-CH achieves positive zeta potential values of 35.6-27.8 mV at pH 3.0-10.5, with a saturation magnetization of approximately 4.0 emu g(-1). The MGO-CH kinetics show a good fit with the pseudo-second order model. The maximum AR88 adsorption capacity of MGO-CH was 3476.7 mg g(-1) at an AR88 equilibrium concentration of 287.4 mg L-1 and pH = 7.0. Equilibrium adsorption data show that the Sips model is more suitable than the Langmuir and Freundlich models. MGO-CH exhibits an AR88 adsorption capacity of more than 1140.2 mg g(-1) in a strongly alkaline solution (pH > 10). The adsorption process is highly pH dependent, corresponding to electrostatic interactions, hydrogen bonding, and competitive adsorption interactions, and the optimal adsorption occurs at pH 3.0-5.8. The AR88 adsorption capacity of the regenerated MGO-CH approaches more than 95% of the fresh MGO-CH at a low initial concentration of 100 mg L-1 from the second to fifth recycles. As AR88 initial concentration increased up to 1500 mg L-1, the reusability of MGO-CH was decreased from the first to third cycle and was maintained stably afterwards. Fourier transform infrared spectroscopy reveals that C-O and C=O functional groups contribute to AR88 adsorption. This finding was also confirmed by C 1s spectra from X-ray photoelectron spectroscopy. The deconvolution of the N 1s spectra before and after AR88 adsorption indicates that the quaternary ammonium group of the cationic hydrogel contributes to AR88 removal.