▎ 摘　　要

Magnetic nanohybrids containing chitosan (CS) and/or graphene have promising applications in environmental remediation. In this study, a ternary nanohybrid based on magnetite (M)-CS-graphene oxide (GO) (MCSGO) was prepared in a facile manner via simultaneous reduction-precipitation at room temperature. The as-prepared nanohybrid was characterized by field-emission scanning electron microscopy/energy dispersive X-ray spec-troscopy, transmission electron microscopy, Raman spectroscopy, Brunauer-Emmett-Teller/Bar-rett-Joyner-Halenda analysis, thermogravimetric-differential thermal analysis, and vibrating sample magnetometry. Most importantly, the mechanism associated with the formation of MCSGO was determined using hard-soft acid-base (HSAB) theory and spectroscopic analyses. HSAB theory predicted the following dominant interactions in MCSGO based on electron transfer calculations and energy lowering between the couplet com-ponents: (1) CS-Fe3O4: NH2 -> Fe(III); (2) GO-Fe3O4: Ar-O-Ar -> Fe(III); and (3) GO-CS: O(Ar-OH)->-OH (-> denotes the direction of electron flow and Ar denotes the aromatic ring). The CS-Fe3O4 and GO-Fe3O4 interactions were much stronger than that for GO-CS. The predictions obtained by HSAB theory were supported by X-ray photo-electron spectroscopy, Fourier transformation infrared spectroscopy, ultraviolet-visible spectra, and fluorescent spectra. According to HSAB theory and spectroscopic analyses, a mechanism was proposed for the formation of MCSGO based on electron transfer-induced energy lowering. In addition, MCSGO still adsorbed 199.41 mg g-1 and 193.96 mg g-1 of Hg(II) and Zn(II), respectively, after six consecutive cycles, thereby demonstrating its favorable removal efficiency. The results obtained in this study may facilitate the development of efficient ad-sorbents based on the MCSGO architecture for environmental remediation.