###### Abstract  
A series of phenolic compounds containing 2-phenylphenol (PPE), bisphenol A (BPA), 4-isopropylphenol (IPE), 4-methylphenol (ME) and phenol (PE) were selected to investigate their major influence factors for their adsorption on graphene oxide (GO) and reduced graphene oxide (RGO) by studying their adsorption isotherms and kinetics. It was found that the adsorption of all tested phenols fitted well with the Freundlich model. In comparison, the adsorption ability of RGO with a stronger \(\pi\)-\(\pi\) interaction was superior to GO, which was confirmed by using naphthalene probe measurements. The thermodynamic characteristics, by studying the effect of the adsorption temperatures (298, 313 and 333 K), demonstrated that the adsorption process was spontaneous, exothermic and entropy-decreasing. The chemical structures of the phenols also affected their adsorption on GO and RGO. It was found that the adsorption capacities of phenols were, in order, PE (0.271 mmol g\({}^{-1}\) on GO and 0.483 mmol g\({}^{-1}\) on RGO) \(<\) ME (0.356 and 0.841 mmol g\({}^{-1}\)) \(<\) IPE (0.454 and 1.117 mmol g\({}^{-1}\)) \(<\) BPA (0.4 and 1.56 mmol g\({}^{-1}\)) \(<\) PPE (0.7 and 2.054 mmol g\({}^{-1}\)), which depended on the \(\pi\)-electron density of the benzene ring by means of a density functional theory (DFT) calculation. Undoubtedly, the reduction of GO and an increase in \(\pi\)-electron density on the chemical structures of phenols facilitated the adsorption. reduced graphene oxide; \(\pi\)-\(\pi\) interaction; phenolic compounds; adsorption +
Footnote †: journal: Applied Physics Letters  
**[PERSON] 1,2,+, [PERSON] 1,+, [PERSON] 1, [PERSON] 1, [PERSON] 1, [PERSON] 3,* and [PERSON] 1,* 1 College of Chemistry and Chemical Engineering, Hubei Polytechnic University, Huangshi 435003, China; [EMAIL_ADDRESS] (X.W. ); [EMAIL_ADDRESS] (Y.H. ); [EMAIL_ADDRESS] (J.M. ); 139959705126163.com (S.L. ); [EMAIL_ADDRESS] (X.D.) Footnote †: journal: Applied Physics Letters  
**[PERSON] 1,2,+, [PERSON] 1,+, [PERSON] 1, [PERSON] 1, [PERSON] 1, [PERSON] 3,* and [PERSON] 1,* and [PERSON] 1,* 1 College of Chemistry and Chemical Engineering, Hubei Polytechnic University, Huangshi 435003, China; [EMAIL_ADDRESS] (X.W. ); [EMAIL_ADDRESS] (Y.H. ); [EMAIL_ADDRESS] (J.M. ); 139959705126163.com (S.L. ); [EMAIL_ADDRESS] (X.D. )**  
Footnote †: journal: Applied Physics Letters  
**[PERSON] 1,2,+, [PERSON] 1,+, [PERSON] 1, [PERSON] 1, [PERSON] 1, [PERSON] 3,* and [PERSON] 1,* and [PERSON]  
hydrodynamic cavitation [8; 9] and adsorption [10; 11; 12; 13]. Among these approaches, adsorption seem to have a particular advantage due to its relatively low cost, speed and convenience of operation. Graphene is a new two-dimensional surface carbon material formed by the composition of an sp\({}^{2}\) hybrid orbital with a single carbon atom sheet structure and has aroused great interest since the report of [PERSON] et al. [14]. Graphene promised to be an excellent adsorbent due to its huge specific surface area and excellent adsorption performances, with a high adsorption capacity and fast adsorption rate. For example, [PERSON] et al. [15] studied the adsorption behaviors of ten halogenated aliphatic compounds on a graphene nanosheet and demonstrated that hydrophobic and \(\pi\)-\(\pi\) electron donor-acceptor interactions were the adsorption mechanisms. [PERSON] et al. [16] made use of density functional theory to calculate the adsorption of caffeine and nicotine molecules on graphene sheets, indicating high adsorption energies for both. [PERSON] et al. [17] summarized the graphene-based nanomaterials used for the adsorption of heavy metal ions. The functionalized bare derivatives of graphene-based nanomaterials exhibited better adsorption performance and a higher adsorptive capacity for aqueous heavy metals removal. As an oxidative product of graphite and a precursor for graphene preparation, graphene oxide (GO) was decorated with various oxygen-containing groups with a very high negative charge density such as hydroxyl, epoxy and carboxyl groups.