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 π-π 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 π-electron density of the benzene ring by means of a density functional theory (DFT) calculation. Undoubtedly, the reduction of GO and an increase in π-electron density on the chemical structures of phenols facilitated the adsorption.

Using six representative feedstocks as carbonaceous precursors, various mesophase pitches and their derived cokes were obtained by a heat-soaking method at a temperature range of 400−450 °C and a pyrolysis treatment at 900 °C, respectively. The optical texture and microstructure of the different mesophase pitches and their derived cokes were characterized by polarized-light microscope, scanning electron microscope, and X-ray diffraction. The results show that the formation and development abilities of liquid crystalline mesophase are obviously different for the various feedstocks. C 9 aromatic hydrocarbons and petroleum-derived paving pitch possess relatively high thermo-chemical reactivity due to the existence of low molecular substances and aliphatic groups, leading to form liquid crystalline mesophase easier and faster than those of naphthalene synthetic pitch and coal tar-based impregnating pitch under a similar condition, which however is undesirable to develop a bulk mesophase. Anthracene possesses a characteristic of forming a homogeneous bulk mesophase with a streamline texture under a suitable condition. The liquid crystalline transformation behavior of C 5 −C 9 aromatic hydrocarbons is unexpectedly similar to that of naphthalene synthetic pitch and markedly different from that of C 9 aromatic hydrocarbons. Carbonaceous precursors have a significant effect on the anisotropic content and the optical texture of the mesophase pitch products, which leads to the microstructure variety of the resultant cokes. Fine-grained and coarse-grained mosaic textures are, respectively, present in the cokes derived from C 9 aromatic hydrocarbons and petroleum-derived paving pitch. The cokes derived both from coal tar-based impregnating pitch and from C 5 −C 9 aromatic hydrocarbons possess a supra mosaic texture mingled with a local flow-induced orientation domain. A well-oriented lamellar texture is clearly found in the cokes derived from anthracene and naphthalene synthetic pitch.

General characteristics of waxes, adhesives and lubricants as well as the recent fundamental investigations on their physical and mechanical behaviour are introduced. The current R&D status for new type/generation of waxes, adhesives and lubricants from natural products is reviewed, with an emphasis on their tribological applications. In particular, some crucial issues and challenges relating to technological improvement and materials development are discussed. Based on the current predicted shortage of energy resources and environmental concerns, prospective research on the development of green waxes, adhesives and lubricants is suggested.

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