As a new kind of adsorbent, graphene sheets (GS) possess large surface areas and excellent adsorption properties. To investigate the adsorption equilibria of C1–C4 from natural gas on GS and fit the isotherms by the Langmuir–Freundlich equation. GS were synthesized with a specific surface area of 805 m2/g and a specific pore volume of 1.03 cm3/g. The adsorption isotherms were measured using a volumetric method at five different temperatures between 263.15 and 303.15 K and at pressures of 0–6 MPa for CH4, 0–1.6 MPa for C2H6, 0–0.3 MPa for C3H8, and 0–0.05 MPa for C4H10. It was shown that, for all four hydrocarbons, the amount of adsorption decreased gradually as the temperature increased. The isotherms were described well by the Langmuir–Freundlich equation. The isosteric heat of adsorption values decreased in the order C4H10 > C3H8 > C2H6 > CH4 which was consistent with those of the extreme heats of adsorption. This suggests that the adsorption capacities of C1–C4 on GS decreased in the order C4H10 > C3H8 > C2H6 > CH4.
We herein report the successful synthesis of molecularly imprinted polymers (MIPs) by surface imprinting methods. The synthesized MIPs were subsequently used to selectively adsorb indole from fuel oil. A new polymerization method (SR&NI ATRP), which combines the atom transfer radical polymerization (ATRP) and reverse atom transfer radical polymerization methods, is applied for the preparation of indole–MIPs. The indole–MIPs prepared have large specific surface area and porosity, as revealed by a series of morphology characterization studies. Static adsorption data indicate that the adsorption capacity of indole–MIPs was 55.8 mg g−1, and the adsorption equilibrium is achieved in 120 minutes. According to the results of thermodynamic analysis, the adsorption process is spontaneous. In addition, results of kinetics analysis indicated that the adsorption performances of indole–MIPs obey pseudo-second-order model. The Sips and Langmuir equations better fitted with the experimental isothermal data than the Freundlich equation. The selectivity of indole–MIPs was significant and the adsorbent could be reused even after five regeneration cycles.
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