Nanoporous Asphalt-Based Activated Carbon Prepared from Emulsified Asphalt and Graphene Oxide as High-Thermal-Conducting Adsorbers for n-Hexane Vapor Recovery

Because of the low thermal conductivity of activated carbon, local overheating often occurs during the adsorption process for volatile organic compounds (VOCs), resulting in a low adsorption efficiency, potential fire hazard, etc. Asphalt-based activated carbon (A-AC) was prepared from emulsified asphalt, and graphene oxide (GO) was evenly dispersed in A-AC in situ to prepare a nanoporous carbon with asphalt/GO as a high-thermal-conducting adsorber for n-hexane vapor recovery. Then this study systematically discusses the effects of GO on the specific surface area, pore size distribution, thermodynamic properties of A-AC, and the adsorption/desorption properties of n-hexane vapor. The results show that the addition of an appropriate amount of GO is beneficial to the formation of a cross-linked structure in the A-AC during the activation process. When the optimized amount of GO is 1.0 wt % (labeled as A-AC/GO-1.0), both the specific surface area and micropore volume reach the maximum, which are 1662 m2·g–1 and 0.49 cm3·g–1, respectively. More importantly, the thermal conductivity of A-AC/GO-1.0 is 2 times that of A-AC. In addition, the A-AC/GO-1.0 material has a good adsorption capacity for n-hexane vapor, which is 1.76 times for A-AC. It can also retain a good regeneration performance after a dynamic adsorption experiment. Therefore, as a promising material, A-AC/GO will break through the technological bottleneck of the adsorption/desorption of activated carbon, such as low adsorption capacity owing to the high adsorption heat effect, difficult desorption and regeneration, and short life.