The regulation of micro/mesoporous silica gel by polyethylene imine for enhancing the siloxane removal

[Display omitted] •MMSG is proven to be an efficient adsorbent for removing L2.•The adsorption of L2 is closely related with monolayer and multilayer adsorption of micro/mesoporous, and even capillary condensation process.•The MMSG adsorbents have good potential for the removal and recovery of siloxanes from biogas or landfill gas. In this study, different micro/mesoporous silica gel (MMSG) materials were prepared by mixed sol-gel process of polyethylene imine (PEI) and silicate. The developed materials were used to explore the optimal conditions for hexamethyldisiloxane (L2) removal in dynamic adsorption experiments. MMSG prepared using the conditions of pH = 3 and mPEI = 1.0 g was observed to be the optimum adsorbent for L2, which demonstrated an adsorption capacity of 367.1 ± 9.5 mg·g−1 using 83.82 mg·L−1 of L2 with dry N2 as the carrier gas. In addition, the influence of adsorption temperature and L2 inlet concentration were also investigated using dynamic adsorption experiments. Characterization of the MMSG material was carried out using several physical and chemical techniques, such as XRD, SEM and N2-BET. The results concluded that the L2 adsorption capacities were strongly related to the textural development of MMSG, especially the pore volume and surface area of micro/mesopores. Finally, MMSG regeneration could be easily achieved via heating at 100 °C, and its adsorption capacity for L2 was observed to be stable in the subsequent continuous dynamic adsorption experiments. These results indicated that the developed MMSG material represents a promising siloxane removal adsorbent for biogas up-gradation.