Effective removal of hexamethyldisiloxane using a citric acid modified three-dimensional graphene aerogel

Abstract

Silica deposition resulting from methyl siloxane combustion represents a problem for the application and development of biogas energy, which creates the need to explore novel materials with high adsorption efficiency of methyl siloxane and excellent cycling performance. Here, citric acid (CA) was used to assist the hydrothermal reduction process and induce self-assembly with the final aim of obtaining three-dimensional reduced graphene oxide aerogels (rGOAs) from industrial-grade graphene oxide. The rGOAs were characterized by XRD, SEM, FTIR, Raman spectroscopy, and N2 adsorption/desorption techniques. The results showed that rGOAs had a significant removal capacity of hexamethyldisiloxane (L2), which could be attributed to the improvement of both texture and hydrophobic properties by CA. Among the rGOAs, the rGOA-2 showed the highest theoretical breakthrough adsorption capacity (QB, th, 337.3 mg g−1). The specific surface area (582.4 m2 g−1) and micropore volume (0.39 cm3 g−1) were the most key structural factors affecting QB, th. Appropriately decreasing the temperature and increasing the inlet concentration was beneficial to improving the adsorption capacity. In addition, the rGOA-2 exhibited excellent recyclability and reuse performance over five consecutive adsorption/regeneration cycles. Thus, our study provides a novel methodology with a high potential to overcome the problem of silica deposition using sustainable materials for the adsorption of methyl siloxane, to provide specific theoretical and technical support for the effective utilization of renewable energy.