Abstract
Volatile methyl siloxanes (VMSs) as a trace impurity in biogas decreases its energy utilization, and thus need to be removed. In this paper, a one-step hydrothermal reduction was performed to produce three-dimensional reduced graphene oxide aerogels (rGOAs) using industrial-grade graphene oxide (IGGO) as raw material and vitamin C (VC) as a reductant to facilitate the fabrication of rGOAs. The synthesis of rGOAs was a simple, green, and energy-efficient process. The developed rGOAs were characterized using the Brunauer–Emmett–Teller method, Raman spectrometry, scanning electron microscopy, Fourier-transform infrared spectroscopy, X-ray diffraction measurements and contact angle. The results obtained showed that rGOA-1 with a VC/IGGO ratio of 1/1 (m/m) exhibited a hierarchical porous structure and super-hydrophobicity, yielding a high specific surface area (137.9 m2 g−1) and superior water contact angle (143.8°). The breakthrough adsorption capacity of rGOA-1 for hexamethyldisiloxane (L2, a VMS model) was 11 times higher than that of IGGO. Low inlet concentration and bed temperature were considered beneficial for the L2 adsorption. Interestingly, rGOA-1 was less sensitive to water, and it was readily regenerated for reuse by annealing at 80 °C. The rGOAs have been demonstrated to have great potential for the removal of siloxanes from biogas.
Highlights
Volatile methyl siloxanes (VMSs) are products of the hydrolytic depolymerization of silicone
Silica gel, activated carbons (ACs), and zeolites were applied in adsorbing VMSs, exhibiting good activity toward the VMS capture [10,11,12,13,14,15]
240 mg of Vitamin C (VC) was dissolved in an Industrial-Grade Graphene Oxide (IGGO) suspension, and the mixed suspension was transferred to a 100 mL Teflon reaction kettle, heated to 95 ◦C and kept 6 h, leading to the formation of hydrogel
Summary
Volatile methyl siloxanes (VMSs) are products of the hydrolytic depolymerization of silicone. Due to the widespread use of silicone, the VMS content in biogas originating from the digestion of organic waste substances in sewage plants, municipal landfills, and farm fermentation tanks has recently grown quickly [4,5,6]. Their presence in biogas is proven to impose significant constraints on its energy application, for example, blocking the fan and wearing out the fenestrae of the engine, etc., which are fatal to the biogas power equipment, substantially increasing the production cost [3]. Novel materials for the VMS adsorption need to be developed
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