The Effects of Hydrophobicity and Textural Properties on Hexamethyldisiloxane Adsorption in Reduced Graphene Oxide Aerogels

Abstract

To expand the applications of graphene-based materials to biogas purification, a series of reduced graphene oxide aerogels (rGOAs) were prepared from industrial grade graphene oxide using a simple hydrothermal method. The influences of the hydrothermal preparation temperature on the textural properties, hydrophobicity and physisorption behavior of the rGOAs were investigated using a range of physical and spectroscopic techniques. The results showed that the rGOAs had a macro-porous three-dimensional network structure. Raising the hydrothermal treatment temperature reduced the number of oxygen-containing groups, whereas the specific surface area (SBET), micropore volume (Vmicro) and water contact angle values of the rGOAs all increased. The dynamic adsorption properties of the rGOAs towards hexamethyldisiloxane (L2) increased with increasing hydrothermal treatment temperature and the breakthrough adsorption capacity showed a significant linear association with SBET, Vmicro and contact angle. There was a significant negative association between the breakthrough time and inlet concentration of L2, and the relationship could be reliably predicted with a simple empirical formula. L2 adsorption also increased with decreasing bed temperature. Saturated rGOAs were readily regenerated by a brief heat-treatment at 100 °C. This study has demonstrated the potential of novel rGOA for applications using adsorbents to remove siloxanes from biogas.

Porous Aerogels and Adsorption of Pollutants from Water and Air: A Review

“…The main approaches employed to obtain GO-based aerogels are hydrothermal reduction/self-assembly (which exemplificative scheme is represented in Figure 3 ), chemical reduction methods, crosslinking, and sol-gel processes [ 110 , 114 , 116 ]. All of these procedures generally end with a drying step to obtain the final aerogel, with the most being common freeze-drying [ 28 , 117 , 118 , 119 ] or, to a lesser extent, supercritical drying [ 120 ].…”

Vitamin C-Assisted Fabrication of Aerogels from Industrial Graphene Oxide for Gaseous Hexamethyldisiloxane Adsorption

“…High-defect populations are found in rGOA-1 flakes, which could be attributed to the strong reducing activity of VC, which results in the oxygen-containing functional groups also being removed, leaving vacancies in the original positions. The 2D bands located in the range of 2300~3100 cm −1 are also a characteristic feature of carbon materials [21]. In the Raman spectra (Figure 4b), rGOA-0 and rGOA-1 demonstrate a wide and up-shifted 2D peaks, indicating a structure with few layers [44].…”

“…rGOA-1 shows the highest adsorption capacity and the longest breakthrough time, with tB,th and QB,th values of 9.66 min and 77.7 mg g −1 , respectively. Accordingly, QB,th is expected to be roughly proportional to SBET, Vtot, and contact angle (Figure S4), which can be hypothesized that the adsorption mechanism of rGOAs on L2 may depend on hydrophobic effect and capillary condensation [21,30].…”

“…As shown in Figure 1a, from N2 adsorption-desorption isotherms, rGOA-1 presents a IUPAC type IV isotherm with a type H3 hysteresis loop [38], suggesting the existence of an external surface and mesopores [30]. On the other hand, IGGO and rGOA-0 have a much smaller nitrogen adsorption volume than rGOA-1, exhibiting type III isotherms, with nearly non-porous structure [21]. Remarkably, rGOA-1 exhibits narrower mesopores than IGGO and rGOA-0, as shown in Figure 1b.…”

“…In addition, the calculated parameters (KYN, τ) by the Yoon-Nelson model tB,th and QB,th are listed in Table 3. The bed temperature decreases while the breakthrough time and adsorption capacity increase, which could be explained by the hydrophobic interaction between the rGOA-1 surface and L2 molecules and the exothermic micropore-filling adsorption of the rGOA-1 for L2 adsorbate [21,49]. Figure 9 shows the adsorption breakthrough curves for rGOA-1 at different bed temperature (0-35 • C) by the Yoon-Nelson model, with m of 0.10 g, C in of 14.62 mg L −1 , and V g of 50 mL min −1 , respectively.…”