Porous structure and liquid‐phase adsorption properties of activated carbon aerogels

Abstract

In this article, activated carbon aerogels (ACAs) were prepared by CO 2 activation. Their pore structures were investigated by N 2 adsorption-desorption analysis. ACAs have excellent microporosity (e.g. 0.36 cm 3 /g) and mesoporosity (e.g. 1.72 cm 3 /g). Adsorption characteristics of phenol, methylene blue, I 2 , and VB 12 on ACAs in the liquid phase were studied by static adsorption experiments. Results showed that CO 2 activation process is an effective way to introduce micropores in carbon aerogels, which is enhanced with the increase of activation time. As a result, the adsorption capacities of the four mentioned adsorbates on ACAs were improved gradually with the increase of activation time. However, mesopore volume is also a factor on improving adsorption properties for the relatively giant molecules methylene blue and VB 12 .

Effect of pyrolysis temperature and thermal oxidation on the adsorption properties of carbon cryogels

“…Nevertheless, adsorption capacity of Pb(II) for our samples was quite the same to 0.17 mmol g -1 for carbon aerogel [26]. In the case of methylene blue adsorption, the other authors have reported a lower adsorption capacities by other adsorbents, such as 0.13 mmol g -1 for carbon aerogel [23] or 0.12 mmol g -1 for carbon xerogel [22]. But it has to be note that these data have been obtained at quite different conditions.…”

“…According to the values shown in Table 1, raising the pyrolysis temperature from 500 °C to 930 °C leads also to the increase of microporous parameter. This pore development is the main reason of increasing adsorption capacities regardless of presence of functional groups [22,23]. Other authors have reported the same trend, that with higher pyrolysis temperature increases Pb(II) [24] and methylene blue adsorption capacity by other adsorbents.…”

Review on the preparation and application of lignin-based carbon aerogels

“… 26 The composition of lignin is related to the specific surface area, mesopores and micropores of CAs. The next step can be physical activation (generally CO 2 activation), which can increase the microporosity of CAs and enhance it with the increase of activation time; 27 or, chemical activation (generally KOH activation) is more likely to facilitate the formation of CAs microporosity and produce CAs with high surface area. 28 Both of the above activation methods can effectively enhance the performance of CAs and optimize their pore structure and surface topography.…”

Ultralight and hydrophobic nanofibrillated cellulose aerogels from coconut shell with ultrastrong adsorption properties

“…Cellulose aerogels, which are green biodegradable nanoporous materials, combine the excellent properties of traditional silica aerogels and hydrocarbon copolymers or polymer‐based aerogels, such as a low density, high specific surface area, and high porosity, and the unique features of native cellulose, such as hydrophilicity and biocompatibility . These intriguing characteristics make cellulose aerogels potential substitutes for some petrochemicals in catalysts, adsorbents, fuel cells, and thermal or electrical insulation materials …”