The aminosilane functionalization of cellulose nanocrystal aerogel via vapor‐phase reaction and its CO₂ adsorption characteristics

Abstract

The cellulose nanocrystal (CNC) aerogel was functionalized using aminosilane via vapor‐phase reaction and then the modified CNC aerogel was characterized by several techniques such as Fourier transform infrared spectroscopy, FE‐SEM, and elemental analysis. Finally, the CO2 adsorption on the aminosilane‐grafted CNC aerogel was featured using a dual‐site Langmuir adsorption model. The result showed triethylamine significantly enhanced the amine loading, being 7.06 mmol g−1 at 120°C. The primary amine groups in the aminosilane survived the vapor‐phase reaction. The amine groups were homogeneously distributed inside the aerogel due to its porous structure. The dual‐site Langmuir model could well describe its CO2 sorption characteristics. The adsorption capacity was up to 2.57 mmolCO2 g−1 at 25°C and 101.33 kPa, of which the chemisorption entirely dominated, and it decreased only 3%–4% after six runs. Therefore, these features positively suggested the vapor‐phase reaction provided a new and feasible method to functionalize CNC aerogel for the capture of CO2.

Recent developments in polysaccharide and lignin-based (nano)materials for CO2 capture

“…Xu and colleagues were able to functionalize CNC aerogel by employing aminosilane in a vapor-phase process. 260 At 25 °C and 101.33 kPa, the adsorption capacity reached 2.57 mmol CO 2 and was completely dominated by chemisorption. The adsorption capacity was reduced only 3-4% after six cycles.…”

Hydrophobic and lipophilic cellulose nanocrystal aerogel prepared by methyltrichlorosilane via vapor‐phase reaction

“…During the vapor‐phase reaction, there is no necessity to separate the obtained samples from the solvent, and no waste liquid is generated. Additionally, the presence of water could be excluded so the self‐condensation and the hydrolysis reactions of silanes encountered in the liquid phase could significantly be reduced 13 . The vapor‐phase reaction takes place on the gas–solid interface, which provides a higher grafting rate when compared to the commonly used liquid process 14 .…”

“…At the same time, the self-condensation of the silane-based modifiers was prone to take place in liquid-phase modification, resulting in the significant consumption of modifiers and noteworthy blockages inside the subsequent product. 13 In contrast, the hydrophobization of nanocellulose by vapor-phase reactions has attracted considerable attention. During the vapor-phase reaction, there is no necessity to separate the obtained samples from the solvent, and no waste liquid is generated.…”

“…Additionally, the presence of water could be excluded so the self-condensation and the hydrolysis reactions of silanes encountered in the liquid phase could significantly be reduced. 13 The vaporphase reaction takes place on the gas-solid interface, which provides a higher grafting rate when compared to the commonly used liquid process. 14 Cervin et al 4 and Rafieian et al 2 prepared hydrophobic CNF aerogel via chemical vapor deposition (CVD) using hexadecyltrimethoxysilane and octyltrichlorosilane, respectively.…”

“…However, for the liquid‐phase modifications, many waste liquids, being environment‐unfriendly, were produced during the sample preparation. At the same time, the self‐condensation of the silane‐based modifiers was prone to take place in liquid‐phase modification, resulting in the significant consumption of modifiers and noteworthy blockages inside the subsequent product 13 …”