Following carbon condensation by in situ TEM: towards a rational understanding of the processes in the synthesis of nitrogen-doped carbonaceous materials

Abstract

Porous carbonaceous materials obtained from biomass have been an important class of CO2 sorbents since ancient times. Recent progress in carbon-based adsorbent technology is based on the implication of the...

Fabrication, characterization, and application of the water hyacinth biochar-polyvinyl alcohol composite as an advantageous sound absorber material

“…On the other hand, comparing the pore volume of the adsorption and desorption analysis we know that not all the adsorbed nitrogen was desorbed again, but a part of them condensed in the pores of the fabricated WHBC-PVA composites. According to reference [34][35][36][37], the nitrogen condensation would just occur in the typical pores of cylindrical in shape and mesopores in size. Thus, the typical pore of the fabricated WHBC-PVA composites could be classified into cylindrical pores in shape and mesopores (2 − 50 nm) in size.…”

“…It means about 0.002 cm 3 g −1 (6.06%) nitrogen condensed in the pores of the WHBC400-PVA as well as the WHBC500-PVA, and 0.003 cm 3 g −1 (6.67%) nitrogen condensed in the pores of WHBC600-PVA composite. The condensation happened due to the capillary forces working inherently in the pore of 2 − 50 nm in size [34][35][36][37]. However, from the chemistry point of view, the nitrogen condensation happened due to the presence of the nitrogen-withdrawing functional groups which constructed the inside wall of the associated pores.…”

“…In correlation to the IUPAC classification of the isotherm adsorption types [34][35][36][37], the curves correlated the quantity of the adsorbed nitrogen (STP, cm 3 ) against relative pressure (P/P o ) happened on the aforementioned WHBC-based materials have been properly drawn as shown in Fig. 3.…”

“…Figure 3 shows all the pores of the WHBC-PVA composites approximately fit to the H3 type hysteresis loop in adsorption-desorption properties. According to references [34][35][36][37] this typical hysteresis is generated by non-rigid aggregates of plate-like particles, and the particles subsequently generated voids of slit-shaped pores. It means that the particles of the WHBC-PVA composites themselves might be nonporous or macro-porous adsorbent as their properties also very match with type II of the IUPAC classification of isotherm adsorption pores.…”