Studies on the structure of activated carbon fibers activated by phosphoric acid

Abstract

By solid-state 13 C-and 31 P-NMR, XPS, and FTIR, the chemical structure of activated carbon fiber-P (ACF-P) and its reaction with phosphoric acid were studied. Even when activated at low temperatures, these fibers developed a graphitelike carbon structure with a certain amount of phenol groups as well as acetal (or methylenedioxy) carbon. As expected, the oxygen-containing groups were greatly reduced at high activation temperatures. Different from the ACF-W, metaphosphoric acid (or polyphosphates) and a small amount of phosphorus exist on ACF-P. The original ACF-P activated at low temperature contained a lot of phosphoric acid, so it had to be washed with water to expose the large surface area. The washing process can be omitted for ACF-P activated at high temperature because most phosphorus compounds in fiber have volatilized. The ACF-P activated at lower temperature possessed a large amount of oxygen-containing surface groups and had enhanced adsorption ability for polar adsorbates. The remaining of metaphosphoric acid enhanced the adsorption of silver ion. The experimental results showed that the peaks of 31 P-NMR, P 2p -XPS, and FTIR at 1620 cm Ϫ1 shifted with the increase of activated temperature.

Hierarchically porous carbon by activation of shiitake mushroom for capacitive energy storage

“…4c), suggesting conversion of phosphate into polyphosphate due to gradual dehydration and condensation of H 3 PO 4 [42]. A similar result was also described in a H 3 PO 4 -activated carbon with sisal and polymers as carbonaceous precursors [42,43]. As summarized in Table 1, thermal annealing of PAC-500 at 800 °C reduces both O and P contents, whereas, KOH activation step increases the O content but eliminate the element P. This change was further verified by Raman spectra in Fig.…”

New phosphorus-containing spherical carbon adsorbents as promising materials in drug adsorption and release

“…The shift mechanism, reported previously [13], is associated with increasing size of graphene layers [14]. Upfield shift of phosphate peak with increasing carbonization temperature was also reported for phosphoric acid activated carbon fibers [15].…”

Comparison of short carbon fibre surface treatments on epoxy composites

“…Another possible reason for the enhancement on interfacial adhesion is chemical interaction. Many researchers [19][20][21][22] have analysed the O 1s /C 1s ratio of carbon fibre surface by means of a Xray photoelectron spectroscopy (XPS), and reported that gaseous oxidative treatment could increase the oxygen concentration on carbon fibre surface, which means that the amount of functional groups could be increased, e.g. hydroxyl (-OH), carbonyl (-C@O) and carboxyl (-COOH) groups.…”