"Nanocomposites and nanomaterials"

The investigation of the structure of biocarbon synthesized from wheat straw
Ptashnyk V.1, Bordun I.2,3, Malovanyy M.3, Chabecki P.2, Księżarek M.2
1 Lviv National Agrarian University, V. Velykogo str. 1, Dubliany, 80381, Ukraine. 
E-mail: ptashnykproject@gmail.com
2 Czestochowa University of Technology, Al. Armii Krajowej 17, Czestochowa, 42-200, Poland.
3 Lviv Polytechnic National University, S. Bandery str. 12, Lviv, 79013, Ukraine.

The investigations conducted in recent years have shown that the parameters of biocarbons are equivalent or even higher than those of commercial activated carbon. Therefore, the synthesis of activated biocarbon of a from wheat straw and investigation of it structural features is carried out in this work. The synthesis was carried out using as activator a 5 % solution of H3PO4 at a temperature of 650 °C without a protective atmosphere.
The parameters of the porous structure of the activated carbon were assessed via isothermic adsorption/desorption processes of nitrogen. They were evaluated by the means of automated analyzer Nova Touch LX2. X-ray diffraction curves of the carbon materials were obtained using the diffractometer DRON-3 in Cu Kα-emission (λ = 0.1542 nm), which had been monochromated through reflection from the plane (002) of the pyrographite monocrystal set on the path of the diffracted beam. The measurements of small angle X-ray scattering spectrums (SAXS) were also obtained from the diffractometer DRON-3 in Cu Kα-emission , which had been monochromated through reflection from the plane (200) of LiF monocrystal via the X-ray beam transmission through the sample.
The analysis of gas adsorption/desorption data by the BET method gives a specific surface area of 798.7 m2/g, pore volume 0.53 cm3/g, average pore diameter 1.32 nm. Two wide diffuse maxima are observed on the diffractograms, which correspond to the interplanar distances of 3.59 Å and 2.11 Å. In addition, the diffraction pattern has a sharp peak at 26,63° (3.35 Å), which indicates the presence in the sample of a certain proportion of polycrystalline graphite. According to the SAXS, the dominant contribution to the porous volume (about 85 %) is given by pores with a radius of up to 2.8 nm. As a result of the calculation we obtain a specific pore surface area of 781 m2/g.
Therefore, the proposed method of biocarbon synthesis makes it possible to obtain highly porous activated carbon with a large proportion of micropores.