Dielectric characterization of white birch–activated biochar composites: A sustainable alternative to radar-absorbing materials

Abstract

Sustainability can be defined as the ability of meet presents needs without compromise the ability of future generations to find their own needs. In this matter, scientists have been warning about natural resource scarcity, and now several researchers are aiming their efforts to develop sustainable technologies. Here, we focus on finding novel uses to biochar, a carbon rich material made from biomass that is usually applied on soil amendment. To expand its applications, biochars were activated using two different methods: a physical activation using CO2; and a chemical one using KOH. We investigate here the dielectric properties of composites made with both activated biochars from white birch, where composites were made using silicone rubber matrix. It was also investigated the influence of composites made with biochar in powder and in flakes. All samples were characterized over the X-band frequency range. Composites made with powder presented a linear permittivity over the frequency range, while composites made with flakes presented oscillations on different frequencies. These oscillations are related to the composite surface, which induces reflection effects because of flakes arrangement in the top surface. Such effects widen opportunities to engineer new materials to be explored as radar-absorbing materials.

The conversion of wood residues, using pilot-scale technologies, into porous activated biochars for supercapacitors

“…The XPS C1s peaks were deconvoluted and used to estimate the relative proportions of the functional groups listed in Table 2. The full range of XPS results has been described elsewhere [35]. The main peak, which was lower than 285 eV for all materials, was (Table 3), which was confirmed by CHNSO analysis (2% of nitrogen detected) while BWB and CO2BWB possessed less than 1%.…”