Investigation of the textural and adsorption properties of activated carbon from HTC and pyrolysis carbonizates

Abstract

Bamboo was converted into a microporous activated carbon (AC) following either a one- or a two-step activation process with KOH. The main objective was to analyze the influence of the carbonization process (pyrolysis and hydrothermal carbonization (HTC)) and mixing method of KOH (dry mixing or impregnation) on the AC textural properties as well as on the adsorption capacity of water-soluble pollutants and hydrogen (H2) storage. The highest AC yields were obtained after a two-step activation process. These ACs presented the largest surface areas (2000–2500 m2 g−1) and the best adsorption capacities not only in aqueous media but also of H2. The type of carbonization process did not have a significant effect on yield and adsorption capacities, but it did affect the surface area and pore size distribution. HTC led to ACs with a larger total pore volume than ACs from pyrolysis, but the microporous surface area was smaller. KOH impregnation led to slightly but significantly higher yields than mixing KOH dry; yet, the textural and adsorption properties were not significantly improved. KOH impregnation led to slightly but significantly higher yields than mixing KOH dry; yet, the surface area and pore size distribution as well as adsorption properties were not significantly improved. H2 adsorption capacity was highest for ACs from impregnated hydrochar, followed closely by ACs from pyrochars.