Title: Quantitative characterization of pore structure of several biochars with 3D imaging,
Abstract: Pore space characteristics of biochars may vary depending on the used raw
material and processing technology. Pore structure has significant effects on
the water retention properties of biochar amended soils. In this work, several
biochars were characterized with three-dimensional imaging and image analysis.
X-ray computed microtomography was used to image biochars at resolution of 1.14
$\mu$m and the obtained images were analysed for porosity, pore-size
distribution, specific surface area and structural anisotropy. In addition,
random walk simulations were used to relate structural anisotropy to diffusive
transport. Image analysis showed that considerable part of the biochar volume
consist of pores in size range relevant to hydrological processes and storage
of plant available water. Porosity and pore-size distribution were found to
depend on the biochar type and the structural anisotopy analysis showed that
used raw material considerably affects the pore characteristics at micrometre
scale. Therefore attention should be paid to raw material selection and quality
in applications requiring optimized pore structure.