Quantitative characterization of pore structure of several biochars with 3D imaging

Hyväluoma, Jari; Kulju, Sampo; Hannula, Markus; Wikberg, Hanne; Källi, Anssi; Rasa, Kimmo

doi:10.1007/s11356-017-8823-x

Cited by 49 publications

(46 citation statements)

References 30 publications

(36 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Thereafter, images were segmented into voids and solids by global thresholding. The threshold value was determined with an automatic approach described by Hyväluoma et al (2018b), which is based on the methods of Otsu (1979) and Hapca et al (2013). Finally, the binary image was processed with a majority filter (radius 2), and isolated solid objects larger than 1000 voxels were removed from the images.…”

Section: X-ray Microtomography and Image Analysismentioning

confidence: 99%

Fertilizer and soil conditioner value of broiler manure biochars

Keskinen

Hyväluoma

Sohlo

et al. 2019

Biochar

Self Cite

View full text Add to dashboard Cite

Pyrolysis is an option for enhancing the sustainable management of broiler manure surpluses by producing a concentrated, hygienic char product with a fertilizer and soil conditioner value. In this study, the impacts of pyrolysis conducted at 350, 400 and 450 °C on total nutrient and harmful element concentrations in biochars derived from peat-bedded broiler manure were examined. Emphasis was placed on the availability of phosphorus (P). In addition, the pore structures of these biochars were explored using X-ray microtomography and image analysis. During pyrolysis, 35-50%, 40-55% and 35-45% of the original carbon, nitrogen and sulfur contents, respectively, of the feedstock biomass were lost as volatiles. Mineral elements, including P, were concentrated in the biochar. Although water-extractable P was found to be converted to less labile forms due to charring, the concentration effect and notable increase in sodium bicarbonate-extractable P rendered broiler manure biochars richer in total labile P in comparison with feedstock manure (7.1, 10.0, 11.1 and 14.8 g labile P kg −1 in feedstock and biochars produced at 350, 400 and 450 °C, respectively). The pore volume of the micrometer-scale porosity of the broiler manure biochar was comparable to that found earlier in wood-based biochars. In comparison with wood-based biochars, the pore structure of broiler manure biochars was more versatile, and the pore size distribution was wider. Consequently, part of the porosity was too large to store plant-available water, which may reduce the potential of broiler manure biochars to improve soil water storage capacity.

show abstract

Section: X-ray Microtomography and Image Analysismentioning

confidence: 99%

Fertilizer and soil conditioner value of broiler manure biochars

Keskinen

Hyväluoma

Sohlo

et al. 2019

Biochar

Self Cite

View full text Add to dashboard Cite

show abstract

“…Obtained grey-scale images were filtered and segmented as described in a previous paper [19]. As in that paper, a fully automatic segmentation algorithm based on a modified version of Otsu's method [22] was used to avoid operator-dependent bias in the results.…”

Section: X-ray Microtomography and Image Analysismentioning

confidence: 99%

“…D A values close to unity describe isotropic pore structure and higher values indicate stronger structural anisotropy. In [19], D A was determined for several biochars derived from different feedstock and biochars with an anisotropic pore structure resulting from vascular cell structure had D A > 20.…”

Section: X-ray Microtomography and Image Analysismentioning

confidence: 99%

Effects of pyrolysis temperature on the hydrologically relevant porosity of willow biochar

Hyväluoma

Hannula

Arstila

et al. 2018

Journal of Analytical and Applied Pyrolysis

Self Cite

View full text Add to dashboard Cite

Biochar pore space consists of porosity of multiple length scales. In direct water holding applications like water storage for plant water uptake, the main interest is in micrometre-range porosity since these pores are able to store water that is easily available for plants. Gas adsorption measurements which are commonly used to characterize the physical pore structure of biochars are not able to quantify this pore-size range. While pyrogenetic porosity (i.e. pores formed during pyrolysis process) tends to increase with elevated process temperature, it is uncertain whether this change affects the pore space capable to store plant available water. In this study, we characterized biochar porosity with x-ray tomography which provides quantitative information on the micrometer-range porosity. We imaged willow dried at 60 • C and biochar samples pyrolysed in three different temperatures (peak temperatures 308, 384, 489 • C, heating rate 2 • C min −1 ). Samples were carefully prepared and traced through the experiments, which allowed investigation of porosity development in micrometre size range. Pore space was quantified with image analysis of x-ray tomography images and, in addition, nanoscale porosity was examined with helium ion microscopy. The image analysis results show that initial pore structure of the raw material determines the properties of micrometrerange porosity in the studied temperature range. Thus, considering the pore-size regime relevant to the storage of plant available water, pyrolysis temperature in the studied range does not provide means to optimize the biochar structure. However, these findings do not rule out that process temperature may affect the water retention properties of biochars by modifying the chemical properties of the pore surfaces.

show abstract

“…It was found that biochar sample (B3), stored under the relative humidity of 56-74%, absorbed water in the amount of 5% by mass. Biochars are porous materials and their pore structure has the effects on the water absorption and water retention properties [58]. Gray et al [59] stated that water uptake by biochars is dependent on both feedstock, which controls residual macroporosity and production temperature, which controls hydrophobicity and pyrogenic nanopore formation.…”

Section: Hygroscopicity Of Brown Coal Biochar and The Selected Brownmentioning

confidence: 99%

Preliminary Study of a Method for Obtaining Brown Coal and Biochar Based Granular Compound Fertilizer

Mikos-Szymańska

Schab

Rusek

et al. 2019

Waste Biomass Valor

View full text Add to dashboard Cite

A purpose of the research was to develop a method for the preparation of novel organo-mineral fertilizers with the use of brown coal and biochars as organic additives. Brown coal was blended simultaneously together with inorganic materials used for the process of urea superphosphate production in a laboratory scale using a pan granulator and in larger scale using a rapid mixer granulator. Biochars were used for the coating purposes of the urea superphosphate granules on a laboratory scale using a pan granulator. Moreover, the aim was to measure and evaluate the physico-chemical properties of organic materials and the obtained organo-mineral fertilizer products and to study the effects of these products on the selected yield components of spring wheat such as grain yield per plant, spike number per plant, and plant height, in pot trials. Results showed that brown coal and biochars can be used as raw materials for production of fertilizer products. Brown coal contained about 50% of total humic acids while biochar contained nearly 6% of total humic-like substances. Brown coal based compound fertilizer granules produced in the large scale were characterized by particle hardness from 15.80 to 23.3 N while those produced in the laboratory scale were classified as "soft" (particle hardness below 2.3 N). The application of brown coal based fertilizers and two studied biochar coated fertilizers had a positive impact on the grain yield per plant of spring wheat.

show abstract

Quantitative characterization of pore structure of several biochars with 3D imaging

Cited by 49 publications

References 30 publications

Fertilizer and soil conditioner value of broiler manure biochars

Fertilizer and soil conditioner value of broiler manure biochars

Effects of pyrolysis temperature on the hydrologically relevant porosity of willow biochar

Preliminary Study of a Method for Obtaining Brown Coal and Biochar Based Granular Compound Fertilizer

Contact Info

Product

Resources

About