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ARS Home » Midwest Area » St. Paul, Minnesota » Soil and Water Management Research » Research » Publications at this Location » Publication #305793

Title: Physical and chemical characterization of waste wood derived biochars

item YARGICOGLU, ERIN - University Of Illinois
item SADASIVAM, BALA YAMINI - University Of Illinois
item REDDY, KRISHNA - University Of Illinois
item Spokas, Kurt

Submitted to: Waste Management
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/28/2014
Publication Date: 2/1/2015
Publication URL:
Citation: Yargicoglu, E.N., Sadasivam, B., Reddy, K.R., Spokas, K.A. 2015. Physical and chemical characterization of waste wood derived biochars. Waste Management. 36:256-268.

Interpretive Summary: Biochar is the solid residual produced from the pyrolysis of biomass, which is focused on the utility of the residue as a vehicle for carbon sequestration. In addition, laboratory and some field results have shown statistically significant impacts in the availability of soil nutrients and the microbial/plant effects following biochar additions. There have been several hypotheses into the potential mechanisms causing these effects. Here we analyzed a series of commercially available biochars to assess the variability and variance in their properties. There was a wide range in the observed properties including carbon content and surface areas. The results of this study emphasizes the importance of pre-screening biochars prior to any application or usage. Since the process to predict their properties appear to be lacking for currently available biochars. These results are significant to farmers and policy makers and will assist scientists and engineers in developing improved biochars based on properties to improve soil carbon management and accurate predictions of the impact of biochars on net greenhouse gas exchanges following soil addition.

Technical Abstract: Biochar, a solid byproduct generated during waste biomass pyrolysis or gasification in the absence (or near-absence) of oxygen, has recently garnered interest for both agricultural and environmental management purposes owing to its unique physicochemical properties, such as its high surface area and porosity, and ability to adsorb a variety of compounds, including nutrients, organic contaminants, and some gases. Physical and chemical properties of biochars are dictated by the feedstock and production processes (pyrolysis temperature, conversion technology and post-treatment processes, if any), which vary widely across commercially produced biochars. In this study, several commercially available waste wood derived biochars are characterized for physical and chemical properties that can signify their relevant environmental applications. Parameters characterized include: physical properties (particle size distribution; specific gravity; density; porosity; surface area); hydraulic properties (hydraulic conductivity and water holding capacity); and chemical properties (organic matter and organic carbon contents; pH, oxidation-reduction potential and electrical conductivity; zeta potential; C/H/N elemental analysis; PAHs, heavy metals, and leachable PAHs and heavy metals). A wide range of fixed C (0 - 47.8%), volatile matter (28 - 74.1%), and ash contents (1.5 - 65.7%) were observed among tested biochars. A high variability in surface area (0.1 - 155.1 g/m2) and PAH and heavy metal contents among commercially available biochars was also observed (0.7 to 83 mg kg-1), underscoring the importance of pre-screening biochars prior to usage. Production conditions appear to dictate PAH content - with the highest PAHs observed in biochar produced via fast pyrolysis and lowest among the gasification produced biochars. However, all PAHs detected in the solid biochars are below groundwater acceptable levels (for Illinois, USA).