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United States Department of Agriculture

Agricultural Research Service

Research Project: THERMOCHEMICAL PROCESSING OF AGRICULTURAL WASTES TO VALUE-ADDED PRODUCTS AND BIOENERGY

Location: Commodity Utilization Research

Title: Contaminant immobilization and nutrient release by carbonized biomass in water and soils

Authors
item UCHIMIYA, SOPHIE
item LIMA, ISABEL
item KLASSON, K. THOMAS
item WARTELLE, LYNDA

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: March 1, 2010
Publication Date: June 27, 2010
Citation: Uchimiya, S.M., Lima, I.M., Klasson, K.T., Wartelle, L.H. 2010. Contaminant immobilization and nutrient release by carbonized biomass in water and soils (abstract). 2010 U.S. Biochar Initiative Conference, June 27-30, 2010, Iowa State University, Ames, IA.

Technical Abstract: Chars contain functional surface groups such as carboxylic, phenolic, hydroxyl, carbonyl, and quinones, in addition to porous structures that can impact essential soil properties such as cation exchange capacity (CEC), pH, and retention of water, nutrients, and pesticides. Physical and chemical properties of chars vary significantly depending on the biomass source, pyrolysis conditions and pre- and post-treatments. Fundamental knowledge in the sorption mechanism is on demand for engineering chars for specific agricultural and environmental remediation strategies. We have investigated the immobilization of inorganic (CdII, CuII, NiII, and PbII) and organic (deisopropylatrazine) priority pollutants, and the release of essential plant nutrients (S, P, K) by carbonized biomass both in water and soils. The following biochars and activated carbons were selected for our study: broiler litter-derived chars formed by pyrolysis at 350 and 700 degrees C and steam-activated analogues, and pecan shell-derived phosphoric acid activated carbons formed at 450 degrees C under 100, 800, and 2000 mL·min-1 air flow rates. These carbonaceous materials were first rigorously characterized for the BET surface area, elemental (CHNS/O) composition, and by Boehm titration, ATR-FTIR, and NMR analyses. For metal pollutants (CdII, CuII, NiII, and PbII) in water, pH increases arising from the addition of basic char brought about precipitation, and the extent of immobilization strongly depended upon the metal ion type. In soil solutions, CEC and pH buffering by soils impacted the ability of amended carbonaceous materials to immobilize metal cations. The addition of natural organic matter (NOM) having high carboxyl and phenolic contents mobilized certain metal ions (e.g., CuII) in biochar and activated carbon-amended soils. For nutrient release in soils, a correlation was observed between the total contents in amended chars and the soluble concentrations. Sorption isotherms of deisopropylatrazine on chars and activated carbons under acidic pH showed a positive correlation between sorption capacity and BET surface area. These findings suggest that an intricate interplay of precipitation, complexation, and surface adsorption controls the fate of contaminants and the availability of nutrients in biochar amended soils.

Last Modified: 8/27/2014
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