You are here:
Macroscopic and Molecular Investigations of Copper Sorption by a Steam-Activated Biochar
Citation:
Ippolito, J. A., D. G. Strawn, K. G. SCHECKEL, J. M. Novak, M. Ahmedna, AND M. A. Niandou. Macroscopic and Molecular Investigations of Copper Sorption by a Steam-Activated Biochar. W. Dick, E.C. Brummer, A. Sharpley, and D. Corwin (ed.), JOURNAL OF ENVIRONMENTAL QUALITY. American Society of Agronomy, MADISON, WI, 41(4):1150-1156, (2012).
Impact/Purpose:
The objective of this work was to identify adsorption behavior of solution-borne Cu on KOH-activated pecan shell-based biochar as affected by solution pH, dtermine the biochar sorption maximum and elucidate the bonding mechanisms that control the solid phase partitioning with biochar. This project is the first phase in a multi-stage project aimed at sequestering Cu from spent Cu-containing dairy hoofbath waste.
Description:
Excessive Cu concentration in water systems can negatively impact biological systems. Because Cu can form strong associations with organic functional groups, we examined the ability of biochar (an O-C-enriched organic bioenergy by-product) to sorb Cu frmo solution. In a batch experiment, KOH-steam activated pecan shell biochar was shaken for 24 hr in pH 6, 7, 8, or 9 buffered solutions containing various Cu concentrations to identify effect of pH on biochar Cu sorption. Afterwards, all biochar solids from the 23-hr shakng period were air-dried and then analyzed using X-ray absorption fine structure (XAFS) spectroscopy to determine solid-phase Cu speciation. In a separate batch experiment, biochar was shaken for 30 days in pH 6 buffered solution containing increasing Cu concentrations; the Cu sorption maximum was calculated based on the exponential rise to a maximum equation. Biochar sorbed increasing amounts of Cu as the solution pH decreased from 9 to 6. The XAFS revealed that Cu was predominantly sorbed onto a biochar organic phase at pH 6 in a molecular structure similar to Cu adsorbed on model humic acid (Cu-HA). The XAFS spectra at pH 7, 8, and 9 suggested that Cu was associated with the biochar as three phases: 1) a complex adsorbed on organic ligands similar to Cu-HA; 2) carbonate phases similar to azurite (Cu3(CO3)2(OH2)); and 3) a Cu oxide phase like tenorite (CuO). The exponential rise equation fit to the incubated samples predicted a Cu sorption maximum of 42,30 mg CU kg-1. The results showed that KOH-steam activated pecan shell biochar could be utilized as a material for sorbing excess Cu from water systems, potentially reducing the negative effects of Cu in the environment.
