Influence of Soil Organic Matter on Copper Extraction from Contaminated Soil

Abstract

Column experiments of copper extraction from four contaminated soils characterized by a content of Soil Organic Matter (SOM) ranging from 1% to 25% are presented and discussed. The extraction was performed by flushing the soil with an aqueous solution of a sodium salt of ethylene diamminotetraacetic acid (EDTA). Preliminary tests were performed on a soil containing 25% of organic matter, to investigate the influence of pH, concentration and volumes of EDTA on its chelant action and on the dissolution of SOM. Having selected the optimal conditions for the extraction process, a further series of tests was conducted on the four soils to evaluate the influence of organic content on copper extraction yields. EDTA solutions at 0.01 M, 0.05 M, 0.1 and 0.2 M were injected at 0.33 ml/s; copper and organic matter extraction yield were determined. At a pH of 5, 15 pore volume (PV) of a solution containing 0.05M EDTA, extracted about 99% of copper contained by the soil with the higher organic matter content. Under the same conditions, and for soil with >6% SOM, extraction yields over 80% were achieved, while at lower organic content, copper extraction was dramatically reduced. This was attributed to the formation of highly stable copper-humate complexes and to their increasingly dissolution that occurred in the soils with higher organic matter level.Experimental tests performed at different contamination levels (1200 mg/kg, 2400 mg/kg) showed that EDTA extraction effectiveness also depended upon initial soil Cu concentration.

Profile distribution of micronutrients in an aquic brown soil as affected by land use

“…For an example, EDTA-extractable Cu was significantly greater at higher SOM content than at lower organic content. This was attributed to the formation of highly stable copper-humate complexes and to their increasing dissolution that occurred in the soils with higher organic matter level (Di Palma et al 2007).…”

Carbon paste electrodes modified with biosolids, soils and biocomposites utilized to study the interaction between organic matter and copper

“…Some authors (Boudesocque et al, 2007;Cheshire et al, 1994;Flogeac et al, 2004) have shown that Cu(II) interacts with the soils and forms "innersphere" complexes where Cu(II) replaces some hydration water molecules of the functional groups, thus forming very stable complexes with the soils, since there is direct coordination between the metal and the functional groups (Palma et al, 2007;Wu et al, 2001). On the other hand, it is likely that Cu(II) forms "outer-sphere" complexes with the biosolid, since the FTIR spectra (Fig.…”

Some DTPA Extractable Micronutrients in Different Hill Forest Soils of Chittagong Region, Bangladesh

“…The significant correlation between extractable Cu and soil organic matter might be attributed to the formation of highly stable copper-humate complexes and to their increasing dissolution that occurred in the soils (Di Palma et al 2007).…”