Changes in the Extractability and Fractionation Of Cadmium and Copper in a Contaminated Soil Amended with Various Sugarcane Bagasse-Based Materials

Abstract

Heavy-metal contamination in soil has puzzled people for many years and in-situ remediation is a potential technique to deal with it. In this paper, a 120-day soil incubation study was conducted to compare the effects of pristine sugarcane bagasse (SB), citric-acid modified (SSB1, SSB2 and SSB3 with increasing proportion of citric acid) and citric-acid/Fe3O4 modified (MSB1, MSB4 and MSB7 with increasing proportion of Fe3O4) sugarcane bagasse at 1% addition rate on cadmium (Cd) and copper (Cu) passivation. The SB, SSB1 and MSB1 did not always decrease the content of CaCl2-extractable Cd while all the seven amendments decreased the CaCl2-extractable Cu during the experiment period. SSB3 and MSB7 exhibited the highest efficiency to decrease the concentrations of CaCl2-extractable Cd and Cu. At Day 120, SB, SSB3 and MSB7 reduced the content of CaCl2-extractable Cd by 8%, 18% and 24%, and of CaCl2-extractable Cu by 25%, 50% and 61%, respectively. The efficiency of Cd and Cu immobilization was associated positively with the pH, functional groups and H-bonds of the amendments. The results suggest that the efficiency of sugarcane bagasse in heavy-metal passivation can be largely enhanced through chemical modifications using high proportions of citric acid and Fe3O4.

Keywords: Cd-Cu pollution, Organic amendments, Passivation, soil remediation, Stabilization.