Issue 12, 2023

Towards engineering mitigation of leaching of Cd and Pb in co-contaminated soils using metal oxide-based aerogel composites and biochar

Abstract

Applications of metal-based nanomaterials for the remediation of heavy metal (HM) contaminated environments are of great importance. The ability of metal oxide-based carbon aerogel composite to immobilize HMs in multi-metal contaminated soils has not yet been investigated, particularly under acidic conditions. Herein, we investigate the performance of metal oxides (Sr0.7 Mn0.3 Co0.5 Fe0.5O3−δ)-based carbon aerogel composite (MO-CAg) compared with coconut coil fiber biochar (CCFB) and carbon aerogel (CAg) for Cd and Pb immobilization in contaminated soil. The MO-CAg, applied at 2% (w/w), significantly decreased Pb leaching by 67–75% and Cd by 60–65%, CAg decreased Cd by 54% and Pb by 46%, while biochar decreased Cd by 40–44% and Pb by 43%. The addition of MO-CAg altered Cd and Pb geochemical fractions by increasing their residual fraction, i.e., stabilized both metals compared to the control. This presents a comprehensive elaboration on the probable reaction interactions between the MO-Cag and heavy metals, including a combination of (co)precipitation, and reduction-oxidation as the predominant mechanisms of metal stabilization with MO-CAg. Moreover, MO-CAg increased Pb and Cd stabilization in soils by strengthening the bonding between metal oxides and Cd/Pb. By imbedding MO into the CAg, in MO-CAg, the immobilization of Cd(II) and Pb(II) occurred through inner-sphere complexation, while with CCFB and CAg metals, immobilization occurred through outer-sphere complexation. MO-CAg is a promising and highly efficient material that could be recommended for the remediation of Cd- and Pb-contaminated soils in subsequent studies.

Graphical abstract: Towards engineering mitigation of leaching of Cd and Pb in co-contaminated soils using metal oxide-based aerogel composites and biochar

Supplementary files

Article information

Article type
Paper
Submitted
04 jul 2023
Accepted
09 okt 2023
First published
02 nov 2023

Environ. Sci.: Processes Impacts, 2023,25, 2110-2124

Towards engineering mitigation of leaching of Cd and Pb in co-contaminated soils using metal oxide-based aerogel composites and biochar

D. Sanaei, M. Sarmadi, M. H. Dehghani, H. Sharifan, P. G. Ribeiro, L. R. G. Guilherme and S. Rahimi, Environ. Sci.: Processes Impacts, 2023, 25, 2110 DOI: 10.1039/D3EM00284E

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