73 - Application of a goethite-carbon foam nanocomposite for Hg immobilization in a co-contaminated soil

"Along with national and international policies, sustainable land management and reclamation technologies are key to reversing soil contamination by metals. Sustainable land reclamation solutions, labeled as nature-based solutions (NBS), focus on in-situ technologies that involve effective soil amendments capable of stabilizing/removing contaminants. Within the context of NBS, a circular approach using sustainably sourced materials to address soil remediation is timely. In the combination of these needs lies the objective of this study, which involves the preparation of carbon materials, in particular, sucrose-based carbon foams. In addition, the use of sugar beet or sugar cane for non-food uses implies generating new opportunities for the agricultural sector.

Two soil samples were taken from an industrial area and an abandoned Hg mining-metallurgy site, severely affected by metals pollution. The carbon foam was elaborated from molten sucrose using iron nitrate as blowing and activating agent. Subsequently, it was loaded with goethite (FeO(OH)) nanoparticles on its surface. The carbon foam was characterized by FTIR, SEM, DRX and N2 adsorption data. The mobility and availability of Hg in soil were evaluated by the toxicity characteristic leaching procedure (TCLP). Hg contents and speciation were determined using an automatic Hg analyzer and by programmed Hg desorption, respectively.

The combination of multimodal porosity (macro-, meso- and microporosity), the presence of oxygenated groups on the surface and the homogeneous distribution of goethite nanoparticles, provided a high efficiency of carbon foams for the immobilization of Hg. In addition, the application of the developed carbon foams decreased the concentration of leachable Fe, thus preventing the taxonomic and functional composition of the soil microbiota from being altered by potential toxicological effects."

Authors: Íria Janeiro-Tato, Maria Antonia Lopez-Anton