Immobilization of metal(loid)s in the soil-plant system using composites of sucrose foams and iron nanoparticles

The extensive contamination of soils with metal(loid)s requires efficient and sustainable remediation strategies. This study evaluates novel Fe-based carbon foams nanocomposites, synthesized from sucrose, as in situ amendments for the immobilization of As, Cd, Cu, Pb, and Zn in polluted soils. The foams, containing 5 % or 10 % Fe as FeO(OH) and FexOy nanoparticles, were tested through batch and pot experiments to optimize their performance and assess scalability. Unlike other traditionally used amendments, the versatility of the developed carbon foams allowed not only the development of suitable textural characteristics but also a homogeneous distribution of Fe, favouring the reduction of contaminants mobility and bioavailability. The alkalinity of the material benefited no only metal retention but also promoted electrostatic interactions with As species. In addition, soil pH, electrical conductivity, and Fe availability, remained unaffected. Pot experiments using Lolium perenne confirmed the absence of phytotoxicity, revealed limited translocation of contaminants to plant tissues. Given its efficiency, low cost and minimal environmental impact, these foam composites emerge as a promising alternative to conventional soil remediation amendments such as biochar.