Synthesis of Novel Core-Shell Magnetic Fe₃O₄@C Nanoparticles with Carboxyl Function for Use as an Immobilisation Agent to Remediate Lead-Contaminated Soils

Abstract

In this study, a carbon shell was coated on Fe 3 O 4 nanoparticles using a hydrothermal method followed by modification of carboxyl end groups on the Fe 3 O 4 @C to form Fe 3 O 4 @C-COOH for creating an immobilisation agent for remediating lead-contaminated soils. The surface of an Fe 3 O 4 @C nanoparticle was successfully covered with carboxyl end groups. The Fe 3 O 4 core possessed the superparamagnetism property; the carbon shell protected the core from being oxidised or dissolved in acid solution, and provided good modifiability. Due to the strong interaction between lead and carboxyl end groups, this synthesised remediation agent exhibited high adsorption capacity. The Fe 3 O 4 @C-COOH nanoparticles principally promoted the transformation of lead (Pb) from a reducible to residual state, while having no obvious effect on the oxidation state of the lead. The amount of Fe 3 O 4 @C-COOH and the composition of soil organic matter had a higher influence on Pb distribution than soil pH, water content, or conductivity. Under optimal immobilisation conditions, the fractionation of the Pb acid-soluble, reducible, oxidative, and residual states in the contaminated soil changed significantly. The leaching and migration of Pb were significantly reduced, thus achieving remediation of lead-contaminated soils by immobilisation. Thus, remediation of lead-contaminated soils via Fe 3 O 4 @C-COOH immobilisation is a potentially practical and technologically feasible method.

Recent Advances of Nanoremediation Technologies for Soil and Groundwater Remediation: A Review

“…Several nanomaterials have been developed for contaminant remediation, such as nZVI, nanoscale zeolites, carbon nanotubes, metal oxides, bimetallic nanoparticles (BNPs), enzymes, and titanium dioxide (TiO 2 ) [52][53][54][55][56][57]. Soil remediation using these three nanoremediation materials (nZVI, TiO 2 , and CNTs) can be found in [58].…”

Recent Advances in Magnetic Nanoparticles and Nanocomposites for the Remediation of Water Resources

“…Another form of surface modification was reported by Zhang et al [39] who generated hollow spheres of magnetic carbon through a hydrothermal synthesis. These spheres (average size~400 nm) were then functionalized with carboxylic acid groups and tested for the removal of Pb 2+ ions from solution.…”

Comparison of the Surface Properties of Hydrothermally Synthesised Fe3O4@C Nanocomposites at Variable Reaction Times

“…Fabrication of carbon-encapsulated magnetite nanocomposite materials (Fe 3 O 4 @C) by hydrothermal treatment is a popular method of rendering prevention to the parent Fe 3 O 4 NPs from agglomeration and deterioration in chemical stability, thereby maintaining their effective surface properties, making them compatible for applications in both inorganic and organic processes. It involves synthesising Fe 3 O 4 @C nanostructures by heating at reaction temperatures and pressures above the ambient conditions of boiling water for a given reaction time, with the mixture of precursors in aqueous media as reported in the literature [ 14 , 15 ]. The method depends on precursor concentrations, the nature of the aqueous solvent, the stabilising agent, the type of precursor, the heating temperature, and the reaction time, which considerably influence the final products.…”