Aerosol-assisted nanoscale Fe/silica particles for dechlorination of trichloroethylene

Nanoscale iron particles are a preferred option for the reductive dehalogenation of trichloroethylene (TCE) due to their environmentally benign nature, high efficiency and low cost. However, nanoscale zerovalent iron (ZVI) particles aggregate and in in-situ remediation technologies, it is difficult to transport these particles to the source of contamination. This study describes a novel approach to the preparation of ZVI nanoparticles that are efficient and effectively transport to contaminant sites. We describe the synthesis of silica supported iron nanoparticles using aerosol technology. While the encapsulated iron nanoparticles are reactive for groundwater trichloroethylene remediation, environmentally benign silica particles serve as effective carriers for nanoiron transport through soil. Encapsulation of iron into submicron silica particles protects ferromagnetic iron nanoparticles from aggregation and may increase their mobility through sedimentation. Additionally, the presence of surface silanol groups on silica particles allows control of surface properties via silanol modification using organic functional groups. Aerosol silica particles with functional groups such as ethyl tails on the surface preferentially adsorb hydrophobic TCE during environmental remediation. This increases the local concentration of TCE in the vicinity of iron nanoparticles, thus promoting the degradation of TCE by iron. These nanoscale iron/silica aerosol particles with controlled surface properties have the potential to be efficiently applied for in-situ remediation and permeable reactive barriers construction.