We describe a novel assisted aerosol process to prepare porous silica particles containing nanoscale zerovalent iron which is a reactive species for the reduction of trichloroethylene (TCE). The 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 increases their mobility through sediments. Additionally, the presence of surface silanol groups on silica particles makes it possible to control surface properties via silanol modification using organic functional groups. Aerosol silica particles with functional groups such as ethyl tails on the surface preferentially absorb 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 can be efficiently applied for in-situ remediation and permeable reactive barriers construction.