title: Transport of nano zero-valent iron supported by mesoporous silica microspheres in porous media.
abstract: Effective in situ remediation of groundwater requires the successful delivery of reactive iron particles through sand. However, the agglomeration of nano zero-valent iron (NZVI) particles limits the migration distance, which inhibits their usefulness. In the study described herein, NZVI supported by mesoporous silica microspheres covered with FeOOH (SiO2@FeOOH@Fe) was synthesized, and its mobility was demonstrated on the basis of transport in porous media. Degradation of decabromodiphenyl ether (BDE209) was more efficient by SiO2@FeOOH@Fe than by 'bare' NZVI. Breakthrough curves and mass recovery showed the mobility of SiO2@FeOOH@Fe in granular media was better than that of bare NZVI. It increased greatly in the presence of natural organic matter (NOM) and decreased when high Ca2+ and Mg2+ concentrations were encountered. Analysis of the transport data on the basis of filtration theory showed diffusion to be the main mechanism for particle removal in silicon sand. Increasing the NOM may decrease agglomeration of the grains of sand, which has a positive effect on the mobility of SiO2@FeOOH@Fe. Presumably, increasing the concentrations of Ca2+ and Mg2+ compresses the diffuse double layer of SiO2@FeOOH@Fe, resulting in a reduction of mobility.
authors.affiliation: School of Chemistry and Environment, South China Normal University, Guangzhou 510006, China E-mail: sunmoon124@163.com.
authors.forename: Zhangmei
authors.initials: Z
authors.lastname: Yang
authors.affiliation: School of Chemistry and Environment, South China Normal University, Guangzhou 510006, China E-mail: sunmoon124@163.com.
authors.forename: Xinhong
authors.initials: X
authors.lastname: Qiu
authors.affiliation: School of Chemistry and Environment, South China Normal University, Guangzhou 510006, China E-mail: sunmoon124@163.com.
authors.forename: Zhanqiang
authors.initials: Z
authors.lastname: Fang
authors.affiliation: Department of Science and Environmental Studies, The Hong Kong Institute of Education, Hong Kong 00852, China.
authors.forename: Tsang
authors.initials: T
authors.lastname: Pokeung
mesh_terms: D052918:Environmental Restoration and Remediation / Q000379:methods; D005374:Filtration / Q000295:instrumentation / Q000379:methods; D060587:Groundwater; D007501:Iron / Q000737:chemistry*; D053768:Metal Nanoparticles / Q000737:chemistry*; D008863:Microspheres; D012822:Silicon Dioxide / Q000737:chemistry*
chemical_list: D012822:Silicon Dioxide; D007501:Iron