| Summary: | 博士 === 國立中興大學 === 環境工程學系所 === 98 === This study modified the surface of nanoscale zero valent iron (NZVI) to synthesize the stabilized and mobile NZVI using two method. The first one is by carboxymethyl cellulose sodium (CMC) coating, and the other is to make NZVI encapsulated into the poly acrylic acid (PAA) vehicle. They are tilted as CNZVI and PNZVI, respectively. Furthermore, this study also synthesized the PFNZVI (PNZVI with finer sizes) using the method of heterogeneous nucleation to enhance the contaminant removal ability of NZVI. The mobility of NZVI in porous media will be evaluated by a series of column tests, and the impacts of groundwater parameters, such as flow velocities and ion strengths, on NZVI mobility will also be investigated. A NZVI trajectory model based on theory of force balance was also developed to simulate the movement of single NZVI particle in porous media, which could also used for evaluating the surface modification of NZVI.
Current results reveal that PAA form a capsule-like gelling network to encapsulate NZVI (PNZVI), decrease the oxidation of NZVI in the air, and result in better mobility than CNZVI. However, when the Ca2+ concentration increases to 40 mM, the PAA gelling network is destroyed by Ca2+ and mobility of PNZVI decrease apparently. In addition, the analysis of trajectory model indicated that for unstabilized NZVI with 80nms diameter moves in porous media, the gravity effects of the particle can''t be neglected. The NZVI movement is dominated by the Brownian motion and most of the deposit occurred at the area of pore inlet. For stabilized NZVI, the particles kept away from the porous media due to electrosteric repulsion force, and no deposit is ever observed.
Keyword : Nanoscale zero valent iron、carboxymethyl cellulose sodium、poly acrylic acid、mobility、motion trajectory
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