To restrain the nano zero-valent iron (NZVI) in aqueous solution from being reunited and oxidized, this paper used sodium carboxymethyl starch (CMS), which is an environmentally friendly and cheap material, for coating and surface modification of NZVI so as to improve its dispersity and suspension property. Transmission Electron Microscope (TEM) and X-ray diffraction (XRD) were used to study the microstructure and components of the modified NZVI, and the 2,4-dichlorophenol 2,4-(DCP) removal efficiency was researched through chemical experiment. Experiments showed that the modified NZVI was about 80~100 nm in diameter, present as chain or dispersed particles. The main component was zero-valent iron, and it had strong reducibility. When the proportion of CMS was 80.00%, the suspension property was the best; The NZVI after CMS coating and surface modification retained the original activity. In the experiment investigating the removal effect of 2,4-DCP using different proportion of cladding, the same finding was obtained. When the CMS's proportion was 80%, the removal effect was the best, reaching up to 83.69%, and the dechlorination and degradation were apparent.
Keywords: 2,4-dichlorophenol; degradation; disperse; nano zero-valent iron; underground water remediation.