羧甲基淀粉钠改性零价纳米铁在饱和多孔介质中的迁移

Transport of CMS-Na modified zero-valent iron particles in saturated porous media

利用羧甲基淀粉钠(CMS-Na)对纳米零价铁(nZVI)进行改性。通过沉降实验,探讨改性剂添加量对纳米零价铁的分散性能的影响。利用柱实验多层位取样,来刻画饱和多孔介质中nZVI悬浮液迁移的过程,并分析其在改性剂添加量(nZVI、nZVI/200%CMS-Na、nZVI/400%CMS-Na)、初始流速(0.023 6,0.047 2,0.070 8 cm/s)、nZVI浓度(0.5,0.75,1 g/L)的条件下的迁移规律。结果表明,分散效果完全不与CMS-Na与nZVI的质量比成正比,nZVI/400%CMS-Na的分散效果最好,nZVI/500%CMS-Na的分散效果反而变差;随着时间的增加,nZVI由下端往上端迁移,nZVI出流浓度也随着时间增加,然后趋于稳定不变。nZVI的迁移能力与分散性能、流速、浓度呈正相关关系。

The dispersion mechanism of sodium carboxymethyl starch （ CMS-Na） modify nanometer zero- valent iron （nZVI） particles in saturated porous media is studied. It discusses the effect of modifier to nZVI by sedimentation experiments. I t ,s analyzes migration patterns under the condition of its modifier content （nZVI, nZVI/200% CMS- Na, nZVI/400% CMS-Na） , initial velocity （0.023 6,0.047 2 and 0. 070 8 cm/s） concentration of nZVI （0.5 ,0.75 and 1 g/L ） . Results show that the dispersion effect is directly proportional to the mass ratio of CMS-Na and nZVI, dispersion effect of nZVI/400% CMS-Na is best,while nZVI/500% CMS-Na is worse; nZVI migrate from bottom to top and discharge concentration increased with time,and then tend to be more stable. It＇s can be seen that migration ability has positively correlated with dispersion properties, flow velocity and concentration.