泡沫强化多孔介质中纳米零价铁迁移试验

通过批量模拟试验考察了纳米零价铁(NZⅥ)在水、十二烷基硫酸钠(SDS)溶液与SDS泡沫3种流体中的沉降性能,以及3种流体输送作用下NZⅥ在多孔介质中的迁移分布特性.结果表明:NZⅥ在SDS溶液中的稳定性远大于其在水中的稳定性;搅拌速度为3000r/min时,NZⅥ在泡沫中的分布较均匀且泡沫对NZⅥ携带量较大;NZⅥ对泡沫稳定性影响不大.水、SDS溶液、SDS泡沫分别作为输送流体时,NZⅥ迁移的最大距离分别为0.8m,7.9m和2.1m,SDS溶液和泡沫均显著促进了其在多孔介质中的运移.当NZⅥ由SDS溶液和泡沫输送时,其在介质中的分布范围(33.5%和42.5%)大于水(12.8%);由于重力作用,SDS溶液携带NZⅥ的迁移主要集中在垂向上,水平迁移能力有限;而泡沫受重力影响较小,其携带的NZⅥ在水平和垂直方向上的分布更为均匀.可见泡沫作为NZⅥ的输送流体具有明显优势.

Enhanced delivery of nanoscale zero valent iron by foam in porous media

Laboratory scale experiments were conducted to investigate the sedimentation and delivery properties in the three vehicles, i.e. water, sodium dodecyl sulfate (SDS) solution and SDS foam. Experimental results showed that the stability of NZVI in SDS solution was much greater than that in water; the optimum foam capability to carry NZVI and the uniformity of NZVI in foams were observed at 3000 r/min stirring speed; the presence of NZVI has slightly influence on foam stability. The maximum delivery distances for NZVI suspension, SDS-NZVI suspension and NZVI-laden foam were 0.8m, 7.9m, and 2.1m, respectively. Therefore, the transport of NZVI in porous media was enhanced apparently by SDS solution and SDS foam. The impact zones for SDS-NZVI suspension (33.5%) and NZVI-laden foams (42.5%) were icreased compared with the bare NZVI suspension (12.8%). Due to gravity, vertical transport of NZVI carried by SDS solution was prior to horizontal transport, and the horizontal delivery distance was limited; NZVI carried by SDS foam could transport in both horizontal and vertical directions, and the distribution of NZVI was more uniform. Additionally, compared with water and SDS solution, SDS foam was an ideal vehicle to deliver NZVI particles and had a promising application in contamination sites.