The injection of nanoscale zero-valent iron (nZVI) can be an effective technique for the treatment of groundwater contaminants, including chlorinated solvents. However, its effectiveness can be limited by natural reductant demand (NRD) reactions, including the reduction of water resulting in the production of hydrogen gas. This study presents results from a series of laboratory experiments to investigate gas production and mobilization following the injection of nZVI solutions, along with sodium borohydride (NaBH₄) that is used for nZVI synthesis. Experiments were performed in a thin, two-dimensional flow cell (22 × 34 × 1 cm³) to measure hydrogen gas volumes and local gas saturations, and to investigate the distribution of gas within and above the injection zone. An additional experiment was conducted in a larger flow cell (150 × 150 × 2 cm³) containing dissolved trichloroethene (TCE) to assess changes in aqueous flow pathways and enhanced vertical transport of TCE by mobilized gas. The results showed substantial gas production (60% to 740% of the injected solution volume) resulting in gas mobilization as a network of gas channels above the injection zone, with more gas produced from greater excess NaBH₄ used during nZVI synthesis. Trapped gas saturations were sufficient to cause the diversion of aqueous flow around the nZVI injection zone. In addition, gas production and mobilization resulted in the bubble-facilitated transport of TCE, and detectable concentrations of TCE and reaction products (ethane and ethene) above the target treatment zone.

纳米级零价铁（nZVI）的注入可以是一种有效的技术，用于处理地下水污染物，包括氯化溶剂。但是，其有效性可能会受到自然还原剂需求（NRD）反应的限制，包括减少水的含量，从而导致氢气的产生。这项研究提供了一系列实验室实验的结果，这些实验研究了nZVI溶液以及用于nZVI合成的硼氢化钠（NaBH ₄）注入后的气体产生和动员。实验是在薄的二维流通池（22×34×1 cm ³）以测量氢气量和局部气体饱和度，并研究注入区内和注入区上方的气体分布。在包含溶解的三氯乙烯（TCE）的较大流通池（150×150×2 cm ³）中进行了另一项实验，以评估水流路径的变化以及流动化气体对TCE垂直传输的增强。结果表明，大量的气体产生（占注入溶液体积的60％至740％）导致气体流动，成为注入区上方的气体通道网络，更多的过量NaBH ₄产生了更多的气体在nZVI合成期间使用。截留的气体饱和度足以引起nZVI注入区周围的水流转移。另外，气体的产生和流动导致了气泡促进三氯乙烯的运输，并在目标处理区上方检测到三氯乙烯和反应产物（乙烷和乙烯）的浓度。