Luong Xuyen Thi Hong, Liang Chenju
Department of Environmental Engineering, National Chung Hsing University, 145 Xingda Road, Taichung 402, Taiwan.
ACS Environ Au. 2025 Jun 25;5(5):468-478. doi: 10.1021/acsenvironau.5c00046. eCollection 2025 Sep 17.
This study investigated the feasibility of foam-enhanced air sparging (FEAS) for remediating trichloroethylene (TCE) dense nonaqueous phase liquid (DNAPL) in water. Various surfactants, including polyoxyethylene (20) sorbitan monooleate (TW80), sodium dodecyl sulfate (SDS), sodium α-olefin sulfonate (AOS), and TW80/SDS and TW80/AOS combinations, were used to generate foam, which were evaluated for foam stability and quality. AOS (32 mM) exhibited the highest foam stability (∼345 min) and quality (∼99.6%) under controlled conditions. Phase contrast microscopy analysis showed foam sizes of 290-400 μm with thin film thicknesses of 6-9 μm. FEAS was tested with and without sodium persulfate (SPS) oxidant (oxidative foam) to treat approximately 10 g of TCE DNAPL in 1 L of water. Injecting AOS foam (32 mM) or oxidative foam AOS (32 mM)/SPS (50 or 1700 mM) for 2 h dissolved 60-82% of TCE, compared to only 4-7% with N injection. The surfactant-stabilized interface in foam facilitated TCE adsorption, increasing its partitioning into bubbles, leading to enhanced volatilization. In the lamella region, surfactant layers promoted TCE dissolution, while SPS aided its mineralization. With oxidative foam at a higher SPS concentration (1700 mM) and an extended reaction time (240 h), TCE mineralization increased to 40-74% across different foam injection rates. These results highlight oxidative FEAS as a promising improvement over conventional air sparging, significantly enhancing TCE dissolution, volatilization, and oxidation.
本研究调查了泡沫强化空气注入法（FEAS）修复水中三氯乙烯（TCE）致密非水相液体（DNAPL）的可行性。使用了各种表面活性剂来产生泡沫，包括聚氧乙烯（20）山梨醇酐单油酸酯（吐温80）、十二烷基硫酸钠（SDS）、α-烯烃磺酸钠（AOS）以及吐温80/SDS和吐温80/AOS组合，并对其泡沫稳定性和质量进行了评估。在控制条件下，AOS（32 mM）表现出最高的泡沫稳定性（约345分钟）和质量（约99.6%）。相差显微镜分析显示泡沫尺寸为290 - 400μm，薄膜厚度为6 - 9μm。采用有无过硫酸钠（SPS）氧化剂（氧化泡沫）的FEAS对1 L水中约10 g的TCE DNAPL进行处理。注入AOS泡沫（32 mM）或氧化泡沫AOS（32 mM）/SPS（50或1700 mM）2小时可溶解60 - 82%的TCE，相比之下，仅注入氮气时溶解率为4 - 7%。泡沫中由表面活性剂稳定的界面促进了TCE的吸附，增加了其在气泡中的分配，从而提高了挥发效率。在液膜区域，表面活性剂层促进了TCE的溶解，而SPS有助于其矿化。在较高SPS浓度（1700 mM）和延长反应时间（240小时）的氧化泡沫条件下，不同泡沫注入速率下TCE的矿化率提高到了40 - 74%。这些结果突出了氧化FEAS作为一种比传统空气注入法更有前景的改进方法，显著提高了TCE的溶解、挥发和氧化效率。
