Journal of Environmental Sciences
·
2025
·
IF 6.3
Shengyu Wu,Zhongran Wu,Guofeng Li,Yongkai Liao,Shanna Lin,Zhao Liu,Chao Cai
The transport behavior of pollutants under dynamic groundwater conditions has attracted significant attention recently. However, there is limited research on the simultaneous effects of groundwater table fluctuations on the transport of co-existing pollutants, especially combined dense and light non-aqueous phase liquids (DNAPLs and LNAPLs). In this study, column experiments investigated toluene and dichloromethane transport in a controlled water table system with varying fluctuation conditions. Results showed that both dichloromethane and toluene accumulated near the groundwater table under static water table conditions, but the concentration of dichloromethane declined more rapidly than toluene due to differences in their physicochemical properties, such as solubility, density, and hydrophobicity. Groundwater fluctuations facilitated pollutants transportation towards deeper layers, potentially resulting in unforeseen increases in pollutant volatilization and downward fluxes. The interactions between dichloromethane and toluene, including competitive adsorption, enhanced dissolution, and altered kinematic viscosities, resulted in the reduced transport potential of dichloromethane while enhancing that of toluene. Furthermore, compared to dichloromethane, the initial upward fluctuation of the water table had a more pronounced impact on toluene due to its lower solubility and volatility. The downward transport risk index assessment indicated that among various factors considered, groundwater fluctuation amplitude exerted the most significant influence on pollutant migration risk. These new findings will provide important insights into understanding and assessment of the potential transport risk associated with combined LNAPLs and DNAPLs in the natural environment.
研究领域:
环境科学
·
水文学
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DOI
PubMed
高影响因子
JOURNAL OF HAZARDOUS MATERIALS
·
2025
·
IF 11.3
Yu Yao,Xueming Qin,Yufeng Fu,Yeping Gao,Chengwu Zhang,Hui Zhang,Chuanyu Qin,Bing Qin,Liming Ren
Surfactant-enhanced aquifer remediation (SEAR) is an effective strategy for removing dense non-aqueous phase liquids (DNAPLs) from contaminated groundwater. While Gemini surfactants possess unique dimeric structures and excellent physicochemical properties, the role of hydrophobic chain length in governing their solubilization performance has not been systematically clarified. Here, five sugar-based anionic–nonionic Gemini surfactants (SANG 06, 08, 09, 10, and 13) with different hydrophobic chain lengths were synthesized and evaluated. The surface activity, hydrophilic–lipophilic balance, and micellar behaviors were characterized, and the relationship between chain length and DNAPL solubilization was systematically investigated. Results showed that increasing hydrophobic chain length significantly influenced micelle formation and solubilization behavior. Among them, SANG 13, with the longest chain, exhibited the most favorable characteristics, including an extremely low critical micelle concentration (0.086 g/L), an optimal HLB value (16.85), and ultra-low interfacial tension with PCE (0.6 mN/m). It also formed the largest micelles (26.80 nm) and the highest aggregation number (Nagg=15.98 at 10 CMC), resulting in superior solubilization and desorption efficiencies for DNAPLs. This study provides the first systematic evidence of how hydrophobic chain length regulates the physicochemical properties and solubilization mechanisms of Gemini surfactants. The findings offer new insights into surfactant structure–function relationships and provide theoretical support for optimizing SEAR technology in DNAPLs-contaminated groundwater remediation.
研究领域:
环境科学
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化学工程
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胶体与界面科学
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地下水修复
·
有机化学
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DOI
PubMed
高影响因子
WATER AIR AND SOIL POLLUTION
·
2025
·Vol. 236
·期 12
·1-17
·
IF 3
Zheng Tianwen,Huang Kangping,Wang Moxi,Leng Wenpeng,Wu Naijin,Zhi Liqin,Li Peizhong,Luo Huilong,Wang Haijian,Wang Jiajia,Luo Nan,Wei Wenxia
DNAPLs are volatile, hardly degradable, highly toxic, and low solubility, which seriously threatens the ecological environment system and human health. While the fine characterization of DNAPLs migration process in porous media is crucial for remediating the contaminated sites. In order to finely characterize the migration process of DNAPLs in porous media, trichloroethylene (TCE) was selected as a typical DNAPLs pollutant in this paper. Then, based on the laboratory sand box model, image method and electrical resistivity tomography (ERT) technology were used to monitor the migration process of DNAPLs in saturated heterogeneous and homogeneous porous media, and the migration rules of TCE in different porous media were discussed and verified to achieve fine characterization of pollutant. The results of the sand box experiment indicated that when the particle size of heterogeneous quartz sand was small, TCE mainly migrated horizontally, and with the increase of quartz sand particle size, the vertical migration gradually dominated. For the homogeneous quartz sand media, TCE was also mainly horizontally migrated, supplemented by vertical migration. With the increase of pollutant injection time, TCE was mainly vertically migrated. When approaching the bottom of the sand box, the vertical migration speed of TCE in both heterogeneous and homogeneous quartz sand media slowed down, and the DNAPLs contamination pool could be formed at the bottom of the sand box. Generally, this paper uses the image method to visually reflect the migration of DNAPLs, and indirectly characterizes the distribution characteristics of DNAPLs by ERT technology, which is of great significance for studying the migration rule of DNAPLs and determining the pollution scope and degree, and can provide certain guiding value for fine characterization and low-cost remediation of DNAPLs pollutants in actual contaminated sites.
研究领域:
环境科学
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水文地质学
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污染物迁移
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地球物理学
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环境修复
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DOI
高影响因子
Journal of Environmental Chemical Engineering
·
2026
·Vol. 14
·期 5
·123755
·
IF 7.5
Huiyi Ye,Zhancheng Fan,Wei Ding,Yu Chang,Dayi Deng
Coal tar dense non-aqueous phase liquids (DNAPLs), widespread legacy contaminants at former industrial sites, pose significant environmental challenges due to high viscosity and persistent polycyclic aromatic hydrocarbons (PAHs) content. Conventional cosolvent flushing is hampered by solvent volatility, flammability, and recycling difficulties. We therefore developed a closed-loop system integrating ionic liquid (IL) flushing, electrical resistance heating (ERH), and activated carbon (AC) regeneration. Batch tests showed that 60% v/v 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIM][BF 4 ]) mobilized coal tar and solubilized > 60% of total PAH (ΣPAH) within 12 h at ambient temperature. Density functional theory calculations confirmed strong π–π stacking between [BMIM]⁺ and PAHs (e.g., interaction energy (ΔE) = –45.1 kJ/mol for phenanthrene). AC rapidly adsorbed PAHs from [BMIM][BF 4 ] solution with even greater affinity (ΔE = –59.1 kJ/mol for phenanthrene), enabling efficient IL regeneration. Column studies demonstrated enhanced ΣPAH removal at elevated temperature (93.6% at 60 °C vs. 76.8% at 20 °C within 2 h); this is particularly critical for the removal of high-molecular-weight PAHs (HMW PAH), attributed to a reduction in coal tar viscosity that promotes mobilization and intra-tar diffusion. A 2D sand tank experiment demonstrated 93.2% ΣPAH removal at 80 °C within 5 h under continuous AC regeneration and ERH-enhanced circular IL flushing. This innovative IL-ERH-AC system offers a safe, sustainable, and efficient solution for recalcitrant coal tar DNAPL remediation.
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高影响因子
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