Key Laboratory of Groundwater Resources and Environment (Ministry of Education), Jilin University, Changchun 130021, PR China.
Environ Sci Process Impacts. 2020 Sep 23;22(9):1908-1915. doi: 10.1039/d0em00248h.
Dense non-aqueous phase liquids (DNAPLs) entrapped and pooled in aquifers serve as a long term source of groundwater contamination because of their low solubility and high density. Density modification displacement (DMD) with colloidal biliquid aphrons (CBLAs) is a promising approach to prevent DNAPL downward migration during surfactant-based remediation processes. CBLA demulsification and quick release of internal light organic matter is the key to density modification of DNAPLs. In this work, it is reported for the first time that polyaluminum chloride (PAC) could destabilize CBLAs efficiently. The optimum conditions for demulsification of CBLAs by PAC were obtained; the effects of several specific ions in groundwater on demulsification of CBLAs by PAC were investigated. The results indicated that the CBLA was completely demulsified by PAC within 10 minutes and released light organic matter. It recorded the highest demulsification efficiency when the addition ratio (VPAC/VCBLA) was 2 : 1, concentration of PAC was 0.7 g L-1 and the PVR of CBLAs was 8. Most cations (sodium, magnesium and calcium ions) had inhibitory effects on demulsification of CBLAs by PAC with increasing ion concentration, but iron ions had no effect on it. Sulfate anions showed a stronger inhibitory effect on demulsification of CBLAs by PAC compared to chloride ions. With PAC as the demulsifier, CBLAs could be demulsified efficiently, irreversibly modifying the density of trichloroethylene in 5 minutes.
entrapped 和 pooled 是被捕获和聚集的意思。
DNAPLs 被捕获和聚集在含水层中，成为地下水污染的长期来源，因为它们的低溶解度和高密度。用胶态双液相乳剂（CBLAs）进行密度改性置换（DMD）是防止表面活性剂修复过程中 DNAPL 向下迁移的一种很有前途的方法。CBLA 的破乳和内部轻有机物的快速释放是 DNAPL 密度改性的关键。在这项工作中，首次报道聚氯化铝（PAC）可以有效地使 CBLAs 失稳。获得了 PAC 破乳 CBLAs 的最佳条件；研究了地下水中几种特定离子对 PAC 破乳 CBLAs 的影响。结果表明，PAC 在 10 分钟内完全破乳 CBLAs 并释放出轻有机物。当 PAC 添加比（VPAC/VCBLA）为 2:1、PAC 浓度为 0.7 g/L 和 CBLAs 的 PVR 为 8 时，破乳效率最高。大多数阳离子（钠离子、镁离子和钙离子）随着离子浓度的增加对 PAC 破乳 CBLAs 的效果有抑制作用，但铁离子没有影响。与氯离子相比，硫酸根阴离子对 PAC 破乳 CBLAs 的抑制作用更强。用 PAC 作为破乳剂，CBLAs 可以在 5 分钟内有效地破乳，不可逆地改变三氯乙烯的密度。
