Yang Zijiang, Ma Yuheng, Jing Qi, Ren Zhongyu
Faculty of Architecture, Civil and Transportation Engineering, Beijing University of Technology, Beijing 100124, China.
Jianghe Water Resources & Hydropower Consulting Center Co., Ltd., Beijing 100120, China.
Polymers (Basel). 2024 Nov 24;16(23):3271. doi: 10.3390/polym16233271.
The study of the co-transport of Cr(VI) and microplastics (MPs) in porous media is important for predicting migration behavior and for achieving pollution removal in natural soils and groundwater. In this work, the effect of MPs on Cr(VI) migration in saturated porous media was investigated at different ionic strengths (ISs) and pHs. The results showed that pH 7 and low IS (5 mM), respectively, promoted the movement of Cr(VI), which was further promoted by the presence of MPs. The Derjaguin-Landau-Verwey-Overbeek (DLVO) results showed that the repulsive energy barrier between MPs and quartz sand decreased with increasing IS and decreasing pH, respectively, which promoted the retention of MPs in quartz sand and constrained the competition of Cr(VI) for adsorption sites on the surface of the quartz sand, thus facilitating the enhanced migration of Cr(VI), while Cr(VI) behaved conversely. Sodium alginate/nano zero-valent iron-reduced graphene oxide (SA/NZVI-rGO) gel beads could achieve the removal of MPs through a π-π interaction, hydrogen bonding, and electrostatic attraction, but the MPs removal would be reduced by 40% due to the competitive adsorption of Cr(VI). Notably, 97% Cr(VI) removal could still be achieved by the gel beads in the presence of MPs. Therefore, the gel beads can be used as a permeation reaction barrier to inhibit the MP-induced high migration of Cr(VI). The Cr(VI) breakthrough curves in reactive migration were well-fitted with the two-site chemical nonequilibrium model. Overall, the findings of this work contribute to the understanding of the migration behavior of Cr(VI) and MPs in saturated porous media and provide a theoretical basis for the remediation of soils and groundwater contaminated with Cr(VI) and MPs.
研究铬（VI）与微塑料（MPs）在多孔介质中的共迁移对于预测其迁移行为以及实现天然土壤和地下水中的污染去除具有重要意义。在这项工作中，研究了在不同离子强度（ISs）和pH值下微塑料对饱和多孔介质中铬（VI）迁移的影响。结果表明，pH为7和低离子强度（5 mM）分别促进了铬（VI）的迁移，而微塑料的存在进一步促进了这种迁移。德亚金-朗道-韦弗-奥弗比克（DLVO）结果表明，微塑料与石英砂之间的排斥能垒分别随着离子强度的增加和pH值的降低而减小，这促进了微塑料在石英砂中的保留，并限制了铬（VI）对石英砂表面吸附位点的竞争，从而促进了铬（VI）的增强迁移，而铬（VI）的行为则相反。海藻酸钠/纳米零价铁还原氧化石墨烯（SA/NZVI-rGO）凝胶珠可以通过π-π相互作用、氢键和静电吸引实现微塑料的去除，但由于铬（VI）的竞争吸附，微塑料的去除率会降低40%。值得注意的是，在存在微塑料的情况下，凝胶珠仍能实现97%的铬（VI）去除率。因此，凝胶珠可以用作渗透反应屏障，以抑制微塑料引起的铬（VI）高迁移。反应迁移中的铬（VI）突破曲线与双位点化学非平衡模型拟合良好。总体而言，这项工作的研究结果有助于理解铬（VI）和微塑料在饱和多孔介质中的迁移行为，并为修复受铬（VI）和微塑料污染的土壤和地下水提供理论依据。
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